Microbial transformation of deoxyandrographolide by Cunninghamella echinulata

The capabilities of twenty strains of filamentous fungi (from 9 genera) to transform deoxyandrographolide (1) were screened. And eleven derivatives of 1 transformed by Cunninghamella echinulata AS 3.3400 were isolated. Their chemical structures were identified by spectral methods including 2D NMR. Among them, 3-oxo-7α-hydroxy-14-deoxyandrographolide (2), 3-oxo-8β,17α-epoxy-14-deoxyandrographolide (3), 8α-formyl-14-deoxyandrographolide (4), 8β-methoxyl-17α-hydroxyl-14-deoxyandro-grapholide (5) and 3α,17,19-trihydroxyl-7,13-ent-labdadien-15,16-olide (6), are new compounds. And their structure–activity relationships (SAR) were also discussed.