Fungal transformation of the diterpenoid kaempulchraol E (1) by Rhizopus oryzae KX685359 afforded two trihydroxlated isopimaradienes: 2α,6β,14β-trihydroxy-isopimara-8(9),15-diene (2) and 2α,6β,14α-trihydroxy-isopimara-8(9),15-diene (3) in addition to the known metabolite roscorane B (4). Chemical structures were established by spectroscopic techniques including: HRMS, FT-IR and 1D- & 2D-NMR. The structure of 2 was confirmed by single-crystal, X-ray diffraction analysis. Bio-transformed metabolites as well as the substrate originally isolated from Kaempheria galanga were tested against two cancer cell lines: HSC-2 and B16-BL6. Compounds 4 showed greater toxicity than the original plant derived diterpene (IC₅₀ 54.08 ± 0.05 versus 96.05 ± 0.03 μM, respectively) when assayed against the HSC-2 cell line. This study confirms the role of fungal transformations in developing novel natural products with efficacious biological activities.

米根霉KX685359对二萜类kaempulchraol E（1）进行真菌转化，得到了两个三羟基异戊二烯：2α，6β，14β-三羟基-异pi（8），15-二烯（2）和2α，6β，14α-三羟基-异pi除了已知的代谢产物roscorane B（4）外，还具有-8（9），15-二烯（3）。化学结构通过光谱技术建立，包括：HRMS，FT-IR和1D-＆2D-NMR。通过单晶X射线衍射分析确认2的结构。对两种癌细胞系：HSC-2和B16-BL6进行了生物转化的代谢物以及最初从高良姜（Kaempheria galanga）分离的底物的测试。化合物4当针对HSC-2细胞系进行测定时，与原始植物衍生的二萜相比，其毒性更高（分别为IC ₅₀ 54.08±0.05和96.05±0.03μM）。这项研究证实了真菌转化在开发具有有效生物活性的新型天然产物中的作用。