Alpha-amylase inhibitory activity of two Anthocleista species and in vivo rat model anti-diabetic activities of Anthocleista djalonensis extracts and fractions

Chemical Characterization of Corydalis chaerophylla D.C. Extracts and Preliminary Evaluation of Their in Vitro and in Vivo Biological Properties

Genus Corydalis is a rich source of isoquinoline alkaloids reported to having potential bioactivities. Corydalis chaerophylla collected from Nepal at an altitude of 2400-4800 m was extracted using hexane, methanol and chloroform as solvents. The resulting hexane, methanol and chloroform extracts were subjected to LC-DAD-MSn analysis to yield fifteen different alkaloids. To assess any potential pharmacological properties, antimicrobial activity against two Gram-positive, two Gram-negative bacterial strains and one fungal strain was assessed, revealing significant inhibitive action of the methanol and chloroform extracts. Of the extracts obtained using chloroform contained the highest content of phenolic compounds at 113 mg GAE/g, while the highest total flavonoid content was found for the hexane extract with a value of 46.45 mg QE/g. The chloroform extract also exhibited a considerable antioxidant activity at IC50 value, 261.5±3 μg/mL, for the DPPH assay. Conversely, the methanol extract exhibited the highest LC50 value for Brine Shrimp cytotoxicity at 196±3 μg/mL being least potential for the test. The methanol extract was found to be the most active against α-amylase inhibition with an IC50 of 51.52±2 μg/mL. In an in vivo acute oral toxicity study against mice, methanol and chloroform extracts presented harmful effects with 1000.36 mg/kg BW and 515 mg/kg BW for LD50 , respectively. By analyzing all the results of the solvents used, the chloroform extract was found to be the most active, a feature that will be used in future isolation procedures and other pharmacological tests.

Inhibition mechanism of alpha-amylase, a diabetes target, by a steroidal pregnane and pregnane glycosides derived from Gongronema latifolium Benth

Alpha-amylase is widely exploited as a drug target for preventing postprandial hyperglycemia in diabetes and other metabolic diseases. Inhibition of this enzyme by plant-derived pregnanes is not fully understood. Herein, we used in vitro, in silico, and in vivo studies to provide further insights into the alpha-amylase inhibitory potential of selected pregnane-rich chromatographic fractions and four steroidal pregnane phytochemicals (SPPs), viz: marsectohexol (P1), 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→14)-β-D-oleandropyranosyl]-11,12-di-O-tigloyl-17β-marsdenin (P2), 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl]-17β-marsdenin (P3), and 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-canaropyranosyl]-17β-marsdenin (P4) derived from Gongronema latifolium Benth. The results revealed that the SPPs source pregnane-rich chromatographic fractions and the SPPs (P1–P4) exhibited inhibitory potential against porcine pancreatic alpha-amylase in vitro. Compounds P1 and P2 with IC50 values 10.01 and 12.10 µM, respectively, showed greater inhibitory potential than the reference acarbose (IC50 = 13.47 µM). Molecular docking analysis suggests that the SPPs had a strong binding affinity to porcine pancreatic alpha-amylase (PPA), human pancreatic alpha-amylase (HPA), and human salivary alpha-amylase (HSA), interacting with the key active site residues through an array of hydrophobic interactions and hydrogen bonds. The strong interactions of the SPPs with Glu233 and Asp300 residues may disrupt their roles in the acid-base catalytic mechanism and proper orientation of the polymeric substrates, respectively. The interactions with human pancreatic amylase were maintained in a dynamic environment as indicated by the root mean square deviation, radius of gyration, surface accessible surface area, and number of hydrogen bonds computed from the trajectories obtained from a 100-ns molecular dynamics simulation. Key loop regions of HPA that contribute to substrate binding exhibited flexibility and interaction potential toward the compounds as indicated by the root mean square fluctuation. Furthermore, P1 significantly reduced blood glucose levels and area under the curve in albino rats which were orally challenged with starch. Therefore, Gongronema latifolium and its constituent SPPs may be exploited as inhibitors of pancreatic alpha-amylase as an oral policy for impeding postprandial blood glucose rise.

