Fermentation of Illigera aromatica with Clonostachys rogersoniana producing novel cytotoxic menthane-type monoterpenoid dimers

Abstract

Illigera aromatica, a medicinal liana, was fermented with Clonostachys rogersoniana. Two novel menthane-type monoterpenoid dimers, dimericilligerates E (1) and F (2) were isolated from the fermented material. Their structures were identified by 1D/2D NMR, electric circular dichroism, derivatization, and Mosher's method. A novel elimination reaction that formed a benzene ring from a menthane moiety afforded derivative 1a, which possesses more resolved NMR signals than the dimeric monoterpenoid, dimericilligerate E (1). The determination of 1a verified the estimation of 1. Compounds 1 and 2 showed potent cytotoxic activities; especially, 1 possessed significant activities against the liver hepatocellular carcinoma cell line (SMMC-7721) with an IC₅₀ value of 3.89 ± 0.23 μM. Three novel precursors, dimericilligerates A–C (3–5), were identified by HPLC-MS and isolated from the original I. aromatica. This paper presents a novel class of monoterpenoid dimers and suggests that C. rogersoniana-fermented I. aromatica is effective to produce cytotoxic dimeric monoterpenoids from inactive original materials.