Antiplasmodial activity of some phenolic compounds from Cameroonians Allanblackia

Background: Ficus elastica is a plant used in traditional medicine for the treatment of allergies and skin infections. This study aimed to investigate the antimicrobial, antiplasmodial, and antiproliferative activities of the crude extract and fraction of F. elatica as well as the study of the in vivo oral acute toxicity of the most active fraction. Methods: The antimicrobial activity of the total extract and the different fractions was evaluated by the determination of the inhibition diameter using the agar well diffusion method on 3 Gram (+) bacteria, 4 Gram (-) bacteria, and 2 fungi, by the determination of MIC using the micro-dilution method only on the strains that showed sensitivity on the agar and by the determination of MMC on Muller Hinton agar. The evaluation of antimalarial activity was done on Plasmodium falciparum 3D7 cells by measuring the parasite lactate dehydrogenase (pLDH) activity using the mixture of Malstat and NBS/PES. Extracts were afterward evaluated for their antiproliferative effect on 2 human cell lines (human oligodendroglioma and breast cancer) and mouse melanoma using colorimetric MTT assay. The toxicity assessment of the most active fraction was performed in vivo according to the modified OECD 425 guidelines. Results: Total extract and different fractions were not active on different strains because the MICs values are > 1024 µg/mL. Dichloromethane and hexane fractions were bactericidal with a ratio CMM/CMI of 2 and the total extract would be bacteriostatic. The antimalarial activity showed that the hexane fraction reduced the viability of P. falciparum 3D7 cells by 61.4% with an IC50 value of 26.41 µg/mL. As for the antiproliferative activity, the dichloromethane fraction significantly inhibited different cell lines with IC50 values between 13 and 16.5 µg/mL. The toxicity study conducted on the hexane fraction, being the most active fraction, resulted in no apparent signs of toxicity and no death at doses of 2000 mg/kg bw and 5000 mg/kg bw over a period of 14 days. Conclusion: Methanolic crude extract of F. elastica lianas and its hexane as well as dichloromethane fractions possess low antibacterial activity. The dichloromethane fraction possesses antiproliferative activity while the hexane fraction possesses antiplasmodial activity and presented no signs of acute toxicity by the oral route. These results support the use of F. elastica in the treatment of several ailments such as skin infections.

Aims: This study aimed at identifying the phytochemical constituents, to evaluate and compare the in vitro antioxidant potential of the methanolic extracts of the leaves, trunk (wood and bark) and roots (wood and bark) of Anonidium mannii (Oliv) Engl. and Diels which is used in Cameroon for the treatment of rheumatism. Place and Duration of Study: The work was conducted at the Pharmacochemistry and Natural Substances Laboratories of the Faculty of Medicine and Pharmaceutical Sciences, University of Douala. All the experiments were carried out from the 15^th October 2019 to the 31^th July 2020. Methodology: Phytochemical screening was based on conventional techniques focusing on color reactions and precipitation. The evaluation of the antioxidant power was carried out by the method of scavenging the free radical DPPH of the extracts and by reading the absorbance for each concentration at 517 nm. Results: The phytochemical screening of the extracts revealed the presence of alkaloïds, flavonoïds, anthraquinones, coumarins, terpenes, steroïds, saponins, phenols and anthocyanins. All extracts tested showed antioxidant activity, particularly root wood with an IC₅₀ = 1.85 µg/ml identical to the standard (BHT: Butylhydroxytoluène). Conclusion: Due to evidence that reactive oxygen species play a causal role in auto-immune diseases, such as rheumatoid arthritis, these results justify the use of the leaves or the stem bark of A. mannii in the traditional pharmacopeia for the treatment of rheumatism. However, the wood of the roots having presented the best activity (IC₅₀ = 1.85 µg/ml). It would be beneficial to suggest this plant part to the local populations for the management of that pathology. This study is the first comparative biological study conducted on the different parts of A. mannii.

Canarium schweinfurthii, also called ‘’Elemierd’Afrique’’, is used in Cameroonian folk medicine (bark decoction) to treat patients suffering from hypertension. Aim of the study: This study aimed at evaluating the antihypertensive activities of the stem bark of Canarium schweinfurthii and identifying potential compounds present in its extract that may support or oppose its ethnomedicinial use. Stem bark extract of Canarium schweinfurthii was prepared by maceration using 70 % ethanol followed by redissolution in methanol and hyphenated. Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) analysis for the detection and characterisation of secondary metabolites. Antihypertensive effects were assessed in Wistar rats after induction of hypertension with sodium chloride (NaCl) 18 % at a dose of 0.01mL/g_{body weight} once a day for four weeks.Hemodynamic parameters were measured weekly by anon-invasive method using the CODA system. The ethanolic bark extract of C. schweinfurthii significantly inhibited the increase of blood pressure with a maximum of 23.18 % (systolic pressure, p < 0.0001), 24.77 % (diastolic pressure, p < 0.001) and 22.95 % (mean pressure, p < 0.0001) at a dose of 200 mg/kg_{body weight} at the 4th week, compared to agroup of Wistar rats that received only NaCl (negative control). Similarly, the extract significantly inhibited the increase in heart rate by 18.84 % (p < 0.001) at 200 mg/kg_{body weight} at week four. Hematological parameters did not differ significantly between the extract-treated and control groups. The UPLC-MS/MS spectrometric analysis provided evidence for the presence of several C30 terpenoids containing three or five oxygen atoms and exhibiting pentacyclic triterpenoid structures, as well as C29 terpenoids and related compounds containing nitrogen in addition to oxygen, using spectral matching, and in silico molecular formula and structure prediction. Additionally, two features were annotated with high-confidence as lignans, structurally closely related to hinokinin and dehydrocubebin through MS/MS-based in silico structure prediction using CSI: Finger ID in SIRIUS5. The lignans have been previously reported from stem bark of plants belonging to the Burseraceae family. Conclusion: The ethanolic stem bark extract of C. schweinfurthii demonstrated antihypertensive properties on the tested Wistar rats. These results support the ethnopharmacological use of C. schweinfurthii concoctions for the treatment of hypertension and suggest a protective effect against salt damage, hypothetically by the up regulation of antioxidative enzymes and/or lipids, mitigatings membrane peroxidation.

The low therapeutic index of available trypanocidal drugs and the increasing emergence of resistant Trypanosoma parasites indicate the urgent need to develop new strategies for trypanosomiasis control. One such strategy is the screening of medicinal plants as sources of new lead compounds. Trypanosoma brucei brucei is a sub-species only infecting animals and thus largely used to screen anti-trypanosomal potential of various substances. Therefore, the present study investigates the anti-trypanosomal activity of crude extract, hexane, dichloromethane, ethyl acetate, and aqueous fractions of Spathodea campanulata P. Beauv. flowers, Trichoscypha acuminata Engl. stem bark, and Ficus elastica Roxb. Ex Hornem lianas using the Alamar Blue assay. Overall results showed that the crude extract of T. acuminata, S. campanulate, and F. elastica did not significantly reduce the viability of Trypanosoma brucei brucei at the tested concentration of 25 µg/mL. However, the hexane and dichloromethane fractions of T. acuminata and the hexane fraction of F. elastica exhibited viability percentages of 23.2 ± 10.5, 18.2 ± 9.7, and 20.1 ± 13.1% with IC₅₀ values of 5.5, 5.0, and 17.5 µg/mL, respectively. Further research to identify compounds responsible for the observed activity and their mechanisms of action towards new leads in parasitical drug discovery is needed.