Cyclitols from Croton celtidifolius

Croton celtidifolius has been found to contain 1l-1-O-methyl-myo-inositol, neo-inositol and sitosterol. Structure of 1l-1-O-methyl-myo-inositol pentaacetate, elaborated by NMR decoupling technique, is described.     

The identification of cholesterol and other steroids in Euphorbia pulcherimma

The 4-desmethyl tetracycles of the whole poinsettia plant (Euphorbia pulcherimma) less roots amounted to 0.07% of the wet wt and were shown by ¹H NMR spectroscopy to be steroids and not euphoids. The most abundant component was cholesterol, constituting half the mixture, followed in order of decreasing concentration by 24α-ethylcholesterol (sitosterol), 24α-methylcholesterol (campesterol) and 24β-methylcholesterol (22-dihydrobrassicasterol). The relative amount of cholesterol in this plant is the highest found so far in a tracheophyte. The 4,4-dimethyl compounds (0.1% of wet wt) included lanosterol (5%), 24-dihydrolansterol (5%), β-amyrin (25%), germanicol (50%), an unidentified pentacyclic triterpenoid (8%) and two or more (7%) unidentified components. Both the 4,4-dimethyl- and the 4-desmethylsterols were in the configurational series with a 20α-H-atom. Dihydrolanosterol and lanosterol are the probable intermediates from cycloartenol to cholesterol and 24-alkylcholesterol, respectively. Such a sequence would differ from that operating in most angiosperms, where the alkylation is thought to precede the opening of the 9,19-cyclopropane ring.     

Phorbol esters as probes of the modulatory site on protein kinase G–an overview

Phorbol esters as probes of the modulatory site on protein kinase C–an overview. The phorbol esters, diterpene derivatives produced by members of the family Euphorbiaceae, are of major scientific importance as tumour promoters. Their primary site of action is protein kinase C, an enzyme involved in the message transduction pathway for a large class of hormones which cause enhanced phosphatidylinositol turnover. Heterogeneity in the response of biological systems to the phorbol esters may be explained in part by heterogeneity in the phospholipids associated with protein kinase C, in its subcellular localization, and by proteolytic processing, as well as by isoforms of the enzyme. Development of other classes of activators of protein kinase C through computer modelling and natural product isolation suggests possible new approaches for intervention in the pathway.     

Naringenin coumaroylglucosides from Mabea caudata

The fruits of Mabea caudata contain, besides 5,7,4′-trihydroxyflavanone (naringenin), naringenin 7-O-β-(3,6-di-p-coumaroylglucoside) and naringenin 7-O-β-(3-p-coumaroylglucoside).     

Geniculatin,a triterpenoid saponin from Euphorbia geniculata

A new triterpenoid saponin, geniculatin, has been isolated from the ethanolic extract of Euphorbia geniculata (Euphorbiaceae). The saponin has been identified as 3β-[L-rhamnopyranosyl-(1→4)-D-xylopyranosyl-(1→4)-D-β-glucoronopyranosyl-(1→3)]-oxyolean-12-en-28-oic acid.     

(2S)-Prenylflavanones and taraxerane triterpenoids from Mallotus mollissimus

Three prenylflavanones, (2S)-5,7-dihydroxy-4′-methoxy-8-(3″,3″-dimethylallyl)flavanone (3), (2S)-5,4′-dihydroxy-7-methoxy-6-(3″,3″-dimethylallyl)flavanone (6), 8-prenylnaringenin (11), and a new epimeric pair (2″S/2″R)-(2S)-5,7-dihydroxy-4′-methoxy-6-(2″-hydroxy-3″-methylbut-3″-enyl)flavanones (4a/4b) were isolated together with taraxerone, taraxerol, epitaraxerol, β-sitosterol, oleanolic acid, 1-O-docosanoyl glycerol, apigenin, and apigenin 7-O-β-D-glucopyranoside from the MeOH extract of the leaves of Mallotus mollissimus. The structures of the isolated compounds were determined on the basis of 1D/2D NMR and HR-MS spectroscopic data; the 2S configuration of the prenylflavanones 3, 4, and 6 was deduced from CD spectroscopic data. The presence of three taraxerane triterpenoids reinforces the inclusion of M. mollissimus (syn. Croton mollissimus) in Mallotus genus. Among species of Mallotus the occurrence of the (2S)-prenylflavanones 3, 4, and 6 is confined to M. mollissimus.     

A Revision of Chinese Phyllanthus (Euphorbiaceae)

The present paper is the outcome of a taxonomic study of Chinese Phyllanthus plants in our flora. Phyllanthus is one of the largest genera in Euphorbiaceae, and is distributed in whole China except for the northwest, extending from 92° to 124° E and 18° to 41°N. It includes 6 subgenera, 7 sections, 33 species and 4 varieties, of which 1 subgenus and 5 species are described as new, and 1 new name and 9 synonyms are proposed.     

A flavanone glycoside from seeds of Sapium sebiferum

The isolation and identification of a new glycoside, eriodictyol 5-O-methyl ether 7-O-β-D-xylopyranosyl-β-D-arabinopyranoside, from seeds of Sapium sebiferum is reported.     

New hydroxy fatty acid from seed oil of Baliospermum axillare

A fatty acid, found as a minor component in the seed oil of Baliospermum axillare, is shown to be the hitherto unknown 11,13-dihydroxytetracos-trans-9-enoic acid (axillarenic acid).     

Embryology and systematics of Euphorbiaceaesens. lat.: a review and perspective

Based on a literature survey, we present a review of the embryology of Euphorbiaceaesensu Webster (with about 8,000 species in five subfamilies), which are one of the largest and most diversified families and have often been considered heterogenous. Nearly 40% of over 110 publications available for the whole family is concerned with a single genusEuphorbia, so that the current level of our knowledge on the embryology of Euphorbiaceae is very poor. Nevertheless we found that, contrary to a conclusion recently published by other authors, available information does not provide evidence to support a monophyly of Euphorbiaceae. Our analysis further suggested that only the following five of over 50 embryological characters of ovules and seeds are likely to be useful for comparison between and within subfamilies: (1) the presence or absence of vascular bundles in the inner integument; (2) whether the inner integument is thick or thin (probably useful only in Phyllanthoideae); (3) whether ovules or seeds are pachychalazal or not; (4) whether seeds are arillate or not; (5) whether an exotegmen is fibrous or not. On the basis of these five characters, a consistency and diversity of individual subfamilies was discussed. The need of further extensive studies on the five characters using herbarium specimens, particularly in genera of Phyllanthoideae, Oldfieldioideae and Acalyphoideae, was also discussed.