In vitro and in vivo antihyperglycemic effects of five selected indigenous plants from Jordan used...

This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution

and sharing with colleagues.

Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party

websites are prohibited.

In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information

regarding Elsevier’s archiving and manuscript policies areencouraged to visit:

http://www.elsevier.com/copyright

http://www.elsevier.com/copyright

Author's personal copy

Journal of Ethnopharmacology 133 (2011) 888–896

Contents lists available at ScienceDirect

Journal of Ethnopharmacology

journa l homepage: www.e lsev ier .com/ locate / je thpharm

In vitro and in vivo acute antihyperglycemic effects of five selected indigenousplants from Jordan used in traditional medicine

Violet Kasabria, Fatma U. Afifib,∗, Imad Hamdanb

a Department of Biopharmaceutics and Clinical Pharmacy, Jordanb Department of Pharmaceutical Sciences, Jordan

a r t i c l e i n f o

Article history:Received 27 May 2010Received in revised form 25 October 2010Accepted 10 November 2010Available online 18 November 2010

Keywords:Medicinal plantsDiabetesAcarboseEnzymatic starch digestionOGTTOSTT

a b s t r a c t

Ethnopharmacological relevance: Achillea santolina L., Pistacia atlantica Desf, Rheum ribes L., Sarcopoteriumspinosum (L.) Spach and Teucrium polium L. have traditionally been used as herbal antidiabetic medicines.However their alleged benefits and mechanisms remain elusive.Aim of the study: This study aimed to evaluate the effect of water extracts of these plants in in vitro andin vivo experiments.Materials and methods: In vitro enzymatic starch digestion with aqueous extracts from plants at concen-trations of 1, 5, 10, 12.5, 25, 50 and 100 mg/ml was assayed using �-amylase and �-amyloglucosidase.Acarbose was used as control and glucose liberation was determined by glucose oxidase method. Oralstarch tolerance test (OSTT) and oral glucose tolerance test (OGTT) were determined for the plant extractsat concentrations 125, 250 and 500 mg/kg b.wt. on Sprague–Dawley rats. Blood glucose levels in ratstreated with plant extracts and drugs (acarbose or metformin and glipizide) were measured at −30, 0,45, 90 and 135 min.Results: Compared to acarbose (IC50 = 1.2 �g/ml), water extracts of Pistacia atlantica, Rheum ribes and Sar-copoterium spinosum exerted significant dose dependent dual inhibition of �-amylase and �-glucosidasein in vitro enzymatic starch digestion bioassay, with IC50s; 46.98, 58.9 and 49.9 mg/ml, respectively.Comparable in vivo results were obtained for starch-fed rats, exhibiting significant acute postprandialantihyperglycemic efficacies. While Achillea santolina and Teucrium polium extracts lacked any favourablein vitro anti-�-amylase and anti-�-glucosidase effect, other modes of action can possibly explain theirsubstantial acute antihyperglycemic activities in starch-treated rats. Except for Pistacia atlantica extracts,none of the investigated extracts qualified for improving the glucose intolerance in fasted rats on glucoseloading.Conclusions: Pistacia atlantica, Rheum ribes and Sarcopoterium spinosum can be considered as potentialcandidates for amelioration/management of type 2 diabetes.

© 2010 Elsevier Ireland Ltd. All rights reserved.

1. Introduction

As in many countries of the world, traditional medicine, in par-ticular the herbal medicine is part of the Jordanian culture. The richflora of Jordan with great variety of medicinal plants contributes tothis practice. In Jordan, the occurrence of about 2500 plant speciesis recorded. Approximately a fifth of them, with other words about500 species, belonging to 100 families and are classified as medici-nal plants. Medicinal plants are not only used for the managementof mild diseases such as common cold, headache or gastrointesti-nal ailments but also in the long term treatment of chronic and/orincurable diseases, such as diabetes, hypertension or cancer.

∗ Corresponding author at: Faculty of Pharmacy, University of Jordan, Queen RaniaStreet, 11942 Amman, Jordan. Tel.: +962 6 5355000; fax: +962 6 5300250.

E-mail address: [email protected] (F.U. Afifi).

Diabetes mellitus (DM) is the most common metabolic disor-der worldwide and is a major risk for cardiovascular diseases. It isone of the leading causes of morbidity and mortality in Jordan. Theprevalence of type 2 diabetes and impaired fasting glycemia is highin Jordan and is increasing (Ajlouni et al., 2008; Zindah et al., 2008).Based on WHO reports the occurrence of type 2 diabetes affectsworldwide more than 170 million persons. It is estimated that thetotal number of people having diabetes will reach 366 millions bythe year 2030 (Wild et al., 2004; Shaw et al., 2010).

Although the practice of traditional medicine in Jordan isbased on hundreds of years of belief and observation scientificknowledge for the majority of the plants used is very limitedor even lacking. To contribute to the existing pool of data fivenative plants with claimed antidiabetic activity were selected andin in vivo and in vitro experiments for their antihyperglycemicactivity evaluated. The selected plants are Achillea santolina L.(Compositae), Pistacia atlantica Desf. (Pistaciaceae), Rheum ribes L.

0378-8741/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved.doi:10.1016/j.jep.2010.11.025


V. Kasabri et al. / Journal of Ethnopharmacology 133 (2011) 888–896 889

(Polygonaceae), Sarcopoterium spinosum (L.) Spach (Rosaceae) andTeucrium pollium L. (Labiatae/Lamiacae). These plants can be easilycollected by the users but also purchased by the herbalists’ shopsthroughout the country (Abu-Irmaileh and Afifi, 2000). Severalethnopharmacological surveys based on the information from theherbalists and inhabitants classify the selected plants as antidi-abetic plants preferably used in form of infusions (Abu-Irmailehand Afifi, 2000; Aburjai et al., 2007; Hudaib et al., 2008; Al-Qura’n,2009). New approaches to the prevention/modulation of post-prandial hyperglycaemia may emerge from the therapeutic use of�-amylase and �-glucosidase inhibitors. Hence, the present studyevaluates the acute (up to 165 min carbohydrate tolerance testingin normal animal models) postprandial antihyperglycemic activityof the selected five plants with claimed antidiabetic activity inin vitro and in vivo experiments exploring the enzymatic starchdigestion as a possible mode of antidiabetic action.

2. Materials and methods

2.1. Chemicals, kits and reagents

�-Amylase, from hog pancreas, �-amyloglucosidase and acar-bose were purchased from Sigma–Aldrich, Switzerland and d (+)glucose monohydrate (Ph.Eu) Riedel-deHaen, Seize, Germany. Glu-cose GOD-PAP kit was obtained from BioLabo Reagents, Franceand Accu-Chek® Active Glucose meter for blood glucose deter-minations from Roche Diagnostics GmbH, Mannheim, Germany.For filtration of the water extracts no. 5 filter paper (What-man, USA) was used. Metformin was purchased from MerckSante’, Semoy, France (Glucophage® 850 mg) while glipizide waskindly donated by Hikma Pharmaceutical, Jordan. Corn starch wasobtained from Uni-Chem, North Carolina, USA. In UV determina-tions UV–vis spectrophotometer from SpectroScan 80D, UK wasused.

