Transformation of wood industry waste into key intermediates for pharmaceutical substances: Biotechnological study

Selective microbial conversion of plant sterols allows direct production of 9α-hydroxyandrost-4-ene-3,17-dione (9-OH-AD), a key intermediate in the synthesis of important pharmaceutical substances from the steroid glucocorticoid group. As substrates for bioconversion, sterol-enriched wastes of local pulp-and-paper industry, particularly, unsaponifiable tall pitch residue and its derivatives can be used. A series of simple and effective one- or two-stage fractionation procedures yielded the derivatives containing 51–88 wt % of convertible sterols. The analysis of the bioconversion dynamics of the sterol-enriched samples demonstrated that while the 9-OH-AD accumulation rates were 2–2.5 times lower than with commercial phytosterol, acceptable molar yields of 53–57% of the product were obtained. The obtained results make it possible to optimize the technological chain starting from the primary products of processing of renewable raw materials (by-products of wood processing) and ending with the desired steroid pharmaceutical substances via 9-OH-AD.