Tamarind-Derived Trypsin Inhibitor as a Potential Therapeutic Agent for Obesity: Evidence from In Vitro and Zebrafish Models

Abstract

Obesity is a multifactorial disease, with numerous therapeutic targets. In this context, various peptides and proteins have been the focus of research due to their ability to influence body weight regulation. This study aimed to investigate the effect of trypsin inhibitor isolated from tamarind seeds (TTI) on lipase activity, both in vitro and in vivo, using the zebrafish (Danio rerio) as an animal model. TTI was first isolated through affinity chromatography using trypsin-Sepharose 4B, followed by characterization of its antitryptic activity, protein quantification, and molecular mass. An in vitro inhibition assay was then performed against porcine pancreatic lipase to determine the half-maximal inhibitory concentration (IC₅₀) and inhibition constant (K_i) of TTI. TTI inhibited the lipase activity by 83%. The IC₅₀ was estimated to be 1.59 × 10^–9 mol L^–1, and the K_i was 2.38 × 10^–8 mol L^–1, indicating that TTI acts as a reversible noncompetitive inhibitor. The preclinical study involved diet-induced obese zebrafish. The fish were divided into five groups: eutrophic and normofed animals without treatment; obese and hyperfed animals without treatment; obese and hyperfed animals treated with Orlistat (50 mg/kg Orlistat); obese and hyperfed animals treated with TTI (25 mg/L TTI); and obese and normofed animals treated with TTI (25 mg/L TTI). After 10 days of treatment, the groups were evaluated for lipase activity, body weight, and lipid profile. Results showed that neither Orlistat nor TTI inhibited lipase activity under the tested in vivo conditions. However, TTI-treated hyperfed and normofed animals showed a significant reduction in body weight compared with the control groups (obese and hyperfed animals without treatment and obese and hyperfed animals treated with Orlistat). Moreover, HDL concentrations were significantly higher in the TTI-treated groups compared with all other groups. Thus, TTI represents a promising strategy for the treatment of obesity and the prevention of dyslipidemia, opening new avenues for exploring its potential benefits against other obesity-associated comorbidities.