Antimicrobial diterpenoids and triterpenoids from the stem bark of Croton macrostachys

Antimicrobial-guided fractionation of the EtOAc extract of the stem bark of Croton macrostachys afforded five known compounds including two lupane triterpenoids, lupeol (1) and betulin (2), and three clerodane diterpenoids, floridolide A (3), hardwickic acid (4) and 12-oxo-hardwickic acid (5). Their structures were elucidated on the basis of spectral studies and comparison with published data. The EtOAc extract and compounds 1, 2, 4 and 5 were evaluated for their antibacterial and antifungal activities by macro-dilutionmethod. The extract displayed significant antibacterial and antifungal activities (MIC = 31.25-1000 μg/ml). Betulin (2) and 12-oxo-hardwickic acid (5) were the most active compounds (MIC = 7.81-500 μg/ml). Themost sensitive microorganisms were Staphylococcus aureus ATCC 25922 for bacteria and two Candida species, Candida albicans ATCC 24433 and Candida krusei ATCC 6258, for fungi. The isolation of these active antibacterial and antifungal principles supports the use of C. macrostachys in traditional medicine for the treatment of microbial infections.Keywords: Croton macrostachys; Euphorbiaceae; triterpenes; diterpenes; antibacterial; antifungal

Antibacterial and antioxidant activities of isolated compounds from Prosopis africana leaves

Yanda L, Tatsimo SJN, Tamokou J-D-D, et al. Antibacterial and antioxidant activities of isolated compounds from Prosopis africana leaves. International Journal of Analytical Chemistry . 2022;2022: 4205823.Prosopis africana (G. &Perr.) Taub (Mimosaceae) is a large tree native to dry tropical Africa and characteristic of dry leguminous forests. Different parts of this plant are used to treat wounds, skin infection, and to fight against cancer. Literature review indicated various pharmacological properties. Despite these medicinal properties, the chemical composition studies remain limited. This study aims to isolate and characterize secondary metabolites from P. africana leaves and evaluate their antibacterial and antioxidant properties. Air-dried powdered leaves of P. africana were macerated in methanol at room temperature and partitioned with ethyl acetate. The EtOAc extract was subjected successively to flash and column chromatographies in order to isolate compounds. The structure of the isolates was determined with help of spectroscopic data including 1D and 2D NMR experiments and comparison with literature data. The antibacterial activities were evaluated via determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antioxidant activities were evaluated via gallic acid equivalent antioxidant capacity (GEAC) and diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. The chemical investigation of the EtOAc extract led to the isolation of seven compounds: (2E, 6E) farnesylamine (1), myricetin-3-O-rhamnoside (2), bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3), lupeol (4), SS-sitosterol (5), stigmasterol glycoside (6), and a mixture of bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3) and bis(2-ethylhexyl) benzene-1,4-dicarboxylate (7) in ratio 1:2. Compound 1 is described here for the first time as a natural product with complete 1H and 13C assignments. Compounds 3 and 7 were identified as artefacts from dichloromethane. Sesquiterpene amine (1) is reported in Prosopis genus for the first time. Antibacterial and antioxidant activities of isolated compounds were investigated. Among the tested samples, the EtOAc extract and compound 2 exhibited the highest antioxidant (EC50=5.67-77.56mug/mL; GEAC=36.58-89.28mug/mL) and antibacterial (MIC=8-64mug/mL) activities against gram-negative and gram-positive bacteria. The EtOAc extract and compound 2 from P. africana exhibited antibacterial activity through bacteriolytic effects and reduction of the antioxidant defenses in the bacterial cells. Furthermore, the chemotaxonomic significance of isolated compounds was discussed. The antibacterial and antioxidant activities of ethyl acetate extract and compound 2 can justify the traditional uses of P. africana leaves for the treatment of diseases related to bacterial infections. The presence of compounds 1, 2, and 4 in this plant should also be considered as valuable chemotaxonomic features. Copyright © 2022 Lambert Yanda et al

Prosojuliflavone and other constituents from Prosopis juliflora Swartz D.C (Fabaceae) and their chemotaxonomic importance

Yanda L, Tatsimo SJN, Tamokou J-D-D, et al. Prosojuliflavone and other constituents from Prosopis juliflora Swartz D.C (Fabaceae) and their chemotaxonomic importance. Biochemical Systematics and Ecology. 2022;105: 104508.The chemical investigation of ethyl acetate extracts of the roots and stem bark of Prosopis juliflora Swartz D.C (Fabaceae) led to the isolation of a new flavonoid, prosojuliflavone (1) and a new natural indole alkaloid dimer, N,N-Bis(2-(1H-indol-3-yl) ethyl) oxalamide (2) along with eight known compounds including three flavonoids, vitexin (3), a mixture of vitexin (3) and isovitexin (4), 4ʹ-O-methyl-ent-gallocathechin (5), two indole alkaloids, N-acetyltryptamine (6), tryptamine (7), a disaccharide, sucrose (8), two monoglycerides, hyloglyceride (9) and 1-(26-hydroxyhexacosanoyl)-glycerol (10). Their structures were elucidated by means of spectroscopic and spectrometric data, as well as by comparison with literature data. Compound 2 is described here for the first time as a natural product with complete 1H and 13C assignments. The antibacterial and antioxidant activities of the extracts and isolated compounds were evaluated. Compounds 1 and 5 (MIC = 8–64 μg/ml) were samples with most antibacterial activities while compound 1 (EC50 = 4.31 μg/mL; GEAC = 94.66 μg/mL) displayed the largest antioxidant activity. Interestingly, the tested samples showed bactericidal effects (MBC/MIC ≤4) with respect to sensitive bacteria. Compounds 1, 2, 6, 8 and 10 were isolated for the first time from the Fabaceae family. The chemotaxonomic significance of these compounds was also discussed. The overall results highlight the potential of P. juliflora as a sustainable source of antibacterial and antioxidant agents