2.2. Plant material

Fresh aerial parts of Achillea santolina [9 COMP-FMJ], Sarcopo-terium spinosum [9 ROSA-FMJ], and Teucrium pollium [12 LABI-FMJ],as well as Pistacia atlantica [2 ANAC-FMJ] leaves were collectedfrom the Greater Amman area and from Zai, 50 km north ofAmman in spring 2009. Dried subterranean parts (roots/rhizomes)of Rheum ribes [2 POLY-FMJ], were purchased from herbalist shopsin Amman. All plants were taxonomically identified by Prof. BarakatAbu Irmaileh, Faculty of Agriculture-University of Jordan. Voucherspecimens were deposited in the Department of PharmaceuticalSciences, Faculty of Pharmacy-University of Jordan. Fresh plantsamples were cut into small pieces and air dried at room tempera-ture.

2.3. Preparation of plant aqueous extracts (AE)

The extracts were prepared by refluxing each 10 g of the driedcoarsely powdered plant material with 100 ml tap water for 15 minand keeping the extract overnight. After filtering twice throughfilter paper, the volume of the filtered solution was increasedto 100 ml with tap water to obtain 10% aqueous stock solution(Hamdan and Afifi, 2004).

2.4. In vitro enzymatic starch digestion assay

In vitro enzymatic starch digestion was assayed according toGranfeldt et al. (1992) with some modifications. In brief, 100 mgcorn starch was suspended and gelatinized in 3 ml distilled waterwith or without plant aqueous extract or acarbose. To this starchsolution 4 �g �-amylase was added, vortexed and the mixture

was incubated for 20 min at 80 ◦C (first incubation). Then, the3 ml mixture was diluted to a total volume of 10 ml with distilledwater, and from this, 1 ml was removed and added to 2 ml of 0.1 Msodium acetate buffer (pH 4.75). To this 3 ml mixture, 30 �g of�-amyloglucosidase was added and the mixture was incubatedfor 30 min at 60 ◦C (second incubation). Samples were removedto ice to inhibit the thermophilic enzymes. Later, samples wereevaluated for glucose liberation by glucose oxidase method (Tietz,1999), using double beam UV–vis spectrophotometer. The extentof polysaccharide breakdown into glucose was evaluated in a con-centration range of plant aqueous extract 1, 5, 10, 12.5, 25, 50 and100 mg/ml. The effects of acarbose at 0, 0.32, 1.6, 8, 40, 200 and1000 �g/ml concentrations were evaluated as well. Control sam-ples contained neither acarbose nor plant extracts.

2.5. In vivo confirmatory studies

2.5.1. Experimental animalsThe study was conducted in the Experimental Animal Labora-

tory of the Faculty of Medicine, University of Jordan. All animalswere housed, fed and treated in accordance with the in-house eth-ical guidelines for animal protection. All animals were kept for oneweek to be acclimatized prior to the investigations under the stan-dard environmental conditions. Throughout the experimentationperiod, female normal Sprague–Dawley rats weighing 200–250 gwere maintained in single cages and had access to standard pel-let diet and water ad libitum. Animals were deprived of food andwater 14 h before in vivo blood glucose determination. Blood glu-cose levels from cut tail tips were determined using Accu-Chek®Active Glucose meter.

2.5.2. Oral starch tolerance test (OSTT)Rats were divided into 5 groups per a test plant (n = 5–8 rats

per group). At −30 min, fasting blood glucose levels were deter-mined and instantly acarbose or treatment plant doses 125, 250and 500 mg/kg b.wt. were administered orally via 2 ml-intra-gastricintubations to corresponding group animals under mild anaesthe-sia. Control untreated animals were given tap water. At 0 min,all rats of 5 different treatment groups were given corn starch3 g/kg b.wt. following the fasting blood glucose determination.Later evaluations of glycemia took place at 45, 90 and 135 min from0 min (Matsuo and Izumori, 2009).

2.5.3. Oral glucose tolerance test (OGTT)Rats were divided into 6 groups per a test plant (n = 5–8 rats

per group). The OGTT was carried out as the above design for OSTTexcept for glucose (3 g/kg b.wt.) (d (+) glucose monohydrate (Ph.Eu)utilization instead of starch and metformin 300 mg/kg b.wt. andglipizide 600 �g/kg b.wt. instead of acarbose (Abesundara et al.,2004; Shokeen et al., 2008; Matsuo and Izumori, 2009).

2.6. Statistical analysis

The values are presented as mean ± S.E.M. A.U.C (incremen-tal Area Under glucose Curve) was determined using GraphpadPrism (version 3.02 for windows; GraphPad Software, San Diego,CA, USA). Statistical differences in plasma glucose levels or in vitroassays glucose samples and AUCs between control and differenttreatment groups were determined using Graphpad Prism oneway analysis of variance (ANOVA) followed by Newman–Keuls testwhenever appropriate. Values were considered significantly differ-ent if p < 0.05.


890 V. Kasabri et al. / Journal of Ethnopharmacology 133 (2011) 888–896

0

1

2

3

4

5

6

7

8

9

10

10002004081.6 0.32 Control (0.0) Acarbose (mg/ml)

Glu

cose

Lib

erta

ed (

mM

)

***

****** ***

***

***

Fig. 1. Effects of acarbose gradient on enzymatic starch digestion in vitro. Resultsare mean ± SEM for n = 3 replicates. ***p < 0.001 compared to control incubations.

3. Results

3.1. In vitro enzymatic starch digestion

Using acarbose gradient as positive control, glucose libera-tion from starch was inhibited highly substantially (p < 0.001)dose dependently (Fig. 1). As shown in Table 1 the lowest effec-tive acarbose concentration was 0.32 �g/ml, compared to controlincubations. An almost complete inhibition (p < 0.001) of enzy-matic starch digestion was obtained by 200 and 1000 �g/mldosages. These findings suggest that the present quantificationmethod is highly reliable with excellent accuracy and sensitiv-ity.

Among the tested five plants Achillea santolina AE and Teu-crium polium AE did not inhibit the release of glucose fromstarch in concentrations 1–50 mg/ml (Fig. 2A and E). Corn starchincubations with the AEs (25–100 mg/ml) of Pistacia atlantica,had the highly substantial dose dependent (p < 0.001) inhibitionsof aldohexose liberation (Fig. 2B). Pistacia atlantica AE exhib-ited at the concentration 100 mg/ml nearly complete inhibitionactivity (Table 1) which is comparable to the therapeutic effi-cacy of antidiabetic drug acarbose, considering the 1000 foldtitration range (plant crude extract in mg/ml versus acarbosein �g/ml). Pistacia atlantica AE 12.5 mg/ml was inactive, whileextract doses 1, 5 and 10 mg/ml potentiated, surprisingly, the�-amylase and �-amyloglucosidase catalytic efficiencies, furtherenhancing markedly (p < 0.05) the starch enzymatic breakdown(Fig. 2B).

