Important medicinal plantshaving antidiabetic potentialGymnema sylvestreGymnema sylvestre (Asclepiadaceae) plantspecies with Indian origin is emerging as a potential treatment for themanagement of diabetes, the leaves of this plant are used for the preparationof antidiabetic herbal drugs. Widely used acrossIndia and parts of Asia as a natural treatment for diabetes.
The plant’s crudeextracts and it’s isolated compound dihydroxy gymnemic triacetate showhypoglycemic against streptozotocin induced diabetic rats in dose and timedependent manner (Daisy et al.,2009). This hypoglycemic effect was due to the ability of gymnemic acids todelay the glucose absorption in theblood.
Because gymnemic acid molecules fill the receptor location in theabsorptive external layers of the intestine, thereby preventing the sugarmolecules absorption by the intestine, which results in a low blood sugarlevel. And also the reduced glucose levels are exerted by the crude extractiondue to the presence of dihydroxy gymnemic triacetate had the ability to releasethe insulin by the stimulation of a regeneration process and revitalization ofthe remaining beta cells. (Liu et al.,2009) also demonstrated the Gymnemasylvestre aqueous extract of leaves stimulates insulin secretion from mousecells and isolated human islets in vitro,without compromising cell viability.
The plasma glucose and insulin levelof the normal rats administered with dihydroxy gymnemic triacetate were notaltered indicating it’s normal glycemic effect of the novel compound. Thecharacteristic loss of body weight associated with STZ- induced diabetes isassociated with muscle reduction in diabetes. With such studies, it canconclusively be affirmed that dihydroxy gymnemic triacetate which was isolatedfrom the leaves of Gymnema sylvestre representas a potential medicine for the management of Diabetes mellitus, since theyexhibited beneficial effects on the blood glucose level and associated biochemical parameters of STZ induceddiabetic animals (Rao et al.
, 2010).BauhiniaforficataBauhinia forficata extensively used asan herbal medicine for control of Diabetes in Brazil, where it is known as Patade Vaca (Cow’s hoof). The essential part of this plant which shows thehypoglycemic activity are the fresh leaves of these plants.
As per an experiment carriedout, (Pepato et al., 2002) Bauhinia forficata decoction wasprepared by boiling 150 g of fresh leaves in 1 litre of water for 5 minutes,allowed the decoction to stand for 30 minutes and filtered. The rats, whichwere used for the experiment were fed with normal chow diet containing (w/w)16% protein, 66% carbohydrate and 8% fat and were housed under a 12:12 hourlight: dark cycle at 22- 25°C . In this experiment the rats weredivided into two groups, i.e.diabetic and non diabetic groups, followed by administered the streptozotocin40 mg kg-1 body weight, after 3 days the serum and urinary glucosewere increased. Then one group was injected with Bauhinia forficata decoction and another with drinking water as thecontrol group. After 31 days of treatment the diabetic group of rats treatedwith decoction showed a significant reduction in plasma glucose and urinaryglucose (Rao et al.
, 2010).Ricinus communisRicinus communis is the traditional medicine,which was used for the management of Diabetes mellitus. It is known as Erandahin Sanskrit, Arandi in Hindi and is also known as Castor oil. It belongs to the family Euphorbiaceae,cultivated all over India for getting it’s seed oil. Fifty percent of ethanolicextract of the root, stem and leavesof this plant showed hypoglycemic activity in normal animals andantihyperglycemic activity in diabetic animals in initial screening studies.The administration of the ethanolicextract for a long duration led to a significant reduction of blood glucoseamongst diabetic rats, while there was no significant alteration in the bloodglucose of control animals. The 50% ethanolic root extracts of Ricinus communis showed a dose dependenteffect on blood glucose of diabetic animals up to dose of 500 mg kg-1body weight. On the other hand, higher doses up to 2000 mg kg-1 bodyweight did not show up any dose dependent effect and a maximum decrease inblood glucose was observed at 8th hour.
The significant hypoglycemiceffect was observed at 500 mg kg-1 body weight of 50% ethanolicextract which decreases the blood glucose to 166 ± 19 from the initial level371 ± 21 mg dl-1. Out of twenty column purified fractions of 50%ethanolic extracts were tested for antihyperglycemic activity in diabetic rats,only one fraction (R18) showed asignificant decrease in blood glucose of the diabetic rats. Fraction (R18)decreased the blood glucose to 294 ± 60 (22.4% decrease), 284± 36 (25%decrease), 184 ± 23 mg dl-1 (51.4% decrease), 182 ± 40 mg dl-1 (51.9% decrease), 149 ± 11mg dl-1 (60.6% decrease) at 1st, 2nd, 4th,6th and 8th hour, respectively from an initial value of 379 ± 72 mg dl-1 at the beginningof the experiment.
