Antioxidant p-terphenyl compounds in the mushroom Boletopsis leucomelas (PERS.) FAYOD and how they change via cooking.

Antioxidant compounds in the mushroom Boletopsis leucomelas (PERS.) FAYOD were isolated using chromatographic methods, and their structures were determined via detailed analyses using high-resolution atmospheric pressure chemical ionization mass spectrometry and nuclear magnetic resonance. We identified five known p-terphenyl compounds (Bl-I, Bl-II, Bl-III, cycloleucomelon-leukopentaacetat, and Bl-IV) and one p-terphenyl new compound (Bl-VI); we determined the complete structure of cycloleucomelon-leukopentaacetat in this study. All these compounds possess potent lipid peroxidation-inhibiting activities. We further investigated changes in their chemical structures and antioxidant activities by applying heat (grilling, boiling, and microwave heating), and proved the production of two known p-terphenyl compounds (BI-V and boletopsin A) and one new p-terphenyl compound (BI-VII) via deacetylation of the original p-terphenyl compounds for the first time. We also found that DPPH radical scavenging activity was enhanced upon moderate heat cooking (boiling and microwave heating) due to changes in p-terphenyl compounds.

Investigation and modeling of diurnal variation in suburban ambient formaldehyde concentration.

Formaldehyde (HCHO) is a naturally occurring compound found in ambient air which can induce cancer and sick-building syndrome. It plays an important role in the formation of OH radicals, which are connected to the formation of various airborne chemicals. Herein, we present a simple modeling for the simulation of diurnal variations in the HCHO concentration of ambient air. This was achieved using data collected during different seasons from November 2015 to March 2017 at a suburban location in Toyama City (Japan), where non-methane hydrocarbon (NMHC) levels were low at sub carbon ppm (ppmC) order. The modeling was based on the assumption that photochemical reactions of methane were the major factor of secondary HCHO formation. The model took into account the production and decomposition of HCHO by photochemical reactions as well as its loss due to other reactions such as dry deposition. Accordingly, the model's equation contained terms for solar radiation, temperature, and methane concentration. The results predicted using the model showed good agreement with the experimental data observed on fine days, i.e., except rainy, foggy, and heavily cloudy days. The relationships between HCHO concentration and solar radiation/temperature on different days as well as the seasonal variation of HCHO concentration were also interpreted by the proposed model. This study contributes to the evaluation of the pollution levels of formaldehyde. Moreover, the model may be used to demonstrate the impact of increasing methane levels, with regard to global warming and the background levels of HCHO in the atmosphere.