Rheum ribes AEs (10–100 mg/ml) demonstrated highly signif-icant (p < 0.05–0.001) concentration dependent inhibitory effectson corn starch enzymatic digestion (Fig. 2C, Table 1).

Fig. 2D demonstrates the marked dose dependent reduc-tions (p < 0.05–0.001) in enzymatic starch hydrolysis exerted by(5–100 mg/ml) AEs of Sarcopoterium spinosum. It is evident, moreimportantly, that 10% AE of Sarcopoterium spinosum abolishedalmost 75% of polysaccharide breakdown (Table 1).

3.2. Confirmatory in vivo studies

3.2.1. OSTTAt −30 min, administration of acarbose 3 mg/kg b.wt. man-

aged to reduce highly significantly (p < 0.001) the starch inducedhyperglycemia at 45, 90 and 135 min post corn starch load at0 min, thus evoking highly substantial reduction (p < 0.001) of theoverall glycemic excursion compared to control rats (Fig. 3A–E).Performing as effectively as acarbose, 125 mg/kg b.wt. AE of Achil-lea santolina enhanced markedly (p < 0.05) glucose tolerance AUC(Fig. 3A). The same figure mirrors the highly significantly (p < 0.001)reduced increments in rats’ acute hyperglycemia evoked by Achil-lea santolina 125 mg/kg b.wt. dose 135 min following the cornstarch oral intake, compared to control untreated animals. Achil-lea santolina 500 mg/kg b.wt. decreased (p < 0.05) starch evokedhyperglycemia in fasted animals over the same time course(Fig. 3A).

Compared to control normal rats, administration of Pistaciaatlantica AEs 30 min pre-starch load did not effect any decreasein overall glycemic excursions, neither did they reduce the starchinduced hyperglycemia at any determination time point exceptfor Pistacia atlantica 500 mg/kg b.wt. after165 min (p < 0.05) fromingestion (Fig. 3B). While none of the Rheum ribes AEs effectsmarked decreases in overall glycemic excursions (Fig. 3C) com-pared to control animals, still, Rheum ribes 125 mg/kg b.wt. AEevoked acute antihyperglycemic activities on corn starch loadedrats at 45 min (p < 0.001) and 135 min (p < 0.001) (Fig. 3C). Sucheffects were comparable to acarbose (p < 0.05, Table 2).

Sarcopoterium spinosum 125 mg/kg b.wt. treatment group hadthe highly significant decrease (p < 0.001) in overall glycemicexcursion (Fig. 3D). Substantial improvements of glucose handlingwere evident at 45 min (p < 0.001), 90 min (p < 0.05) and 135 min(p < 0.001) in the same treatment group (Fig. 3D). More importantly,Table 2 illustrates the overlapping and comparable antihyper-glycemic effects of Sarcopoterium spinosum 125 mg/kg b.wt. andacarbose 3 mg/kg b.wt. on effective sugar tolerance.

Teucrium polium AEs did not evoke any substantial reductionin the overall glycemic excursion in the treated animals (Fig. 3E).However, each of Teucrium polium supplemented group had signifi-cant decrease (p < 0.05) in cornstarch induced acute hyperglycemia45 min post starch intragastric administration (Fig. 3E).

3.2.2. OGTTCompared to control normal rats, 30 min pre-glucose load

treatments with metformin 300 mg/kg b.wt. and glipizide0.6 mg/kg b.wt. reduced highly significantly (p < 0.001) the overallglycemic excursions in OGTTs (Fig. 4A–E). It is evident in thesame figures the highly substantial (p < 0.001) antihyperglycemicefficacies of both oral antidiabetic therapeutics 45, 90 and 135 minfollowing sugar load. Table 3 illustrates the improved glucosetolerance in the minimized increments of blood sugar levels incomparison to control postprandial hyperglycemia at 45 min(metformin; p < 0.01) and 90 min (metformin; p < 0.001; glipizide;p < 0.01)

Table 1Effects of plants aqueous extracts (AE) concentrations (mg/ml) on %reduction of enzymatic starch digestion in vitro.

0 0.32 1.6 8 40 200 1000

Acarbose (�g/ml) 0.00 ± 0.23 26.2 ± 1.29*** 53.1 ± 1.45*** 81.1 ± 0.32*** 89.9 ± 0.4*** 96.1 ± 0.15*** 97.1 ± 0.63***Plant AE (mg/ml) 1 5 10 12.5 25 50 100P. atlantica −17.3 ± 3.9*** −18.1 ± 0.9*** −15.5 ± 0.5*** 4.0 ± 1.0 24.7 ± 3.6*** 56.2 ± 1.1*** 95.4 ± 0.4***R. ribes −12.2 ± 3.8* 4.4 ± 2.5 18.0 ± 2.6*** 25.9 ± 4.8*** 41.0 ± 2.3*** 44.2 ± 1.0*** 68.2 ± 1.7***S. spinosum 19.5 ± 7.0*** 28.4 ± 4.2*** 25.5 ± 3.6*** 37.3 ± 4.2*** 44.7 ± 1.4*** 50.0 ± 2.3*** 74.4 ± 0.7***

Results expressed as % decrease in control values are mean ± SEM (n = 3 replicates). *p < 0.05 and ***p < 0.001 compared to control (drug-free or plant-free) determinations.



0

1

2

3

4

5

6

7

8

9

10 A B

AcarboseControl (1mg/ml)

1051 25 12.5 50

Achillea santolina extract (mg/ml)

Glu

cose

Lib

erat

ed (

mM

)

***

0

1

2

3

4

5

6

7

8

9

10

Acarbose Control (1mg/ml)

10050 25 12.510 51

Glu

cose

Lib

erat

ed (

mM

)

* * *

***

***

*** ***

Pistacia atlantica extract (mg/ml)

0

1

2

3

4

5

6

7

8

9

10


1051 12.5 10050 25

Rheum ribes extract (mg/ml)

Glu

cose

Lib

erat

ed (

mM

)

***

*** ***

****

***

0

1

2

3

4

5

6

7

8

9

10

Control Acarbose (1mg/ml)

10050 2512.51051

Sarcopoterium spinosum extract (mg/ml)

Glu

cose

Lib

erat

ed (

mM

) ******

***

**

***

***

0

1

2

3

4

5

6

7

8

9

10


51 10 12.5 5025 Teucrium polium extract (mg/ml)

Glu

cose

Lib

erat

ed (

mM

)

***

C

D

E

Fig. 2. Effects of plants extracts on enzymatic starch digestion in vitro. (A) Achillea santolina. (B) Pistacia atlantica. (C) Rheum ribes. (D) Sarcopoterium spinosum. (E) Teucriumpolium. Results are mean ± SEM for n = 3 replicates. *p < 0.05 and ***p < 0.001 compared to control incubations.

