Microcrystallization method use for assessing the content of secondary metabolites of lichens

The paper presents photographs of crystals of fumarprotocetraric, evernic, usninic, solorinic, olivetoric, perlatolinic, physodalic, salazinic, tamnolic acids and atranorin obtained from their acetone extracts of lichens. The shape of the crystals is specific to each substance, and their number, size and degree of aggregation depend on the concentration in the solution. Stellate crystals have atranorine, salazinic and evernic acids, with atranorine having the largest and salacic acid having the smallest; rod–shaped branched crystals form solorinic and fumarprotocetraric acids, wider in the first, but longer in the second; the oval shape of crystals in the larger tamnolic and small and narrow perlatolinic acid; usnic, physodalic and olivetoric acids form unique crystal forms – prismatic, needle branched and pinnate, respectively. It is possible to observe crystals of secondary metabolites of lichens with a conventional light microscope under a ×40 lens without immersion oil. For the subsequent comparative assessment of the amount of substances, it is necessary to standardize the suspension of the studied lichen thallus, use a strictly fixed volume of acetone, view at least four sides of the dried drop on the slide and identify their total number in points, noting the presence, degree of branching and aggregation of crystals into conglomerates.