Juliette Catherine Vardamides

A prenylated xanthone from Allanblackia floribunda.

A new prenylated xanthone, named allanxanthone A, was isolated from the stem bark of Allanblackia floribunda in addition to known compounds, 1,5-dihydoxyxanthone, 1,5,6-trihydroxy-3,7-dimethoxyxanthone, stigmasterol and stigmasteryl-3-O-beta-D-glucopyranoside. The structure of the new compound was assigned as 1,3,5-trihydroxy-2-(3-methylbut-2-enyl)-4-(1,1-dimethylprop-2-enyl) xanthone, by means of spectroscopic analysis. The 13C NMR spectral data of 1,5-dihydroxyxanthone is reported here for the first time as well as the in vitro cytotoxic activity of xanthone metabolites against the KB cell line.

Scaphopetalone and scaphopetalumate, a lignan and a triterpene ester from Scaphopetalum thonneri.

From the methanol extract of the stem bark of Scaphopetalum thonneri, two new compounds, including one lignan, named scaphopetalone, one new ester of ferulic acid, named scaphopetalumate were isolated together with three known compounds including: two coumarins (scopoletin and scopolin), and one pentacyclic triterpene (oleanolic acid). The structure of the new compounds were elucidated by means of spectroscopic analyses.

Antimicrobial and antileishmanial xanthones from the stem bark of Allanblackia gabonensis (Guttiferae)

The phytochemical study of stem bark of Allanblackia gabonensis has resulted in the isolation and characterisation of one new xanthone derivative, named allanxanthone D, together with 10 known compounds, including 6 xanthones derivatives, allanxanthone A, 1,5-dihydroxyxanthone, 1,7-dihydroxyxanthone and 1,3,6,7-tetrahydroxy-2-(3-methylbut-2-enyl)xanthone, forbexanthone, 6-deoxyisojacareubin, one polyisoprenylated benzophenone, guttiferone F, one flavanol, epicathechin, two phytosterols, beta-sitosterol and campesterol. The structures of these compounds were established on the basis of one- and two-dimensional NMR homo- and hetero-nuclear evidence. These compounds were evaluated for their activity against Leishmania amazonensis in vitro and antimicrobial activities against a range of Gram negative and Gram positive bacteria.

ANTIMICROBIAL AND ANTILEISHMANIAL XANTHONES FROM THE STEM BARK OF Allanblackia gabonensis

The phytochemical study of the stem bark of Allanblackia gabonensis has resulted in the isolation and characterization of one new xanthone derivative, named allanxanthone D, together with ten known compounds, including six xanthone derivatives, allanxanthone A, 1,5-dihydroxyxanthone, 1,7-dihydroxyxanthone and 1,3,6,7-tetrahydroxy-2-(3-methylbut-2-enyl)xanthone, forbexanthone, 6-deoxyisojacareubin, one polyisoprenylated benzophenone, guttiferone F, one flavanol, epicathechin, two phytosterols, β-sitosterol, and campesterol. The structures of these compounds were established on the basis of one- and two-dimensional NMR homo- and heteronuclear evidence. These compounds were evaluated for their activity against Leishmania amazonensis in vitro and antimicrobial activities against a range of Gram-negative and Gram-positive bacteria.

Urease inhibitory isoflavonoids from different parts of Calopogonium mucunoides (Fabaceae)

The dichloromethane-methanol (1:1) soluble part of Calopogonium mucunoides (Fabaceae) resulted in the isolation of 10 isoflavones (4′-O-methylalpinumisoflavone, 4′-O-methylderrone, alpinumisoflavone, daidzeine, Calopogonium isoflavone A, atalantoflavone, 2′,4′,5′,7-tetramethoxyisoflavone, 7-O-methylcuneantin, cabreuvin and 7-O-methylpseudobaptigenin) and a rotenoid (6a,12a-dehydroxydegueline). Among these, daidzeine, 7-O-methylcuneantin, atalantoflavone and 6a, 12a-dehydroxydegueline have been isolated for the first time from C. mucunoides while remaining are already reported from this source. Structures of all the isolated constituents were elucidated with the aid of NMR spectroscopic and mass spectrometric techniques. Among all the isolated constituents, nine were evaluated for their urease inhibitory potential. However, six were found potent. These include 4′-O-methylderrone, daidzeine, atalantoflavone, 2′,4′,5′,7-tetramethoxyisoflavone, 7-O-methylcuneantin and 6a, 12a-dehydroxydegueline.

