Phyllanthus emblica fruit extract attenuates lipid metabolism in 3T3-L1 adipocytes via activating apoptosis mediated cell death

Abstract

Background: Phyllanthus emblica L. (Indian gooseberry) is widely used in the Ayurveda for thousands of years to treat health complications including disorders of the immune system, diabetes, and obesity.

Purpose: For the first time, our study aims to demonstrate the molecular mechanisms of the fruit extract of Phyllanthus emblica (PEFE) involved in the promotion of fat cell apoptosis and alleviation of adipogenesis.

Methods: The active constituents from PEFE were identified using high performance liquid chromatography-mass spectrometry (HPLC-MS). We carried out the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay to evaluate the cytotoxic effects of PEFE using 3T3-L1 pre-adipocytes. The colonogenic assay was carried out to determine the inhibitory effect of 3T3-L1 adipocytes after PEFE treatment. In addition, inhibition of pancreatic lipase activity was performed and the lipolytic activity of PEFE and digallic acid was compared with the well-known standard drug orlistat. Besides, the molecular interaction and ligand optimization between digallic and adipogenesis/apoptosis markers were also carried out. Furthermore, to confirm fat cell apoptosis we have used several detection methods that includes Hoechst staining, PI staining, Oil staining and qPCR respectively.

Results: Digallic acid was identified as a major component in the PEFE. The IC₅₀ values of digallic acid and PEFE were found to be 3.82 µg/ml and 21.85 µg/ml respectively. PEFE and digallic acid showed significant anti-lipolytic activity compared to the standard drug orlistat. In the mature adipocytes, PEFE significantly decreased triglyceride accumulation by downregulating adiponectin, PPARγ, cEBPα, and FABP4 respectively. We further analyzed the expression of apoptosis related genes upon PEFE treatment. Apoptotic process initiated through upregulation of BAX and downregulation of BCL2 resulting in an increased caspase-3 activity. In addition, we have also confirmed the apoptosis and DNA fragmentation in 3T3-L1 cells using Hoechst, PI and TUNEL assays.

Conclusion: PEFE negatively regulates adipogenesis by initiating fat cell apoptosis and therefore it can be considered as a potential herbal medicinal product for treating obesity.

Keywords: Adipocytes; Adipogenesis; Apoptosis; HPLC-MS; Phyllanthus emblica; Triglycerides.