Antimycobacterial flavonoids from the leaf extract of Galenia africana.
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.
Mativandlela
Sannah P N
SP
South African Medical Research Council, TB Epidemiology and Intervention Research Unit, South African National Blood Service, Pretoria, South Africa.
Muthivhi
Tshilidzi
T
Kikuchi
Haruhisa
H
Oshima
Yoshiteru
Y
Hamilton
Chris
C
Hussein
Ahmed A
AA
van der Walt
Martha L
ML
Houghton
Peter J
PJ
Lall
Namrita
N
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
D000995:Antitubercular Agents; D005419:Flavonoids; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C089267:disulfide reductase, mycothiol