Phytochemical Analysis of the Phenolic Fat-Suppressing Substances in the Leaves of Lactuca raddeana in 3T3-L1 Adipocytes

ABSTRACT

Lactuca raddeana (Compositae) is used to treat obesity and complications due to diabetes. The five phenolic compounds including chlorogenic acid, chicoric acid, luteolin 7-O-glucoside, luteolin 7-O-glucuronide, luteolin were qualitatively identified by LC-ESI-MS analysis. The contents were quantitatively determined by HPLC, under the condition of a Capcell Pak C18 column (5 microm, 250 mm x 4.6 mm i.d.) and a gradient elution of 0.05% trifluoroacetic acid (TFA) and 0.05% TFA in MeOH-H2O (60 : 40). The contents of chicoric acid (100.99 mg/g extract) and luteolin 7-O-glucoside (101. 69 mg/g extract) were high, while those of other three phenolic substances were very low. The 3T3-L1 adipocyte cells treated with chicoric acid and luteolin 7-O-glucuronide significantly suppressed the accumulation of fat, suggesting they are effective against obesity. Since high level of peroxynitrite (ONOO) causes cardiovascular disease in obese patients, its scavenging activity was also studied.