Mh. Kweon et al., Identification and antioxidant activity of novel chlorogenic acid derivatives from bamboo (Phyllostachys edulis), J AGR FOOD, 49(10), 2001, pp. 4646-4655
One known and two novel antioxidant compounds have been isolated from bambo
o (Phyllostachys edulis). The butanol-soluble extract of the ba m-boo leave
s was found to have a significant antioxidant activity, as measured by scav
enging the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and the
superoxide anion radical (O-2(-)) in the xanthine/xanthine oxidase assay s
ystem. Antioxidant activity-directed fractionation of the extract led to th
e isolation and characterization of three structural isomeric chlorogenic a
cid derivatives: 3-O-(3'-methylcaffeoyl)quinic acid (1), 5-O-caffeoyl-4-met
hylquinic acid (2), and 3-O-caffeoyl-1-methylquinic acid (3). Compounds 2 a
nd 3 were isolated and characterized for the first time from the natural pr
oducts. In the DPPH scavenging assay as well as in the iron-induced rat mic
rosomal lipid peroxidation system, compounds 2 (IC50 = 8.8 and 19.2 muM) an
d 3 (IC50 = 6.9 and 14.6 muM) showed similar to2-4 times higher antioxidant
activity than did chlorogenic acid (IC50 = 12.3 and 28.3 muM) and other re
lated hydroxycinnamates such as caffeic acid (IC50 = 13.7 and 25.5 muM) and
ferulic acid (IC50 = 36.5 and 56.9 muM). Among the three compounds, compou
nd 1 yielded the weakest antioxidant activity, and the DPPH scavenging and
lipid peroxidation inhibitory activity (IC50 = 16.0 and 29.8 muM) was lower
than those of chlorogenic and caffeic acids. All three compounds exhibited
both superoxide scavenging activities and inhibitory effects on xanthine o
xidase. Their superoxide anion (O-2(-)) scavenging activities (IC50 = 1, 4.
3 muM; 2, 2.8 muM; and 3, 1.2 muM) were markedly stronger than those of asc
orbic acid (IC50 = 56.0 muM), alpha -tocopherol (IC50 > 100 muM), and other
test compounds, although their inhibition effects on xanthine oxidase may
contribute to the potent scavenging activity. cc-Tocopherol exerted a signi
ficant inhibitory effect (65.5% of the control) on superoxide generation in
12-O-tetradecanoylphorbol-13-acetate-induced human promyelocytic leukemia
HL-60 cells, and compound 3 showed moderate activity (36.0%). On the other
hand, other compounds including 1, 2, chlorogenic acid, and other antioxida
nts were weakly active (24.8-10.1%) in the suppression of superoxide genera
tion.