In vitro and in vivo studies on anti-malarial activity of Commiphora africana and Dichrostachys cinerea used by the Maasai in Arusha region, Tanzania

Abstract Background Traditional medicinal plants are one of the potential sources of anti-malarial drugs and there is an increasing interest in the use and development of traditional herbal remedies for the treatment of malaria and other ailments. This study was carried out with the aim to investigate the phytochemical screening, cytotoxic effect and antiplasmodial activities of Dichrostachys cinerea and Commiphora africana. Both plants are used by the Maasai in Tanzania in suspected malaria and other diseases. No previous work appears to have investigated the potential anti-malarial activity of the two plants. Methods This study aimed to investigate the in vitro anti-malarial activity of methanol and dichloromethane extracts of the two plants against chloroquine sensitive (D6) and chloroquine resistant (Dd2) strains of Plasmodium falciparum. The anti-malarial property was assessed by the lactate dehydrogenase method (pLDH). The in vivo anti-malarial study was carried out using the Peters’ 4-day suppressive test in Plasmodium berghei in Balb/c mice. Cytotoxic tests were carried out using monkey kidney epithelial cell line in [3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay. Qualitative phytochemical screening was carried out using standard methods of analysis. Results The phytochemical screening of plant extracts revealed the presence of alkaloids, flavonoids, tannins, steroids, triterpenoids, glycosides and saponins. However, alkaloids were absent in most plant extracts. The dichloromethane extracts of C. africana (stem bark); D. cinerea (stem bark) and methanol extracts of D. cinerea (whole stem) all showed promising in vitro anti-malarial activities. All other extracts did not show any significant anti-malarial activity. The two most promising extracts based on in vitro studies, DCM extracts of C. africana (stem bark) and D. cinerea (stems bark), equally exhibited very significant anti-malarial activities in the mouse model. They exhibited parasite suppression rates of 64.24 and 53.12%, respectively, and considerable improvement in weight and survival rate. Most plant extracts were not cytotoxic except for DCM extract of D. cinerea (whole stem) CC50 (29.44 µg/mL). Conclusion The findings of this study provide scientific evidence supporting the traditional use of the plants in the treatment of malaria by the Maasai in Arusha region, Tanzania. Consequently, further work including bioassay-guided fractionation and advanced toxicity testing may yield new anti-malarial drug candidates from the two plants

Constituents of the Stem Bark of Trichilia monadelpha (Thonn.) J. J. De Wilde (Meliaceae) and Their Antibacterial and Antiplasmodial Activities

Djoumessi AK, Nono RN, Neumann B, et al. Constituents of the Stem Bark of Trichilia monadelpha (Thonn.) J. J. De Wilde (Meliaceae) and Their Antibacterial and Antiplasmodial Activities. Metabolites. 2023;13(2): 298.The chemical investigation of the EtOH extract from the stem bark of Trichilia monadelpha (Thonn.) J. J. De Wilde afforded two new limonoids (1 and 2): 24-acetoxy-21,25-dihydroxy-21,23-epoxytirucall-7-en-3-one (1) and (6R)-1-O-deacetylkhayanolide E (2), together with eleven known compounds (3–13), including additional limonoids, flavonoids, triterpenoids, steroids, and fatty acid. Their structures were determined using 1D- and 2D-NMR experiments, ESI mass spectrometry, and single crystal X-ray diffraction analysis. The antibacterial and antiplasmodial activities of the extracts, sub-extracts, fractions, and some of the isolated compounds were evaluated in known pathogenic strains, including Staphylococcus aureus and Plasmodium falciparum. Fraction E (n-Hex/EtOAc 30:70, v/v) showed significant activity against S. aureus ATCC 25923 with a MIC value of 3.90 µg/mL, while one of its constituents (epicatechin (9)) exhibited significant activity with MIC values of 7.80 µg/mL. Interestingly, grandifotane A (6) (IC50 = 1.37 µM) and khayanolide D (5) (IC50 = 1.68 µM) were highly active against the chloroquine-sensitive/sulfadoxine-resistant plasmodium falciparum 3D7 strain, unlike their corresponding plant extract and fractions

High Prevalence of Polyclonal <i>Plasmodium falciparum</i> Infections and Association with Poor IgG Antibody Responses in a Hyper-Endemic Area in Cameroon

Malaria remains a major public health problem worldwide, with eradication efforts thwarted by drug and insecticide resistance and the lack of a broadly effective malaria vaccine. In continuously exposed communities, polyclonal infections are thought to reduce the risk of severe disease and promote the establishment of asymptomatic infections. We sought to investigate the relationship between the complexity of P. falciparum infection and underlying host adaptive immune responses in an area with a high prevalence of asymptomatic parasitaemia in Cameroon. A cross-sectional study of 353 individuals aged 2 to 86 years (median age = 16 years) was conducted in five villages in the Centre Region of Cameroon. Plasmodium falciparum infection was detected by multiplex nested PCR in 316 samples, of which 278 were successfully genotyped. Of these, 60.1% (167/278) were polyclonal infections, the majority (80.2%) of which were from asymptomatic carriers. Host-parasite factors associated with polyclonal infection in the study population included peripheral blood parasite density, participant age and village of residence. The number of parasite clones per infected sample increased significantly with parasite density (r = 0.3912, p p P. falciparum antigens (MSP-1p19, MSP-3 and EBA175) and two soluble antigen extracts (merozoite and mixed stage antigens). Surprisingly, we observed no association between the frequency of polyclonal infection and susceptibility to clinical disease as assessed by the recent occurrence of malarial symptoms or duration since the previous fever episode. Overall, the data indicate that in areas with the high perennial transmission of P. falciparum, parasite polyclonality is dependent on underlying host antibody responses, with the majority of polyclonal infections occurring in persons with low levels of protective anti-plasmodial antibodies