Inhibition of low-density lipoprotein oxidation and up-regulation of low-density lipoprotein receptor in HepG2 cells by tropical plant extracts.
Twelve edible plant extracts rich in polyphenols were screened for their potential to inhibit oxidation of low-density lipoprotein (LDL) in vitro and to modulate LDL receptor (LDLr) activity in cultured HepG2 cells. The antioxidant activity (inhibition of LDL oxidation) was determined by measuring the formation of conjugated dienes (lag time) and thiobarbituric acid reagent substances (TBARS). Betel leaf (94%), cashew shoot (63%), Japanese mint (52%), semambu leaf (50%), palm frond (41%), sweet potato shoot, chilli fruit, papaya shoot, roselle calyx, and maman showed significantly increased lag time (>55 min, P < 0.05) and inhibition of TBARS formation (P < 0.05) compared to control. LDLr was significantly up-regulated (P < 0.05) by Japanese mint (67%), semambu (51%), cashew (50%), and noni (49%). Except for noni and betel leaf, most plant extracts studied demonstrated a positive association between antioxidant activity and the ability to up-regulate LDL receptor. Findings suggest that reported protective actions of plant polyphenols on lipoprotein metabolism might be exerted at different biochemical mechanisms.
Salleh
Mohd Nizar
MN
Department of Food Science, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia, Australia.
Runnie
Irine
I
Roach
Paul D
PD
Mohamed
Suhaila
S
Abeywardena
Mahinda Y
MY
D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D003300:Copper / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects*; D008077:Lipoproteins, LDL / Q000737:chemistry* / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D010945:Plants, Edible / Q000737:chemistry; D011973:Receptors, LDL / Q000378:metabolism*; D013662:Tea / Q000737:chemistry; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014329:Tropical Climate; D014407:Tumor Cells, Cultured
D000975:Antioxidants; D008077:Lipoproteins, LDL; D010936:Plant Extracts; D011973:Receptors, LDL; D013662:Tea; D017392:Thiobarbituric Acid Reactive Substances; D003300:Copper