Author(s):
Mendes, Nuno Eduardo dos Anjos Serra 
Date: 2012
Persistent ID: http://hdl.handle.net/10362/8056
Origin: Repositório Institucional da UNL
Subject(s): Obesity; Lipase; Trypsin; Thylakoids; Phytochemicals; Enzyme inhibition
Description
Dissertation to obtain a Master’s Degree in Chemical and Biochemical Engineering Using natural ingredients to combat obesity has emerged as a promising alternative to
conventional therapies which present many side effects. Satiety induction by the ingestion of certain natural compounds has been proven to be an interesting strategy. In this context, the present study had the following objectives:
- Isolation of rucola, watercress and spinach, plum and tomato waste and cladodes of Opuntia ficus-indica extracts, rich in compounds with the potential to induce a prolonged feeling of satiety
- Assess the satiety inducing potential of isolated extracts using two enzymatic methods:
- Inhibition of pancreatic lipase, an enzyme responsible for the conversion of complex lipids into simple and easily absorbable fat, which when inhibited is associated with a prolongation of satiety and a reduction in fat absorption, being the therapeutic target of Orlistat (the most common anti-obesity drug)
- Inhibition of trypsin’s proteolytic activity, which is associated with a prolongation of satiety as it promotes the secretion of cholecystokinin (CCK), a polypeptide which regulates pancreatic
enzyme release, which not only promotes satiety but also slows gastric emptying.
In this work a method for extracting thylakoids, which are potent inhibitors of pancreatic lipase,was optimized. In addition to spinach, this method was applied for the first time to rucola and watercress. The extracts from these three matrixes exhibited lipase inhibitory activity, with spinach being the most efficient one.
Hydroalcoholic extracts were prepared from plum residue, rich in polyphenols and saponins, which also showed efficient inhibitory capacity of pancreatic lipase.
A protocol was optimized for the extraction of proteins which applied to the plum residue,tomatoes and cladodes of Opuntia ficus-indica. Only the opuntia and tomato extracts presented effective inhibition of trypsin’s proteolytic activity.
