Nanophytomedicines for the prevention of metabolic syndrome

Abstract

Metabolic syndrome (MetS), also known as "syndrome X" and "insulin-resistance syndrome", is characterized by several metabolic abnormalities, including insulin resistance, type 2 diabetes, obesity, hypertension, and dyslipidaemia (Kaur, 2014; Dalvand et al., 2017; Ebrahimi-Mameghani et al., 2018). About 20–30% of the world population is diagnosed with MetS, which makes the disease as a global health issue (Beltrán-Sánchez et al., 2013; Xi et al., 2013; Vishram et al., 2014; Pucci et al., 2017). MetS is the result of a series of genetic and environmental factors; however, the exact etiology is not yet understood (Feldeisen and Tucker, 2007). The underlying mechanisms encompass insulin resistance, elevated plasma free fatty acids, chronic inflammation, and oxidative stress (Bergman et al., 2001; Pan and Kong, 2018). The increased level of free fatty acids results in suppression of insulin clearance and is closely associated with insulin resistance in obese individuals. To overcome the resistance, pancreas secretes more insulin, leading to hyperinsulinemia (Oh et al., 2018). Free fatty acids cause induction and suppression of protein kinase in the liver and the muscle cells, respectively, which subsequently increases gluconeogenesis in liver and diminishes glucose uptake in muscles (Rochlani et al., 2017). Chronic inflammation is implicated in visceral obesity and exacerbates insulin resistance, which is characterized by the abnormal production of adipocytokines such as tumour necrosis factor-α (TNF-α), interleukin-1 (IL-1), IL-6, leptin, and plasminogen activator inhibitor-1 (PAI-1) (Vaziri et al., 2005; Di Lorenzo et al., 2013). Oxidative stress induces insulin resistance and also abrogates the adiponectin production by adipocytes (Furukawa et al., 2017). Adiponectin is an important anti-inflammatory and anti-atherogenic adipokine and is considered as a protective factor against the development and progression of chronic diseases related to metabolic disorders and oxidative stress including diabetes, hypertension, and cardiovascular diseases (Becic et al., 2018). Secretions of adipose tissue stimulate mineralocorticoid release from adrenal cells and promote the renin angiotensin aldosterone system activity. Consequently, an elevation in renal sodium retention and vascular tone, as well as an inhibition of norepinephrine reuptake occur, which leads to hypertension. There is a direct relationship between obesity and the pathogenesis of hypertension (Ehrhart-Bornstein et al., 2003; Cabandugama et al., 2017). Management of MetS involves lifestyle modification, which consists of particular recommendations on physical activity and dietary interventions to achieve a normal weight, modulation of glycaemic and lipid profile, as well as a decrease in blood pressure (Grundy, 2016). Nano-emulsions are stable colloidal systems that are favorable and suitable vehicles for controlled delivery of lipophilic ingredients (Aswathanarayan and Vittal, 2019). SLNs are lipid-based NPs that can be easily fabricated by biodegradable and biocompatible solid lipids (Ghasemiyeh and Mohammadi-Samani, 2018). NLCs are another type of lipid-based nano carrier systems with colloidal particles composed of both solid and liquid lipids (Madane and Mahajan, 2016). Nanoliposomes provide a useful technology for delivering and targeting both hydrophilic and lipophilic phytobioactive constituents (Khorasani et al., 2018). Biodegradable polymeric NPs offer numerous advantages, since they protect bioactive constituents from degradation, enhance solubility, and provide controlled delivery and targeting (Pereira et al., 2018). Ganesan et al. (2017) reviewed the beneficial effects of nanostructured formulations of phytochemicals to counteract diabetes. In our previous study, we reviewed the beneficial effects of nano-formulation originated from phytochemicals to combat MetS and its related complications (Taghipour et al., 2019). There is no comprehensive review about the potential use of various nanostructured formulations fabricated from herbal extracts, as promising future drugs to treat MetS and its associated complications. The present study, for the first time, provides a comprehensive review on the beneficial effects of nano-formulated herbal extracts on MetS and related disorders considering the in vitro and in vivo experiments.