Stemofurans from Stemona collinsae

Accompanied by stemofurans A-K (92-102), the bibenzyls and stilbostemins A-F (132-137), were also isolated from Stemona collinsae roots together with five known derivatives —the stilbenes pinosylvin and 4-methylpinosylvin and the dihydrophenanthrene stemanthrene D (359) [57], Stilbostemin B (133) and D (135) have been previously isolated from Stemona tuberosa [75]. The consecutively designated stilbostemin G (138) was isolated from Stemona cf. pierrei [76]. It became apparent that the stilbenoids of Stemona genus can be characterized mainly by the C-methylation of aromatic rings and the formation of phenylbenzofurans. 

A series of stemofurans A-K (92-102) were isolated and identified from the methanolic extract of Stemona collinsae roots, many of which have the C-methylation of aromatic rings. The structural characteristics inferred that ring B on stemofurans A-K (92—102) was formed via the polyketide pathway always showing two oxygen substitutions in the meta position at C-3 and C-5 [57]. 

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