In Vitro Antiplasmodial Activity and Cytotoxicity of Extracts of Selected Medicinal Plants Used by Traditional Healers of Western Cameroon

Medicinal plants play a key role in malaria control in Africa, especially in remote areas where health facilities are limited. In order to assess their acclaimed potentials, eleven extracts were prepared from seven selected plants commonly used in Western Cameroon, and tested both for their antiplasmodial activity and cytotoxicity. The antiplasmodial activity was assessed using Lactate Dehydrogenase Assay (pLDH) and the cytotoxicity estimated on LLC-MK2 monkey kidney epithelial cells. Seven extracts from five different plants were significantly active, with very weak or no cytotoxicity. The Dacryodes edulis leaves showed the highest activity (IC50 of 6.45 μg/mL on 3D7 and 8.2 μg/mL on DD2) followed by the leaves of Vernonia amygdalina (IC50 of 8.72 and 11.27 μg/mL on 3D7 and DD2 resp.) and roots of V. amygdalina (IC50 of 8.72 μg/mL on 3D7), Coula edulis leaves (IC50 of 13.80 μg/mL and 5.79 μg/mL on 3D7 and DD2 resp.), Eucalyptus globulus leaves (IC50 of 16.80 μg/mL and 26.45 μg/mL on 3D7 and DD2) and Cuviera longiflora stem bark (IC50 of 20.24 μg/mL and 13.91 μg/mL on 3D7 and DD2). These findings justify the use of five of the seven plants in malaria treatment by traditional healers of Western Cameroon

Antimicrobial and antioxidant activities of extracts and ten compounds from three Cameroonian medicinal plants : Dissotis perkinsiae (Melastomaceae), Adenocarpus mannii (Fabaceae) and Barteria fistulosa (Passifloraceae)

BACKGROUND : We decided to investigate the antimicrobial and the antioxidant activities of extracts and compounds isolated from Dissotis perkinsiae, Adenocarpus mannii and Barteria fistulosa, three Cameroonianmedicinal plants used for the treatment of skin diseases, wounds, fever, rheumatism, malaria and/or infectious diseases. METHODS : Standard chromatographic and spectroscopic methods were used to isolate and identify ten compounds from the three plant species [1–5 (from D. perkinsiae), 2, 6–8 (from A. mannii) and 2, 4, 9, and 10 (fromB. fistulosa)]. A two-fold serial microdilutionmethod was used to determine the minimuminhibitory concentration (MIC) against a panel of fungal and bacterial species. The radical scavenging capacity using 2,2- diphenyl-1-picryhydrazyl (DPPH) was determined to evaluate the antioxidant activity of the samples. RESULTS : The compounds isolated were: ursolic acid (1), oleanolic acid (2), quercetin 3-O-(6″-O-galloyl)- β-galactopyranoside (3), 3-O-β-D-glucopyranoside of sitosterol (4), ellagic acid (5), isoprunetin (6), chrysin 7-O- β-D-glucopyranoside (7), isovitexin (8), hederagenin (9) and shanzhiside methyl ester (10). The ethanol extract of D. perkinsiae had good antibacterial activity against Enterococcus faecalis (MICs 0.04 and 0.08 mg/ml), Escherichia coli (MIC 0.08 mg/ml) and Staphylococcus aureus (MIC 0.08 mg/ml). The extract of B. fistulosa had significant antifungal activity against Cryptococcus neoformanswith an MIC of 0.08 mg/ml. Other extracts hadmoderate to poor antimicrobial activities with the MIC ranging from 0.16 to 2.50 mg/ml. The isolated compounds were generally more active against bacteria (MIC ranging from 16 to 250 μg/ml) than fungi (MIC between 31 and 250 μg/ml). Moderate antibacterial activity was obtained with compound 3 against E. faecalis and E. coli (MIC of 16 μg/ml in both cases), compounds 6 and 10 against E. faecalis (MIC of 16 μg/ml), and compound 9 against E. faecalis (MIC 31 μg/ml) and S. aureus (MIC 31 μg/ml). The B. fistulosa extract had the greatest radical scavenging activity (IC50 100.16 μg/ml) followed by extracts of D. perkinsiae (IC50 130.66 μg/ml), and A. mannii (IC50 361.30 μg/ml). Compounds 3 and 5 had significant antioxidant activities with the IC50 of 9.84 and 9.99 μg/ml as compared to that of ascorbic acid (IC50 2.41 μg/ml). CONCLUSION : The results obtained support the traditional use of the three plant species (D. perkinsiae, A. mannii and B. fistulosa) in traditional medicine for the treatment of infections. Some extracts and isolated compounds could be useful in development of antimicrobial agents.We are currently investigating the toxicity and other pharmacological activities with the potential use as topical antimicrobial agents.University of Dschang. The NRF and the University of Pretoria for the Postdoctoral Fellowship awarded to work at the Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science.http://www.elsevier.com/locate/sajbhb201

A new Dieis-Alder-type adduct flavonoid from Dorstenia barteri

A new Dieis-Alder-type adduct, dorstenone (1), was isolated from Dorstenia barteri together with three known fiavonoids, 4,2',4'-trihydoxy-3'- prenylchalcone; 4,2',4'-trihydoxy-3,3'-diprenylchalcone; and 5,7,4'- trihydoxy-8-prenylflavone. The structure of 1 was elucidated using a combination of highfield NMR techniques, particularly, gradient-enhanced HMQC and HMBC

New antimalarial hits from Dacryodes edulis (Burseraceae)--part I: isolation, in vitro activity, in silico "drug-likeness" and pharmacokinetic profiles.

