A study of 15 phenolic acids and six flavonoids were studied for their ability to affect fat cells in laboratory cultures of mouse cells, with o-coumaric acid and rutin reported to inhibit activity of the glycerol-3-phosphate dehydrogenase (GPDH) enzyme that forms triglycerides - fatty materials which at high levels increase the risk of heart disease.
"These results indicate that flavonoids and phenolic acids may play a role in the control of adipogenesis and they might have further implication in in vivo anti-obesity effects," wrote Chin-Lin Hsu and Gow-Chin Yen from National Chung Hsing University.
According to the International Obesity Task Force, an estimated 300 million adults worldwide are obese (body mass index over 30).
Moreover, rising obesity is predicted to have a huge impact on public health services.
A recent Foresight report predicted that the cost of the epidemic in Britain, in terms of health care provision and lost working hours, could reach £45bn a year by 2050.
The new study, published in the Journal of Agricultural and Food Chemistry , looked at the effects of the flavonoids and phenolics on levels of triglyceride in the cells and GPDH activity in 3T3-L1 adipocytes (fat cells).
The researchers chose the 3T3-L1 cell line because it has been used widely for several decades as a cell model for fat cell biology research.
Among the 15 phenolic acids and six flavonoids tested o-coumaric acid and rutin were found to inhibit intracellular triglyceride the most, by 61 and 83 per cent, respectively.
Moreover, the same two compounds were found to be the most potent inhibitors of GPDH, reducing activity by 54 and 67 per cent, respectively.
These two compounds also inhibited the expression of peroxisome proliferators-activated receptor gamma (PPAR-gamma), a protein that plays a role in metabolic functions, and the hormone leptin.
The compounds also up-regulated expression of adiponectin, a hormone that modulates a number of metabolic processes.
"Adipose tissue is now known to produce and secrete a PPAR-gamma , which [has a role] in the early stage of adipocyte differentiation, " wrote the researchers. "
Some studies have addressed the important role that PPAR -gamma plays in the regulation of insulin sensitivity and glucose homeostasis. "
" The present experiment indicated that o-coumaric acid and rutin treatment inhibited the expression of PPAR -gamma protein levels , which demonstrated that compounds inhibited adipogenesis by affecting the transcriptional factor cascade upstream of PPAR -gamma expression . "
In the present study, o-coumaric acid and rutin also inhibited the expression of leptin and then stimulated the up-regulation of adiponectin at the protein level.
Adiponectin expression would, therefore, be regulated by PPAR -gamma transcriptional activity ," they added. "
These results suggest that o-coumaric acid and rutin targeted for adipocyte functions could be effective in improving the symptoms of metabolic syndrome ," concluded the researchers.
Metabolic syndrome (MetS) is a condition characterised by central obesity, hypertension, and disturbed glucose and insulin metabolism.
The syndrome has been linked to increased risks of both type-2 diabetes and CVD.
Fifteen per cent of adult Europeans are estimated to be affected by MetS, while the US statistic is estimated to be a whopping 32 per cent.
Source: Journal of Agricultural and Food Chemistry Volume 55, Pages 8404-8410 "Effects of Flavonoids and Phenolic Acids on the Inhibition of Adipogenesis in 3T3-L1 Adipocytes" Authors: C.-L. Hsu, G.-C. Yen