Fermentation sitosterol

The byproduct sitosterol was for many years quite useless due to the lack of a chemical point of attack on the side chain that would permit its removal. Extensive efforts on the part of many laboratories eventually led to the discovery of a pseudomonas microbe that efficiently effected that transformation. Fermentation of (4-1) digests the entire aliphatic side chain at 17 to afford a mixture of 17-keto products including dehydroepiandrosterone (4-2) [4]. 

Fermented soy such as tempeh, miso, and tamari are healthy sources of both genistein and daidzein. Soy also contains two other antitumor compounds beta-sitosterol and Bowman-Birk inhibitor. 

The at one time superfluous sitosterol 11-2 has found minor use as a drug for treating elevated cholesterol levels by inhibiting the absorption of dietary cholesterol. Methods have been developed within the past decade for converting sitosterol to androst-4-ene-17,20-dione (12-1) by fermentation (Scheme 2.12). 

Fermentation of a mixture of soy sterols, sitosterol, stigmasterol and traces of related compounds with Microbacteria sp. produces androstenedione (1-6). Relatively recent patents describe the production of the steroid from phytoserols from various crude vegetable oils, bypassing the need for prior isolation of the phytosterol fraction. 

To avoid the limitation of plant sources, several groups initiated studies of tissue culture from the TW plant as a source of triptolide 1. Kutney s group first studied TW tissue culture. The shake-flask and stirred fermenter batch cultures of TW cell tissue line TRP 4a grown on modified PRL-4 medium were harvested after 6 weeks. Cell cultures were extracted and separated by column chromatography. Compounds 1 and 2 were separated in yields that were 3 and 16 times greater, respectively than those observed in the plant itself. Additionally, dehydroabietic acid, celastrol, oleanoic acid, polpunonic acid, fl-sitosterol and other compounds were separated from the culture [104]. Zhu and his group cultivated tissue induced from TW leaves and stems, on the 67-v medium containing 0.1 mg/L, 2,4-D and 0.1 mg/L KT for 7 weeks. After separation of the cultivated material, the yield of 1, 2 and 4 was 12 times more than that in the plant (9.184 mg/L) [105]. 

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