Absolute Stereochemistries Of Sylvaticin And 12,15-Cis-Sylvaticin, Bioactive C-20,23-Cis Non-Adjacent Bistetrahydrofuran Annonaceous Acetogenins, From Rollinia-Mucosa

A new acetogenin, 12, 15-cis-sylvaticin (2), and its stereoisomer, sylvaticin (1), a known acetogenin whose stereochemical structure has remained unsolved until now, were isolated, using activity-directed fractionation, from the leaf extracts of Rollinia mucosa (Jacq.) Baill. (Annonaceae). 1 is cis at C-20, 23 and trans at C-12, 15; 2 is cis at C-20, 23 and at C-12, 15. A key step in solving their absolute stereochemistries was the determination of the relative configurations (cis or trans) of their 1, 4-diols; this was achieved by a new procedure using the pattern recognition of the NOSEY spectra of their 1, 4-diol formaldehyde acetal derivatives (1b and 2b). Both 1 and 2 showed potent and selective cytotoxicities, against the A-549 lung cancer and the PACA-2 pancreatic cancer, in a panel of six human solid tumor cell lines.