Characterization of Possible α-Glucosidase Inhibitors from Trigonella stellata Extract Using LC-MS and In Silico Molecular Docking

The current study accentuates the significance of performing the multiplex approach of LC-HRESIMS, biological activity, and docking studies in drug discovery, taking into consideration a review of the literature. In this regard, the investigation of antioxidant and cytotoxic activities of Trigonella stellata collected from the Egyptian desert revealed a significant antioxidant capacity using DPPH with IC₅₀ = 656.9 µg/mL and a moderate cytotoxicity against HepG2, MCF7, and CACO2, with IC₅₀ values of 53.3, 48.3, and 55.8 µg/mL, respectively. The evaluation of total phenolic and flavonoid contents resulted in 32.8 mg GAE/g calculated as gallic acid equivalent and 5.6 mg RE/g calculated as rutin equivalent, respectively. Chemical profiling of T. stellata extract, using LC-HRESIMS analysis, revealed the presence of 15 metabolites, among which eleven compounds were detected for the first time in this species. Interestingly, in vitro testing of the antidiabetic activity of the alcoholic extract noted an α-glucosidase enzyme inhibitory activity (IC₅₀ = 559.4 µg/mL) better than that of the standard Acarbose (IC₅₀ = 799.9 µg/mL), in addition to a moderate inhibition of the α-amylase enzyme (IC₅₀ = 0.77 µg/mL) compared to Acarbose (IC₅₀ = 0.21 µg/mL). α-Glucosidase inhibition was also virtualized by binding interactions through the molecular docking study, presenting a high binding activity of six flavonoid glycosides, as well as the diterpenoid compound graecumoside A and the alkaloid fenugreekine. Taken together, the conglomeration of LC-HRESIMS, antidiabetic activity, and molecular docking studies shed light on T. stellata as a promising antidiabetic herb.

Ameliorative effect of Annona reticulata L. leaf extract on antihyperglycemic activity and its hepato-renal protective potential in streptozotocin induced diabetic rats

BACKGROUND

Annona reticulata L. is a traditionally important plant due to its versatile source of medicine and industrial products. It is used to treat cardiac problems, wound healing, diabetes, ulcers and bacterial infections. As it is a commercial fruit bearing plant, wide range studies on this plant reaches the mankind efficiently.

OBJECTIVE(S)

The present study was focussed on antihyperglycemic potential of A. reticulata leaves under in vitro and in vivo.

MATERIAL AND METHODS

The in vitro phytochemical analysis, total phenolic, flavonoid content, inhibition activity on alpha amylase and alpha glucosidase enzymes were determined for various solvent extracts, followed by in vivo oral toxicity, short term, dose dependant antihyperglycemic studies, oral glucose tolerance tests were performed. The activity of methanolic extract of A.reticulata (MeEAR)-500 mg/kg b.wt was studied for 28 days in diabetic rat model. Histopathological examinations and serum biochemical assays were performed. Gas chromatography-Mass spectrometry (GC-MS) analysis was performed to identify the compounds present in MeEAR.

RESULTS

Among the various extracts, MeEAR possesses higher amount of phenols and flavonoids with effective inhibition on carbohydrate hydrolysing enzymes (P < 0.05) and also exhibited higher glycemic control in vivo, with simultaneous improvement in the hepatic and renal activities in diabetic rats. GC-MS analysis revealed the presence of 63 bioactive compounds including carboxylic-acids, alcoholic groups, fattyacid esters, amino acid derivatives.

CONCLUSION

Altogether, our study demonstrated that leaves of A.reticulata possess better antihyperglycemic activity and could be developed in to a potential antidiabetic drug with further studies.

Role of Anthocleista vogelii in serum antioxidant defence system in cadmium-induced oxidative stress in Wistar rats

Background

Cadmium (Cd) toxicity, which runs across the food chain, is chiefly regulated by in vivo antioxidant defence system or through antioxidant supplementation of biological systems predisposed to this environmental stressor. The present study was designed to examine the role of Anthocleista vogelii leaves in Cd-induced oxidative stress in the serum of Wistar rats through the application of response surface methodology (RSM) and biomonitoring of selective responses: malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione-s-transferase (GST) and peroxidase (POD) activities, respectively. The cold macerated plant leaves were subjected to fractionation process using methanol-hexane-chloroform (3:2:1 v/v) solvent system such that n-hexane fraction with ample antioxidant levels in terms of total phenolic content (TPC) and total flavonoid content (TFC) among others at p <  0.05 was selected for the study. The study employed central composite design (CCD) with twenty experimental “runs” of male Wistar rats for twenty-eight days, following a week of acclimatization, where n-hexane fraction of A. vogelii (NFAV), cadmium chloride (CdCl2) and body weights of rats were considered input factors in the study.

