Microbial transformation of the labdane diterpene 13-epi-cupressic acid
The labdane diterpene, 13-epi-cupressic acid 1, was isolated from the n-hexane-chloroform extract of Araucaria heterophylla resin. Of the 20 fungi screened for possible transformation, only four showed to produce metabolites including 13, 14, 15-trihydroxy-8(17)-labden-19-oic acid 2, 7α,13-dihydroxy-8(17),14-labdadien-19-oic acid 3,13-epi-cupressic acid β-glucosyl ester 4 and iso-communic acid 5 by Cunninghamilla echiulata NRRL 1382 , Aspergillus restrictus NRRL 2869, Coriolus hirsutus ATCC MYA-828 and Cordyceps sinclairii ATCC 24400, respectively. The identity of the isolated compounds was confirmed using 1D and 2D NMR and MS spectroscopies. Compound 4 is a new metabolite while 5 is first time being produced by biotransformation technique. Compound 3 was proved to be a potent anti-inflammatory agent through selective inhibition of COX-2 enzyme assay.
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