Bioassay-guided isolation of antiplasmodial and antimicrobial constituents from the roots of Terminalia albida.

ETHNOPHARMACOLOGICAL RELEVANCE: Terminalia albida (Combretaceae), widely used in Guinean traditional medicine, showed promising activity against Plasmodium falciparum and Candida albicans in previous studies. Bioassay-guided fractionation was carried out in order to isolate the compounds responsible for these activities. MATERIALS AND METHODS: Fractionation and isolation were performed by flash chromatography, followed by semi-preparative HPLC-DAD-MS. The structural elucidation of the isolated compounds was carried out by 1D and 2D NMR as well as HR-ESI-MS. Isolated compounds were evaluated against Plasmodium falciparum, Candida albicans, Staphylococcus aureus and Escherichia coli, and their cytotoxicity against MRC-5 cells was determined. RESULTS: Bioassay-guided fractionation of Terminalia albida root resulted in the isolation of 14 compounds (1-14), and their antimicrobial properties were evaluated. Pantolactone (1) (IC50 0.60 ± 0.03 µM) demonstrated significant activity against P. falciparum. Other compounds, including 3,4,3'-tri-O-methyl-ellagic acid (3), the triterpenes arjunolic acid (5), arjungenin (6), arjunic acid (7) and arjunglucoside II (10), and the phenol glycoside calophymembranside-B (14), were less active and showed IC50 values in the range 5-15 µM. None of the tested compound showed antibacterial or antifungal activity. CONCLUSION: These results may explain at least in part the activity of the root extract of T. albida against P. falciparum.

Antimicrobial investigation of ethnobotanically selected guinean plant species.

ETHNOPHARMACOLOGICAL RELEVANCE: In Guinea, medicinal plants play an important role in the management of infectious diseases including urinary disorders, skin diseases and oral diseases. This study was carried out to collect medicinal plant species employed for the treatment of these diseases and to investigate their antimicrobial potential. MATERIALS AND METHODS: Based on an ethnobotanical investigation carried out in three Guinean regions, 74 traditional healers and 28 herbalists were interviewed and medicinal plants were collected. The most quoted plant species were evaluated for their antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, and in addition against Plasmodium falciparum. RESULTS: A total of 112 plant species belonging to 102 genera distributed over 42 botanical families were inventoried. Among the selected plant species, promising activities against C. albicans were obtained for the methanolic extracts of the stem bark of Terminalia albida (IC50 1.2 µg/ml), the leaves of Tetracera alnifolia (IC50 1.6 µg/ml) and the root bark of Swartzia madagascariensis (IC50 7.8 µg/ml). The highest activity against S. aureus was obtained for the dichloromethane extracts of the leaves of Pavetta crassipes (IC50 8.5 µg/ml) and the root of Swartzia madagascariensis (IC50 12.8 µg/ml). Twenty one extracts, obtained from twelve plant species, were strongly active against Plasmodium falciparum, including the dichloromethane extracts of the root and stem bark of Terminalia albida root (IC50 0.6 and 0.8 µg/ml), the leaves of Landolphia heudelotii (IC50 0.5 µg/ml), the stem bark of Combretum paniculatum (IC50 0.4 µg/ml) and the leaves of Gardenia ternifolia (IC50 1.3 µg/ml). CONCLUSION: The present study provides a comprehensive overview of medicinal plants employed by Guinean traditional healers for the treatment of various microbial diseases, including urinary disorders, skin diseases and oral diseases. Some of the studied plant species showed promising antimicrobial activity and could be considered as a potential source for the development of new antifungal and/or antimalarial agents.

The malaria co-infection challenge: An investigation into the antimicrobial activity of selected Guinean medicinal plants.

ETHNOPHARMACOLOGICAL RELEVANCE: In sub-Saharan Africa, concomitant occurrence of malaria and invasive infections with micro-organisms such as Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli and yeasts or fungi such as Candida albicans and Aspergillus fumigatus is common. Non-tuberculous mycobacteriosis caused by Mycobacterium chelonae has been recognized as a pulmonary pathogen with increasing frequency without effective therapy. Although less important, the high incidence of Trichophyton rubrum infections along with its ability to evade host defense mechanisms, accounts for the high prevalence of infections with this dermatophyte. Considering the treatment cost of both malaria and microbial infections, along with the level of poverty, most affected African countries are unable to cope with the burden of these diseases. In sub-Saharan Africa, many plant species are widely used in the treatment of these diseases which are traditionally diagnosed through the common symptom of fever. Therefore it is of interest to evaluate the antimicrobial activities of medicinal plants reported for their use against malaria/fever. MATERIALS AND METHODS: Based on an ethnobotanical survey, 34 Guinean plant species widely used in the traditional treatment of fever and/or malaria have been collected and evaluated for their antimicrobial activities. Plants extracts were tested against Candida albicans, Trichophyton rubrum, Aspergillus fumigatus, Mycobacterium chelonae, Staphylococcus aureus and Escherichia coli. RESULTS: The most interesting activities against Candida albicans were obtained for the polar extracts of Pseudospondias microcarpa and Ximenia americana with IC50 values of 6.99 and 8.12 µg/ml, respectively. The most pronounced activity against Trichophyton rubrum was obtained for the ethanol extract of Terminalia macroptera (IC50 5.59 µg/ml). Only 7 of the 51 tested extracts were active against Staphylococcus aureus. From these, the methanolic extracts of the leaves and stem bark of Alchornea cordifolia were the most active with IC50 values of 2.81 and 7.47 µg/ml, respectively. Only Terminalia albida and Lawsonia inermis showed activity against Mycobacterium chelonae. None of the tested extracts was active against Escherichia coli. CONCLUSION: A number of traditional Guinean plant species used against malaria/fever showed, in addition to their antiplasmodial properties and antimicrobial activity. The fact that some plant species are involved in the traditional treatment of malaria/fever without any antiplasmodial evidence may be justified by their antimicrobial activities.

In vitro antiprotozoal and cytotoxic activity of ethnopharmacologically selected guinean plants.

Based on an ethnobotanical survey, 41 Guinean plant species widely used in the traditional treatment of fever and/or malaria were collected. From these, 74 polar and apolar extracts were prepared and tested for their in vitro antiprotozoal activity along with their cytotoxicity on MRC-5 cells. A potent activity (IC50 < 5 µg/mL) was observed for Terminalia albida, Vismia guineensis, Spondias mombin, and Pavetta crassipes against Plasmodium falciparum; for Pavetta crassipes, Vismia guineensis, Guiera senegalensis, Spondias mombin, Terminalia macroptera, and Combretum glutinosum against Trypanosoma brucei brucei; for Bridelia ferruginea, G. senegalensis, V. guineensis, P. crassipes, and C. glutinosum against Trypanosoma cruzi. Only the extract of Tetracera alnifolia showed a good activity (IC50 8.1 µg/mL) against Leishmania infantum. The selectivity index of the active samples varied from 0.08 to > 100. These results may validate at least in part the traditional use of some of the plant species.