758. West African timbers. Part III. Petroleum extracts from the genus Entandrophragma

Abstract

As part of a phytochemical survey of the family Meliaceae, heartwood timber of the four species of the W7est African genus Entandrophragma has been examined. Light-petroleum extraction of all gave " @ "-sitosterol, and four new and apparently related substances have been isolated. The distribution of these within the genus is described.THE relation of plant chemistry to phylogeny has attracted interest for many years.lY2 The heartwood chemistry of the broad-leaved trees of the division Angiospermae has, except for the genus P t e r o~a " J P z t s ,~~~ been little investigated from this point of view. The family Meliacae contains many species of commercial value, and yields various woods known as " mahogany." The genus Entandrophragma, limited to four West African ~pecies,~ is at present one of the common sources of this type of timber. Authentic specimens of these four species have been obtained by the courtesy of the Forestry Research Department, Ibadan, and the extraction of each with light petroleum has been examined.furnishing a valuable timber known as '( gedunohor." Authentic specimens of this gave " @ "-sitosterol and either an unsaturated lactone, double m. p. 157"/218", [aID2O -M", which we name gedunin, or a methyl ester, m. p. 197", In no case were both of these found in the same specimen. It has not yet been possible to correlate botanical and chemical variation in this species.E. candoleii is not common in trade. The wood is denser than water, being locally known as " sapele wood-sinker." The only crystalline material obtained from the specimen examined was '( p "-sitosterol.E. cylindricurn, the most important commercial species, furnishes the wood known as " sapele mahogany,'' much used in the manufacture of plywood. It is distinguished by a fragrant smell and yields a volatile oil on steam-distillation. Extraction gave '( ',sitosterol and a crystalline lactone, m. p. 241", [aID2O -4", which we name entandrophragmin.E. utile, which has a softer timber, gave with light petroleum (' p "-sitosterol, entandrophragmin, and a fourth lactone, utilin, m. p. 278", [aID2O -355.5".Further extraction of the wood with acetone then gave methyl angolensate.Analyses of gedunin agree with the formula C2,H34, ,,O,,QCH,*OH, supported by an X-ray molecular-weight determination of the dihydro-derivative which crystallises without solvent. The absorption spectrum suggests the presence of ester or lactone groups. Absorption bands at 1500 and 875 cm.-l may be due to the presence of a furan ring, also indicated6 by nuclear magnetic resonance absorption at -70 and -95 C.P.S. Steam-distillation in the presence of alkali gave furan-3-aldehyde.Methyl angolensate, C2,H2,05,+H20 gave an infrared spectrum indicating the presence of a lactone and an ester, and bands referable to a furan ring, as in gedunin. Alkaline E. angolense is a botanically variable species -43", which we name methyl angolensate. (12 kg.) gave an extract (43 g.) which partly crystallised. The solid fraction crystallised from ethanol to give utilin (7 g.), m. ...

Spasmolytic Activity of Methyl Angolensate. A Triterpenoid Isolated from Entandrophragma angolense.

“…The charcoal meal test, allows for comparative evaluation of the degree of inhibition or stimulation of gastrointestinal mobility in laboratory animals. 15) Our findings showed that methyl angolensate reduced gastrointestinal transit in mice agreeing with some of the results of in vitro studies in which the extract relaxed the gastrointestinal smooth muscles. It is therefore possible that these properties of methyl angolensate may contribute to the overall effects of the plant in humans.…”

“…15) There are no reports in the literature on the direct effects of methyl angolensate on the gastrointestinal smooth muscles and gastrointestinal transit time in mice. In this report, we present the results of the effects of methyl angolensate on these isolated smooth muscle preparations and suggest a possible mechanism of action.…”

Tirucallane triterpenes from the leaf extract of Entandrophragma angolense

“…The limonoids gedunin (Akisanya et al, 1960) and the ring B-seco methyl angolensate (Bevan et al, 1967) were previously isolated from the stem and root extracts of E. angolense thus giving a clear distinction from the protolimonoids entandrolide, contained in the seeds, and these new, identified in the leaves. Our investigation of a Nigerian specimen of E. angolense, also suggests a chemotaxonomic differentiation within this genus.…”

“…E. angolense is used in Western Nigeria as an antimalarial and as an antiulcer (Njar et al, 1995) in ethnomedicine. The meliacins (limonoids) hitherto isolated from E. angolense are gedunin (Akisanya et al, 1960) and methyl angolensate (Bevan et al, 1967) from the stem wood and bark as well as from the root (Orisadipe et al, unpublished work). Gedunin has been shown in vitro to possess antimalarial activities (Bray et al, 1990;MacKinnon et al, 1997).…”

Behavioural Effects in Rodents of Methyl Angolensate: a Triterpenoid Isolated from Entandrophragma angolense*

“…There has been no change in the general opinion of Pharmacology & Toxicology that for ethical reasons LD50 should not be used to document effects (Letter from the Editor 1995Editor & 1997Svendsen et al 1997;Notice to contributors 2002 have recently been reported (Orisadipe et al 2000). Other compounds isolated from E.angolense include entandrolide (Okorie & Taylor 1977), gedunin and b-sitosterol (Akisanya et al 1960). There are no reports in literature on the behavioural effects of methyl angolensate so we decided to study the behavioural effects of methyl angolensate on spontaneous motor activity, exploratory activity, pentobarbital induced sleep, amphetamine-induced stereotype behaviour and apomorphine-induced climbing in mice.…”