Results

The study generated five quadratic models, which differed significantly at p <  0.05 for MDA levels as well as CAT, SOD, GST and POD activities in the sera of Wistar rats. The study revealed that exposure to Cd toxicity caused a marked increase (p <  0.05) in serum MDA levels, but a significant inhibition (p <  0.05) of serum SOD, CAT, GST and POD activities. However, Cd interaction with NFAV showed marked amelioration of Cd-induced oxidative stress, which was confirmed by significant decrease in serum MDA levels, but significant increase in serum SOD, CAT, GST and POD activities at p <  0.05 via the response surface plots. The study also confirmed the reliability and adequacy of the models for accurate prediction of the responses since R-squared (R2) values obtained were greater than 90%.

Conclusion

It was inferred from the present study that the adequacy of the models validated the potency of A. vogelii leaves graphically in the amelioration of Cd-induced oxidative stress in the serum of Wistar rats. Hence, the plant was considered a rich source of bioactive compounds with significant antioxidant properties.

Nutritional Composition, Total Phenolic Content, Antioxidant and α-Amylase Inhibitory Activities of Different Fractions of Selected Wild Edible Plants

Wild plants are considered the richest source of essential nutrients and other beneficial phytochemicals. Hence, the objective of this study was to evaluate the nutritional composition, antioxidant- and α-amylase inhibition activities of leaves and roots of selected Bangladeshi wild plants. These wild plants were found to have high fiber (13.78-22.26 g/100 g), protein (7.08-21.56 g/100 g) and ash (8.21-21.43 g/100 g) contents. The total phenolic and total flavonoid contents were significantly higher in the leaves than the roots. Additionally, antioxidant activity was evaluated using ferric-reducing antioxidant power, 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) and trolox equivalent antioxidant capacity assays and was strongly correlated with phenolic compounds. The leaf extracts of the selected plants also exhibited potent α-amylase inhibition (~71%) and were significantly higher than their root counterparts. Thus, the study findings concluded that the investigated plants were good sources of fiber, protein, mineral, natural antioxidant compounds and α-amylase inhibitors, and their increased intake could provide health benefits. The principal component analysis (PCA) of analyzed variables divided the samples into three clear groups, and the first two principal components accounted for 86.05% of the total data set variance.

Antidiabetic activities of chloroform fraction of Anthocleista vogelii Planch root bark in rats with diet- and alloxan-induced obesity-diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

Anthocleista vogelii Planch is a medicinal plant traditionally used in West Africa for the management and treatment of diabetes mellitus.

AIM OF THE STUDY

To determine the antidiabetic activities of chloroform fraction (CF) of Anthocleista vogelii Planch root bark in rats with diet- and alloxan-induced obesity-diabetes.

MATERIALS AND METHODS

Inhibitory activities of CF against α-amylase and α-glucosidase activities were determined in vitro. Three weeks old rats were fed with high-fat diet for 9 weeks to induce obesity prior to further induction of diabetes using alloxan (150 mg/kg body weight, i.p.). Blood glucose levels and body weight were measured every 7 days throughout the experiment. Glucose tolerance was assessed in normal and CF-treated rats on day 21. Terminal blood samples were collected from sacrificed animals for the measurement of serum insulin levels. Pancreases were excised from treated and untreated animals for histopathological examination.

