Microbial biotransformation of ruscogenins

The powder roots of Ruscus aculeatus (Asparagaceae), extracts and the mixture of the major bioactive steroidal sapogenins ruscogenins (neoruscogenin and ruscogenin), have been component of various pharmaceutical preparations to treat chronic venous insufficiency, varicose veins, hemorrhoids and orthostatic hypotension due to their pharmacological activites. Biotransformation studies performed on ruscogenin have so far been limited and there has been neither in vitro nor in vivo report on ruscogenins revealing its metabolism. The aim of this thesis is to estimate metabolism of ruscogenins and obtain new analogs deriving from neoruscogenin. In order to shed light into metabolism of ruscogenins, biotransformation studies performed by C. blakeseleena. Additionally, in order to investigate the potential use of endophytes as biocatalyst; prior to preparative scale studies of neoruscogenin by Alternaria eureka and Neosartorya hiratsukae, analytical scale biotransformation studies performed by endophytes isolated from Astragalus angustifolius. As a result twenty five previously unreported metabolites isolated and the chemical structures elucidated by NMR and HRTOFMS. Fermentation of ruscogenins with C. blakesleeana yielded 8 new oxygenated metabolites. Biotransformation of neoruscogenin by endophytic fungus N. hiratsukae afforded three new neoruscogenin derivatives. Mainly P450 monooxygenase products obtained together with a glycosylated metabolite . A. eureka performed hydroxylation, oxidation, epoxidation reactions and cleavage of the spiroketal system together with further transformations. As far as can be ascertained from the literature; this is the first study reporting conversion of the spirostanol skeleton to cholestane type. In addition conversion to furostanol-type and then leading to an epoxy bridge between C-18 and C-22 was encountered for the first time in steroid chemistry.