FREE-RADICALS OF SHILAJIT HUMUS

The occurrence, structure and reactions of free radicals of shilajit h umus (humic, HAs; fulvic acids, FAs) are reported on the basis of spec troscopic analyses, chemical transformations, and synthesis. The stabi lity of the free radicals is ascribed to chelation with iron ions and intra-molecular donor-acceptor complex formation by condensed aromatic hemiquinone-semiquinone nuclei of the types (4a,b). Such resonance-st abilized species would find ecological niche in the mineral-rich micro pores of shilajit humus and would be protected from extranuous stresse s for a long period of time (residence time of shilajit on mountain ro cks). These soft spin free radicals act as scavangers of nitric oxide and hydroxyl radical in solution to give compounds 5 and 6 respectivel y. They sequester free/loosely bound iron ions from cytosols. The biol ogical significance of these findings is indicated.