RESULTS

LCMS/MS chromatographic profile of CF via positive and negative modes revealed 13 and 23 compounds respectively. Further analysis revealed quebrachitol (QCT), loganin, sweroside, oleoside 11-methyl ester and ferulic acid, which have been previously reported for their antidiabetic activities, as constituents of CF. CF inhibited activities of α-amylase (IC₅₀ = 51.60 ± 0.92 µg/ml) and α-glucosidase (IC₅₀ = 5.86 ± 0.97 µg/ml) in a dose-dependent manner. Treatment of animals with obesity-diabetes with 100 and 200 mg/kg CF significantly improved glucose tolerance (P < 0.001) and enhanced serum insulin levels (P < 0.05) compared to diabetic control rats.

CONCLUSIONS

Antidiabetic activities of CF might be mediated via inhibition of α-amylase and α-glucosidase activities, elevation of serum insulin concentration, and enhancement of insulin and leptin sensitivity in obesity-diabetes rats. This study further substantiates the traditional use of A. vogelii in the management and treatment of diabetes in Africa and encourages further studies to investigate its mechanism of action.

An overview of anti-diabetic plants used in Gabon: Pharmacology and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed.

MATERIALS AND METHODS

Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including 'Diabetes', 'Gabon', 'Toxicity', 'Constituents', 'hyperglycaemia' were used.

RESULTS

A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver.

CONCLUSION

An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.

Experimental Validation of Antidiabetic and Antioxidant Potential of Cassia tora (L.): An Indigenous Medicinal Plant

The present study was undertaken to evaluate antidiabetic and antioxidant activities of Cassia tora (C. tora) seeds extract against streptozotocin induced diabetes in experimental rats to scientifically validate its use against diabetes. Ethanolic extract of C. tora seeds extract and standard drug (glibenclamide) prepared in aqueous gum acacia (2 %, w/v) suspension and fed orally to streptozotocin induced male adult diabetic rats of Charles Foster strain for 15 days. Biochemical parameters in normal, diabetic control, standard (600 μg/kg bw p.o.) and treated (500 mg/kg bw p.o.) animal groups were quantified and compared. Treatment of streptozotocin induced diabetic rats with ethanolic seeds extract caused significant (p < 0.001) reduction in blood glucose (270-220 mg/dl), total cholesterol (140-104 mg/dl), triglyceride (149-99 mg/dl), phospholipids (100-74 mg/dl), free fatty acid (2.39-2.00 μmol/l), lipid peroxide (9-5.63 nmol MDA/dl) and significantly increased post heparin lipolytic activity (11-14 nmol FFA released/h/l plasma) (p < 0.001). Furthermore, the seeds extract (100-400 μg) when tested for its antioxidant activity in vitro, showed significant (p < 0.001) inhibition in the generation of super oxide anions in enzymic system a (46-37, 33, 23, 21 nmol uric acid formed/min), in enzymic system b (113-91, 77, 60, 51 nmol formazon formed/min), non-enzymic system (324-230, 211, 161, 141 nmol uric acid formed/min) and hydroxyl radicals in enzymic system (544-501, 411, 319, 291 nmol 2,3-dihydroxybenzoate formed/h) and non-enzymic system (28-21, 17, 14, 12). The results of the present study demonstrated antidiabetic, antidyslipidemic and antioxidant activities of C. tora seeds which could help in prevention of diabeticdyslipidemia and related complications.

Optimization of Extraction Process for Antidiabetic and Antioxidant Activities of Kursi Wufarikun Ziyabit Using Response Surface Methodology and Quantitative Analysis of Main Components

By using extraction yield, total polyphenolic content, antidiabetic activities (PTP-1B and α-glycosidase), and antioxidant activity (ABTS and DPPH) as indicated markers, the extraction conditions of the prescription Kursi Wufarikun Ziyabit (KWZ) were optimized by response surface methodology (RSM). Independent variables were ethanol concentration, extraction temperature, solid-to-solvent ratio, and extraction time. The result of RSM analysis showed that the four variables investigated have a significant effect (p < 0.05) for Y₁, Y₂, Y₃, Y₄, and Y₅ with R² value of 0.9120, 0.9793, 0.9076, 0.9125, and 0.9709, respectively. Optimal conditions for the highest extraction yield of 39.28%, PTP-1B inhibition rate of 86.21%, α-glycosidase enzymes inhibition rate of 96.56%, and ABTS inhibition rate of 77.38% were derived at ethanol concentration 50.11%, extraction temperature 72.06°C, solid-to-solvent ratio 1 : 22.73 g/mL, and extraction time 2.93 h. On the basis of total polyphenol content of 48.44% in this optimal condition, the quantitative analysis of effective part of KWZ was characterized via UPLC method, 12 main components were identified by standard compounds, and all of them have shown good regression within the test ranges and the total content of them was 11.18%.

