Structural properties and evaluation of the antiproliferative activity of limonene-1,2-diol obtained by the fungal biotransformation of R-(+)- and S-(-)-limonene.

Limonene-1,2-diol is a limonene oxygenated metabolite that possesses eight different stereoisomers, which could result in different biological properties. Nonetheless, the relation between its spatial configuration and biological function is still little explored. The present study aimed to perform the stereoisomers identification using nuclear magnetic resonance (NMR) investigation of the limonene-1,2-diol produced via R-(+)- and S-(-)-limonene biotransformation by Colletotrichum nymphaeae and S-(-)-limonene biotransformation by Fusarium oxysporum 152B. Besides, in vitro antiproliferative activity was evaluated against human tumor and nontumor cell lines. The NMR analysis showed that R-(+)-limonene biotransformation afforded exclusively (+)-(1S,2S,4R-limonene-1,2-diol), whereas S-(-)-limonene biotransformation afforded exclusively (-)-(1R,2R,4S-limonene-1,2-diol) independent on the fungi used. Despite no significant cytostatic effects, a possible influence of stereogenic center on the antiproliferative activity of these limonene biotransformation products was evidenced. Moreover, the lack of in vitro antiproliferative effect of limonene-1,2-diol against nontumor cells suggested a safe dose range for further in vivo evaluations, including food applications.