Obesity and insulin resistance (IR) are interdependent multifactorial processes that cannot be understood separately. Obesity leads to systemic inflammation and increased levels of free fatty acids that provoke IR and lipotoxicity. At the same time, IR exacerbates adipose cell dysfunction, resulting in chronic inflammation and major lipotoxic effects on nonadipose tissues. 4-Hydroxyisoleucine (4-OHIle), a peculiar nonprotein amino acid isolated from fenugreek (Trigonella foenum-graecum) seeds, exhibits interesting effects on IR related to obesity. 4-OHIle increases glucose-induced insulin release, and the insulin response mediated by 4-OHIle depends on glucose concentration. The beneficial effects observed are related to the regulation of blood glucose, plasma triglycerides, total cholesterol, free fatty acid levels, and the improvement of liver function. The mechanism of action is related to increased Akt phosphorylation and reduced activation of Jun N-terminal kinase (JNK)1/2, extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), and nuclear factor (NF)-κB. Here, we present a review of the research regarding the insulinotropic and insulin-sensitising activity of 4-OHIle in in vitro and in vivo models.

The fruit, vegetable, legume, and cereal industries generate many wastes, representing an environmental pollution problem. However, these wastes are a rich source of antioxidant molecules such as terpenes, phenolic compounds, phytosterols, and bioactive peptides with potential applications mainly in the food and pharmaceutical industries, and they exhibit multiple biological properties including antidiabetic, anti-obesity, antihypertensive, anticancer, and antibacterial properties. The aforementioned has increased studies on the recovery of antioxidant compounds using green technologies to value plant waste, since they represent more efficient and sustainable processes. In this review, the main antioxidant molecules from plants are briefly described and the advantages and disadvantages of the use of conventional and green extraction technologies used for the recovery and optimization of the yield of antioxidant naturals are detailed; finally, recent studies on biological properties of antioxidant molecules extracted from plant waste are presented here.

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Aim: To evaluate the efficacy and safety of 2 analogs of L-carnitine on rats made insulin resistant by a high-fructose diet. Methods: Using rats made insulin resistant by a high-fructose diet, we investigated the impact of 2 analogs of L-carnitine (25 mg/kg) and L-carnitine (250 mg/kg) on glucose, triglycerides and cholesterol blood levels, and liver glycogen. We also evaluated the safety of both analogs by the assessment of some biochemical and hematological parameters, a histological analysis and a study of embryotoxicity. Results: Both analogs reduced the levels of triglycerides in the liver and plasma, but only analog 2 reduced the cholesterol levels in insulin-resistant rats. No changes were observed in glycogen content. Safety evaluations revealed alterations in blood lymphocytes and embryotoxicity data. Conclusion: This study demonstrated that the 2 analogs maintain the pharmacological properties of L-carnitine but have a different efficacy, potency and toxicity.