Experimental Validation of Antidiabetic Potential of Cayratia trifolia (L.) Domin: An Indigenous Medicinal Plant

The present study was undertaken to evaluate antidiabetic and antioxidant activities of Cayratia trifolia root extract against streptozotocin induced diabetes in experimental rats to scientifically validate its use against diabetes in some parts of India. Ethanolic extract, showing the highest activity in in vitro experiments, was prepared in saline and administered orally to streptozotocin induced albino Wistar diabetic rats for 21 days. Biochemical parameters liver and muscles glycogen and in vivo antioxidant activity in normal, diabetic control, standard (metformin) and treated animals were determined and compared. Attempt was made to isolate, purify and characterize one of the major secondary metabolites in extract by range of chromatographic and spectroscopic techniques. Treatment of streptozotocin induced diabetic rats with ethanolic root extract (500 mg/kg) caused significant (P < 0.01) reduction in blood glucose (312-178 mg/dL), increase in body weight (181-219 g) and serum insulin (1.28-2.26 IU/dL). It also maintained lipid profile and tests of liver and kidney functions within normal range as compared to diabetic control rats and almost at par with standard drug metformin. The oxidative stress induced decline in glutathione and catalase in liver and kidney tissues showed recovery nearly to normal level as a function of treatment. The GC-MS profile of the extract showed relatively high concentration of β-sitosterol which was characterized by different spectroscopic and chromatographic techniques. The result scientifically and comprehensively validate the reported use of roots of this indigenous plant against diabetes. A strong antioxidant activity of the ethanolic root extract suitably compliments the antidiabetic effect.

In vitro antioxidant and, α-glucosidase inhibitory activities and comprehensive metabolite profiling of methanol extract and its fractions from Clinacanthus nutans

BACKGROUND

This study was aimed to evaluate antioxidant and α-glucosidase inhibitory activity, with a subsequent analysis of total phenolic and total flavonoid content of methanol extract and its derived fractions from Clinacanthus nutans accompanied by comprehensive phytochemical profiling.

METHODS

Liquid-liquid partition chromatography was used to separate methanolic extract to get hexane, ethyl acetate, butanol and residual aqueous fractions. The total antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazy (DPPH) radical scavenging and ferric reducing antioxidant power assay (FRAP). The antidiabetic activity of methanol extract and its consequent fractions were examined by α-glucosidase inhibitory bioassay. The chemical profiling was carried out by gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC Q-TOF MS).

RESULTS

The total yield for methanol extraction was (12.63 ± 0.98) % (w/w) and highest fractionated value found for residual aqueous (52.25 ± 1.01) % (w/w) as compared to the other fractions. Significant DPPH free radical scavenging activity was found for methanolic extract (63.07 ± 0.11) % and (79.98 ± 0.31) % for ethyl acetate fraction among all the fractions evaluated. Methanol extract was the most prominent in case of FRAP (141.89 ± 0.87 μg AAE/g) whereas most effective reducing power observed in ethyl acetate fraction (133.6 ± 0.2987 μg AAE/g). The results also indicated a substantial α-glucosidase inhibitory activity for butanol fraction (72.16 ± 1.0) % and ethyl acetate fraction (70.76 ± 0.49) %. The statistical analysis revealed that total phenolic and total flavonoid content of the samples had the significant (p < 0.05) impact on DPPH free radical scavenging and α-glucosidase inhibitory activity.

CONCLUSION

Current results proposed the therapeutic potential of Clinacanthus nutans, especially ethyl acetate and butanol fraction as chemotherapeutic agent against oxidative related cellular damages and control the postprandial hyperglycemia. The phytochemical investigation showed the existence of active constituents in Clinacanthus nutans extract and fractions.

