Laurus nobilis ethanolic extract attenuates hyperglycemia and hyperinsulinemia-induced insulin resistance in HepG2 cell line through the reduction of oxidative stress and improvement of mitochondrial biogenesis – Possible implication in pharmacotherapy

• Published in: Mitochondrion 2021-07, Vol.59, p.190-213
• Main Authors: Bourebaba, Nabila, Kornicka-Garbowska, Katarzyna, Marycz, Krzysztof, Bourebaba, Lynda, Kowalczuk, Anna
• Format: Article
• Language: English
• Subjects: Antioxidants - pharmacology; Apoptosis - drug effects; Chromatography, Liquid; Ethanol - pharmacology; Glucose - adverse effects; Hep G2 Cells; Humans; Hyperglycaemia; Hyperglycemia - chemically induced; Hyperglycemia - drug therapy; Hyperglycemia - metabolism; Hyperinsulinism - chemically induced; Inflammation; Insulin - adverse effects; Insulin Resistance; Laurus nobilis; Mitochondria; Models, Biological; Organelle Biogenesis; Oxidative Phosphorylation - drug effects; Oxidative stress; Oxidative Stress - drug effects; OXPHOS; Plant Extracts - chemistry; Reactive Oxygen Species - metabolism; Tandem Mass Spectrometry
• ISSN: 1567-7249; 1872-8278
• DOI: 10.1016/j.mito.2021.06.003

•Nowadays, IR is recognized as one of the most common metabolic alterations.•Hyperglycaemia inhibit mitochondrial biogenesis and oxidative metabolism.•L. nobilis derived active compounds exhibit antioxidant and antidiabetic effects.•L. nobilis extract decreased apoptosis and NF-κB and Tlr4 markers expression.•The extract reduced HepG2’ ROS levels and improved mitochondrial OXPHOS machinery. The aim of this study was to establish the potential effect of Laurus nobilis ethanolic extract on improving insulin sensitivity and protecting liver cells from apoptosis, mitochondrial dysfunction, oxidative stress (OS), and inflammation; all of which considered as major alterations occurring during insulin resistance (IR) as well as diabetes onset, in hyperinsulinemic and hyperglycemic-induced HepG2 cell line. Thereby, L. nobilis ethanolic extract has been first chemically characterized using LC-MS/MS technique. Subsequently, HepG2 cells were pre-treated with an optimal concentration of L. nobilis ethanolic extract for 24 h, and then, subjected to 30 mM D-glucose and 500 nM insulin mixture for another 24 h in order to induce hyperinsulinemia and hyperglycaemia (HI/HG) status. Several parameters such as biocompatibility, hepatotoxicity, reactive oxygen species (ROS), mitochondrial transmembrane potential, dynamics, and metabolism, multicaspase activity, glucose uptake, in addition to genes and proteins expression levels were investigated. The obtained results showed that the bioactive extract of Laurus nobilis increased the number of living cells and their proliferation rate, significantly attenuated apoptosis by modulating pro-apoptotic pathways (p21, p53 and Bax genes), allowed a relative normalization of caspases-activity, and decreased the expression of inflammatory markers including c-Jun, NF-κB and Tlr4 transcripts. L. Nobilis ethanolic extract reduced considerably total intracellular ROS levels in challenged HepG2 cells, and regulated the mitochondrial OXPHOS pathway, demonstrating the potential antioxidant effect of the plant. Ethanolic plant extract increased insulin sensitivity, since an elevated expression of master transcripts responsible for insulin sensitivity including IRS1, IRS2, INSR was found. Taken together, obtained data suggest that L. nobilis ethanolic extract offers new insights in the development of potential antioxidant, insulin sensitizing as well as hepatoprotective drugs.