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

Anthocleista vogelii Planch is a medicinal plant traditionally used in West Africa for the management and treatment of diabetes mellitus. To determine the antidiabetic activities of chloroform fraction (CF) of Anthocleista vogelii Planch root bark in rats with diet- and alloxan-induced obesity-diabetes. 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. 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. 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.

Anyanwu GO ，Iqbal J ，Khan SU ，Zaib S ，Rauf K ，Onyeneke CE ，Ojo OO ，Nisar-Ur-Rahman ... -  《-》

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

Anthocleista djalonensis (A. Chev) and Anthocleista vogelii Planch are plants being used in West Africa traditionally to treat various diseases such as malaria, hernia, hypertension, stomach aches, hemorrhoids, syphilis, and diabetes. Diabetes causes about 5% of all deaths globally each year. Chemotherapeutic agents such as biguanides, sulfonylureas, and thiozolidinediones are available for the treatment of diabetes, however, they have undesirable side effects. The need for newer, more effective and less toxic drugs is imperative and the biodiversity of Nigeria has a high potential for drug discovery based on plants used in the ethnomedicine. To investigate the leaves, stem bark and roots of these plants for their probable alpha-amylase inhibitory activities and establish their anti-diabetic activities. The overall goal is do bioassay-guided fractionation and isolation of active anti-diabetic compounds. Powdered samples (leaves, stem bark and roots) macerated with 80% aqueous methanol were evaluated in vitro using alpha-amylase inhibitory assay while in vivo investigations were carried out on hyperglycemic rats. Diabetes was induced in albino rats by an intraperitoneal injection of alloxan monohydrate (80mg/kg). Plant extracts (1g/kg) were given orally for 7 days, while blood glucose levels were monitored using a one touch glucometer. The crude methanol extracts found to be most active were further partitioned into hexane and ethyl acetate fractions which were also tested in vivo on the diabetic animals. The leaves and stem bark crude methanol extracts of Anthocleista djalonensis gave comparable α-amylase inhibition of 73.66% and 72.90%, respectively which were quite higher than the 38.93% and 22.90% of the same plant parts given by Anthocleista vogelii. The crude stem bark extract of Anthocleista djalonensis exhibited significant peak blood glucose reduction on day 6 (72.59%, p<0.05) which was higher than the leaves or roots which gave 45.73% and 47.46% (p<0.05), respectively The stem bark ethyl acetate fraction of Anthocleista djalonensis gave reduction in blood glucose level of 60.86% (p<0.05). From our results, the leaves, stem bark and whole root of both plants exhibited α-amylase inhibitory activities with Anthocleista djalonensis also showing good anti-diabetic activities in vivo indicating that they contain active principles for the management of diabetes. There is justification for the use of the plants traditionally to manage diabetes.

Olubomehin OO ，Abo KA ，Ajaiyeoba EO 《-》

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

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. 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. 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. 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.

Anyanwu GO ，Nisar-ur-Rehman ，Onyeneke CE ，Rauf K ... -  《-》

Antidiabetic effects of Morus alba fruit polysaccharides on high-fat diet- and streptozotocin-induced type 2 diabetes in rats.

Type 2 diabetes mellitus (T2DM) is becoming a serious threat to human health. The fruit of Morus alba L. is widely used as a traditional Chinese medicine for the treatment of DM, dizziness, tinnitus, insomnia, and premature graying, as well as to protect the liver and kidneys. Several studies have demonstrated that the aqueous extracts of the roots bark, leaves, and ramuli of mulberry, which are known to contain polyphenols and polysaccharides, have antihyperglycemic and antihyperlipidemic activities. The aim of the present study was to further investigate the active polysaccharides from M. alba fruit by evaluating the antidiabetic activities of different fractions on T2DM rats and elucidate the mechanism underlying these activities. Diabetic rats were treated with two fractions of M. alba fruit polysaccharides (MFP50 and MFP90). The disease models were induced by a high-fat diet and low dose injection of streptozotocin and were compared to normal rats and metformin-treated diabetic rats. After seven weeks, the fasting blood glucose (FBG), oral glucose tolerance test (OGTT), fasting serum insulin (FINS) levels, homeostasis model of assessment-insulin resistance (HOMA-IR), glycated serum protein (GSP), and serum alanine transaminase (ALT) levels, as well as serum lipid profiles and histopathological changes in the pancreas were measured. Next, the expressions of the insulin signaling pathway were measured by western blot analysis to elucidate the potential mechanism underlying these antidiabetic activities. After seven weeks of treatment, a significant reduction in the FBG levels, OGTT-area under the curve (OGTT-AUC), FINS, HOMA-IR, ALT, and triglyceride (TG) values of the MFP50 group was observed. On the other hand, in the MFP90 group, the FBG, OGTT-AUC, FINS, HOMA-IR, GSP, and TG levels were significantly reduced. The level of high-density lipoprotein cholesterol (HDL-c) and the proportion of HDL-c to total cholesterol (TC) significantly increased in the MFP50 group. Moreover, MFP50 and MFP90 induced repair of damaged pancreatic tissues of the diabetic rats. The hypoglycemic effect of MFP50 was more stable than MFP90, whereas the hypolipidemic effect of MFP90 was slightly better than MFP50. Moreover, the expression levels of InsR, IRS-2, Akt and GLUT4 in the MFP90 group significantly increased relative to that of the T2DM group. MFP50 and MFP90 have markedly antihyperglycemic and antihyperlipidemic effects and can clearly relieve diabetes symptoms in the T2DM rat model. The M. alba fruit polysaccharides may potentially be utilized as an effective treatment for T2DM. Further research into the structures of active M. alba fruit polysaccharides and their mechanisms in promoting antidiabetic effects are underway.

Jiao Y ，Wang X ，Jiang X ，Kong F ，Wang S ，Yan C ... -  《-》

Assessment of anti-diabetic activity of an ethnopharmacological plant Nerium oleander through alloxan induced diabetes in mice.

Nerium oleander L. (syn. Nerium indicum Mill. and Nerium odorum Aiton.) is used for its anti-diabetic properties in Pakistan, Algeria, Morocco and is also recognized in Ayurveda. The present study was undertaken to investigate the anti-diabetic capacity of a standardized hydromethanolic extract of Nerium oleander in alloxan induced diabetes in mice. Nerium oleander leaf extract (NOLE) was orally administered at 50 and 200mg/kg body weight (BW) dose to alloxanized mice (blood glucose >200mg/dl). After 20 consecutive days of treatment, various diabetic parameters were studied and compared with untreated mice. Furthermore, gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC) analysis was employed to reveal the phytochemical composition of the plant extract. NOLE demonstrated antihyperglycaemic activity by reducing 73.79% blood glucose level after 20 days of treatment. Oral glucose tolerance test (OGTT) revealed increase in glucose tolerance as evident by 65.72% decrease in blood glucose in 3h post treatment. Percentage decrease in different liver marker enzymes were significant along with decrease in triglyceride and cholesterol levels, displaying potent antihyperlipidemic activity. Peroxidase and catalase activity in liver, kidney and skeletal muscle were significantly restored besides marked reduction in lipid peroxidation and normalization of hepatic glycogen level in the NOLE treated alloxanized mice. Different bioactive phytocompounds with potent anti-diabetic activity were identified by GC-MS and HPLC analysis. The present investigation revealed that Nerium oleander possess potent anti-diabetic activity as claimed in different ethnopharmacological practices.

Dey P ，Saha MR ，Chowdhuri SR ，Sen A ，Sarkar MP ，Haldar B ，Chaudhuri TK ... -  《-》