None of Achillea santolina or Pistacia atlantica AEs evoked anyacute antihyperglycemic activity in supplemented rats (Fig. 4Aand B, respectively). Interestingly, however, Pistacia atlantica125 mg/kg b.wt. AE induced reductions in glycemic incrementsversus control determinations (Table 3) at 45 (p < 0.05) and 90 min

(p < 0.01) comparable to metformin and glipizide therapeutic effi-cacies.

In parallel terms, oral administration of Rheum ribes or Sar-copoterium spinosum AEs had no marked improvement of glucosetolerance AUCs (Fig. 4C and D, respectively). Furthermore, the

Table 2The effects of plants aqueous extract (AE) concentrations in mg/kg b.wt. on %change in oral starch tolerance test glycemia from basal fasting levels at −30 min, over 165 minperiod in normal rats.

Treatment/determination time point 0 min 45 min 90 min 135 min

Starch 3 g/kg b.wt. 19.2 ± 5.5 73.8 ± 9.7 72.2 ± 13.5 84.2 ± 5.2Acarbose 3 mg/Kg b.wt 28.8 ± 7.1 40.6 ± 6.6 45.8 ± 9.8 44.7 ± 12.6*

Pistacia atlantica AE 125 mg/kg b.wt. 21.2 ± 5.8 42.9 ± 10.9 46.6 ± 3.1 82.4 ± 11.7Rheum ribes AE 125 mg/kg b.wt. 35.8 ± 9.3 36.7 ± 14.2 50 ± 18.8 45.4 ± 11.9*

Sarcopoterium spinosum AE 125 mg/kg b.wt. 17.7 ± 6.5 40.1 ± 10.6 47.7 ± 7.6 43.8 ± 12.1*

Values are mean ± SEM for 5–8 rats per treatment group.* p < 0.05 compared to control untreated animals at the respective time point.



0

1

2

3

4

5

6

7

8

9

10

A B

C D

-30 0 45 90 135Time (min)

Gly

cem

ia (

mM

)

Starch 3 g/Kg b.wt A. santolina AE 125 mg/Kg b.wt A. santolina AE 250 mg/Kg b.wt A. santolina AE 500 mg/Kg b.wt

Acarbose 3 mg/Kg b.wt

****

A.santolina or acarbose

Starch

*** ***

***

0

200

400

600

80010001200

Starch 3 g/Kg b.wt


****

AU

C (m

M.m

in)

A santolina AE 500 mg/Kg b wtA. santolina AE 250 mg/Kg b.wt A. santolina AE 125 mg/Kg b.wt

0

1

2

3

4

5

6

7

8

9

10

-30 0 45 90 135Time (min)

Gly

cem

ia (

mM

)

Starch 3 g/Kg b.wt P. atlantica AE 125 mg/Kg b.wt

P. atlantica AE 250 mg/Kg b.wt P. atlantica AE 500 mg/Kg b.wt


*P.atlantica or acarbose

Starch

****** ***

0

200

400

600

800

100

1200 Starch 3 g/Kg b.wt P.atlantica AE 125 mg/Kg b.wtP.atlantica AE 250 mg/Kg b.wtP.atlantica AE 500 mg/Kg b.wtAcarbose 3 mg/Kg b.wt

AU

C (

mM

.min

)

***

0

1

2

3

4

5

6

7

8

9

10

-30 0 45 90 135

Gly

cem

ia (

mM

)

Starch 3 g/Kg b.wt S.spinosum AE 125 mg/Kg b.wt

S.spinosum AE 250 mg/Kg b.wt S.spinosum AE 500 mg/Kg b.wt


Starch

S.spinosum or acarbose

***

*

***

******

******

******

*

0200 400 600 800

1000 1200 Starch 3 g/Kg b.wt

S.spinosum AE 125 mg/Kg b.wtS.spinosum AE 250 mg/Kg b.wtS.spinosum AE 500 mg/Kg b.wtAcarbose 3 mg/Kg b.wt

*** ***

AU

C (

mM

.min

)

Time (min)

-30 0 45 90 135

Time (min)

0

1

2

3

4

5

6

7

8

9

10

-30 0 45 90 135

Time (min)

Gly

cem

ia (

mM

)

Starch 3 g/Kg b.wt T. polium AE 125 mg/Kg b.wt

T. polium AE 250 mg/Kg b.wt T. polium AE 500 mg/Kg b.wt


T.polium oracarbose

Starch

***

******

0

200

400

600

800

1000

1200Starch 3 g/Kg b.wt T. polium AE 125 mg/Kg b.wtT. polium AE 250 mg/Kg b.wtT. polium AE 500 mg/Kg b.wtAcarbose 3 mg/Kg b.wt

***

AU

C(m

M.m

in)

* *

**

E

0

1

2

3

4

5

6

7

8

9

10

Gly

cem

ia (

mM

)

Glucose 3 g/Kg b.wt Metformin 300 mg/Kg R. ribes AE 125 mg/Kg b.wt

R. ribes AE 250 mg/Kg R. ribes AE 500 mg/Kg Glipizide 0.6 mg/Kg b.wt

*** ***

***

R.ribes or drugs

Glucose

***

*** ***

*

Glucose 3 g/Kg b.wt

AU

C(m

M.m

in)

*** ***

R. ribes AE 500 mg/Kg b.wt

R. ribes AE 125 mg/Kg b.wt R. ribes AE 250 mg/Kg b.wt

2000

400

600 800

1 000 1 200

Metformin 300 mg/Kg b.wt

Glipizide 0.6 mg/Kg b.wt

Fig. 3. Effects of plants extracts on oral starch tolerance. (A) Achillea santolina. (B) Pistacia atlantica. (C) Rheum ribes. (D) Sarcopoterium spinosum. (E) Teucrium polium. Resultsare mean ± SEM for n = 5–8 rats per treatment group. *p < 0.05, **p < 0.01 and ***p < 0.001 compared to control untreated rats.



