Antibacterial Flavonoids and Other Compounds from the Aerial Parts of Vernonia guineensis Benth. (Asteraceae)

Abstract

An extensive phytochemical study of the aerial parts of Vernonia guineensis Benth. (Asteraceae) led to the isolation of a new flavone, vernoguinoflavone and a naturally isolated glycerol ester, eicosanoic acid 2‐hydroxy‐1,3‐propanediyl ester, together with eighteen known secondary metabolites including quercetin, luteolin, vernopicrin, vernomelitensin, β‐amyrin, oleanolic acid, ursolic acid, lupeol, betulinic acid, β‐carotene, a mixture of stigmasterol and β‐sitosterol, β‐sitosterol‐3‐O‐β‐D‐glucoside, 2,3‐dihydroxypropyl heptacosanoate, pentacosanoic acid, docosan‐1‐ol, tritriacontan‐1‐ol, and heptatriacontan‐1‐ol. Eleven compounds are reported herein for the first time from this species. The structures of these compounds were elucidated on the basis of extensive spectroscopic analyses, particularly 1D and 2D NMR, and HR‐ESI‐MS and by comparison of their data with those reported in the literature. The crude extract, fractions and some isolated compounds were evaluated for their antibacterial activity against Gram‐negative bacteria: Escherichia coli (ATCC 25922), Shigella flexineri (NR 518), Salmonella muenchen, Salmonella typhimurium and Salmonella typhi (ATCC 19430). All the tested compounds demonstrated inhibitory activities against the tested enteric bacteria with MIC values ranging from 3.12 to 100 μg/ml. Three flavonoids isolated from the most active fraction demonstrated the best bioactivities against Escherichia coli, Salmonella muenchen and Salmonella typhimurium with MIC values ranging from 3.12 to 25 μg/mL.

Antioxidant Activity of Flavonoids in LPS-Treated IPEC-J2 Porcine Intestinal Epithelial Cells and Their Antibacterial Effect against Bacteria of Swine Origin

“…Reported MIC values of LUT against E. coli and Salmonella strains vary in the literature. Wouamba et al [57] reported a low MIC of 3.12 µg/mL against E. coli and 6.25 µg/mL against S. Typhimurium; however, only one reference strain per each bacterial species was tested in their study. MIC values of 64 µg/mL were obtained by Qian et al [58] when they tested the activity of LUT against four strains of E. coli, including one ATCC strain and three isolates from raw pork meat.…”

Bioassay‐Guided Isolation of Antiplasmodial Compounds from Hypericum lanceolatum Lam. (Hypericaceae) and Their Cytotoxicity and Molecular Docking

“…The antiplasmodial bioassay-guided investigation of H. lanceolatum twigs and stem bark methanolic extract led to the identification of the dichloromethane-soluble fraction as the most active one from which four distinct compounds ( Figure 3 ) have been isolated as major leads with significant yields in the range of 0.05–0.15% of the dichloromethane active subextract ( Table 1 ). The structure elucidation of the isolated compounds was conducted by exploration of their spectral data (see Figures S 1 –S 8 on supplementary data) which allow their characterization as two xanthones including 1,6-dihydroxyxanthone ( 1 ) [ 31 ] and norathyriol ( 2 ) [ 32 ] as well as two triterpenes, namely, betulinic acid ( 3 ) [ 14 , 33 ] and ursolic acid ( 4 ) [ 34 ].…”

UPLC-QToF-ESI-MS identification and anthelmintic activity of Mitragyna inermis (Willd.) Kuntze (Rubiaceae)

“…The identification of the constituents of the hydroethanolic extract prepared from the leaf powder of M. inermis was carried out by a rapid untargeted UHPLC-QTOF-ESIMS/MS-Based metabolomic profiling method described by Wouamba et al [ 19 ] and the main results obtained are recorded in Table 1 . Fifteen compounds were identified ( Fig.…”