Morphological study and alkaloidal analysis of Uncaria scandens (Ribiaceae) from Nepal

Hooks with short stems of Uncaria spp. of the family Rubiaceae are called Diao-teng-gou, and have been used in Chinese medicine. The alkaloids contained are considered to be its effective components. Anatomical studies of the small stems of U. scandens and of U. sessilifructus Roxb. showed that the botanical origin of the hooks with short stems collected in the Far West of Nepal was U. scandens (Smith) Hutch. The anatomical diagnostics of the two species were as follows; U. scandens had hairy epidermis, smooth cuticle and no cortical sclerenchyma cell, whereas U. sessilifructus had few short hairs, dented cuticle and many cortical sclerenchyma cells. The alkaloids contained in the materials from the Far West of Nepal were of oxindole type, such as pteropodine, isopteropodine, uncarine P and speciophilline. Chinese Diao-teng-gou from Guizhou Prov. of China was morphologically determined as a mixture of the hooks of U. rhynchophylla and U. lancifolia. U. rhynchophylla contained alkaloids such as geissoschizine methyl ether, hirusteine and hirsutine, (a previous report gave different results), whereas U. lancifolia contained isomitraphylline as its single major alkaloid. The result of this study shows marked variations in the alkaloid profiles in the hooks of the plants of this genus.