0

1

2

3

4

5

6

7

8

9

10

A B

C D

-30 450 90 135

Time(min)

Gly

cem

ia (

mM

)

Glucose 3g/kg b.wt Metformin 300 mg/Kg b.wtA. santolina AE 125 mg/Kg b.wt A. santolina AE 250 mg/Kg b.wtA. santolina AE 500 mg/Kg b.wt Glipizide 0.6 mg/Kg b.wt

***

******

* *

*

******

***

0200400600800

10001200 Glucose 3 g/Kg b.wt

Metformin 300 mg/Kg b.wt* *


***

AU

C (

mM

.min

)

***

A.santolinaor drugs

Glucose

A. santolina AE 125 mg/Kg b.wtA. santolina AE 250 mg/Kg b.wtA. santolina AE 500 mg/Kg b.wt

0

1

2

3

4

5

6

7

8

9

10

-30 450 90 135

Gly

cem

ia (

mM

)

Glucose 3 g/Kg b.wt Metformin 300m g/Kg b.wt

P. atlantica AE 125mg/Kg b.wt P.a tlantica AE 250m g/Kg b.wt

P. atlantica AE 500 mg/Kg b.wt Glipizide 0.6 mg/Kg b.wt

*********

*********

*

P.atlanticaor drugs

Glucose

0200400600800

10001200 Control 3 g/Kg b.wt



AU

C (

mM

.min

)

*** ***

Time (min)

P atlantica AE 125m g/KgbwtP. atlantica AE 250 mg/Kg b.wtP. atlantica AE 500 mg/Kg b.wt

0

1

2

3

4

5

6

7

8

9

10

-30 0 45 90 135

Time (min)

Gly

cem

ia (

mM

)

Glucose 3 g/Kg b.wt Metformin3 00 mg/Kg R. ribes AE 125 mg/Kg b.wt

R. ribes AE 250 mg/Kg R. ribes AE 500 mg/Kg Glipizide 0.6 mg/Kg b.wt

*** ***

***

R.ribesS.spinosum AE 250 mg/Kg b.wt

Glucose

***

******

*

Glucose 3 g/Kg b.wt

AU

C(m

M.m

in)

*** ***

R. ribes AE 500 mg/Kg b.wt

R. ribes AE 125 mg/Kg b.wtR. ribes AE 250 mg/Kg b.wt

0200400 600800

1000 1200



0

1

2

3

4

5

6

7

8

9

10

-30 450 90 135Time (min)

Gly

cem

ia (

mM

)

Glucose 3 g/Kg b.wt metformin 300m g/Kg b.wt

S.spinosumm AE 125 mg/Kg b.wt S.spinosum AE 250 mg/Kg b.wt

S.spinosum AE 500 mg/Kg b.wt Glipizide 0.6 mg/Kg b.wt

*** ***

****

***

******

Glucose S.spinosum or drugs

AU

C(m

M.m

in)

S.spinosum AE 250 mg/Kg b.wtS.spinosum AE 500 mg/Kg b.wt

S.spinosum AE 125 mg/Kg b.wt

0

200400600800

1000

1200Glucose 3 g/Kg b.wtMetformin 300 mg/Kg b.wt


*** ***

0

1

2

3

4

5

6

7

8

9

10

-30 0 45 90 135

Gly

cem

ia (

mM

)

Glucose 3 g/Kg b.wt Metformin 300 mg/Kg b.wt T. polium AE 125 mg/Kg bwt

T. polium AE 250 mg/Kg T. polium AE 500 mg/Kg Glipizide 0.6 mg/Kg b.wt

*** *** ***

*** *** ***

0200400600800

10001200 Glucose 3 g/Kg b.wt


T.polium AE 500 mg/Kg b.wt ***


***

AU

C (

mM

.min

)

T.poliumor drugs

Glucose

T.polium AE 125 mg/Kg b.wt T.polium AE 250 mg/Kg b.wt

Time (min)

E

Fig. 4. Effects of plants extracts on oral glucose tolerance. (A) Achillea santolina. (B) Pistacia atlantica. (C) Rheum ribes. (D) Sarcopoterium spinosum. (E) Teucrium polium. Resultsare mean ± SEM for n = 5–8 rats per treatment group. *p < 0.05 and ***p < 0.001 compared to control untreated rats.

respective glycemic incremental curves were not affected byRheum ribes or Sarcopoterium spinosum extracts ingestion duringthe 135 min experiments. Similarly, none of Teucrium polium AEsexerted any acute antihyperglycemic activity in glucose-induced-hyperglycemia rats compared to control untreated rats (Fig. 4E),thus lacking any improvement in overall glucose tolerance AUC (thesame figure).

4. Discussion

Elevated fasting and postprandial glycaemia can contribute toexaggerated non enzymatic protein glycation or to toxic effectson the vascular endothelium. Consequently, maintaining bloodglucose homeostasis prevents the detrimental effects of hypergly-caemia (Gin and Rigalleau, 2000). So, given the strong link between



Table 3The effects of plants aqueous extract (AE) concentrations in mg/kg b.wt. on %change in oral glucose tolerance test glycemia from basal fasting levels at −30 min, over 165 minperiod in normal rats.

Treatment/determination time point 0 min 45 min 90 min 135 min

Glucose 3 g/kg b.wt. 32.45 ± 7.73 71.69 ± 8.44 96.16 ± 8.75 74.47 ± 7.07Metformin 300 mg/kg b.wt. 22.99 ± 5.17 28.32 ± 8.4** 37.85 ± 11.1*** 46.03 ± 12.8Glipizide 600 �g/kg b.wt. 36.06 ± 7.25 65.21 ± 6.72 57.1 ± 5.02** 59.18 ± 2.67Pistacia atlantica AE 125 mg/kg b.wt. 14.39 ± 7.84 33.08 ± 10.11* 36.28 ± 15.47** 44.4 ± 14.69

Values are mean ± SEM for 5–8 rats per treatment group. *p < 0.05, **p < 0.01 and ***p < 0.001 compared to control untreated animals at the respective time point.

postprandial hyperglycaemia and diabetes complications, severalherbal extracts were investigated to clarify their effectiveness inexperimental animals and in vitro bioassays.

�-Amylase and �-glucosidase inhibitors are widely used oralagents for improving postprandial hyperglycaemia due to lackof a hypoglycemic threat and more importantly, the prospect ofblood glucose control without hyperinsulinemia and body weightgain (Mooradian and Thurman, 1999). Inhibition of �-glucosidaseand �-amylase results in delayed carbohydrate digestion and glu-cose absorption with attenuation of postprandial hyperglycaemicexcursions. Acarbose, the first dual inhibitor of the two enzymes(�-glucosidase and �-amylase) is in clinical use since 1990s. It low-ers postprandial glucose elevation in diabetics thereby reducingcarbohydrate digestion after meals (Bressler and Johnson, 1992).

In our course of screening, over the dose response curve,acarbose abolished completely the glucose liberation from starchhydrolysis at 1 mg/ml concentration. In this model of in vitro starchdigestion, the obtained IC50 for acarbose (1.2 �g/ml; correspond-ing to 1.8 �M) was strikingly far less than those reported recentlyin literature (Tshikalange et al., 2008; Li et al., 2009; Mou et al.,2009), thus validating the reliable sensitivity of this test tube assay.Remarkably, the potent extracts (namely Pistacia atlantica, Rheumribes and Sarcopoterium spinosum) proved to be dual inhibitors ofthe two enzymes tested, which is a significant finding in light ofthe operatively successive relationship between these intestinaldigestive enzymes.

