Green silver nanoparticles ameliorate diet-induced obesity through antioxidant and anti-inflammatory properties

Abstract This study aims to evaluate the anti-obesity effect of silver nanoparticles biosynthesized in Aloe vera leaf extract (AV-AgNPs) administrated to Sprague Dawley rats  that fed with high-fat diet (HFD) for up to 12 weeks. AV-AgNPs were recognized by transmission electron microscopy (TEM) and dynamic light scattering. The in vitro study investigated the antioxidant ability, effects on coagulation time, anti-inflammatory, cytotoxicity of AVLE and AV-AgNPs and cytokinesis-block micronucleus (CBMN) assay for genotoxic effects. When the in vivo experiment is completed, different parameters such as body weight, fasting plasma glucose (FPG), serum lipid levels, white adipose tissue (WAD) oxidative stress markers and adipokines were evaluated. Green AV-AgNPs were spherical with sizes of 19.4–25.9 nm as revealed using TEM. The sizes and zeta potentials of AV-AgNPs presented particle stability up to 70 days. AV-AgNPs had a high in vitro antioxidant and anti-inflammatory abilities with no significant effects on partial thromboplastin time and the prothrombin time. In vitro CBMN assay indicated no significant genotoxic effects of AVLE or AV-AgNPs at low concentration (25 µg/ml). AV-AgNPs and AVLE showed significant decline in body FPG and lipid profile in HFD-fed rats with no apparent effects on normal pellet diet (NPD)-fed ones. In addition, oxidative stress markers, size of subcutaneous adipocytes and micro-vesicular steatosis of hepatocytes in the HFD group were significantly reduced after AVLE and AV-AgNPs administration. Finally, WAD analysis of M2 interleukin (IL)-4 and IL-10 was significantly elevated with AVLE and AV-AgNPs supplementation. Further, both significantly lowered M1 pro-inflammatory cytokines as tumor necrosis factor-α (TNF-α), IL-1β and IL-6 in the WAD of HFD-fed group. In terms of body weight, adiposity and hepatic steatosis, the anti-obesity properties of AV-AgNPs were significant (34.4–35.17% weight reduction) compared to whole AVLE (13.9–18.36% weight reduction). The biochemical and immunological effects were comparable and mediated by amelioration of oxidative stress and induction M2 polarization in WAD.