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.

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.