Structure of lithocarpic lactone, a new triterpenoid from two Lithocarpus species of Hong Kong

Abstract

By (Miss) Wai-Haan Hui," Man Moon Li, and (in part) (Miss) Yuk-Chun Lee, Department of Chemistry, Lithocarpic lactone. a new triterpenoid isolated from the leaves of both Lithocarpus lifchioides Chun and L. irwinii (Hance) Rehd. has been shown to be 2,3-secofriedelano-3,2-lactone (I).

Synthetic Secofriedelane and Friedelane Derivatives as Inhibitors of Human Lymphocyte Proliferation and Growth of Human Cancer Cell Lines in Vitro

“…(Fagaceae). 27 An anomalous oxidation had already been observed in the ozonization of a hindered enol silyl ether. 28 Compound 7 was characterized by 1 H and 13 C NMR data (Tables 1 and 2) and by comparison with an authentic sample obtained by reduction of cerin (5) with sodium borohydride.…”

“…Attempts to cleave ring-A of 3 by reductive ozonolysis did not give the expected 2,3-secofriedelane derivative, giving instead 2 α ,3 β -dihydroxyfriedelane ( 7 ), pachysandiol-A, previously isolated from Pachysandra terminalis Sieb et Zucc (Buxaceae) and from leaves of Lithocarpus sp. (Fagaceae) . An anomalous oxidation had already been observed in the ozonization of a hindered enol silyl ether .…”

“…In particular, 2R,3β-dihydroxyfriedelane ( 7) is made available as a starting material for the production of known secofriedelane derivatives. 5,27 The inhibitory activity of the 11 compounds against the in vitro proliferation of human lymphocytes was examined. Phytohemaglutinin was used as a T-mitogen.…”

“…The reactive silyl enol ether 3 is a convenient intermediate for the synthesis of a variety of friedelane derivatives. In particular, 2 α ,3 β -dihydroxyfriedelane ( 7 ) is made available as a starting material for the production of known secofriedelane derivatives. , …”

Investigations on Leaf Waxes Iii* Pentacyclic Triterpenes, Seco-Triterpenes and Non-Volatile Aliphatics of Four Hoya Species and Ficus Benjamina in Relation to Leaf Age

“…Seeo-triterpenoids have been found in almost all aerial parts of higher plants, e.g. in the wax covering fruit peel (LANTZ & WOLF 1968) and galls (MANGONI & BELARDINI 1963, 1964, in flowers (HIRATA et al 1977a, b;SUGA & HIRATA 1979, SUGA et al 1977, in resins (MILLS & WERNER 1955, ARIGONI et al 1960), in wood (CROWLEY 1962, RAO et al 1975), bark (AOYAGI, MORIYAMAet al 1973, PRADHAN & KHASTGIR 1973), stem (KIKUCHI & YOSHIKOSHI 1972 and in leaves (GOVINDACHARI et al 1968, CHOPRA et al 1968, 1969, 1970HUI et al 1975).…”