It has been well-acknowledged that the plant derived extractsand phytochemicals are potential alternatives to syntheticinhibitors of �-amylase and �-glucosidase (Lee and Kim, 2001).It might be expected then that the active principles of theseefficacious plants have a range of pharmacological actions forantidiabetic therapeutics.

In the effective plant AEs treatment groups (Pistacia atlantica,Rheum ribes and Sarcopoterium spinosum), the glucose intolerancewas improved post-starch bolus administration, despite the lackof appreciable postprandial antihyperglycemic effect in glucose-loaded rats. This suggests that such effectiveness was achievedprimarily by restrictive enzymes inhibition, not by hindering glu-cose transportation across the luminal absorptive brush bordervia a Na+/glucose symporter. Taken together, the reduction ofglycaemia peaks by efficacious extracts was probably due to extra-pancreatic retardation of intestinal glucose production, rather thanpancreatic potentiating of insulin secretion. It is noteworthy thatthe hypoglycaemic effect decreased (and even reversed) at higherdoses for some plant extracts e.g. Sarcopoterium spinosum or Pistaciaatlantica. The maximum reduction in postprandial glycemic peakwas observed at 125 mg/kg b.wt. dose of the aqueous extracts. Simi-lar observations have been made with some plant extracts (Adebajoet al., 2007; Shokeen et al., 2008). It has also been reported thathigh concentrations of plant extracts may auto-inhibit its hypogly-caemic action (Prince et al., 1998). These effects could be explainedin terms of the presence of two opposing mechanisms that influ-ence the overall glucose levels with one of the mechanisms beingresponsible for the inhibition of alpha amylase, which has beendemonstrated in vitro. The second (opposing) mechanism might

be inhibition of insulin release from specialized cells. Such a sug-gestion is encouraged by the fact that some plant extracts, oreven isolated constituents, have been previously reported to inhibitinsulin release from cells (Szkudelski, 2007, 2008). Looking intothe phytochemical constituents of such reported extracts revealedtheir high content of phenolic constituents. Some reports have evendemonstrated the ability of purified polyphenols such as epigallo-catechin gallate and resveratrol, a well known phenolic compound,to block the release of insulin in vitro and in vivo (Szkudelski,2007, 2008). Therefore, a link might be established between somephenolic substances and inhibition of insulin release. Phytochem-ical screening of the employed plant extracts in this study provedtheir high contents of phenolic substances (Al Maayeh, 2005).Therefore, the link between phenolic contents and possibility ofblocking insulin release is further supported. Furthermore, thedecreased activity at a higher dose of the extract might be alsodue to reduced or no effect of components present in the extractat higher doses (Rao et al., 2001a,b). An additional hypothesisis the presence of some other substances in the plant extracts,which interfere with the hypoglycemic effect. Murthy et al. (2003)have reported the presence of some hyperglycemic compoundsalong with hypoglycaemic components in three plants, Trigonellafoenum graecum (fenugreek) seeds, Ficus bengalensis (banyan tree)bark and Momordica charantia (bitter gourds). So, higher dosesof the extract might have higher doses of hyperglycaemic com-pounds.

Looking at the results of OGTT, all plant extracts could be saidto be ineffective as hypoglycaemic agents in response to glucoseingestion. The obvious explanation is that the observed hypogly-caemic effect in case of OSTT was essentially brought about throughinhibition of alpha amylase activity. In case of OGTT, there wasno rule for alpha amylase, as glucose itself was directly admin-istered; consequently no significant hypoglycemic effect of theextract was observed. Moreover, some plant extracts e.g. Pistaciaatlantica, Rheum ribes and Sarcopoterium spinosum, exhibited higherglucose levels even higher than those of the control at higher con-centrations in particular. Thus the possibility of inhibition of insulinrelease by the plant extracts became further supported.

The literature illustrates that Achillea santolina had a high hypo-glycemic activity, mainly attributed to its antioxidant potential(Ardestani and Yazdanparast, 2007; Yazdanparast et al., 2007) instreptozotocin (STZ) diabetic rats. In our studies, a favourable acuteantihyperglycemic trend was observed for Achillea santolina bolusin starch-fed rats. However, the lack of an in vitro inhibitory activ-ity does not relate to the notable in vivo efficacy. Nevertheless, theintestinal luminal activation of effective entities is a valid justifica-tion for the acute in vivo outcomes. Moreover, the effects ascribedto Achillea santolina does not necessarily role out any other poten-tial pancreatic or extrapancreatic mode of action.

Antioxidative properties were strongly attributed to Pistaciaatlantica (Benhammou et al., 2008) mainly because of its richnesswith natural phenolic compounds (Yousfi et al., 2009). The sub-stantially significant inhibitory effects of Pistacia atlantica aqueousextracts on enzymatic starch digestion are absolutely in line withand complementary to previously reported �-amylase inhibition in



Hamdan and Afifi (2004). They demonstrated that Pistacia atlanticahad no significant hypoglycemic activity in STZ diabetic rats despitethe significant anti-alpha amylase effects. In light of our study,among the effective extracts, Pistacia atlantica had the inhibitorysuperiority indicating that it could act as “starch blocker” and, thus,an “effective antiobesity agent” (Kotowaroo et al., 2006)

The antioxidant activity of chloroform and methanol extracts ofrhubarb (Rheum ribes), which are used for medicinal purposes andare consumed as vegetable, was demonstrated (Ozturk et al., 2007).In addition Rheum ribes insulin releasing activity was demonstratedin vitro, evoking a significant hypoglycemic effect in fasted healthymice over 24 h periods (Naqishbani et al., 2009). The hypoglycemiceffect in alloxan-diabetic animals is mentioned as well (Ozbek et al.,2004). Our complementary and significant in vitro and in vivoresults for Rheum ribes aqueous extract show a striking similarityto the trends of acarbose. Hence, the Rheum ribes AE evoked retar-dation and delay of carbohydrate digestion and absorption witha plant-based �-amylase and �-glucosidase inhibitory principlesoffer a prospective therapeutic approach for the treatment of type2 diabetes (McCue et al., 2005).

Sarcopoterium spinosum extract, interestingly, increased basaland glucose induced insulin secretion, had insulin mimetic effectswith a preventive effect on the progression of diabetes in KK-Ay

mice despite the low antioxidative capacity and phenolic con-tents of the plant (Al-Mustafa and Al-Thunibat, 2008; Smirin et al.,2010). Hamdan and Afifi (2008) highlighted the favourable effectof Sarcopoterium spinosum on controlling the surge of blood glu-cose level after the ingestion of high sucrose in rats. This potencywas further verified by in vitro �-amylase inhibitory effect with anIC50 of 0.13 mg/ml (Hamdan and Afifi, 2008). Remarkably, Sarcopo-terium spinosum -based dual inhibitory efficacy of �-amylase and�-glucosidase in vitro was confirmed by significant acute antihy-perglycemic trends in starch-fed rats. Collectively, the substantialextrapancreatic activity further complements the pancreatic activ-ities the literature illustrated above of Sarcopoterium spinosum,advocating the plant as a potential nutritious food with diabetespharmacological modulation qualities.