Evaluation of Hypoglycemic and Genotoxic Effect of Polyphenolic Bark Extract from Quercus sideroxyla

Quercus sideroxyla is a wood species whose bark has phenolic compound and should be considered to be bioactive; the hypoglycemic and genotoxic properties of Q. sideroxyla bark were evaluated in this study. Total phenolic compound was determined in crude extract (CE) and organic extract (OE). The OE has the highest amount of phenols (724.1 ± 12.0 GAE/g). Besides, both CE and OE demonstrated effect over the inhibition of α-amylase in vitro. Hypoglycemic activity was assessed by glucose tolerance curve and the area under curve (UAC); OE showed the highest hypoglycemic activity. In addition, diabetes was induced by streptozotocin (65 mg/kg) and the extracts (50 mg/kg) were administered for 10 days; OE showed hypoglycemic effect compared with diabetic control and decreased hepatic lipid peroxidation. Acute toxicity and genotoxicity were evaluated in CE; results of acute toxicity did not show any mortality. Besides, the comet assay showed that CE at a dose of 100 mg/kg did not show any genotoxic effect when evaluated at 24 h, whereas it induced slight damage at 200 mg/kg, with the formation of type 1 comets.

Antidiabetic, antihyperlipidaemic, and antioxidant activity of Syzygium densiflorum fruits in streptozotocin and nicotinamide-induced diabetic rats

Context Syzygium densiflorum Wall. ex Wight & Arn (Myrtaceae) has been traditionally used by local tribes of the Nilgiris, Tamil Nadu, India, for the treatment of diabetes, however, no definitive experimental studies are available. Objective This study investigates the antidiabetic, antihyperlipidaemic and antioxidant activities of ethanol extract of S. densiflorum (EFSD) fruits in streptozotocin (STZ) and nicotinamide (NA)-induced diabetic rats. Materials and methods Acute oral toxicity and oral glucose tolerance were assessed in normal rats. The antidiabetic, antihyperlipidaemic and antioxidant activities were investigated in STZ - NA-induced diabetic rats. Diabetic rats were orally administered with glibenclamide (10 mg/kg b.wt), EFSD (200, 400 and 800 mg/kg b.wt) for 28 d. Further, changes in the blood glucose level (BGL), biochemical parameters, antioxidants were observed and histology of pancreas was performed. Results No toxicity and lethality were observed. Results of the following parameters are represented by treated versus disease control (STZ + NA) groups. BGL (161.33 ± 22.8 versus 476.17 ± 56.58 mg/dl), glycosylated haemoglobin (5.285 ± 0.19 versus 8.05 ± 0.55%), urea (40.32 ± 1.96 versus 75.37 ± 2.91 mg/dl), uric acid (1.2 ± 0.07 versus 2.16 ± 0.05 mg/dl), total cholesterol (89.3 ± 5.14 versus 139.7 ± 5.95 mg/dl) and triglycerides (79.65 ± 2.52 versus 108.9 ± 3.61 mg/dl) were significantly decreased, whereas haemoglobin (11.75 ± 0.73 versus 7.95 ± 0.42 g/dl), high-density lipoprotein cholesterol (14.2 ± 1.11 versus 6.97 ± 0.84 mg/dl), total protein (45%) and liver glycogen (87%) were significantly increased in EFSD-treated diabetic group. Significant changes were observed in the enzymatic and non-enzymatic antioxidants in EFSD-treated groups (p < 0.001). Histopathological examination showed the regeneration of β-cells in Islets of Langerhans. Conclusion This study confirms the antidiabetic, antihyperlipidaemic and antioxidant activities of S. densiflorum fruits.

In vitro and in vivo α-amylase and α-glucosidase inhibiting activities of the protein extracts from two varieties of bitter gourd (Momordica charantia L.)

Background

α-amylase and α-glucosidase digest the carbohydrates and increase the postprandial glucose level in diabetic patients. Inhibiting the activity of these two enzymes can control postprandial hyperglycemia, and reduce the risk of developing diabetes. Bitter gourd or balsam pear is one of the important medicinal plants used for controlling postprandial hyperglycemia in diabetes patients. However, there is limited information available on the presence of α-amylase and α-glucosidase inhibiting compounds. In the current study, the protein extracts from the fruits of M. charantia var. charantia (MCC) and M. charantia var. muricata (MCM) were tested for α-amylase and α-glucosidase inhibiting activities in vitro, and glucose lowering activity after oral administration in vivo.

