Investigation of Yacon Leaves (Smallanthus sonchifolius) for α-Glucosidase Inhibitors Using Metabolomics and In Silico Approach

Yacon (Smallanthus sonchifolius (Poepp.) H. Robinson) leaves is traditionally consumed as herbal tea in many countries including Indonesia. This plant’s antidiabetic properties have been extensively researched, but studies on the responsible active compound identification are scarce. Information on the active compounds is critical for the consistency of Yacon herbal tea quality. The aim of this study was to identify α-glucosidase inhibitors in Indonesian Yacon leaves grown in two different locations using FTIR- and LC–MS/MS-based metabolomics in combination with in silico technique. Yacon leaves ethanol (50 and 95%) and water extracts were tested for α-glucosidase inhibitory activity, with the 95% ethanol extract being the most active. Geographical origins were found to have no major impact on the activity. In parallel, chemical profile of Yacon leaves extract was determined using FTIR and LC–MS/MS. Orthogonal Projection to Latent Structure (OPLS) was used to analyze both sets of data. OPLS analysis of FTIR data showed that compounds associated to α-glucosidase inhibitor activity included those with functional groups –OH, stretched CH, carbonyl, and alkene. It was consistent with the result of OPLS analysis of LC–MS/MS data, which revealed that based on their VIP and Y-related coefficient value, nystose, 1-kestose, luteolin-3′-7-di-O-glucoside, and 1,3-O-dicaffeoilquinic acid isomers, strongly linked to Yacon’s α-glucosidase inhibitor activity. In silico study supported these findings, revealing that the four compounds were potent α-glucosidase inhibitors with docking score in the range of ? 100.216 to ? 115.657 kcal/mol, which are similar to acarbose (? 115.774 kcal/mol) as a reference drug.

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Effect of wine inhibitors on free pineapple stem bromelain activity in a model wine system

The influence of potential inhibitors, naturally present in wine, on the activity of stem bromelain was investigated in order to evaluate the applicability of this enzyme for protein stabilization in white wine. Bromelain proteolytic activity was tested against a synthetic substrate (Bz-Phe-Val-Arg-pNA) in a model wine system after adding ethanol, sulfur dioxide (SO(2)), skin, seed, and gallic and ellagic tannins at the average range of their concentration in wine. All the inhibitors of stem bromelain activity tested turned out to be reversible. Ethanol was a competitive inhibitor with a rather limited effect. Gallic and ellagic tannins have no inhibitory effect on stem bromelain activity, while both seed and skin tannins were uncompetitive inhibitors. The strongest inhibition effect was revealed for sulfur dioxide, which was a mixed-type inhibitor for the enzyme activity. This study provides useful information relative to a future biotechnological application of stem bromelain in winemaking.     

Macrofungal diversity of holm-oak forests at the northern limit of their distribution range in the Iberian Peninsula

Given the current gap in knowledge concerning the macrofungal diversity of holm-oak forests at the northern limit of their distribution range and in the Basque Country, a mycocoenological study was conducted by sampling 23 randomly selected permanent plots from 6 holm-oak forests. To obtain a better understanding of the macrofungal diversity distribution pattern on a regional scale, forests from both the temperate and Mediterranean-type climate regions of the Basque Country were selected, covering all their phytocoenological variation. After 4 years of sampling, a total of 377 macrofungal species were collected: 209 ectomycorrhizal species, 86 humicolous saprotrophs, 40 saprotrophs on litter, 36 lignicolous saprotrophs, 3 coprophilous saprotrophs and 3 parasitic species. Species considered characteristic of this kind of forest, such as Cortinarius aurilicis, Cortinarius callochrous, Cortinarius ionochlorus, Hygrophorus leucophaeo-ilicis, Hygrophorus persoonii, Hygrophorus russula, Lactarius atlanticus, Lactarius ilicis, Leccinellum lepidum, were recorded all over the territory, but Mediterranean forests were richer in species and more productive in sporocarps than temperate ones. Species assemblage was found to change gradually at local scale from temperate to Mediterranean climate zones, and was distinct to each phytocoenological association with all species, with ectomycorrhizal species and with saprotrophs.     