In our in vitro model of enzymatic starch digestion, Teucriumpolium demonstrated no appreciable anti-�-amylase or anti �-glucosidase effectiveness. Nevertheless, the plant extracts exertedmarked acute reductions in glycemic rise following starch bolusadministration in fasting rats. Possible other mechanistic studiesmay offer plausible explanations. In one approach, Teucrium poliumfed-diabetic rats experienced significant reductions in serum glu-cose levels (Esmaeili and Yazdanparast, 2004; Shahraki et al.,2007). One proposed mechanism was that flavonoids in Teucriumpolium extract appeared to be helpful in protecting pancreatic isletsagainst exposure to STZ in vitro due to their remarkable antioxidantactivity (Ardestani et al., 2008; Esmaeili et al., 2009). Neverthe-less, in another report, Teucrium polium was classified among theantidiabetic plants used in Jordan with low antioxidative capac-ity (Al-Mustafa and Al-Thunibat, 2008). Especially important, thecombination of the molybdate with Teucrium polium improved cul-tured islet cells insulin-secretory function significantly (Monfaredand Pournourmohammadi, 2010).

5. Conclusions

In conclusion, our data contribute to the evidence that Pistaciaatlantica, Rheum ribes and Sarcopoterium spinosum can improve glu-cose homeostasis via delaying carbohydrate digestion significantly.However, further chronic investigation is required to validate theiruse prior to clinical implementation as therapeutic agents forimprovements in carbohydrate tolerance. These effective plants arewidely distributed as edible items implying a relative lack of tox-icity. Therefore they represent potentially useful dietary adjuncts

for the treatment of diabetes and potential sources for discovery ofnew orally active antidiabetic therapeutics.

Role of the funding source

This research work was supported by a grant from the Deanshipof Academic Research, University of Jordan.

Acknowledgements

We graciously acknowledge Mr. Ismail Abaza for technical help.

References

Abesundara, K.J.M., Matsui, T., Matsumoto, K., 2004. �-Glucosidase inhibitory activ-ity of some Sri Lanka plant extracts, one of which Cassia auriculata, exerts a strongantihyperglycemic effect in rats comparable to the therapeutic drug acarbose.Journal of Agricultural and Food Chemistry 52, 2541–2545.

Abu-Irmaileh, B., Afifi, F., 2000. Treatment with medicinal plants in Jordan. Dirasat27, 53–74.

Aburjai, T., Hudaib, M., Tayyem, R., Yousef, M., Qshawi, M., 2007. Ethnopharmaco-logical survey of medicinal herbs in Jordan, the Ajloun Heights region. Journalof Ethnopharmacology 110, 294–304.

Adebajo, A.C, Olawode, E.O., Omobuwajo, O.R., Adesanya, S.A., Begrow, F., Elkhawad,A., Akanmu, M.A., Edrada, R., Proksch, P., Schmidt, T.J., Klaes, M., Verspohl, E.J.,2007. Hypoglycaemic constituents of Stachytarpheta cayennensis leaf. PlantaMedica 73, 241–250.

Ajlouni, K., Khader, Y.S., Batieha, A., Ajlouni, H., El-Khateeb, M., 2008. An increase ofdiabetes mellitus in Jordan over 10 years. Journal of Diabetes and its Complica-tions 22, 317–324.

Al Maayeh, T. M., 2005. Screening of some common medicinal plants of Jordan foealpha amylase inhibition activity. MSc Thesis. University of Jordan, Amman,Jordan.

Al-Mustafa, A.H., Al-Thunibat, O.Y., 2008. Antioxidant activity of some Jordanianmedicinal plants used traditionally for treatment of diabetes. Pakistan Journalof Biological sciences 11, 351–358.

Al-Qura’n, S., 2009. Ethnopharmacological survey of wild medicinal plants in Show-bak, Jordan. Journal of Ethnopharmacology 123, 45–50.

Ardestani, A., Yazdanparast, R., 2007. Antioxidant and free radical scavenging poten-tial of Achillea santolina extracts. Food Chemistry 104, 21–29.

Ardestani, A., Yazdanparast, R., Jamshidi, Sh., 2008. Therapeutic effects of Teucriumpolium extract on oxidative stress in pancreas of streptozotocin-induced diabeticrats. Journal of Medicinal Foods 11, 525–532.

Benhammou, N., Bekkara, F.A., Panovska, T.K., 2008. Antioxdant and antimicrobialactivities of the Pistacia lentiscus and Pistacia atlantica extracts. African Journalof Pharmacy and Pharmacology 2, 022–028.

Bressler, R., Johnson, D., 1992. New pharmacological approaches to therapy ofNIDDM. Diabetes 30, 64–69.

Esmaeili, M.A., Yazdanparast, R., 2004. Hypoglycaemic effects of Teucrium polium:studies with rat pancreatic islets. Journal of Ethnopharmacology 95, 27–30.

Esmaeili, M.A., Zohari, F., Sadeghi, H., 2009. Antioxidant and protective effects ofmajor flavonoids from Teucrium polium on beta-cell destruction in a model ofstreptozotocin-induced diabetes. Planta Medica 75, 1418–1420.

Granfeldt, Y., Bjorck, I., Drews, A., Tovar, J., 1992. An in vitro procedure based onchewing to predict metabolic response to starch in cereal and legume products.European Journal of Clinical Nutrition 46, 649–660.

Gin, H., Rigalleau, V., 2000. Postprandial hyperglycemia Postprandial hypergly-caemia and diabetes. Diabetes Metabolism 26, 265–272.

Hamdan, I.I., Afifi, F.U., 2004. Studies on the in vitro and in vivo hypoglycemicactivities of some medicinal plants used in treatment of diabetes in Jordaniantraditional medicine. Journal of Ethnopharmacology 93, 117–121.

Hamdan, I.I., Afifi, F.U., 2008. Screening of Jordanian flora for �-amylase inhibitoryactivity. Pharmaceutical Biology 46, 746–750.

Hudaib, M., Mohammad, M., Bustanji, Y., Tayyem, R., Yousef, M., Abuirjeie, M.,Aburjai, T., 2008. Ethnopharmacological survey of medicinal plants in Jordan,Mujib Nature Reserve and surrounding area. Journal of Ethnopharmacology 120,63–71.