The results of thisplant showed a potent blood glucose lowering activity both in normal as well asalloxan diabetic rats. The effective dose of Ricinus communis was found to be 500 mg dl-1 bodyweight. Administration of this ethanolic extract to diabetic rats for 20 days,not only significantly lowered the blood glucose of the diabetic animals to almost normal level, but also increasedthe insulin levels and caused improvement in lipid profile and body weight ofthe diabetic animals. It therefore seems to have a promising value for thedevelopment of a potent phytomedicine for diabetes (Rao et al., 2010).SwertiapuniceaSwertia punicea plants native to Japanare most widely used traditional medicines in the treatment of Diabetes.
Administration of Swertia punicea extractand the methylswertianin and bellidifolin fractions of the extract to Type 2diabetic mice improved insulin sensitivity (Tian et al., 2010). Themechanism involved increased expression of key proteins insulin receptor,insulin receptor substrate -1 and phosphatidylinositol 3- kinase that areinvolved in the insulin signaling processes. Additionally, methylswertianin andbellidifolin decreased the activity of glucokinase and increased the activityofglucose-6-phosphate, enzymes that are involved in the secretion of insulinfrom pancreatic ? cells (Coman et al.,2012).
The herbal medicine Swertiapunicea plays an important role in the management of Type 2 diabetesmellitus and supports the development of new phytomedicine for this deadlydisease (Rao et al., 2010).CombretummicranthumCombretum micranthum is a medicinal plant used for treating Diabetes inNorthwestern Nigeria. Commonly known as ‘Geza’ in Hausa, belong to the familyof Combretaceae. The plants have also been documented to show antioxidant,antimicrobial as well as anti inflammatory properties. The aqueous extract ofCombretum micranthum was prepared by usingSoxhlet extractor and was dried in an evaporator at 45°C and storedat 4°C until ready for use. The hypoglycemic activity of this plantextract was tested by using a glucosetolerance test and fasting blood sugar assessment in normal rats.
The antihyperglycemic potential of the plant was performed by taking two groups of animals diabetic group and a non diabeticgroup. The aqueous leaf extract of Combretummicranthum dissolved in normal saline and administered to both the groupsat 100 mg kg-1, 200 mg kg-1 and 400 mg kg-1body weight, but 100 mg kg-1 bodyweight of the extract was found to be the optimum dose out of the three doses. The aqueous leaf extract of 100 mgkg-1 body weight dose produced a significant reduction in blood glucose level and 24.
6% maximumreduction when compared to the maximum decrease of 21.9% and 18.9% produced 200mg and 400 mg kg-1 bodyweight doses, respectively (Chika & Bello, 2010).
In this study the aqueousleaf extract of Combretum micranthum wasproved to have anti diabetic property for both Type 1 and 2 diabetes mellitus (Rao etal., 2010).SarcoporiumspinosumSarcoporium spinosum is a commonmedicinal plant in the Mediterranean region; it is widely used as anantidiabetic drug by Bedouin healers. Several studies were performed to showthat the root extract of Sarcoporiumspinosum exhibits a hypoglycemic effect on rats. The aqueous root extractof Sarcoporium spinosum was preparedby cutting the 100 g of fresh roots into small pieces and they were boiled in alitre of water for 30 minutes.
The aqueous extract was used to carry out theexperiment in 0.001-10 mg dl-1 concentrations. The Sarcoporium spinosum extract exhibitedinsulin like effect on glucose uptake in hepatocytes by inducing a 148 ± 10,133± 23 and 119 ± 14% increase in glucose uptakerespectively, compared to 160 ± 12% increase in glucose uptake obtained byinsulin.
The root extract of this plant at 0.001 mg ml-1concentration showed maximum activity than lower or higher doses. The aqueousroot extract was assumed that it showed antidiabetic effect in the progressivehyperglycemia of genetically diabetic mice. Hence, the aqueous root extract of Sarcoporium spinosum shows insulin likeactions on target tissues, increases insulin secretion in vitro, and have an improved tolerance in vivo (Smirin et al.,2010). The identification of active compounds in the Sarcoporium spinosum plantextract may be a source for thedevelopment and improvement of new antidiabetic drugs (Rao et al.
, 2010).ParinariexcelsaEmerging as a potent antidiabeticherbal drug option, Parinari excelsa, familyChrysobalanaceae is one of the most widely used medicinal plants. In Africa, itis found in Guinea, in Congo and in Senegal particularly in Casamance. Parinari excelsa bark is used for thetreatment of Diabetes mellitus. (Jayaprakasam et al.
