Publications by authors named "John M Wanjohi"

Two novel compounds, alienusolin, a 4α-deoxyphorbol ester (1), crotonimide C, a glutarimide alkaloid derivative (2), and ten known compounds, julocrotine (3), crotepoxide (4), monodeacetyl crotepoxide (5), dideacetylcrotepoxide, (6), β-senepoxide (7), α-senepoxide (8), (+)-(2S,3R-diacetoxy-1-benzoyloxymethylenecyclohex-4,6-diene (9), benzyl benzoate (10), acetyl aleuritolic (11), and 24-ethylcholesta-4,22-dien-3-one (12) were isolated from the Kenyan Croton alienus. The structures of the compounds were determined using NMR, GCMS, and HRESIMS studies.

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From the roots of the African plant Bulbine frutescens (Asphodelaceae), two unprecedented novel dimeric phenylanthraquinones, named joziknipholones A and B, possessing axial and centrochirality, were isolated, together with six known compounds. Structural elucidation of the new metabolites was achieved by spectroscopic and chiroptical methods, by reductive cleavage of the central bond between the monomeric phenylanthraquinone and -anthrone portions with sodium dithionite, and by quantum chemical CD calculations. Based on the recently revised absolute axial configuration of the parent phenylanthraquinones, knipholone and knipholone anthrone, the new dimers were attributed to possess the P-configuration (i.

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