Anticoccidial constituents from the stem bark of Turraeanthus africanus

In order to study some biological active products, phytochemical investigation of the stem bark of Turraeanthus africanus have led to the isolation of a novel compound 1, a new benzoic acid derivative, named turraeanthin C, and two known compounds sesamin (2) and stigmasterol. The structures of these compounds were established by spectral analysis, including two-dimensional nuclear magnetic resonance. The extract and the isolated compounds 1 and 2 showed noteworthy activity against Toxoplasma gondii intracellular parasite in mammals.

Sesquiterpene lactones from Crepis cameroonica (Asteraceae).

In addition to one known compound, 3β,8α-dihydroxyguaian-4(15),10(14),11(13)-trien-6,12 olide (8-desacylcynaropicrin) (3), two new sesquiterpene lactones have been isolated from the aerial parts of Crepis cameroonica. By means of spectroscopic analysis, the structures and relative configurations of the new compounds were established as 3β,9β-dihydroxyguaian-4(15),10(14),11(13)-trien-6,12 olide (1) and 8α-hydroxy-4α(13),11β(15)-tetrahydrozaluzanin C (2). The in vitro antimicrobial spectrum of pure compounds and crude extracts are also reported.

Diterpenoid and limonoids from the stem of Pterorhachis zenkeri

One new diterpenoid, methyl 3alpha-hydroxy-7-oxo-dehydroabietate (1), two new limonoids, 3alpha-deacetyl-amoorastatin (2) and 9beta-amoorastatin (3), and the known limonoid amoorastatin (4) were isolated from the stem of Pterorhachis zenkeri.

Antiplasmodial activity of some phenolic compounds from Cameroonians Allanblackia

BACKGROUND Plasmodium falciparum, one of the causative agents of malaria, has high adaptability through mutation and is resistant to many types of anti-malarial drugs. This study presents an in vitro assessment of the antiplasmodial activity of some phenolic compounds isolated from plants of the genus Allanblackia. METHODS Tests were performed on well plates filled with a fixed parasitized erythrocytes volume. Compounds to be tested were then added in wells. After incubation, tritiated hypoxanthine is added and the plates were returned to the incubator. After thawing, the nucleic acids are collected. Inhibitory Concentration 50 (IC50) was determined by linear interpolation. RESULTS From Allanblackia floribunda, have been isolated and characterized 1,7-dihydroxyxanthone 1, macluraxanthone 4, morelloflavone 9, Volkensiflavone 10 and morelloflavone 7-O-glucoside 11; from Allanblackia monticola, α-mangosine 2, rubraxanthone 3, allaxanthone C 5, norcowanine 6, tovophiline A 7, allaxanthone B 8 and from Allanblackia gabonensis, 1,7-dihydroxyxanthone 1. Six of them were evaluated for their antimalarial properties. The most active compound, macluraxanthone, presented a very interesting activity, with an IC50 of 0.36 and 0.27 µg/mL with the F32 and FcM29 strains respectively. CONCLUSION This work confirms that species of Allanblackia genus are medicinally important plants containing many biologically active compounds that can be used effectively as antiplasmodial.

Conocarpol, a new cycloartane triterpenoid from Diospyros conocarpa

Abstract A new cycloartane triterpenoid named conocarpol (1) was isolated from the stem bark of Diospyros conocarpa, together with the known compounds aridanin (2), lupeol (3), betulin (4), betulinic acid (5), stigmasterol (6), and stigmasterol 3-O-β-d-glucopyranoside (7). Their structures were established on the basis of 1D and 2D NMR spectroscopy as well as mass spectrometry. Aridanin (2) is reported for the first time in the family Ebenaceae, and conocarpol (1) represents the first cycloartane triterpene within this family.