Flavonoid constituents of Chorizanthe diffusa with potential cancer chemopreventive activity.
An ethyl acetate-soluble extract of Chorizanthe diffusa was found to exhibit significant antioxidant activity, as judged by scavenging stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals and inhibition of 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced free radical formation with cultured HL-60 cells. Bioassay-directed fractionation of this extract using the DPPH antioxidant assay as a monitor led to the isolation of five structurally related flavonoids (1-5), including the novel compound 5,8,3',4',5'-pentahydroxy-3, 7-dimethoxyflavone (1). Isolates 1-5 demonstrated varying degrees of antioxidant or antimutagenic activity. Two of the compounds, 5,7,3', 4'-tetrahydroxy-3-methoxyflavone (2) and quercetin (4), were subsequently found to inhibit carcinogen-induced preneoplastic lesions in a mouse mammary organ culture model. Inhibitory activity of this type is known to correlate with cancer chemopreventive effects in full-term models of tumorigenesis.
Chung
H S
HS
Program for Collaborative Research in the Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, USA.
Chang
L C
LC
Lee
S K
SK
Shamon
L A
LA
van Breemen
R B
RB
Mehta
R G
RG
Farnsworth
N R
NR
Pezzuto
J M
JM
Kinghorn
A D
AD
D000818:Animals; D016588:Anticarcinogenic Agents / Q000032:analysis* / Q000494:pharmacology*; D005419:Flavonoids / Q000032:analysis* / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D010944:Plants / Q000737:chemistry*
D016588:Anticarcinogenic Agents; D005419:Flavonoids