Stem bark of Allanblackia monticola has been used in association with others plant in the Cameroonian folk medicine for the treatment of various diseases such amoebic dysentery, diarrhoea, lung infections, and skin diseases. The methylene chloride fraction, its isolated compounds like alpha-mangostin, lupeol and acid betulinic were screened for antioxidant activity using free radical scavenging method. These isolated compounds were further tested for anti-inflammatory properties using carrageenan-induced model. Methylene chloride fraction, showed concentration-dependent radical scavenging activity, by inhibiting 1,1-diphenyl-1-picryl-hydrazyl radical (DPPH) with an IC(50) value of 14.60 microg/ml. alpha-Mangostin and betulinic acid (500 microg/ml), showed weak radical scavenging activity with a maximum inhibition reaching 38.07 microg/ml and 26.38 microg/ml, respectively. Betulinic acid, lupeol and alpha-mangostin (5 mg/kg and 9.37 mg/kg) showed anti-inflammatory activity with a maximum inhibition of 57.89%, 57.14% and 38.70%, respectively. Methylene chloride fraction of Allanblackia monticola and some derivatives, have antioxidant and anti-inflammatory activities.

There has been a recent increase in the research efforts on secondary metabolites of the genus Allanblackia.1-3) Our interest was stimulated by the fact that, many of the secondary metabolites from this genus such as xanthones, biflavonoids, benzophenones and pentacyclic triterpenes exhibited a wide range of biological and pharmacological activities, including cytotoxic, anti-inflammatory, antimicrobial, antifungal and HIV inhibitory activities.2,4,5) Allanblackia monticola STANER L.C., which belongs to the plant family Clusiaceae, is a large forest tree found throughout the west and south province of Cameroon, where it is used as medicinal plant to treat several diseases including, respiratory infections, diarrhoea and toothache. 6) In a previous paper, we have reported the isolation and structural elucidation of a novel polyisoprenylated xanthone, allanxanthone B, along with the known compounds: tovophyllin A, rubraxanthone, garciniafuran, lupeol and stigmasterol from the CH 2 Cl 2 -MeOH (1 : 1) extract of the stem bark of this plant. 7) In the present paper, we report the isolation and characterization of seven compounds isolated from the MeOH extract of this plant, including a new triprenylated xanthenedione, designated allanxanthone C (1), together with the known compounds norcowanin (2), 8) mangostin (3), 9) tovophyllin A (5), 10) garciniafuran (6), 11) rubraxanthone (7) 12) and stigmasterol-3-O-b-D-glucopyranoside (4).13) The structure of known compounds were identified from their spectral data and confirmed by comparison with those published in the literature. We also report on the antiplasmodial, cytotoxic and antimicrobial activities of the methanol extract and some isolated compounds.Extensive column chromatography of a methanol extract of the stem bark of A. monticola led to the isolation allanxanthone C (1).Allanxanthone C (1) was obtained as a sticky yellow oil. It reacts positively to ferric chloride test, suggesting the presence of a phenolic groups. Its molecular formula, C 28 H 32 O 6 , was deduced from the high resolution Electro Spray Ionisation-Time of Flight (ESI-TOF) mass spectrometry which showed the pseudomolecular ion [MϩH] ϩ at m/z 465.5545 (Calcd for 465.5580). The IR spectrum of 1 confirmed the presence of phenolic group (3350 cm Ϫ1 ) and suggested the presence of conjugated carbonyl group (1674 cm Ϫ1) and xanthone carbonyl group (1643 cm Ϫ1).14) The 1 H-NMR and Heteronuclear Single Quantum Coherence (HSQC) spectra of allanxanthone C (1) showed the presence of a hydrogenbonded hydroxyl at d 13.50 (1H, s, 8-OH) and two singlet protons at d 6.55 (1H, s, H-4) and d 6.45 (1H, s, H-5), d 109.5 (d, C-4) and 93.5 (d, C-5). The presence of a set of signals at d 4.74 (2H, t, Jϭ7.6 Hz, H-2Љ), 3.43 (2H, dd, Jϭ7.60, 13.6 Hz, H-1Љ), 2.73 (2H, dd, Jϭ7.6, 13.6 Hz, H-1Љ) and 1.47 (12H, s) was typical of a gem bis(3-methylbut-2-enyl) groups linked to a sp 3 carbon atom (d 56.9, C-1). Further study of the methanol extract of the stem bark of Allanblackia monticola STANER L.C. resulted in the isolati...

IntroductionThere is emerging interest in medicinal plants in the biomedical field, due to their multitude of chemicals which show anti-inflammatory, antimicrobial, antiviral, or antitumoral potential. Research on medicinal plants has shown that nanotechnology could offer new solutions in the quality control, delivery aspects, or in sustaining herbal biological activities. This work reports on the preparation and characterization of silver nanoparticle-mediated Selaginella myosurus plant extract.MethodsUltraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy, and selected area electron diffraction have been used to characterize the prepared silver nanoparticles. The synthetic stability was studied by varying concentrations and pH of reactants. Egg albumin denaturation and carrageenan-induced rat paw edema model were used to ascertain the anti-inflammation.ResultsUltraviolet-visible spectroscopy gave plasmon resonance ranging between 420 and 480 nm while Fourier transform infrared spectroscopy proved nano interface functionalized with organics. The powder X-ray diffraction pattern is in agreement with silver and silver chloride nanoparticles of crystallite size 33.7 nm and 44.2 nm for silver and silver chloride, respectively. Energy dispersive X-ray spectroscopy enables elemental characterization of the particles consisting of silver and silver chloride among main elements. Spherical silver grain of 58.81 nm average size has been depicted with high-resolution scanning electron microscopy and high-resolution transmission electron microscopy. Inhibitions of 99% and 60% were obtained in vitro and in vivo, respectively.ConclusionThe albumin denaturation and carrageenan-induced rat hind paw edema model to assess the anti-inflammatory potential of generated nanoparticles suggests that the silver nanoparticles may act as reducing/inhibiting agents on the release of acute inflammatory mediators. Hence, this work clearly demonstrated that silver nanoparticles mediated-Selaginella myosurus could be considered as a potential source for anti-inflammatory drugs.

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.

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