A chemical investigation of a KwaZulu-Natal medicinal plant, Momordica foetida Schum. & Sond.
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Date
1994
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Abstract
Momordica foetida Schum. & Sond. (Cucurbitaceae), locally known as
iNtshungu, is widely used by the Zulu people of Natal-KwaZulu for the
treatment of a variety of ailments.
The dried leaves leaves and stems of this plant was subjected to soxhlet
extraction by refluxing with hexane, chloroform and methanol successively.
Thin layer chromatography of the chloroform extract of the leaves revealed a
multiplicity of compounds. The chloroform extract was further partitioned with
sodium hydroxide resulting in an organic and aqueous phase. The organic
phase, containing extract A, afforded two compounds, viz. compounds 1 and 2.
The basic aqueous fraction was neutralised and re-extracted with chloroform to
give extract B, affording five compounds, viz. compounds 3,4,5,6 and 7.
Structural elucidation was accomplished by techniques such as IH and 13C NMR
spectroscopy, HETCOR, COSY, FTIR and High Resolution Mass
Spectrometry.
Compounds 1 and 2 were identified as cucurbitane triterpenoids known as
momordicines which had been previously discovered in the related species of
this plant, Momordica charantia L. The remaining five compounds were
identified as novel compounds, although natural derivatives of compounds 6
and 7 had been isolated previously from Momordica charantia L. Compounds
3-7 were each isolated as an epimeric mixture but it was possible to select the
resonances corresponding to the major epimer. These five epimers were
respectively identified as 5, 19-epoxy-19(R)-hydroxy-25-methoxy-5β-
cucurbita-6,23-diene-3β-ol [102], 5,19-epoxy-19(R),25-dihydroxy-5β-cucurbita-
6,23-diene-3β-ol [103], 5,19-epoxy-19(R)-methoxy-25-hydroxy-5β-cucrbita-
6,23-diene-3β-ol [104], 5,19-epoxy-25-methoxy-5β-cucurbita-6,23diene-
3β-ol [105] and 5,19-epoxy-19(R),25-dimethoxy-5β-cucurbita-6,23diene-
3β-ol [106].
Appropriate reactions were performed, where possible, on the compounds
isolated in order to confirm their identity.
Description
Thesis (M.Sc.)-University of Natal, Durban, 1994.
Keywords
Theses--Chemistry., Plants--Analysis., Botanical chemistry., Cucurbitaceae--KwaZulu-Natal., Medicinal plants--KwaZulu-Natal.