The ethnopharmacological study of plant drugs used traditionally in Djibouti for malaria treatment.

ETHNOPHARMACOLOGICAL RELEVANCE: Djibouti was a country where malaria has been endemic for centuries. The local population use the plants as repellents or first aid for uncomplicated malaria. AIM OF THE STUDY: The aim was, for the first time, to collect and identify plants used by the local population to treat malaria and select the most interesting plants (those that are more commontly used, more available, and have fewer studies). These plants were evaluated for their antiplasmodial activity as well as their cytotoxicity on human cell lines for the most active ones. MATERIALS AND METHODS: A semi-structured questionnaire was developed for this study to collect information about the use and identity of botanical drugs used to treat malaria. The use-reports (percentage) of each plant were recorded to determine their use importance. Also, the availability status of the plants was assessed; and those in critical condition were discarded excluded from further study. Fifteen plants, out of the 41 listed, were extracted with hydro alcohol, ethyl acetate, and dichloromethane for biological testing. Chloroquine-resistant strain FcB-1 of P. falciparum and a human diploid embryonic lung cell line were used for the antiplasmodial test, and to assess the cytotoxicity for human cells respectively. Preliminary analysis of extract constituents was carried out using thin layer chromatography (TLC). RESULTS: This study identifies 41 plant taxa belonging to 32 families and records their use against malaria. Balanites rodunfolia, belonging to the Zygophyllaceae family, was the most commonly used plant, representing 44 % of use-reports. It was followed by Cadaba rodunfolia (15 %) from the Capparaceae family, and then the three species of Aloe: Aloe djiboutiensis (8.2 %), Aloe ericahenriettae (3.4 %), and Aloe rigens (3.4 %) from the Asphodelaceae family. The leaves are the most commonly used part of the plants to treat malaria, accounting for 76 % of usage. The preparation methods were decoction (52 %), maceration (29 %), and boiling (19 %). The administration routes were by oral (80 %), inhalation 19 %), and bathing (1 %). The best antiplasmodial activities were observed in the dichloromethane extracts of Cymbopogon commutatus and the ethyl acetate extracts of Aloe rigens and Terminalia brownii, with IC50 values of 9.8, 5, and 7.5 µg/mL, respectively. Their toxicity/activity levels were very favorable with selectivity indices of 5.6, 8.1, and 11.8 for C. commutatus, A. rigens, and T. Brownii, respectively. CONCLUSION: Forty-one species of botanical drugs were listed as being used to treat malaria in Djibouti. All fifteen selected species showed antiplasmodial activity (IC50 < 50 µg/mL). This work will help guide the valorization of botanical drugs used to treat malaria in Djibouti.

In vitro and in silico analysis for elucidation of antioxidant potential of Djiboutian Avicennia Marina (Forsk.) Vierh. phytochemicals.

The present work aims to study the phytochemical composition, the antioxidant capacity of the crude extracts, and the fraction of extract giving the best antioxidant activity of Avicennia marina. The leaves contain high TFC compared to other parts of the plant, whereas fruits have the highest amount of TPC. Fat-soluble pigments are strongly present in the leaves of Avicennia marina i.e. ß-carotene, lycopene, chlorophyll a, and chlorophyll b. The crude methanolic flower extracts showed strong DPPH and ABTS radical scavenging activity with IC50 values of 0.30 and 0.33 mg/mL respectively compared to the leaf and stem methanolic extracts for the DPPH and ABTS models with a value IC50 greater than 1 mg/mL. The crude fruit extract shows good activity with the ABTS model, unlike the DPPH model whose IC50 values are 0.95 and 0.38 mg/mL, respectively. Fractionation improved the antioxidant effect of crude flower extract. The ethyl acetate fraction exhibits the best antioxidant activity for both DPPH and ABTS methods with IC50 values of 0.125 and 0.16 mg/mL. The HR-LCMS/MS led to the identification of 13 compounds: 6 flavonoids and 7 iridoid glycoside compounds in the different parts of the plant. A bioinformatics study was performed to evaluate the antioxidant activity of the three major Iridoid glycosides towards the target protein Catalase compound II through free binding energy. Out of these three iridoid glycosides, compound C10 does not represent any toxicity, unlike C8 and C9 which showed an irritancy effect. Furthermore, molecular dynamics shows good stability of the C10-2CAG complex. HighlightsExtraction and fractionation of different part (leaf, stem, flower and fruit) of Avicennia marina.Botanical description and phytochemical analysis of crude extract methanolic. Investigation by HR-LCMS characterization of polyphenols and iridoid glycosides.Evaluation the antioxidant activity of crudes extracts methanolics by two methods in vitro DPPH and ABTS.Antioxidant activity of the fraction of the crude flower extracts presenting the best biological response.Evaluate the contribution of three major compounds 2'-Cinnamoylmussaenosidic acid, 10-O-[E-Cinnamoyl]-geniposidic acid and 10-O-[(E)-p-Coumaroyl]-geniposidic acid in the ethyl acetate fraction on the antioxidant activity through docking and dynamic molecular.Communicated by Ramaswamy H. Sarma.