Specific sub fractions from Terminalia mantaly (H. Perrier) extracts potently inhibit Plasmodium falciparum rings, merozoite egress and invasion.

ETHNOPHARMACOLOGICAL RELEVANCE: Terminalia mantaly (H. Perrier) and Terminalia superba (Engl. & Diels) are sources of treatment for various diseases, including malaria and/or related symptoms in parts of Southwestern Cameroon. However, there is limited information on the extent of the antiplasmodial potential of their extracts. AIM OF THE STUDY: The present study was designed to investigate the antiplasmodial potential of chromatographic sub fractions (SFs) from promising fractions of Terminalia mantaly (Tm) [TmsbwChl, the chloroform fraction from water extract of Tm, IC50 (µg/mL) PfINDO: 0.56, Pf3D7: 1.12; SI > 357 (HEK/PfINDO) & 178 (HEK/Pf3D7)] and Terminalia superba (Ts) [TsrmEA, the ethyl acetate fraction from methanolic extract of Ts, IC50 (µg/mL) PfINDO: 1.82, Pf3D7: 1.65; SI > 109 (HEK/PfINDO) & 121 (HEK/Pf3D7)] obtained from previous studies. The SFs were tested against Plasmodium falciparum 3D7 (Pf3D7-chloroquine sensitive) and INDO (PfINDO-chloroquine resistant) strains in culture. Also, the phytochemical profile of potent SFs was determined and finally, the inhibition of the asexual blood stages of Plasmodium falciparum by the SFs with the highest promise was assessed. MATERIAL AND METHODS: Selected SFs were submitted to a second bio-guided fractionation using silica gel column chromatography. The partial phytochemical composition of potent antiplasmodial SFs was determined using gas chromatography coupled to mass spectrometry (GC-MS). The SYBR Green I-based fluorescence microtiter plate assay was used to monitor the growth of Plasmodium falciparum parasites in culture in the presence or absence of extracts. Microscopy and flow cytometry counting was used to assess the Plasmodium falciparum stage-specific inhibition and post-drug exposure growth suppression by highly potent extracts. RESULTS: Twenty-one of the 39 SFs afforded from TmsbwChl showed activity (IC50: 0.29-4.74 µg/mL) against both Pf3D7 and PfINDO strains. Of note, eight SFs namely, Tm25, Tm28-30, Tm34-36 and Tm38, exerted highly potent antiplasmodial activity (IC50 < 1 µg/mL) with IC50PfINDO: 0.41-0.84 µg/mL and IC50Pf3D7: 0.29-0.68 µg/mL. They also displayed very high selectivity (50 < SIPfINDO, SIPf3D7 > 344) on the two Plasmodial strains. On the other hand, 7 SFs (SFs Ts03, Ts04, Ts06, Ts09, Ts10, Ts12 and Ts13) from TsrmEA showed promising inhibitory potential against both parasite strains (IC50: 2.01-5.14 µg/mL). Sub fraction Tm36 (IC50PfINDO: 0.41 µg/mL, SIPfINDO > 243; IC50Pf3D7: 0.29 µg/mL, SIPf3D7 > 344) showed the highest promise. The GC-MS analysis of the 8 selected SFs led to the identification of 99 phytometabolites, with D-limonene (2), benzaldehyde (12), carvone (13), caryophyllene (35), hexadecanoic acid, methyl ester (74) and 9-octadecenoic acid, methyl ester (82) being the main constituents. Sub fractions Tm28, Tm29, Tm30, Tm36 and Tm38 inhibited all the three intraerythrocytic stages of P. falciparum, with strong potency against ring stage development, merozoite egress and invasion processes. CONCLUSIONS: This study has identified highly potent antiplasmodial SFs from Terminalia mantaly with significant activity on the intraerythrocytic development of Plasmodium falciparum. These SFs qualify as promising sources of novel antiplasmodial lead compounds. Further purification and characterization studies are expected to unravel molecular targets in rings and merozoites.

Garcinia kola (Heckel) and Alchornea cordifolia (Schumach. & Thonn.) Müll. Arg. from Cameroon possess potential antisalmonellal and antioxidant properties.

Drug resistant Salmonella species and shortcomings related to current drugs stress the urgent need to search for new antimicrobial agents to control salmonellosis. This study investigated the antisalmonellal and antioxidant potentials of methanolic and hydro-ethanolic extracts of Garcinia kola and Alchornea cordifolia as potential sources of drugs to control Salmonella species and to reduce related oxidative stress. The antisalmonellal activity was assessed using the broth microdilution, membrane destabilization and time-kill kinetic assays. While, the DPPH, ABTS and FRAP assays were used for the determination of the antioxidant activities. The minimum inhibitory concentrations ranged from 125 to 1000 µg/mL, with the methanolic root extract of G. kola being the most active. The time kill kinetic assay revealed a concentration-dependent bacteriostatic activity for promising extracts. Potent extracts from G. kola showed the ability to destabilize S. typhi outer membrane, with the methanolic root extract presenting the highest activity; two-fold higher than those of polymyxin B tested as reference. In addition, this methanolic root extract of G. kola also provoked nucleotide leakage in a concentration-dependent manner. From the antioxidant assays, the hydro-ethanolic extract from the stem bark of A. cordifolia presented significant activities comparable to that of Vitamin C. The methanolic root extract of G. kola also presented appreciable antioxidant activities, though less than that of A. cordifolia. Overall, the phytochemical screening of active extracts revealed the presence of anthocyanins, flavonoids, glycosides, phenols, tannins, triterpenoids and steroids. These results provide evidence of the antibacterial potential of G. kola and offer great perspectives in a possible standardisation of an antisalmonellal phytomedicine.