World Botanical Associates Web Page
Prepared by Richard W. Spjut
May 2004; November 2006, April 2010
Santa Barbara Co., CA, Robert H. Miller 3535, 27 May 1965
Chung H.S., L. C. Chang, S. K. Lee, L. A. Shamon, R. B. van Breemen, R. G. Mehta, N. R. Farnsworth, J. M. Pezzuto and A. D. Kinghorn. 1999. Flavonoid constituents of Chorizanthe diffusa with potential cancer chemopreventive activity. J. Agric. Food Chem. 47(1): 36-41. “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.”
Lee S. K., Z.
H. Mbwambo, H. Chung, L. Luyengi, E. J. Gamez, R. G. Mehta, A. D. Kinghorn
and J. M. Pezzuto. 1998. Evaluation of the antioxidant potential of
natural products. Comb. Chem. High Throughput Screen 1(1): 35–46. “Since
reactive oxygen radicals play an important role in carcinogenesis and
other human disease states, antioxidants present in consumable fruits,
vegetables, and beverages have received considerable attention as cancer
chemopreventive agents. Thus, in order to identify antioxidants in plant
extracts, test materials were assessed for potential to scavenge stable
1,2-diphenyl-2-picrylhydrazyl (DPPH) free radicals, reduce TPA-induced
free radical formation in cultured HL-60 human leukemia cells, and inhibit
responses observed with a xanthine/xanthine oxidase assay system.
Approximately 700 plant extracts were evaluated, and 28 were found to be
active in the DPPH free radical scavenging assay. Based on secondary
analyses performed to assess inhibition of
7,12-dimethylbenz(a)anthracene-induced preneoplastic lesion formation with
a mouse mammary organ culture model, Chorizanthe diffusa Benth.
(Polygonaceae), Mezoneuron cucullatum Roxb. (Leguminosae),
Cerbera manghas L. (Apocynaceae) and Daphniphyllum calycinum
Benth. (Daphniphyllaceae) were selected and subjected to bioassay-guided
6,3',4'-trihydroxy-7-methoxyflavonol were identified as active principles
from C. diffusa. Piceatannol, trans-resveratrol, apigenin and
scirpusin A were found as the active principles of M. cucullatum,
olivil, (-)-carinol, and (+)-cycloolivil were active principles from C.
manghas, and 5,6,7,4'-tetrahydroxyflavone 3-O-rutinoside and
kaempferol 3-O-neohesperidoside were active principles from D. calycinum.
Of these substances, the hydroxystilbenes piceatannol and transresveratrol
have thus far been shown to inhibit carcinogen-induced preneoplastic
lesion formation in the mouse mammary gland organ culture model.”