title: Antimycobacterial flavonoids from the leaf extract of Galenia africana.
abstract: The bioassay-guided fractionation of the EtOH extract of the leaves of Galenia africana led to the isolation of three known flavonoids, (2S)-5,7,2'-trihydroxyflavanone (1), (E)-3,2',4'-trihydroxychalcone (2), and (E)-2',4'-dihydroxychalcone (3), and the new (E)-3,2',4'-trihydroxy-3'-methoxychalcone (4). Compounds 1 and 3 exhibited moderate antituberculosis activity. During synergistic studies, a combination of compound 4 and an existing antituberculosis drug, isoniazid, reduced their original MICs 4-fold, resulting in a fractional inhibitory concentration of 0.50. The most pronounced effect was demonstrated by compound 1 and isoniazid reducing their MICs 16-fold and resulting in an FIC of 0.12. Both EtOH extract and isolated compounds failed to exhibit any NADPH oxidase activity at 800.0 muM concentrations, indicating that mycothiol disulfide reductase is not the target for their antituberculosis activity.
authors.affiliation: South African Medical Research Council, TB Epidemiology and Intervention Research Unit, South African National Blood Service, Pretoria, South Africa.
authors.forename: Sannah P N
authors.initials: SP
authors.lastname: Mativandlela
authors.forename: Tshilidzi
authors.initials: T
authors.lastname: Muthivhi
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Oshima
authors.forename: Chris
authors.initials: C
authors.lastname: Hamilton
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Hussein
authors.forename: Martha L
authors.initials: ML
authors.lastname: van der Walt
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Houghton
authors.forename: Namrita
authors.initials: N
authors.lastname: Lall
mesh_terms: D000995:Antitubercular Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D006801:Humans; D019684:Magnoliopsida / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D009247:NADH, NADPH Oxidoreductases / Q000187:drug effects; D019255:NADPH Oxidases / Q000187:drug effects; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D013019:South Africa; D013237:Stereoisomerism
chemical_list: D000995:Antitubercular Agents; D005419:Flavonoids; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C089267:disulfide reductase, mycothiol