New Pyranone Derivatives and Sesquiterpenoid Isolated from the Endophytic Fungus Xylaria sp. Z184.

The fungus Xylaria sp. Z184, harvested from the leaves of Fallopia convolvulus (L.) Á. Löve, has been isolated for the first time. Chemical investigation on the methanol extract of the culture broth of the titles strain led to the discovery of three new pyranone derivatives, called fallopiaxylaresters A-C (1-3), and a new bisabolane-type sesquiterpenoid, named fallopiaxylarol A (4), along with the first complete set of spectroscopic data for the previously reported pestalotiopyrone M (5). Known pyranone derivatives (6-11), sesquiterpenoids (12-14), isocoumarin derivatives (15-17), and an aromatic allenic ether (18) were also co-isolated in this study. All new structures were elucidated by the interpretation of HRESIMS, 1D, 2D NMR spectroscopy, and quantum chemical computation approach. The in vitro antimicrobial, anti-inflammatory, and α-glucosidase-inhibitory activities of the selected compounds and the crude extract were evaluated. The extract was shown to inhibit nitric oxide (NO) production induced by lipopolysaccharide (LPS) in murine RAW264.7 macrophage cells, with an inhibition rate of 77.28 ± 0.82% at a concentration of 50 µg/mL. The compounds 5, 7, and 8 displayed weak antibacterial activity against Staphylococcus areus subsp. aureus at a concentration of 100 µM.

Unraveling the relationship between key aroma components and sensory properties of fragrant peanut oils based on flavoromics and machine learning.

Key aroma components of 33 fragrant peanut oils with different aroma types were screened by combined using flavoromics and machine learning. A total of 108 volatile compounds were identified and 100 kinds of them were accurately quantified, and 38 compounds out of them were with odorant activity value ≥1. The 33 peanut oils presented varied intensity of 'fresh peanuts', 'roasted nut', 'burnt', 'over-burnt', 'sweet', 'peanut butter-like', 'puffed food' and 'exotic flavor', and could be classified into four aroma types, namely raw, light, thick and salty. Partial least squares regression analysis, random forest and classification regression tree revealed that 2-acetyl pyrazine had a negative effect on 'fresh peanuts' and could distinguish raw flavor samples well; 2-methylbutanal and 4-vinylguaiacol were key compounds of 'roasted nut' and had significant differences (P < 0.0001) in thick and raw flavor samples; furfural contributed to the 'puffed food' as well as key compound of salty flavor.