Abstract:
Three secondary metabolites named a mixture of two diasterromer O-1-(2-hydroperoxy-1,2-dimethylethyl)-O-1’-(mercaptoethyl-S-oxide)-peroxocarbonate, together with a phenolic metabolite, tyrosol, and a Kreb’s cycle metabolite, succinic acid, were isolated from the ethyl acetate extract of the fermentation broth of an endophytic fungus, Phomopsis sp. AANN8 by antileukemic-guided fractionation. The endophytic fungus was obtained from the twigs of a Thai medicinal plant, Artemisia annua L. (family Asteraceae). The identification and structure determination of the isolated compounds were elucidated by analyses of UV, IR, MS and NMR spectroscopic data along with comparison with previous publications. The isolated compounds were evaluated for in vitro antileukemic activity against THP-1 cell line by a sulforhodamine B colorimetric bioassay using ellipticine as a positive control with EC50 79 μM. The results showed that tyrosol and succinic acid had no antileukemic activity while the mixture of O-1-(2-hydroperoxy-1,2-dimethylethyl)-O-1’-(mercaptoethyl-S-oxide)-peroxocarbonate exhibited weak antileukemic activity with EC50 131 μM.
