CHEMICAL CONSTITUENTS AND SOME BIOACTIVITIES OF EXTRACTS OF TETRAPLEURA TETRAPTERA (TAUB) AND FICUS EXASPERATA (VAHL) USED IN ETHNO-MEDICINE

Abstract

The work investigated the traditional uses of the fruit of Tetrapleura tetraptera and the root bark of Ficus exasperata Vahl (Moraceae) as an anti-inflammatory and hypoglycemic agents. It also described the isolation and characterization of the active principles from T. tetraptera and F. exasperata. The extracts of the fruit and root bark were assessed for anti-inflammatory, hypoglycemic, antioxidant and anti-bacterial activities. The anti-inflammatory activities of the extracts and isolates were investigated using the carrageenan – induced foot pad oedema model in Wistar rats and using Diclofenac as standard. Both extracts exhibited anti – inflammatory effect with the root bark showing the higher activity, 30%, G-1 24%, D-1 20% while Diclofenac is 34% inhibition. These figures showed that groups treated with 250mg/kg and 375mg/kg of both extracts and 10mg/kg of diclofenac and the isolates showed a significant reduction in paw oedema (p<0.05) at the later phase of inflammation when compared to control, conversely, the group treated with 250mg/kg of Ficus spp registered increased paw oedema. The increase was significantly higher (p<0.05) than that of control and the other groups. Hypoglycemic activities of the extracts were determined in Wistar rats of both sexes using Oral Glucose Tolerance Test (OGTT). In OGTT, the standard use, glibenclamide showed reduction of blood glucose level of 29% and 63.5% at 90 min and 120 minutes respectively, while the fruit of T. tetraptera showed 22% and 43%, the root bark of F. exasperata showed 18% and 41.3% respectively at 90 min and 120 min. Antioxidant properties of the extracts were also investigated using four assays; total phenolic content, DPPH scavenging activity, ferric reducing antioxidant potential and total flavonoid. The antioxidant activity of both extracts increased with increasing concentration with that of F. exasperata comparing favourably with the standard. Antibacterial evaluation of extracts at concentrations of 10 mg/ ml was done using the agar well diffusion assay. Four organisms; P. aeruginosa, S. typhi, E. coli, and B. subtilis were used. In the present study, both extracts inhibited the growth of all test organisms used except B. subtilis which was not inhibited by T. tetraptera. The bioassay guided chemical investigation of the F. exasperata root bark resulted in the isolation of a new compound, (2S)-2-hydroxy-N-((3S,4R)-1,3,4-trihydroxytridecan-2-yl)undecanamide, an amide. From another active fraction of F. exasperata, bergapten was isolated from the root bark of F. exasperata. This is the first report of the isolation of bergapten from the root bark of FE. Aridanin was isolated from the active fraction of T. tetraptera. The results of these studies have demonstrated that extracts of the fruit of T. tetraptera and root bark of F. exasperata possess hypoglycemic and anti-inflammatory activities and also display antioxidant and antibacterial activities. This project on local medicinal plants has opened new vista for future research work on indigenous medicinal plants.