Chronic oral safety study of the aqueous extract of Combretum molle twigs on biochemical, haematological and antioxidant parameters of Wistar rats.

BACKGROUND: Combretum molle R.B/G. Don (Combretaceae) is a graceful deciduous shrub, distributed especially in tropical Africa and used in traditional medicine in the treatment of malaria, diabetes, and bacterial, liver and cardiovascular deseases. To our knowledge, no long-term toxicity studies of C. molle has ever been realized yet. METHODS: The long-term toxicity study was conducted in accordance with OECD 408 guidelines with slight modifications. In fact, rats were divided in groups and treated orally with CMAE at doses of 62.5, 125 and 250 mg/kg for 6 months. The general behavior and signs of toxicity of the rats were daily observed. Body weight, food and water intake were recorded every 2 months for 6 months. At the end of treatment period, urine and blood samples were collected for hematological, biochemical and antioxidant estimations. Immediately, internal organs were collected and weighed. RESULTS: The results showed that no mortality and visible signs of the toxicity were recorded in all experimental animals. The administration of CMAE had no significant effects on body weight, organ weights, serum electrolyte, and food and water intake. However, all doses of CMAE produced an increase in high density lipoprotein cholesterol, white blood cells, platelets, glutathione, and a decrease in low density lipoprotein cholesterol and malondialdehyde rate. CMAE at doses of 125 and 250 mg/kg decreased in serum proteins and the activity of aspartate amino transferase, and increased the activity of catalase. In addition, CMAE (250 mg/kg) significantly decreased the alanine aminotransferase activity and the level of triglycerides, very low density cholesterol, total proteins and creatinine, and increased in renal clearance, red blood cells, hemoglobin, hematocrit and superoxide dismutase activity. CONCLUSIONS: At the end of this study, no signs of major intoxication was noted during 6 months of treatment. These results suggest that long-term consumption of CMAE at the therapeutic dose (250 mg/kg) presents low risks to human health.

In vitro toxicity determination of antifungal constituents from Combretum zeyheri.

BACKGROUND: Candida albicans is one of the organisms living on the human body symbiotically, but, in hosts with low immunity it becomes one of the most pathogenic fungal organisms. Combretum zeyheri has been reported to have antifungal, antibacterial and antioxidant activities. Medicinal plants are believed to be non-toxic by the general public. Toxicity studies, however, have indicated that they are capable of causing numerous side effects, therefore, evaluation of safety is required. The objective of this study was to determine the toxicity of the antifungal constituents of Combretum zeyheri on mammalian cells. METHODS: Alkaloids, saponins, flavonoids-enriched extracts and crude ethanol extracts were prepared from the leaves of Combretum zeyheri. The broth microdilution method was used to investigate for antifungal activity, with miconazole used as the positive control. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to determine cell viability of the Candida albicans cells. The most potent extracts; the ethanol extract, alkaloids and saponins respectively, were further tested for their toxicity on sheep erythrocytes, mouse peritoneal macrophages and Jurkat T cells. RESULTS: All Combretum zeyheri extracts displayed a dose-dependent antifungal activity and had IC50 values ranging from 16 µg/ml to 159 µg/ml for Candida albicans. The alkaloids, saponins and ethanol extracts were found to be non-toxic towards mouse peritoneal cells and Jurkat T cells. In the haemolysis assay, all extracts were haemolytic at varying degrees and showed their greatest haemolytic activity at the highest concentration of 5 mg/ml. The saponins were the least haemolytic, followed by the ethanol extracts and the alkaloids respectively. Although these extracts were haemolytic to some extent, they may considered safe at therapeutic concentrations since there was a large difference between the antifungal IC50 and haemolysis EC50 values, hence a large therapeutic window. CONCLUSIONS: Combretum zeyheri antifungal constituents are, therefore, a potential source of lead compounds which can be developed into antifungal drugs of natural origin owing to Combretum zeyheri's effective antifungal activity and low toxicity to mammalian cells.

Antibacterial, anti-HIV-1 protease and cytotoxic activities of aqueous ethanolic extracts from Combretum adenogonium Steud. Ex A. Rich (Combretaceae).

BACKGROUND: Records have shown that Combretum adenogonium Steud. Ex A. Rich (Combretaceae) is used in traditional medicine systems of several tribes in Tanzania. This study focused on the investigation of antibacterial activity, anti-HIV-1 protease activity, toxicity properties and classes of phytochemicals in extracts from C. adenogonium Steud. Ex A. Rich (Combretaceae) to evaluate potential of these extracts for development as herbal remedies. METHODS: Dried plant material were ground to fine powder and extracted using 80% aqueous ethanol to afford root, leaf and stem bark extracts. The extracts were assayed for anti-HIV-1 protease activities, antibacterial activities using microdilution methods and cytotoxicity using brine shrimps lethality assay. Screening for major phytochemical classes was carried out using standard chemical tests. RESULTS: All extracts exhibited antibacterial activity to at least one of the test bacteria with MIC-values ranging from 0.31-5.0 mg/ml. Two extracts, namely, root and stem bark exhibited anti-HIV-1 PR activity with IC50 values of 24.7 and 26.5 µg/ml, respectively. Stem bark and leaf extracts showed mild toxicity with LC50 values of 65.768 µg/ml and 76.965 µg/ml, respectively, whereas roots were relatively non-toxic (LC50 = 110.042 µg/ml). Phytochemical screening of the extracts indicated presence of flavonoids, terpenoids, alkaloids, tannins, glycosides and saponins. CONCLUSION: These results provide promising baseline information for the potential development of C. adenogonium extracts in treatment of bacterial and HIV/AIDS-related opportunistic infections.