Results

The protein extract from both MCC and MCM inhibited the activity of α-amylase and α-glucosidase through competitive inhibition, which was on par with Acarbose as indicated by in vitro percentage of inhibition (66 to 69 %) and IC50 (0.26 to 0.29 mg/ml). Both the protein extracts significantly reduced peak blood glucose and area under the curve in Streptozotocin-induced diabetic rats, which were orally challenged with starch and sucrose.

Conclusions

Protein extracts from the fruits of the two varieties of bitter gourd inhibited α-amylase and α-glucosidase in vitro and lowered the blood glucose level in vivo on par with Acarbose when orally administrated to Streptozotocin-induced diabetic rats. Further studies on mechanism of action and methods of safe and biologically active delivery will help to develop an anti-diabetic oral protein drug from these plants.

Medicinal plants of the genus Anthocleista--A review of their ethnobotany, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Anthocleista of the Gentianaceae family contains 14 species of trees and shrub-like plants distributed in tropical Africa, in Madagascar and on the Comoros. Traditionally, they are commonly used in the treatment of diabetes, hypertension, malaria, typhoid fever, obesity, diarrhea, dysentery, hyperprolactinemia, abdominal pain, ulcer, jaundice, asthma, hemorrhoids, hernia, cancer, wounds, chest pains, inflammations, rheumatism, STDs, infertility and skin diseases. They serve as an anthelmintic, laxative, diuretic and contraceptive. This review aims to provide for the first time a repository of ethnopharmacological information while critically evaluating the relation between the traditional medicinal uses, chemical constituents and pharmacological activities of the Anthocleista species so as to unveil opportunities for future research.

MATERIALS AND METHODS

A search for relevant information on Anthocleista species was performed on scientific databases (Pubmed, Google Scholar, SciFinder, Web of Science, Scopus, PubChem and other web sources such as The Plant List, Kew Botanical Garden and PROTA) and books, PhD and MSc dissertations for un-published resources.

RESULTS

Out of the 14 species of Anthocleista, 6 have been reported in literature to be widely used in traditional medicine for the treatment of various ailments. The six species include: A. djalonensis, A. vogelii, A. nobilis, A. grandiflora, A. schweinfurthii, and A. liebrechtsiana. The chemical compounds isolated from Anthocleista species fall into the class of phytochemicals such as secoiridoids, nor-secoiridoids, xanthones, phytosterols, triterpenes, alkaloids, and others of which majority of the compounds were isolated from A. djalonensis and A. vogelii. The in vitro and in vivo pharmacological studies on the crude extracts, fractions and few isolated compounds of Anthocleista species showed antidiabetic, antiplasmodial, antimicrobial, hypotensive, spasmogenic, anti-obesity, antiulcerogenic, analgesic, anti-inflammatory, antioxidant, antitrypanosomal, anthelmintic, fertility, diuretic and laxative activities which supports most of their uses in traditional medicine. However, the bulk of the studies where centered on the antidiabetic, antiplasmodial and antimicrobial activities of Anthocleista species, although the evidence of its antiplasmodial effect was not convincing enough due to the discrepancies between the in vitro and in vivo results.

CONCLUSION

A. djalonensis and A. vogelii are potential antidiabetic and antibacterial agents. The antibacterial potency relates to infections or diseases caused by E. coli, S. typhi and S. aureus such as urinary tract infections, typhoid, diarrhea, skin diseases, and food poisoning. Pharmacological research on this genus is quite elementary and limited, thus, more advanced research is necessary to isolate and determine the activities of bioactive compounds in vitro and in vivo, establish their mechanisms of action and commence the process of clinical research.

The use of plants in the traditional management of diabetes in Nigeria: pharmacological and toxicological considerations

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system.

MATERIALS AND METHODS

Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. 'Diabetes' and 'Nigeria' were used as keywords for the primary searches; and then 'Plant name - accepted or synonyms', 'Constituents', 'Drug interaction' and/or 'Toxicity' for the secondary searches.

RESULTS

The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs.

CONCLUSION

This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb-drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided.