Dihydric phenolic lipids urushiol type

ABSTRACT This review is concerned with non-isoprenoid phenolic lipids typified by compounds biosynthesised by the polyketide pathway. Botanical, biological and entomological sources of such phenolic lipids are described which contain monohydric phenols, notably cardanol and relatives, dihydric phenols such as cardols, alk(en)ylresorcinols,urushiols and phenolic acids, particularly anacardic acids. Some recently investigated mixed types of dihydric phenolic lipids are included. Separatory methods are briefly reviewed. Synthetic methods for the saturated and unsaturated members of the three main classes of interest in structure/activity studies are summarised. Biological properties of members of the three main classes are given and discussed. 

Dihydric phenolic lipids are the most abundant phenolic lipids. They are of the cardol-or urushio 1-type, i.e. with hydroxyl groups in the metha position (1,3-dihydroxy) or in the ortho (1,2-dihydroxy) position respectively. Urushiol-type, dihydroxy phenolic lipids, are practically restricted to the Anacardiaceae family (Rhus genus) of poisonous plants. The most well-known are poison ivy, poison oak and the Indian marking nut. The sap from various plants belonging to Anacardiaceae from which Japanese, Chinese, Burmese, Formosan and Vietnamese lacs is one of the richest source of these phenols. The occurrence of dihydric phenolic lipid of the urushiol type is depicted in Table 3. 

Table 3. Occurrence of dihydric phenolic lipids of the urushiol type...

Fig. (3). Structures of known dihydric phenolic lipids Of urushiol (1,2-dihydroxy) type...

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