Kotowaroo, M.I., Mahomoodally, M.F., Gurib-Fakim, A., Subratty, A.H., 2006. Screen-ing of traditional antidiabetic medicinal plants of Mauritius for possible alphaamylase inhibitory effects in vitro. Phytotherapy Research 20, 228–231.

Lee, H.S., Kim, M.K., 2001. Rat intestinal �-glucosidase and lens aldose reductaseinhibitory activities of grain extracts. Food Science Biotechnology 10, 172–177.

Li, Y.Q., Zhou, F.C., Gao, F., Bian, J.S., Shan, F., 2009. Comparative evaluation ofquercetin, isoquercetin and rutin as inhibitors of alpha-glucosidase. JournalAgriculture Food Chemistry 57, 11463–11468.

Matsuo, T., Izumori, K., 2009. d-Psicose inhibits intestinal �-glucosidase and sup-presses the glycemic response after ingestion of carbohydrates in rats. Journalof Clinical Biochemistry and Nutrition 45, 202–206.

McCue, P., Kwon, Y.I.I., Shetty, K., 2005. Antidiabetic and antihypertensive potentialof sprouted and solid-state bioprocessed soybean. Asia Pacific Journal of ClinicalNutrition 14, 145–152.



Monfared, M.S.S.S., Pournourmohammadi, S., 2010. Teucrium polium complex withmolybdate enhance cultured islets secretory function. Biological Trace ElementsResearch 133, 236–241.

Mooradian, A.D., Thurman, J.E., 1999. Drug therapy of posprandial hyperglycemia.Drugs 57, 19–29.

Mou, M., Zhang, Q., Kang, W., Pi, K., Chen, Q., Yao, R., 2009. Chemical constituentsand bioactivity of Teucrium pilosum. Zhongguo Zhong Yao Za Zhi 34, 2189–2193.

Murthy, P.S., Moorti, R., Pugazhenthi, S., Babu, B.V., Prabhu, K.M., Ratnakar, P., Shukla,R., Puri, D., Dev, G., Rusia, U., Aggarwal, S., 2003. Studies with purified orallyactive compounds from fenugreek seeds, banyan tree bark, bittergourd fruitsand garlic bulbs in diabetes mellitus, hypercholesterolemia and tuberclosis.Trends in Clinical Biochemistry Laboratory Medicine, 635–639.

Naqishbani, A.M., Josefsen, K., Pedersen, M.E., Jager, A.K., 2009. Hypoglycemic activ-ity of Iraqi Rheum ribes root extract. Pharmaceutical Biology 47, 380–383.

Ozbek, H., Ceylan, E., Kara, M., Ozgokce, F., Koyuncu, M., 2004. Hypoglycemic effectof Rheum ribes roots in alloxan induced diabetic and normal mice. ScandinavianJournal of Laboratory Animal Science 31, 113–115.

Ozturk, M., Aydozmus-Ozturk, F., Duru, M.E., Topcu, G., 2007. Antioxidant activityof stem and root extracts of Rhubarb (Rheum ribes): an edible medicinal plant.Food Chemistry 103, 623–630.

Prince, P.S., Menon, V.P., Pari, L., 1998. Hypoglycaemic activity of Syzygium cuminiseeds: effect on lipid peroxidation in alloxan diabetic rats. Journal of Ethnophar-macology 6, 1–7.

Rao, K.B., Kesavulu, M.M., Giri, R., Rao, Ch.A., 2001a. Effect of oral administration ofbark extracts of Pterocarpus santalinus L. on blood glucose level in experimentalanimals. Journal of Ethnopharmacology 74, 69–74.

Rao, K.B., Kesavulu, M.M., Giri, R., Rao, Ch.A., 2001b. Antihyperglycemic activity ofMomordica cymbalaria in alloxan diabetic rats. Journal of Ethnopharmacology78, 67–71.

Shahraki, M.R., Arab, M.R., Mirimokaddam, E., Palan, M.J., 2007. The effect of Teucriumpolium (Calpoureh) on liver function, serum lipids and glucose in diabetic malerats. Iran Biomedical Journal 11, 65–68.

Shaw, J.E., Sicree, R.A., Zimmet, P.Z., 2010. Global estimates of the prevalence ofdiabetes for 2010 and 2030. Diabetes Research and Clinical Practice 87, 4–14.

Shokeen, P., Anand, P., Murali, K., Tandon, V., 2008. Antidiabetic activity of 50%ethanolic extract of Ricinus communis and it purified fractions. Food and Chem-ical Toxicology 46, 3458–3466.

Smirin, P., Taler, D., Abitbol, G., Brutman-Barazani, T., Kerem, Z., Sampson, S.R.,Rosenzweig, T., 2010. Sarcopoterium spinosum extract as an antidiabetic agent:in vitro and in vivo study. Journal of Ethnopharmacology 129, 10–17.

Szkudelski, T., 2007. Resveratrol-induced inhibition of insulin secretion from ratpancreatic islets: evidence for pivotal role of metabolic disturbances. AmericanJournal of Physiology–Endocrinology and Metabolism 293, E901–E907.

Szkudelski, T., 2008. The insulin-suppressive effect of resveratrol—an in vitro andin vivo phenomenon. Life Sciences 82, 430–435.

Tietz, N.W., 1999. In: Burtis, C.A., Ashwood, E.R. (Eds.), Tietz Textbook of ClinicalChemistry, third ed. Saunders W.B., pp. 750–778.

Tshikalange, T.E., Meyer, J.J.M., Lall, N., Munoz, E., Sancho, R., Van de Venter, M.,Oosthuizen, V., 2008. In vitro anti-HIV properties of ethnobotanically selestedSouth African plants used in the treatment of sexually transmitted diseases.Journal of Ethnopharmacology 119, 478–481.

Wild, S., Sicree, R., Roglic, G., King, H., Green, A., 2004. Global prevalence of dia-betes. Estimates for the year 2000 and projections for 2030. Diabetes Care 27,1047–1053.

Yazdanparast, R., Ardestani, A., Jamshini, S., 2007. Experimental diabetes treatedwith Achillea santolina: effects on pancreatic oxidative parameters. Journal ofEthnopharmacology 112, 13–18.

Yousfi, M., Djeridane, A., Bombarda, I., Chahrazed-Hamia, Duhem, B., Gaydou, E.M.,2009. Isolation and characterization of a new hispolone derivative from antiox-idant extracts of Pistacia atlantica. Phytotherapy Research 23 (9), 1237–1242.

Zindah, M., Belbeisi, A., Walke, H., Mokdad, A.H., 2008. Obesity and diabetes inJordan: findings from the behavioural risk factor surveillance system, 2004.Preventing Chronic Disease 5, 1–8.

In vitro and in vivo antihyperglycemic effects of five selected indigenous plants from Jordan used...

Documents

Transcript of In vitro and in vivo antihyperglycemic effects of five selected indigenous plants from Jordan used...