Three stilbenoids from the orchid Agrostophyllum callosum

摘要: Abstract Callosumin, callosuminin and callosumidin, three new stibenoids, were isolated from the orchid Agrostophyllum callosum which earlier afforded, besides 4-hydroxy-3,5-dimethoxybenzoic acid, 10 other structurally related stilbenoids, viz. orchinol, 6-methoxycoelonin, imbricatin, flaccidin, oxoflaccidin, isooxoflaccidin, flaccidinin, agrostophyllin, callosin callosinin. The structures of callosumin, callosumidin established as 2,4,6,7-tetramethoxy-9,10-dihydrophenanthrene, 2,4,6,7-tetramethoxyphenanthrene 2,7-dihydroxy-5-ethoxy(ax)-6-methoxy-9,10-dihydro-5H-phenanthro[4,5-bcd]pyran, respectively, spectral chemical evidence. Although in naming systematic numbering system has been adopted, for ease comparison results phenanthrene compound its structural analogues is used.