Aqueous extract of Psidium guajava leaves: phenolic compounds and inhibitory potential on digestive enzymes

ABSTRACT Leaves of Psidium guajava L. (guava) have been widely used in the popular way for prevention and treatment of various diseases. Thus, the objective of this study was to evaluate the inhibitory potential of leaves aqueous extract from three cultivars of P. guajava (Pedro Sato, Paluma and Século XXI) on α-amylase, α-glycosidase, lipase, and trypsin enzymes, in the presence or not of simulated gastric fluid and to determine the content of phenolic compounds by high performance liquid chromatography. All cultivars presented the same composition in phenolic compounds, but in different proportions. The compounds identified are gallic acid, epigallocatechin gallate, syringic acid, o-coumaric acid, resveratrol, quercetin, and catechin (which was the major compound in all the cultivars evaluated). In the absence of simulated gastric fluid, it was observed different inhibitions exercised by the leaves aqueous extracts from three cultivars of P. guajava on each enzyme. In presence of simulated gastric fluid, all cultivars showed increase in the inhibition of lipase and α-glycosidase, and decrease in inhibition of α-amylase and trypsin enzymes. These results indicate that P. guajava leaves aqueous extracts from all cultivars evaluated possess potential of use as an adjuvant in the treatment of obesity and other dyslipidemias.

Metanolic extract of Malpighia emarginata bagasse: phenolic compounds and inhibitory potential on digestive enzymes

ABSTRACT Adding value to fruit residues is of great interest, since they can be presented as a viable solution in search of new drugs for the treatment of obesity and related diseases, due to bioactive substances, especially phenolic compounds. Thus, the objective of this study was to prepare the methanol extract of acerola bagasse flour, in order to evaluate its potential as a source of inhibitors of the enzymes α-amylase, α-glucosidase, lipase and trypsin, and determine the content of phenolic compounds by high performance liquid chromatography. Enzymatic inhibition assays were conducted in the presence or absence of simulated gastric fluid. In the methanol extract of acerola bagasse flour, the following phenolic compounds were identified: gallic acid, syringic and p-coumaric acid, catechin, epigallocatechin gallate, epicatechin and quercetin; epicatechin was the major compound. In the absence of gastric fluid, simulated enzymes had a variable inhibition of the acerola bagasse flour extract, except for lipase, which was not inhibited. In the presence of simulated gastric fluid, there was an inhibition of 170.08 IEU (Inhibited Enzyme Unit in µmol min−1 g−1) for α-amylase and 69.29 IEU for α-glucosidase, indicating that this extract shows potential as an adjuvant in the treatment of obesity and other dyslipidemia.

Antioxidants from Medicinal Plants Used in the Treatment of Obesity.

Aims: The objective of this work was to quantify phenolic compounds, flavonoids, vitamin C, total carotenoids, β-carotene and lycopene and to measure the antioxidant activity in the medicinal plants Aloe vera (L.) Burm. (aloe), Simaba ferruginea St. Hil. (calunga), Baccharis trimera (Less.) DC (carqueja), Garcinia cambogia Desr., and Tournefortia paniculata Cham. (marmelinho) and of the phytotherapic made with the combination of these plants. Place and Duration of Study: Chemistry Department of Federal University of Lavras – UFLA, Brazil between June 2011 and September 2012. Methodology: Phenolic compounds, flavonoid, vitamin C, total carotenoids and β-carotene and lycopene contents were quantified by UV-Vis spectrophotometer and antioxidant activity by ABTS and β-carotene/linoleic acid methods. Results: High contents of phenolic compounds were found in marmelinho (36.19g 100g-1 dry matter – DM), followed by carqueja (4.03g 100g-1DM) and calunga (1.62g 100g-1DM); of flavonoids in marmelinho (480.30mg 100g-1DM) and carqueja (173.68mg 100g-1DM); of vitamin C in marmelinho (652.80mg 100g-1DM) and G. cambogia (127.63mg 100g-1DM); and of carotenoids in marmelinho (23.16 mg 100 g-1). The antioxidant activity, in µmol trolox g-1, by the ABTS method, was considered moderate in the aqueous (728.80) and ethanolic (731.06) marmelinho extracts, and weak for the other plants. However, by the β-carotene/linoleic acid method, the aqueous and ethanolic marmelinho extracts show great antioxidant potential at all tested concentrations (above 80% inhibition), and those of carqueja, calunga and the ethanolic of the phytotherapic, at the concentrations of 40,000 and 20,000mg L-1, also showed good antioxidant potencies (over 60% inhibition). Conclusion: Those five species of plants showed antioxidant activity with potential for use in pharmaceutical and food preparations, with possible health benefits.