PHYTOCHEMICAL AND SOME PHARMACOLOGICAL STUDIES OF THE LEAF, STEM BARK AND ROOT BARK EXTRACTS OF STACHYTARPHETA ANGUSTIFOLIA (MILL) VAHL. (VERBENACEAE)

PHYTOCHEMICAL AND SOME PHARMACOLOGICAL STUDIES OF THE LEAF, STEM BARK AND ROOT BARK EXTRACTS OF STACHYTARPHETA ANGUSTIFOLIA (MILL) VAHL. (VERBENACEAE)

Abstract:

The extracts of the leaf, stem bark and root bark of Stachytarpheta angustifolia (Mill) Vahl. (Verbenaceae), were subjected to preliminary phytochemical screening and the result revealed the presence of carbohydrates, steroids, cardiac glycosides, terpenoids, flavonoids, tannins and Saponins. Silica gel column chromatography of n- butanol soluble fractions of the leaf, stem bark and root bark extract followed by gel filtration using sephadex LH20 and preparative thin layer chromatography resulted in the isolation of two iridoid glycosides 1-[3,4-dihydroxy-5-(3-hydroxy-cycloprop-1-enyloxy)-6-hydroxymethyl-tetrahydro- pyran- 2-yloxy] - 7-methyl-1, 4a, 5, 6, 7, 7a hexahydrocyclopenta [c] pyran -4- carboxylic methyl ester and 4a, 7 – dihydroxy – 7 – methyl – 1 – (3, 4, 5 – trihydroxy – 6– hydro methyl – tetrahydropyran – 2 – yloxy) – 1 -, 4a, 5, 6, 7, 7a, hexahydro – cyclopentano [C] pyran – 4 – carboxylic acid methyl ester from the leaf and root bark respectively, while -β – (3‟, 4‟ – dihydroxy phenyl) – ethyl – O – – L – rhamnopyranosyl (1 3) – β – D – (4 – O – Caffeoyl) – glucopyranoside was isolated from the stem bark. The structures of these compounds were elucidated using chemical tests, spectroscopic techniques (FTIR, ID and 2D NMR) and by comparison with reference data. The ethanol leaf extract and its n-butanol and residual aqueous fractions exhibited concentration dependent contraction of the rabbit jejunum which was blocked by atropine, suggesting that the observed pharmacological effect were mediated through muscarinic receptors. In contrast, chloroform and Ethylacetate fraction of the ethanolic root bark extract exhibit concentration dependent relaxation of the rabbit jejunum. The ethanol leaf extract was screened for antimicrobial activity using disc diffusion and agar well dilution methods. The organisms tested were clinical isolates of S. aureus, S. pyogenes, E. coli and S. typhi. The ethanol extract inhibited the growth of all the microbes. The zone of inhibition ranging from 10-30mm). Conclusively, the use of S. angustifolia as a remedy for venerable infection by the folkloric healers has scientific basis . Keywords: Stachytarpheta angustifolia, Antimicrobial activity, Gastrointestinal activity.

PHYTOCHEMICAL AND SOME PHARMACOLOGICAL STUDIES OF THE LEAF, STEM BARK AND ROOT BARK EXTRACTS OF STACHYTARPHETA ANGUSTIFOLIA (MILL) VAHL. (VERBENACEAE)

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