Localization of plaunotol in the leaf of croton stellatopilosus Ohba

Abstract

Plaunotol, a well-known protective factor-enhancing agent isolated from the leaves of Cretan stellatopilosus Ohba (Thai name: Plau-Noi, known previously as Croton sublyratus Kurz), was shown to be accumulated in the chloroplasts of palisade mesophyll cells. This was confirmed by both detection of plaunotol in specific leaf tissues and examination of electron microscopic pictures of subcellular organelles of the plaunotol-containing tissue. The detection of plaunotol by a TLC-densitometric technique showed the presence of 95% of the plaunotol in the palisade cells and only about 5% in the spongy mesophyll cells. Inside the palisade mesophyll cells, the electron micrographs showed the presence of numerous oil globules in the chloroplasts. Since plaunotol is an acylic diterpenoid (C-20) and is nonpolar, it was suggested that the observed oil globules are sites of plaunotol accumulation.