Degradation of pretilachlor and fenclorim and effects of these compounds on bacterial communities under anaerobic condition.

Pretilachlor and safener fenclorim are the main components of herbicides widely applied to control weeds. Although some pure cultures of bacteria and fungi which degraded these compounds under aerobic conditions were isolated, no isolated pretilachlor- and fenclorim-degrading bacterial strains under anaerobic condition had been available. In this study, the degradation of these compounds and the effects of them on bacterial community structures were investigated under anaerobic conditions. The dissipation rates of pretilachlor and fenclorim in slurries were in the order: soil from paddy field ≈ sediment from river > sediment from mangrove. Moreover, three pretilachlor-degrading bacterial strains (Pseudomonas sp. Pr1, Proteiniclasticum sp. Pr2 and Paracoccus denitrificans Pr3) and two fenclorim-degrading strains (Dechloromonas sp. Fe1 and Ralstonia pickettii Fe2) isolated from a slurry of paddy soil utilized the substrates as sole carbon and energy sources under anaerobic conditions. The degradation of pure pretilachlor and fenclorim at various concentrations by corresponding mixed pure cultures followed the Michaelis-Menten model, with the maximum degradation was 3.10 ± 0.31 µM/day for pretilachlor, and 2.08 ± 0.18 µM/day for fenclorim. During the degradation, 2-chloro-N-(2,6-diethylphenyl) acetamide and 2,6-dimethylaniline were produced in pretilachlor degradation, and benzene was a product of fenclorim degradation. The synergistic degradation of both substrates by all isolated bacteria reduced the metabolites concentrations accumulated in media. This study provides valuable information on effects of pretilachlor and fenclorim on bacterial communities in soil and sediments, and degradation of these substrates by isolated bacteria under anaerobic condition.

A flexible and wearable paper-based chemiresistive sensor modified with SWCNTs-PdNPs-polystyrene microspheres composite for the sensitive detection of ethylene gas: A new method for the determination of fruit ripeness and corruption.

This study developed a flexible and wearable paper-based chemoresistive sensor (FWPCS) by modifying a SWCNT-PdNP-polystyrene microsphere (SPPM) composite (SPPM/FWPCS) for the low-cost and online determination of fruit ripeness and corruption. A new method for the batch and low-cost fabrication of SPPM/FWPCSs based on laser direct writing was proposed. The sensing mechanism of FWPCS relies on the electron depletion layer in the sensing composite created by the Schottky barriers among SWCNTs, PdNPs, and the adsorbed oxygen, along with the construction of O2-. When the SPPM sensing film is exposed to ethylene, trapped electrons are released into the conduction band through oxidation and cleavage of ethylene, causing a decrease in resistance. The properties and morphology of the synthesized SPPM composite were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Additionally, the key parameters for the fabrication of SPPMs/FWPCS related to the sensing performance were optimized. The concentration of C2H4 can be detected down to 100 ppb using the SPPMs/FWPCS at 25 °C. Finally, the real-time determination of banana ripeness and corruption verified the feasibility of the sensor, indicating that the SPPMs/FWPCS has prospects in monitoring fruit ripeness and corruption during storage and transportation.

Antioxidant and a-amylase Inhibitory Activities and Phytocompounds of Clausena indica Fruits.

Background: Clausena indica fruit is commonly used for food ingredients and traditional medicines in tropical countries, however, information about its biological activities and chemical profiles has been inadequately reported. Methods: In this study, a bio-guided fractionation of antioxidants and α-amylase inhibitors from hexane (MH) and ethyl acetate (ME) extracts of C. indica fruit (pericarp and seed) was carried out. Eleven fractions from MH (D1-D11) and 17 fractions from ME (T1-T17) were obtained from column chromatography over silica gel, which were then examined for anti-radical capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, and pancreatic α-amylase inhibition, a key enzyme linked to type 2 diabetes. Results: Of isolated fractions, the fraction T4 revealed the most potent anti-DPPH activity (IC50 = 0.13 mg/mL), whereas T2 exhibits the strongest ABTS cation scavenging ability (IC50 = 0.31 mg/mL). In the enzymatic assay, the fractions D3 and T4 significantly inhibit the α-amylase reaction with IC50 values of 0.34 and 0.86 mg/mL, respectively. Remarkably, α-amylase suppression of T4 is close to acarbose and over four times stronger than palmitic acid, which are the well-known α-amylase inhibitors (IC50 = 0.07 and 1.52 mg/mL, respectively). The active constituents from fractions were identified by gas chromatography-mass spectrometry (GC-MS). The results show that the fraction D3 contains five major compounds, which are grouped in five classes consisting of fatty acids, phenols, benzodioxoles, alcohols, and sesquiterpenes. Among them, palmitic acid is the most dominant compound (32.64%), followed by 2R-acetoxymethyl-1,3,3-trimethyl-4t-(3-methyl-2-buten-1-yl)-1t-cyclohexanol (16.69%). Whilst, six major compounds belonging to fatty acid and coumarin classes are identified in the fraction T4. The most abundant compound in T4 is dentatin (47.32%), followed by palmitic acid (15.11%). Conclusions: This is the first finding that C. indica fruit can be a promising source for the development of natural antioxidant and antidiabetic agents. Additionally, the outcome reveals that dentatin, a known natural antineoplastic agent, can be feasibly exploited from C. indica fruit.

Inhibitory Activities of Momilactones A, B, E, and 7-Ketostigmasterol Isolated from Rice Husk on Paddy and Invasive Weeds.

Rice husk has been exploited as a potential source of allelochemicals. In this study, four bioactive compounds including momilactone E (ME), 7-ketostigmasterol (7KS), momilactone A (MA), and momilactone B (MB) were isolated by column chromatography (CC) to yield 2.7, 0.3, 11.7, and 8.3 mg/kg rice husk, respectively. The structures of the isolated compounds were identified and confirmed by spectroscopic techniques consisting of 1H and 13C nuclear magnetic resonance (NMR), electrospray ionization mass (ESI), high-resolution mass spectrometry (HR-MS) and infrared spectroscopy (IS). An advanced quantitative method for MA and MB was achieved to increase the detectable yields of MA and MB in rice husk to 51.96 and 42.33 µg/mL, respectively. The inhibitory activities of MA, MB, ME, and 7KS were examined on lettuce (Lactuca sativa), barnyard grass (Echinochloa crus-galli), and tall goldenrod (Solidago altissima) in bioassays. The allelopathic activities of ME and 7KS were compared with those of potent phytoalexin momilactones A (MA) and B (MB), and the standard p-hydroxybenzoic acid (pHA). Results showed that both MA and MB exhibited stronger inhibitory activity than ME and 7KS. MB exerted greater inhibitions than MA but the mixture of MA and MB (1:1, v/v) possessed a similar level of inhibition to MB. On the other hand, although ME and 7KS presented non-significant inhibition, their mixture of ME-7KS (1:1, v/v) displayed a remarkable inhibition on the growth of S. altissima. Findings of this study revealed that MA, MB, and the mixture ME-7KS had the potential to control the invasive plant S. altissima and the noxious paddy weed E. crus-galli in vitro, but their mode of actions should be further investigated.