, 2005) studies show thatthe flavonoids of the bark of this plant shows the hypoglycemic effect and hasthe ability to induce insulin secretion in diabetic animal models. The aqueous bark extract was prepared by using 25 g dried and powdered barks and these were infused in 200 ml of aqueousethanol (3.1) for overnight. After that the infusion is subjected to filtrationand the solvent was evaporated to give the extract. The hypoglycemic activityof this plant was studied with two groups of animals; alloxan induced diabeticand normal glycemic rats. The aqueous extract is then administered to both thegroups at doses of 100 and 300 mg kg-1 day-1 for a week.
The antidiabetic activity of extract was performed on overnight fasting rats.The plant’s aqueous extract at 100 and 300 mg kg-1 day-1reverse the permanent hyperglycemia induced by alloxan and the blood glucoselevel decreased from 3.11± to 0.91 ± 0.02 g l-1 and3.60 ± 0.12 to 0.
85 ± 0.04 g l-1, respectively. The oraladministration of aqueous extract of Parinariexcelsa at 100 and 300 mg kg-1 also showed significant reductionin blood glucose level in 30 minutes from the time of consumption (Rao et al.
,2010).Vernonia anthelminticaThe popular name of this plant iswild cumin/purple/worm seed and in Hindi it is known as ‘Kalizeeri’. Belongingto the family Asteraceae, Vernoniaanthelmintica is found throughout India and an annual herbaceous plant. Theethanolic extract of this plant seeds has an hypoglycemic effect instreptozotocin induced diabetic rats. The ethanolic extract was prepared by using200 g powdered seeds and these were extracted with a litre of 95% ethanol in asoxhlet extractor for 24 hours. The antidiabetic activity of this plant was determined using theglucose peroxidase method.
The ethanolic extract of the plant at a dosage of 0.25 and 0.75 g kg-1 body weight showed a decrease of 30.6% and 17.
5%in the blood glucose level of the diabetic rats after 6 hours of treatment,respectively. A dosage of 100 mg kg-1 body weight of the extractshowed a significant antihyperglycemic activity in the diabetic treated ratswith a maximum fall of 82.3% in the blood glucose level after 6th hour of treatment whencompared to other fractions (Fatima et al.,2010).ElephantopusscaberElephantopus scaber is a traditionalmedicinal plant, having the property to reduce the blood glucose levels instreptozotocin induced diabetic rats significantly. It is popularly known as Elephant’s foot and belongs to theAsteraceae.
It is a scabrescentaromatic herb distributed in the moist deciduous forests of the central WesternGhats. The acetoneextract of the plant was Prepared from 1 kg dried, powderedplant and was extracted using hexane, acetone and methanol in a soxhletextraction apparatus sequentially and the extracts were evaporated to drynessunder reduced pressure. After 60 days of treatment with the acetone extract of Elephantopus scaber, showed asignificant reduction in blood glucose level from the initial 534.6 mg dl-1to 86.14 mg dl-1 and reached a level closer to the untreated controlof 85.6 mg dl-1 (Daisy et al.
,2009). The antidiabetic property of plants shows their mechanism by improvinginsulin sensitivity, augmenting glucose dependent insulin secretion andstimulating the regeneration of islets of langherhans in pancreas ofstreptozotocin induced diabetic rats.The administration of Elephantopus scaber acetone extractlowering the blood sugar level in streptozotocin induced hyperglycemic animalsit may be due to stimulating effect on insulin release from regenerated ? cellsof the pancreas or increased cellularity of the islets tissues and regenerationof the granules in the ? cells. The significant and consistent antidiabeticeffect of acetone extract of the plant in diabetic rats indicates that thiseffect can be mediated by stimulation of glucose utilization by peripheraltissues. LiriopespicataLiriope spicata is a medicinal plantnative to China and Vietnam belongs toLiliaceae family, frequently used as a treatment for Diabetes mellitus due to itshigh availability and safety. The plant possesses the antidiabetic property dueto two important active components inwater as well as crude polysaccharides. The aqueous extract of Liriope spicata tuberous roots wasprepared by using 500 g of powdered material and it was boiled in distilledwater for three times 1:4, 1:4, and 1:2 in w/v for half an hour each time.Afterwards the extract was filtered, combined and then concentrated by using a rotaryevaporator at 45ºC under reduced pressure.
The aqueous extract was administeredat a dose of 100 mg kg-1 and200 g kg-1 to both control and diabetic rats. After 28 days oftreatment the blood glucose level in streptozotocin induced diabetic rats wasdecreased. But, it did not show any marked results on fasting blood glucose innormal mice (Chen et al., 2009; Rao et al.,2010).Artemisiadracunculus L.Artemisia dracunculus L. has beenreported by several researchers for possessing hypoglycemic effects (Ribnicky et al.