The aims of the present study were to identify the compounds responsible for the anti-malarial activity of Dacryoedes edulis (Burseraceae) and to investigate their suitability as leads for the treatment of drug resistant malaria. Five compounds were isolated from ethyl acetate and hexane extracts of D. edulis stem bark and tested against 3D7 (chloroquine-susceptible) and Dd2 (multidrug-resistant) strains of Plasmodium falciparum, using the parasite lactate dehydrogenase method. Cytotoxicity studies were carried out on LLC-MK2 monkey kidney epithelial cell-line. In silico analysis was conducted by calculating molecular descriptors using the MOE software running on a Linux workstation. The "drug-likeness" of the isolated compounds was assessed using Lipinski criteria, from computed molecular properties of the geometry optimized structures. Computed descriptors often used to predict absorption, distribution, metabolism, elimination and toxicity (ADMET) were used to assess the pharmacokinetic profiles of the isolated compounds. Antiplasmodial activity was demonstrated for the first time in five major natural products previously identified in D. edulis, but not tested against malaria parasites. The most active compound identified was termed DES4. It had IC50 values of 0.37 and 0.55 µg/mL, against 3D7 and Dd2 respectively. In addition, this compound was shown to act in synergy with quinine, satisfied all criteria of "Drug-likeness" and showed considerable probability of providing an antimalarial lead. The remaining four compounds also showed antiplasmodial activity, but were less effective than DES4. None of the tested compounds was cytotoxicity against LLC-MK2 cells, suggesting their selective activities on malaria parasites. Based on the high in vitro activity, low toxicity and predicted "Drug-likeness" DES4 merits further investigation as a possible drug lead for the treatment of malaria

Diarylheptanoids from Myrica arborea

Investigations of the stem and root bark of Myrica arborea (Myricaceae) have yielded two novel diarylheptanoids, myricarborin and 11-O-β-D-xylopyranosylmyricanol along with the known myricanol and 5-O-β-D-glucopyranosylmyricanol. The structures of the novel compounds were determined by spectroscopic methods. (C) 2000 Elsevier Science Ltd

C-28/C-30 oxidized cycloartanes from the leaves and twigs of Caloncoba dusenii Gilg

Nguetsa LZ, Mpetga JDS, Bitchagno GTM, et al. C-28/C-30 oxidized cycloartanes from the leaves and twigs of Caloncoba dusenii Gilg. Phytochemistry Letters. 2021;43:145-149.Four hitherto unreported cycloartane-type triterpenes (1-4) with C-28/C-30 oxidized methyl groups together with two known compounds (5-6) have been obtained from the leaves and twigs of Caloncoba dusenii Gilg. The compounds were isolated through extraction and silica gel column chromatography. Their structures and relative stereochemistry were determined by extensive use of spectroscopic techniques including IR, 1D and 2D-NMR as well as mass spectrometry. This is the first report of C-28/C-30 oxidized positions in cycloartanes from nature

Chemical constituents from Ficus natalensis hochst (Moraceae) and their chemophenetic significance

Mbougnia JFT, Happi GM, Bitchagno Mbahbou GT, et al. Chemical constituents from Ficus natalensis hochst (Moraceae) and their chemophenetic significance. Biochemical Systematics and Ecology. 2021;95: 104227.Phytochemical investigation of the stem bark of Ficus natalensis afforded eleven compounds including one ceramide (1), two anthraquinones (2, 3), four triterpenes (4–7), two polyols (8, 9) and two steroids (10, 11). The structures of the compounds were determined by spectroscopic analyses including IR, UV, MS, 1D- and 2D- NMR (1H, 13C, 1H–1H COSY, HMQC, HMBC and NOESY), as well as by comparison with literature data. The antibacterial activity and the cytotoxicity of the extract, fractions and some isolated compounds (3, 5, 8 and 9) were evaluated. Some fractions and sub-fractions from various column chromatography displayed moderate antibacterial activity with diameter zone of inhibition (DZI) ranging from 7 to 10 mm. None of the compounds tested had activity. In the present study, all the compounds are isolated for the first time from the species F. natalensis. Compounds 2, 4–7, 10 and 11 were previously reported from the genus Ficus. The chemophenetic significance of the isolated compounds is discussed