摘要：

This article comprises part of a chapter from a monograph on phytochemistry. Lichen substances, the metabolic products of lichens, are classified into 19 categories. Isolation and purification methods are generally described; rapid qualitative chemical analysis can be done using thalline reactions (some color reactions with potassium hydroxide, sodium hypochlorite, and p- phenylenediamine are tabulated), thin layer chromatography (TLC), or study of the morphology of crystallized organic extracts using light microscopy (LM). Some lichens can be distinguished under ultraviolet light (UV). Extraction with organic solvents or water (for polysaccharides) is used for isolation; elementary column chromatography methods (CC) are described. Structural elucidation can be done using paper chromatography (PC) and thin-layer chromatography (TLC). Paper chromatography RF values are tabulated for 19 depsides, 12 depsidones, 2 quinones, 5 pulvinic acid derivatives, and 1 debenzofuran derivative in different solvent systems. Instrumental analysis methods outlined are gas chromatography (GC of zeorin) and infrared spectroscopy (some typical IRS absorptions are tabulated for gamma-lactonic acid derivatives, for monobasic, dibasic, and tribasic fatty acids and triterpenes).

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