, 2009; Wang et al., 2011). It was found that Artemisia dracunculus L.
improved insulin sensitivity and IRsignaling in insulin-resistant KK-Ay mice models. They could not explain thecellular mechanism behind the effect. The suggestion given was the modulationof skeletal muscle protein degradation and phosphate activity. 4, 5-Di-O-caffeoylquinic acid, 6-demothoxycapillarisin and 2′, 4′-dihydroxy-4-methoxy-dihydrochalcone were isolated from the ethanolic extract ofthe above mentioned plant. The compounds showed inhibitory effects toward theenzyme aldose reductase, a key enzyme involved in diabetic complications, whichmay explain the antidiabetic effect. The bioactive components in Artemisia dracunculus L.
also includedavidigenin, sakuranetin and 5-O-caffeoylquinic acid (Eisenman et al., 2011; Coman et al., 2012).
Present scenario, challenges andfuture prospects of plant based medicine worldwidePresently, all over the world, thereis an increasing awareness towards herbal medicine. This has resulted in anincrease in funds for research and establishment of new departments such asherbal science department. There are numerous trialsbeing carried out to find out more alternatives for this slow poisoningdisease (Subramoniam, 2014). Some notable medicines which are scientificallyvalidated but not clinically proven due to lack of proper information anddocumentation are Allium cepa, Zingiberofficinale, Momordica charantia. There are numerous like these plantsfacing a challenge of limited taxonomy, efficient testing, proper trials anddocumentation.
Some notable plants under clinical trial are Cannabis indica, Clerodendron phlomoides,and Withania somnifera (Chawla et al., 2013).Challenges with herbaldrugsHerbal drugs are prescribed widely becauseof their effectiveness, less side effects, broad range of action and relativelylow cost. However, there are certain facts that pose great challenges for completechangeover with synthetic drugs. Non trial drugs are usually not evaluated forpurity and consistency of active compounds.
Moreover, lack of standardizationkeeps it an alarming mode about the after effects of the drug after consumptionwithout proper prescriptions.The various shortcomings of herbal medicines primarily include-1. Self prescribed or prescribed byunauthorized organizations.2.
Quality assurance is not guaranteedand also may interact with other drugs.3. active ingredients can change in differentenvironmental conditions.
4. Contains powerful pharmacologicallyactive compounds that need to be evaluated for drug-drug interactions.5. Difficulty in identification of thecausative agent associated with adverse reactions encountered as these maycontain multiple ingredients.6. Mode of action of herbal plantconstituents is not clear enough to support therapeutic utility (Chawla et al.,2013). Safety is a major concern with herbalmedicines as due to lack of proper documentation of major segments of informationwhich are still not available.
Astheir consumption without proper guidance can not only be harmful with long term or short term effects but could alsobe fatal in certain situations. Today with the discovery of alternativemedicine pathways it is also very much essentialto maintain a proper databaserather a proper segment which couldsystemize the information gathered along with synchrony with its testing andvalidation and open new doors for a more safer and efficient drug discovery andimplantation.FUTURE PROSPECTS It is likely that an increasingawareness of the effectiveness of herbal medicine alternatives will lead to asignificant increase in patient’s growing interest and understanding towardsthese resources. As mentioned proper testing and documentation will lead to amassive development and pace to this particular sector. Plants under trial suchas Cannabis indica, Clerodendronphlomoides, and Withania somnifera, their proper study and documentationwill result in providing many more such options. Diabetes mellitus is a slowpoisoning disorder which slowly engulfs the functioning of essential and vital organs in such a scenarioproviding greater options are only possible when specific or target groups arededicated towards the development of alternative medicines. Diabetes has a multifactorialpathogenicity, thereby requiring multimodal management approach.
Todayintegrated herbal drug development model are being proposed and are beingconstantly developed in order to provide a strong backbone of understanding theherbal formulations and their effects. Hand in hand with regularizing databases will be the most effective tool forenabling implantation of herbal alternatives at a faster pace. Another veryimportant facet is herbal drug standardization which requires inputs fromvarious branches including botanists, plant physiologists, chemi-informatics,biochemistry, pharmacology, drug development, etc. Along with these further studies are warranted withthese models to ensure effective drug usage and guide the future researchendeavors in a more systematic way (Chawla etal., 2013).CONCLUSION Pharmacological and Phytochemicalevaluation is an integral and essential part of drug development.
Antidiabeticherbal options which are available are mostly easily and locally availableherbal options. Today when more and more people are focusing upon and adaptingherbal formulations, their proper evaluation and documentation is of utmostpriority. In such a scenario the Pharmacological and Phytochemical study ofantidiabetic herbal plants provides concrete information about the therapeuticutility and active compounds, required for the drug formulation. Properdocumentation will enable to study better alternatives with greaterinformation. With constant researches and improvements herbal medicines canturn up to be a better alternative which is both cost effective and possesslesser side effects. Considering various herbal options and there availabilityvarious researches at regular intervals are also taking place thereby thearticle turns out to be as a helpful source of information which can act as ahelping guide towards a systematic approach.