Evaluation of Botanicals for Mechanisms Related to Appetite and Fat Metabolism

Overview

Excess caloric consumption, particularly from inexpensive, energy dense foods that are high in fat and refined carbohydrates, is a major driver of the global obesity epidemic. Dietary supplements that promote reduced intake of energy dense foods and/or impact the absorption and metabolism of fat and carbohydrates in the body can be used to help consumers control their weight. We identified two separate mechanistic approaches to target these effects. Diacylglycerol acyltransferase-1 (DGAT-1) is an enzyme involved in the formation of dietary fat into circulating triglycerides within the body. Once dietary fat is digested and absorbed, the resulting fatty acids are re-esterified into triglycerides. Inhibition of DGAT-1 results in delayed and decreased re-esterification of dietary fats into circulating triglycerides. It is hypothesized that this effect may lead to decreased deposition of excess dietary fat as adipose tissue, possibly due to increased fatty acid oxidation in the enterocytes. Ghrelin is a hormone that is known to stimulate appetite in humans. When calorie dense fatty foods are sensed in the stomach, ghrelin is acylated and activated via ghrelin O-acyltransferase (GOAT). The activation step attaches a medium chain fatty acid to the ghrelin molecule that enables it to transmit a signal in the brain that triggers eating and fat storage in adipose tissue. Interfering with the GOAT pathway will inhibit ghrelin activation and possibly diminish food intake and lipid storage. This concept is supported by animal studies in which weight gain in a high fat diet model is prevented when GOAT is inhibited. Our objective was to determine whether botanicals demonstrating in vitro DGAT-1 and GOAT inhibition have similar mechanistic effects in the human body. Based on the results of this study, prototype formulas may be developed and clinically- tested for outcomes related to weight management.

Excess caloric consumption, particularly from inexpensive, energy dense foods that are high in fat and refined carbohydrates, is a major driver of the global obesity epidemic. Dietary supplements that promote reduced intake of energy dense foods and/or impact the absorption and metabolism of fat and carbohydrates in the body can be used to help consumers control their weight. We identified two separate mechanistic approaches to target these effects. Diacylglycerol acyltransferase-1 (DGAT-1) is an enzyme involved in the formation of dietary fat into circulating triglycerides within the body. Once dietary fat is digested and absorbed, the resulting fatty acids are re-esterified into triglycerides. Inhibition of DGAT-1 results in delayed and decreased re-esterification of dietary fats into circulating triglycerides. It is hypothesized that this effect may lead to decreased deposition of excess dietary fat as adipose tissue, possibly due to increased fatty acid oxidation in the enterocytes. Ghrelin is a hormone that is known to stimulate appetite in humans. When calorie dense fatty foods are sensed in the stomach, ghrelin is acylated and activated via ghrelin O-acyltransferase (GOAT). The activation step attaches a medium chain fatty acid to the ghrelin molecule that enables it to transmit a signal in the brain that triggers eating and fat storage in adipose tissue. Interfering with the GOAT pathway will inhibit ghrelin activation and possibly diminish food intake and lipid storage. This concept is supported by animal studies in which weight gain in a high fat diet model is prevented when GOAT is inhibited. Ghrelin levels are positively associated with stress, sleep deprivation, and caloric restriction. Weight loss induced by exercise does not have the same positive association with ghrelin levels that caloric restriction alone has. Ghrelin levels are influenced by diet composition, however, the results vary considerably between trials. Over 160 botanical extracts from our internal ingredient library were screened at a single concentration for inhibition of both DGAT-1 and GOAT. Botanicals that were identified as having at least 75% activity were then titrated to identify those with IC50 values \< 25 g/ml or less. We narrowed our list of viable ingredients by looking at those with activity in both the DGAT-1 and GOAT in vitro enzyme bioassay models. The top performing botanicals were then evaluated in a cellular model for DGAT-1 inhibition. Those with the highest inhibition activity in this model were considered lead candidates. A preliminary literature search was conducted and the final filter included factors such as cost and regulatory acceptability which results in the four ingredients being tested in the current clinical protocol.Our objective was to determine whether these four ingredients have similar mechanistic effects in the human body.