The role of mushroom polyphenols on enzyme inhibition : A Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Food Innovation at Lincoln University

Shiitake mushroom (Lentinula edodes), black ear mushroom (Auricularia auricula) and silver ear mushroom (Tremella fuciformis) are a common type of mushrooms. Recent year, bioactivity phenolic compound isolated from them has been attended and investigated by researchers and further focusing on their inhibition of starch digestion as well as the improvement of quality of starch in the food industry. Therefore, we hypothesize that the pasting properties and hydrolysis of red sorghum flour may affect by bioactivity phenolic compounds inhibiting the digested enzyme, such as α‐amylase and intestinal α‐glucosidase, derived from the mushroom. The objective of this study was to investigate the extract bioactive polyphenolic compounds from three different species of edible mushrooms, namely shiitake mushroom, black ear mushroom and silver ear mushroom as ingredients. The results of this study suggest that water extraction at 50°C for 3 hours in neutral pH could obtain optimal extraction condition for a great TPC and antioxidant activity. Shiitake mushroom water extract was the highest TPC and antioxidant activity among all mushroom extract, followed by shiitake mushroom 50% ethanol extracts. Besides, addition with each mushroom extracts all reduced the pasting properties of red sorghum paste, in particular, peak viscosity and final viscosity. Shiitake water extract has a significant (p<0.05) high comparing with others. Moreover, the TPC, antioxidant activity and protein digestibility were observed an increasing trend during in vitro digestion of all red sorghum paste incorporated in each mushroom extracts, while the reducing sugar and AUC were significant (p<0.05) decrease. Shiitake mushroom water extracts remain to present the greatest TPC and antioxidant activity during in vitro digestion of red sorghum paste, followed by shiitake ethanol mushroom extracts. Our preliminary result supported that mushroom extract, ie. shiitake mushroom, black ear mushroom and silver ear mushroom could be used as a functional ingredient of red sorghum food products development, which provides bioactivity phenolic compounds and enhances antioxidant activity. What is more, it may display as a modification agent by decrease the hydrolysis of starch during digestion for further reducing sugar release as well as raising protein digestibility of red sorghum flour products

Conserved Extracellular Cysteines Differentially Regulate the Potentiation Produced by Zn2+ in Rat P2X4 Receptors

One feature of the amino acid sequence of P2X receptors identified from mammalian species, Xenopus laevis and zebrafish is the conservation of ten cysteines in the extracellular loop. Little information is available about the role of these conserved ectodomain cysteines in the function of P2X receptors. Here, we investigated the possibility that ten conserved cysteine residues in the extracellular loop of the rat P2X4 receptor may regulate zinc potentiation of the receptor using a series of individual cysteine to alanine point mutations and functional characterization of recombinant receptors expressed in Xenopus oocytes. For the C116A, C132A, C159A, C165A, C217A and C227A mutants, 10 µM zinc did not significantly affect the current activated by an EC40 concentration of ATP. By contrast, 5 µM zinc shifted the ATP concentration-response curve to the right in a parallel manner for both the C261A and C270A mutants and the magnitudes of those shifts were similar to that of the wildtype receptor. Interestingly, for the C126A and C149A mutants, 5 µM zinc potentiated ATP-activated current, but increased the maximal response to ATP by 90% and 81% respectively, without significantly changing the EC50 value of ATP. Thus, these results suggest that cysteines and disulfide bonds between cysteines are differentially involved in the potentiation of the rat P2X4 receptor by zinc

(E)-Benzo­yl[1-(2-hydroxy­ethyl)imidazolidin-2-yl­idene]acetonitrile

In the title compound, C14H15N3O2, the C=C(H)—C=O grouping and the imidazolidine ring are coplanar as a result of an intra­molecular N—H⋯O hydrogen bond and extended electronic conjugation. Inter­molecular N—H⋯O and O—H⋯N hydrogen bonds help to establish the packing

Climatology and Change of Extreme Precipitation Events in Taiwan Based on Weather Types

Taiwan\u27s most significant natural hazards are caused by hydrological extremes resulting from excessive precipitation. The threat of extreme precipitation is posed by several different types of weather patterns that affect Taiwan. This study examined the bi‐decadal changes in rainfall by defining an extreme precipitation occurrence (EPO) for a range of event durations from 1 to 24 hr. Three major weather types affecting EPO in Taiwan were identified from 1993 to 2015: the front type consisting of either a frontal zone or convective systems developing with an apparent Meiyu cloudband, diurnal rainfall events when no apparent synoptic features are present, and a tropical cyclone (TC) type according to the maximum sustained wind radius of a TC. Results show that TC‐type events have the greatest overall contribution to EPO at longer (\u3e6 hr) durations. Diurnal/afternoon convection events contribute most to the shorter (\u3c3 hr) duration EPO, while frontal/Meiyu systems prevail in the medium (3–6 hr) duration. EPO of almost all durations have experienced an increase, with the 3‐ and 12‐hr EPO having increased by 4.6 days each over the 23 years. However, apparent decadal‐scale variability exists in these EPO associated with the decreasing tendency of EPO after the mid‐2000s, particularly the longer duration (\u3e6 hr) EPO associated with the TC‐type events in summer. The distinction between EPO trends for the entire island of Taiwan and for the Taipei metropolitan area alone (northern Taiwan, population of 7 million) were compared, and an intriguing interannual variation is reported in the TC‐type EPO associated with the TC season 1 year to a year and half just before an El Niño–Southern Oscillation event. The analysis here provides refined statistical distributions of extreme rainfall, and these can contribute to the revision of governmental definitions for weather disasters that are used in mitigation and response strategies