PHYTOCHEMICAL AND PHARMACOLOGICAL STUDIES OF THE BARK OF MITRAGYNA INERMIS (WILLD) O. KUNTZE (RUBIACEAE)

ABSTRACT

The bark of Mitragyna inermis (Wild) 0. Kuntze was screened phytochemically and the results of the preliminary studies on the light petroleum ether and methanolic extract of the plant’s bark revealed it to be rich in steroids, terpenes, flavonoids, tanins, alkaloids, saponins and carbohydrate.

Saponification of the light petroleum ether extract of the bark gave 0.84 g of unsaponifiable matter, while the saponified portion gave 84.5 mg. The unsaponfiable matter was subjected to gas chromatography and mass spectroscopy to yield azelaic acid, myristic acid, 2-methyl heptyl acetate and 9-oxo decanoic acid. These fatty acids and their derivatives were reported for the first time from this species.

The defatted marc was subjected to the usual extraction process for alkaloids to afford a portion referred to as “alkaloid extract”. This portion gave positive tests for alkaloids. Column chromatography of the alkaloid extract and subsequent purification afforded an a morphous compound. Thin Layer Chromatography, chemical tests, UV, I.R. spectra of F3 in comparison with spectra of known alkaloids, showed F3 to be an oxindole alkaloid.

Pharmacological studies of the methanolic extract on isolated rabbit ileum showed a dose – dependent relaxation of rhythmic contractions of the tissue.

However, the extract did not block the contraction of acetylcholine indicating that the relaxation of the rabbit ileum is not via the muscannic blockade on guinea pig ileum, it slightly reduced the histamine induced contraction from 75%, response to 64.02% response, indicating a weak anti histaminic activity. This suggests the beneficial use and explains some traditional claims of the plant in relieving abdominal pains and colics.