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Chemical composition and bioactivities including bacterial and fungal resistance of the essential oils extracted from leaves of Piper betle L. (T) and Cleistocalyx operculatus L. (V) and aerial parts of Ageratum conyzoides L. (H) were investigated. The components presenting in the essential oils of the natural sources were analysized by a gas chromatography–mass spectrometry. Molecular docking simulation was utilised to support an antimicrobial mechanism of the essential oil compounds on Candida albicans fungus and Streptococcus pyogenes bacteria. This was based on the inhibition of the extracted compounds onto the microbial proteins, i.e. 4ESW and P0C0C7, respectively. There are 32 compounds identified in total in the three essential oils. The most effective inhibitors are the following: (i) chavicol acetate (T3), eugenol acetate (T11) and eugenol (T4) found in Piper betle L.; (ii) precocene II (H10) and precocene I (H6) found in Ageratum conyzoides L.; and (iii) caryophyllene oxide (V15) and cis-Lanceol (V19) found in Cleistocalyx operculatus L.. The overall antifungal and antibacterial capability of the investigated essential oils given indirect justification via their average inhabitability towards the two proteins accords with the order Piper betle L. Ageratum conyzoides L. Cleistocalyx operculatus L.. The results suggest these as promising natural sources for antimicrobial remedies. [ABSTRACT FROM AUTHOR]

GC‐MS was applied to identify 24 main substances in Melaleuca cajuputi essential oil (TA) extracted from fresh cajeput leaves through steam distilling. The inhibitory capability of active compounds in the TA from Thua Thien Hue, Vietnam over the Angiotensin‐Converting Enzyme 2 (ACE2) protein in human body ‐ the host receptor for SARS‐CoV‐2 and the main protease (PDB6LU7) of the SARS‐CoV‐2 using docking simulation has been studied herein. The results indicate that the ACE2 and PDB6LU7 proteins were strongly inhibited by 10 out of 24 compounds accounting for 70.9% in the TA. The most powerful anticoronavirus activity is expressed in the order: Terpineol (TA2) ≈ Guaiol (TA5) ≈ Linalool (TA19) > Cineol (TA1) > β‐Selinenol (TA3) > α‐Eudesmol (TA4) > γ‐Eudesmol (TA7). Interestingly, the synergistic interactions of these 10 substances of the TA exhibit excellent inhibition into the ACE2 and PDB6LU7 proteins. The docking results orient that the natural Melaleuca cajuputi essential oil is considered as a valuable resource for preventing SARS‐CoV‐2 invasion into human body. [ABSTRACT FROM AUTHOR]

Visible‐light‐driven photocatalysis has received considerable attention in the environmental treatment in recent years. In this paper, WS2/g‐C3N4 composite photocatalysts with various contents of WS2 and g‐C3N4 were synthesized by a facile method via heating the mixtures of tungstic acid and thiourea, and denoted as nWCN, where n is weight ratio of thiourea to tungstic acid. The composites were characterized by XRD, SEM, EDS, TEM, IR, Raman spectroscopy, XPS, TGA, and UV–vis DRS. The characterizations reveal that the composites contain WS2 nanosheets coated by g‐C3N4 and the relative content of WS2 in the composites decreases with increasing amount of thiourea in the reaction mixtures. All the composites exhibited the better photocatalytic activity in degradation of methylene blue in aqueous solution than the single components, WS2, and g‐C3N4. Among them, 7WCN sample performed the highest activity. A synergistic effect between WS2 and g‐C3N4 in photocatalytic activity for the composites was observed. [ABSTRACT FROM AUTHOR]

Graphitic g-C3N4-WO3 composite was synthesized simply by decomposing melamine in the presence of WO3 at 500°C. The obtained material was characterized by XRD, SEM, IR and XPS. The results showed that the as-prepared composite exhibits orthorhombic WO3 phase coated by g-C3N4 and the g-C3N4 decomposed completely with N-doped WO3 remaining at elevated calcination temperatures. The photocatalytic activity of the composite was evaluated by the photodegradation of methylene blue under visible light. An enhancement in photocatalytic activity for the graphitic g-C3N4-WO3 composite compared to the conventional nitrogendoped WO3 was observed, which can be attributed to the presence of g-C3N4 in the material. [ABSTRACT FROM AUTHOR]