Development of avocado derived polyhydroxylated fatty alcohols as metabolic modulators

Abstract

Obesity and associated disorders like cardiovascular disease and Type 2 Diabetes share a common pathophysiological process in which adipose tissue dysfunction causes fatty acid spill-over and accumulation in non-adipose tissues like skeletal muscle, heart, pancreas and liver. Recent evidence strongly points towards the inhibition of fatty acid oxidation (FAO) in metabolically active tissue as an effective treatment strategy for obesity and associated disorders, however, safe and efficacious FAO inhibitors are currently not clinically available. Avocado derived polyhydroxylated fatty alcohols (PFAs), avocadene and avocadyne, have been previously shown to selectively induce cell death in leukemia stem cells by inhibiting FAO. This thesis investigates the potential of avocado PFAs to be developed as FAO inhibitors or metabolic modulators for the treatment of obesity and insulin resistance. First, a validated analytical method for the quantitation of avocadene and avocadyne in an array of biological matrices was developed. Second, delivery systems of avocadene and avocadyne were tested in two in vitro digestion models (i.e. static and dynamic (i.e. TIM-1)) and a pilot pharmacokinetic in vivo study. The effects of a 1:1 mixture of pure avocadene and avocadyne (AVO) were then evaluated in treatment and prevention mouse models of diet-induced obesity (DIO). In the treatment DIO study, five-week oral administration of AVO (twice weekly) slowed weight gain, improved whole body glucose tolerance, reversed insulin resistance, and increased postprandial skeletal muscle glucose utilization. AVO’s mechanism of action was further explored in cell culture models of lipotoxicity where AVO inhibited excessive FAO and restored glucose oxidation which restored insulin action in C2C12 myotubes (mouse skeletal muscle cells) and increased glucose stimulated insulin secretion (GSIS) in INS-1 (832/13) cells (rat pancreatic β-cell line), respectively. Finally, a nutritional supplement containing 50 or 200 mg AVO was manufactured for evaluation in a Phase I, double-blind, placebo-controlled human clinical trial. AVO consumption (once daily for 60 days) showed no dose limiting toxicities in healthy human participants. In summary, the use of a safe and potent FAO inhibitor like AVO was shown to ameliorate obesity-associated pathologies. This thesis lays the groundwork for future large scale preclinical and clinical studies for AVO.