Larvicidal properties of simalikalactone D from Quassia africana (Simaroubaceae) Baill and Baill, on the malaria vector Anopheles gambiae.

BACKGROUND: Botanical and microbial insecticides have been increasingly used for the control of mosquito given their efficacy and documented nontoxic effects on non-target organisms. The discovery of new insecticides is imperative because of the development of resistance by the mosquitoes to the readily available insecticides. The aim of this study was therefore to isolate and characterize compounds from a local medicinal plant, Quassia africana Baill and Baill (Simaroubaceae) that were toxic to Anopheles gambiae. MATERIAL AND METHODS: The methanol extracts of the leaves, stem and roots of Quassia africana were tested against fourth instar larvae of An. gambiae. The root extract was partitioned into hexane, chloroform and ethyl acetate and the resulting extracts screened for larvicidal properties. The extracts and the fraction with the highest bioactivity were subjected to repeated column chromatography and isolated compounds evaluated for potential toxicity to An. gambiae larvae. The structure of the active compound was elucidated using spectroscopic techniques. The root extract showed the strongest activity profile (LC50 = 17.58 µg/mL). The chloroform soluble fraction obtained after partitioning the crude extract into solvents based on polarities was the most toxic. Further bio-activity-guided chromatographic separation of the chloroform fraction of the root extract led to the identification and isolation of a simalikalactone D as the larvicidal compound in Q. africana (LC50 = 1.25 µg/mL). RESULTS: Results suggest that Q. africana may serve as a source for vector control agent for malaria. CONCLUSION: Simalikalactone D was identified as the larvicidal compound in Q. africana (LC50 = 1.25 µg/mL).

Isoflavone dimers and other bioactive constituents from the figs of Ficus mucuso.

Phytochemical investigation of the figs of Ficus mucuso led to the isolation of three new isoflavone dimer derivatives, mucusisoflavones A-C (1-3), together with 16 known compounds. Some of the isolates were tested in vitro for their inhibitory properties toward ß-glucuronidase and Plasmodium falciparum enoyl-ACP reductase (PfENR) enzymes. Compound 1 (IC50) 0.68 µM) showed inhibitory activity on ß-glucuronidase enzyme, while 3 (IC50) 7.69 µM) exhibited a weak inhibitory activity against P. falciparum enoyl-ACP reductase (PfENR).

Hypoglycemic activity of Buchholzia coriacea (Capparaceae) seeds in streptozotocin-induced diabetic rats and mice.

The present study evaluates the possible hypoglycemic activity and ameliorative effects of oral administration of ethanol extracts (EEBC) and butanol fraction (BFBC) of Buchholzia coriacea seeds, a plant in use traditionally for treating diabetes, hypertension, rheumatism, cold, cough and catarrh, in streptozotocin (STZ)-induced diabetic mice and rats. Fasting blood glucose (FBG) levels were evaluated before and after extracts administration. EEBC and BFBC significantly decreased (P<0.05) FBG in hyperglycemic mice and normoglycemic rats within 4 and 12 h, respectively after extract administration. The administration of EEBC, BFBC and glibenclamide (a standard antidiabetic drug) for 10 days significantly lowered (P<0.05) FBG level in STZ-induced diabetic rats by 55%, 64% and 56%, respectively. EEBC and BFBC significantly (P<0.05) decreased hepatic injury induced by STZ as evident in the decreased activity of serum alanine amino transferase and aspartate amino transferase compared to in the STZ-only treated group. Similarly, both extracts significantly decreased (P<0.05) the elevated levels of serum creatinine, urea, total cholesterol, triglyceride and thiobarbituric acid reactive species (TBARS) products in diabetic rats. Serum superoxide dismutase activity was significantly enhanced (P<0.05) by treatments with EEBC, BFBC and glibenclamide. Overall, the results suggest that B. coriacea seeds contain a potent hypoglycemic and antioxidant agent suggested to be a flavone glycoside concentrated in BFBC which may find clinical application in amelioration of diabetes-induced secondary complications.

In vitro cytotoxic activity of isolated acridones alkaloids from Zanthoxylum leprieurii Guill. et Perr.

Chemical investigation of the roots and fruits of Zanthoxylumleprieurii Guill. et Perr. led to the isolation of three new alkaloids including two acridone derivatives, 3-hydroxy-1,4-dimethoxy-10-methyl-9-acridone (2) and 3-hydroxy-1,2-dimethoxy-10-methyl-9-acridone (3) named helebelicine A and B, respectively, and one secobenzo[c]phenantridine, 10-O-demethyl-12-O-methylarnottianamide (10), together with thirteen other compounds. The structures of compounds 2, 3 and 10 as well as those of the known compounds were elucidated by using spectroscopic methods and by comparison with reported data. The brine-shrimp (artemia salina) lethality bioassay of the chloroform extract of the fruits showed modest cytotoxicity with LD(50) at 13.1microg/mL. Isolated compounds 1, 4-6 were found to be moderately active against lung carcinoma cells (A549), colorectal adenocarcinoma cells (DLD-1) and normal cells (WS1) with IC(50) values ranging from 27 to 77microM. In contrast to the positive control etoposide used, the cytotoxicity of the most active compound 4 was found to be selective against cancer cells in comparison to normal cells WS1 with IC(50) of 51+/-8microM and 4.3+/-0.4microM, respectively.

Hypoglycaemic and biochemical properties of Cnestis ferruginea.

Increasing incidences of diabetes in Africa has prompted the search for safe and readily available alternative herbal remedies for the treatment of diabetes mellitus. Cnestis ferruginea was extracted with methanol and ethylacetate and the extracts obtained were tested for hypoglycaemic activities in streptozotocin (STZ)-induced diabetic rats and mice. The extracts (250 mg/kg body weight) were administered orally for 10 consecutive days to STZ-induced diabetic rats while a single dose (250 mg/kg body weight) of the extracts were administered to STZ-induced diabetic mice. Fasting blood glucose (FBG) levels were determined in the two groups of animals after extract administration. There was significant reduction in FBG (P< 0.005) by MCF and ECF within 4 hrs of extract administration in a time- dependent manner. Furthermore, administration of MCF and ECF for 10 days significantly lowered FBG in STZ diabetic rats (P<0.005) by 74% and 68%, respectively, whereas, glibenclamide - a standard antidiabetic drug reduced FBG by 60%. The levels of serum creatinine, urea, triglyceride, total cholesterol, total protein and level of lipid peroxidation were also evaluated. The extracts reduced significantly (P<0.005) the elevated levels of serum ALT and AST in diabetic treated rats. Similarly, both extracts significantly lowered (P<0.005) the levels of serum creatinine, urea, total cholesterol, triglyceride and thiobarbituric acid reactive species (TBARS).These results suggest that Cnestis ferruginea leaves contain a highly potent hypoglycaemic principle and could be a potential source for isolation of new orally active antihyperglycaemic compounds for attenuating secondary complications of diabetes such as atherosclerosis, liver and renal dysfunction.