Assaying the Antioxidant Activity of Banana Peel

Musa paradisiaca L. leaf and fruit peel hydroethanolic extracts improved the lipid profile, glycemic index and oxidative stress in nicotinamide/streptozotocin-induced diabetic rats

This study aimed to assess antihyperlipidemic, cardiac and antioxidant effects as well as mode of actions of Musa paradisiaca (M. paradisiaca) leaf and fruit peel hydroethanolic extracts in nicotinamide (NA)/streptozotocin (STZ)‐induced diabetic rats. Experimental diabetes mellitus was induced by a single intraperitoneal injection of STZ (60 mg/kg body weight), 15 min after intraperitoneal injection of NA (120 mg/kg body weight). NA/STZ‐induced diabetic rats were orally supplemented with M. paradisiaca leaf and fruit peel hydroethanolic extracts in a dose of 100 mg/kg body weight/day for 28 days. The treatment of NA/STZ‐induced diabetic rats with M. paradisiaca leaf and fruit peel extracts significantly decreased the elevated fasting and post‐prandial serum glucose, total cholesterol, triglycerides, LDL‐cholesterol and vLDL‐cholesterol levels and significantly increased the lowered serum insulin level, liver glycogen content, serum HDL‐cholesterol level, homeostasis model assessment‐insulin resistance (HOMA‐IS) and HOMA‐β cell function. The elevated cardiovascular risk indices in diabetic rats were significantly improved due to treatment with M. paradisiaca extracts. Concomitant with the increase in liver glycogen content, the glucose‐6‐phosphatase activity significantly decreased reflecting the decrease in hepatic glucose output. The heart function was potentially ameliorated as manifested by decrease in the elevated serum creatine kinase‐MB, lactate dehydrogenase and aspartate aminotransferase activities after treatments of diabetic rats with M. paradisiaca extracts. The elevated liver lipid peroxidation and the decline in liver glutathione content and superoxide dismutase, glutathione peroxidase and glutathione‐S‐transferase activities were significantly reversed by treatments. Thus, it can be concluded that M. paradisiaca leaf and fruit peel hydroethanolic extracts may have antihyperlipidemic and cardioprotective potentials in NA/STZ‐induced diabetic rats. These effects may be mediated via improvements in the glycemic state, β‐cell function, tissue insulin sensitivity, and antioxidant defense mechanism.

Valorization of Banana and Red Beetroot Peels: Determination of Basic Macrocomponent Composition, Application of Novel Extraction Methodology and Assessment of Biological Activity In Vitro

The nutritional and bioactive content of banana and red beetroot peels was investigated. The basic macrocomponent composition was determined using standard AOAC (Association of Official Analytical Chemists) methods, while the recovery efficiency of bioactive compounds was investigated using conventional and innovative extraction techniques (subcritical water extraction, ultrasound- and microwave-assisted extraction). Extracts were analyzed for biological effects in vitro on human hepatic, tongue and colon cancer cell lines. A macrocomponent analysis revealed a notable amount of dietary fiber in banana and beetroot peels (39.0 and 33.6% dmb) and a relatively high content of protein in beetroot peel (18.3% dmb). Regarding the micronutrients-minerals, banana and beetroot peels were shown to be a very good source of potassium (75.06 and 41.86 mg g−1 dmb). Both extracts of banana and beetroot peels obtained by conventional extraction - decoction (100 °C, 20 min) exhibited the highest total phenolic content and antioxidant capacity. Additionally, in banana peel, these extracts were the richest in dopamine content (12.63 mg g−1 dmb). Extraction by infusion (80 °C, 30 min) yielded a beetroot peel extract with the highest total betacyanin content (9.80 mg g−1 dmb). Biological effects in vitro were dose- and time-dependent, as well as influenced by the presence of polysaccharides.