Lipolytic effect of methanol extracts from luffa cylindrica in mature 3T3-L1 adipocytes

The effect of methanol extract from Luffa cylindrica (LCM) on lipid metabolism and underlying mechanisms of lipolysis in mature 3T3-L1 adipocytes were investigated. The intracellular lipid droplets were stained with Oil Red O dye and quantified. Compared to the control, lipid accumulation was significantly decreased by 19.4% with the treatment of LCM at the concentration of 1000 μg/mL. Intracellular triglyceride (TG) level was also reduced by 21% at the concentration of 1000 μg/mL. To determine the mechanism for the reduction in TG content, levels of glucose uptake and glycerol release were measured. Incubation of the 3T3-L1 adipocytes with LCM did not affect the cellular uptake of glucose. However, the level of free glycerol released into the cultured medium drastically increased by 24.3% with the treatment of LCM. In subsequent measurements using quantitative real-time PCR, mRNA levels of hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) except lipoprotein lipase (LPL) were significantly elevated at higher concentration. These results suggest that LCM partially stimulates the lipolysis through the induction of HSL and/or ATGL gene expression, resulting in the reduced lipid accumulation and increased glycerol release.