Modeling of urea degradation in white and rosé wines by acid urease

The specific activity of a whole cell acid urease preparation was tested in five wines manufactured in the Apulia region of Italy in the 2003 vintage at both short and long treatment times, thus confirming the validity of the pseudo-first-order kinetic model to describe urea removal in real wines. The ratio between the experimental pseudo-first-order kinetic rate constant (kIe) for any real wine tested and that (kI) referred to a model wine solution having the same composition and pH reduced from about 0.21 to 0.02 as the overall content of phenolic compounds (P) increased from 109 to 853 g m-3 of gallic acid equivalent (GAE). The specific inhibitory effect of such compounds was explained by accounting for the equilibrium constant (KP) of the reaction of polyphenols with acid urease, which was found to be about 21 g of GAE m-3 for the real wines tested, whereas it ranged from about 16 to 45 g of GAE m-3 when the model wine solution was enriched with tannins extracted from grape seeds or skins, respectively. A sequential experimental procedure consisting of accelerated acid urease tests at high doses of enzyme followed by accelerated ethyl carbamate tests on the resulting acid urease treated wine was recommended to assess preliminarily the technoeconomic feasibility of the acid urease hydrolytic process for the wine of concern. Keywords: Acid urease; real and model wines; phenolics; pseudo-first-order kinetic rate constant; inhibitory effect; urea degradation kinetics.     

Growth performance,digestibility, and blood biochemical parameters of Nile tilapia (Oreochromis niloticus) reared in floating cages and fed poultry by-product meal

ABSTRACT

A 120-day feeding trial was conducted in floating cages to evaluate growth performance and digestibility of Nile tilapia (Oreochromis niloticus) juveniles fed diets containing different levels of poultry by-product meal (PBM) as a replacement for fishmeal. Nile Tilapia with an average body weight of 56.6 ± 0.28 g were used in this experiment. Five diets were formulated to contain graded levels of PBM at 0%, 5%, 10%, 20%, and 30% poultry by-product meal (PBM) and are referred as PBM0, PBM5, PBM10, PBM20, and PBM30, respectively. Groups of 25 Nile tilapia were fed close to the apparent satiation, three times a day. The results showed that growth performance, survival and whole-body composition for fish fed the experimental diets were not significantly different (P > .05) than fish fed the control diet. Apparent digestibility of dry matter, protein, lipid and amino acids of fish fed the PBM20 and PBM30 were lower compared to the other treatments (P < .05). The PBM dietary levels significantly lowered total protein, high-density-lipoprotein (HDL) and cholesterol concentration. The results of this study indicated that good quality PBM can be used up to 30% in commercial diets for Nile tilapia without any adverse effect.     

Betalain Extracts from Beetroot as Food Colorants: Effect of Temperature and UV-Light on Storability

Plant Foods for Human Nutrition - Beetroot is a good source of natural food colorants given that it contains significant amount of betalain pigments. This study investigates the three-months...     

Assessment of urea degradation rate in model wine solutions by acid urease from Lactobacillus fermentum

The specific activity (piA) of a whole cell acid urease preparation was assessed in model wine solutions at different levels of malic (M) and lactic acids, metabisulfite, ethanol, and pH by performing a central composite design. M and then pH were found to be the most controlling variables, their effects being practically coincident but of opposite sign. For urea concentrations up to approximately 1 mol m(-3) the ammonium formation rate was assumed of the pseudo-first-order with respect to urea, this being confirmed by two independent validation tests performed at 20 degrees C for as long as 24 h. In the case of real wines the effective pseudo-first-order kinetic rate constants were found to be smaller than those pertaining to the model solutions having the same wine composition and pH by a factor varying from 10 to 1000, this affecting significantly the specific urease treatment costs per liter of wine treated.