Constituents of twig bark of pear cultivars (Pyrus species).

Organic solvent extracts from fresh twig bark of Japanese pear cultivars (Pyrus serotina) Shinko and Nijisseiki, and European pear cultivar (P. communis) Le Lectier were obtained by maceration with n-hexane and EtOAc, and analyzed in GC-EIMS experiments. In these two Japanese cultivars, the lupeol, betulin, epifriedelinol, friedelin and arbutin contents of Nijisseiki were higher than those of Shinko.