G. B. Marini Bettolo

Research on African medicinal plants—II: Hypoxoside, a new glycoside of uncommon structure from hypoxis obtusa busch☆

Abstract A new glycoside, hypoxoside, was isolated from rhizome of Hypoxis obtusa , a plant used in Mozambique in native medicine for the treatment of urinary diseases. The structure 1 of a diglycoside of 1-(3′,4′-dihydroxyphenyl)-5-(3″,4″-dihydroxyphenyl)-1-penten-4-yne was attributed to hypoxoside on the basis of physico-chemical determinations and chemical behaviour.

Insect antifeedant activity associated with compounds isolated from species ofLonchocarpus andTephrosia.

The antifeedant activity of a series of 21 chalcones, flavanes, and flavanones isolated from the generaLonchocarpus andTephrosia (Leguminosae) was assessed by behavioral and electrophysiological bioassays against larvae ofSpodoptera littoralis andS. exempta. The antifeedant activity is related to the molecular structure of the compounds, and possible modes of interaction with the insect taste receptors are discussed.

Xanthones, xanthonolignoids and other constituents of the roots of vismia guaramirangae

Abstract A new prenylated benzophenone, vismiaphenone C, has been isolated from the root bark of Vismia guaramirangae together with the known vismiaphenone A, chrysophanic acid, γ-hydroxyferruginin A and γ-anthrone A 3 . The woody part of the roots has been shown to contain 10 xanthones, three xanthonolignoids and syringaresinol. Three of the xanthones and one of the xanthonolignoids are described for the first time. The co-occurrence of xanthones, xanthonolignoids and syringaresinol is of biogenetic significance.

A pyrano-isoflavone from seeds of Milletia thonningii

Abstract Extraction of the seeds of Milletia thonningii gave alpinumisoflavone, its monomethyl and dimethyl derivatives, robustic acid and a new pyrano-isoflavone. The structure of the latter was established by chemical transformation and spectroscopic means.

Vismione H and prenylated xanthones from vismia guineensis

Abstract The root bark of Vismia guineensis , collected on the Ivory Coast, contained the known geranyloxyemodin, geranyloxyemodin anthrone, madagascin anthrone, bianthrone A 1 and five new compounds: vismione H and the prenylated xanthones V 1 , V 2 , V 1a and V 2a .

Prenylated bianthrones and vismione F from Psorospermum febrifugum

Abstract The roots of Psorospermum febrifugum collected in Malawi contained together with the known vismione D and geranyloxyemodin four new compounds: vismione F and the three bianthrones A 1 , A 3a and A 3b . All the isolated compounds contained C- or O-geranyl substituents and showed a close biogenetic relationship.

Cyclohexanols of Halleria lucida

Abstract From the stems of Halleria lucida a new 1,4-yclohexandiol, a tranS -1-(2′-hydroxyethyl)cyclohexan-1,4-diol named isorengyol, together with the known cis isomer rengyol, was isolated. The leaves of the same plant contain acteoside, rutin, luteolin-5- O -glucoside and a 4-hydroxy-4-(2′-hydroxyethyl)cyclohexanone, of which the hemiketalic tautomer has recently been described.

p-Hydroxybenzaldehyde as a major constituent of the epicuticular wax of seedling Sorghum bicolor

Abstract p-Hydroxybenzaldehyde is present in concentrations up to 30% in the wax of Sorghum bicolor seedlings. It is highly deterrent to locusts, reducing their normal feeding by 90%.

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.

2-Isoprenylemodin and 5,5′-dimethoxysesamin from vismia guaramirangae

Abstract The secondary metabolises γ-hydroxyferruginin A, madagascin, chrysophanic acid, physcion, β-caryophyllene, humulene, sitosterol, sesamin and a rare triterpene, dammaradienol were isolated from the bark and exudate of Vismia guaramirangae . The structures of a new anthraquinone, 2-isoprenylemodin, and of a new lignan, 5,5′-dimethoxysesamin, were established on the basis of chemical and spectroscopic evidence.