Biotransformation of 3-hydroxydibenzo-α-pyrone into 3,8 dihydroxydibenzo-α-pyrone and aminoacyl conjugates by Aspergillus niger   isolated from native

"Shilajit" is a panacea in Ayurveda, the Indian traditional system of medicine. The major bioactives of "shilajit" have been identified as dibenzo-α-pyrones (DBPs), its oligomers and aminoacyl conjugated derivatives. These bioactive compounds play a crucial role in energy metabolism in all animal cells including those of man. 3-hydroxydibenzo-α-pyrone (3-OH-DBP), a key DBP component of "shilajit" is converted, among other products, to another active DBP derivative, viz. 3,8-hydroxydibenzo-α-pyrone, 3,8(OH)2-DBP, in vivo, when its precursor is ingested. 3,8(OH)2-DBP is then involved in energy synthesis in the mitochondria in the reduction and stabilization of coenzyme Q10 in the electron transport chain. As the chemical synthesis of 3,8(OH)2-DBP is a complex, multi-step process and economically not readily viable, we envisioned the development of a process using microorganisms for bioconversion of 3-OH-DBP to 3,8(OH)2-DBP. In this study, the biotransformation of 3-OH-DBP is achieved using Aspergillus niger, which was involved in the humification process on sedimentary rocks leading to "shilajit" formation. A 60% bioconversion of 3-OH-DBP to 3,8(OH)2-DBP and to its aminoacyl derivatives was achieved. The products were characterized and estimated by high performance liquid chromatography (HPLC), high performance flash chromatography (HPFC) and gas chromatography-mass spectrometry (GC-MS) analyses. Among the Aspergillus species isolated and identified from native "shilajit", A. niger was found to be the most efficient for this bioconversion.

Keywords
Coenzyme Q10 reduction, electron transport chain humification, paleohumus.