Biochemical characterisation of a Kunitz-type inhibitor fromTamarindus indicaL. seeds and its efficacy in reducing plasma leptin in an experimental model of obesity

Abstract

A trypsin inhibitor isolated from tamarind seed (TTI) has satietogenic effects in animals, increasing the cholecystokinin (CCK) in eutrophy and reducing leptin in obesity. We purified TTI (pTTI), characterised, and observed its effect upon CCK and leptin in obese Wistar rats. By HPLC, and after amplification of resolution, two protein fractions were observed: Fr1 and Fr2, with average mass of [M + 14H]+ = 19,594,690 Da and [M + 13H]+ = 19,578,266 Da, respectively. The protein fractions showed 54 and 53 amino acid residues with the same sequence. pTTI presented resistance to temperature and pH variations; IC50 was 2.7 × 10−10 mol.L−1 and Ki was 2.9 × 10−11 mol.L−1. The 2-DE revealed spots with isoelectric points between pH 5 and 6, and one near pH 8. pTTI action on leptin decrease was confirmed. We conclude that pTTI is a Kunitz trypsin inhibitor with possible biotechnological health-related application.

Anti-TNF-α Agent Tamarind Kunitz Trypsin Inhibitor Improves Lipid Profile of Wistar Rats Presenting Dyslipidemia and Diet-induced Obesity Regardless of PPAR-γ Induction

“…We have also purified TTI (TTIp), and it presented an approximate mass of 18 kDa (TTIp), reducing leptin in obese mice [29]. With fully purified TTIp, it is relevant to investigate its action on satiety and biochemical parameters, as well as the effect on molecular markers altered by unbalanced, hyperglycemic diets.…”

Trypsin inhibitors: promising candidate satietogenic proteins as complementary treatment for obesity and metabolic disorders?

“…Purified TTI, called TTIp, is heat resistant, presenting 100% antitryptic activity at the maximum temperature of 80° C, presenting IC50 of 2.7 × 10 −10 mol/l and K i of 2.9 × 10 −11 mol/l . The primary sequences obtained showed high homology with the Kunitz-type soybean trypsin inhibitor, classifying it as belonging to the Kunitz-type family 17 .…”

“…Subsequent studies involving the trypsin inhibitor of tamarind seeds, isolated 72 and purified 17 these proteins administering them by gavage in Wistar rats with diet-induced obesity, evaluating its action on CCK and leptin. At both stages of purification, in both studies, the inhibitor was able to reduce serum leptin concentrations five-fold compared to the untreated obesity group.…”

“…in these studies there was no influence on CCK concentrations in obese animals. It was assumed that the satiety effect of the tamarind inhibitor has no connection neither with the antitryptic activity nor with the modulation of CCK concentrations 14 , 17 , 72 .…”

“…As already described, a series of hormones with satiety activity contribute to energy balance and food consumption regulation. These studies have pointed out that trypsin inhibitors may not have exclusive action on CCK but also on leptin 17 , 72 .…”