Photochemical advanced oxidative process treatment effect on the pesticide residues reduction and quality changes in dried red peppers.

Pesticide residues in crops are widely monitored, and the residue reduction techniques at the post-harvest stage are important to maintain food safety. In dried crops, pesticide residues can be concentrated after dehydration, which increases concerns regarding residue risk. Therefore, the residue reduction effects of ultraviolet (UV), ozone, and photochemical advanced oxidative process (pAOP) were investigated for dried peppers at the post-harvest stage. UV254 treatment reduced 59.7% of the residue concentration on average, while UV360 showed a reduction of only 13.3% under 9.6 W m-2 of UV exposure for 24 h. Gaseous ozone treatments reduced the residue concentrations up to 57.9% on average. In contrast, the pAOP treatment reduced the concentration up to 97% and was superior to UV or ozone treatment alone. Increased drying temperature under pAOP condition resulted in higher reduction ratios at 40-80 °C. The pAOP conditions with 12 and 24 µmol/mol of ozone and UV254 irradiation for 24-48 h reduced the residue concentrations to 39-67%. Particularly, difenoconazole, fludioxonil, imidacloprid, and thiamethoxam residue concentrations were drastically reduced by over 50% under 12 µmol/mol ozone of the pAOP condition, while carbendazim, fluquinconazole, and pyrimethanil were relatively stable and their concentrations reduced below 50% under 24 µmol/mol ozone of the pAOP treatment. Various drying-related quality parameters of drying peppers such as water-soluble color, capsanthin, capsaicinoids, acid value, peroxide value, and thiobarbituric acid value were slightly altered, but not significantly, under 12 µmol/mol ozone of the pAOP condition, while the peroxide value was significantly altered under the higher ozone conditions. Therefore, pAOP treatment combined with gaseous ozone can be used for reducing residual pesticides in peppers without greatly reducing quality.

Fate of endosulfan in ginseng farm and effect of granular biochar treatment on endosulfan accumulation in ginseng.

Endosulfan was widely used as an insecticide in the agricultural sector before its environmental persistence was fully understood. Although its fate and transport in the environment have been studied, the effects of historic endosulfan residues in soil and its bioaccumulation in crops are not well understood. This knowledge gap was addressed by investigating the dissipation and bioaccumulation of endosulfan in ginseng as a perennial crop in fresh and aged endosulfan-contaminated fields. In addition, the effect of granular biochar (GBC) treatment on the bioaccumulation factor (BAF) of endosulfan residue in ginseng was assessed. The 50% dissipation time (DT50) of the total endosulfan was over 770 days in both the fresh and aged soils under mulching conditions. This was at least twofold greater than the reported (6- > 200 days) in arable soil. Among the endosulfan congeners, the main contributor to the soil residue was endosulfan sulfate, as observed from 150 days after treatment. The BAF for the 2-year-old ginseng was similar in the fresh (1.682-2.055) and aged (1.372-2.570) soils, whereas the BAF for the 3-year-old ginseng in the aged soil (1.087-1.137) was lower than that in the fresh soil (1.771-2.387). The treatment with 0.3 wt% GBC extended the DT50 of endosulfan in soil; however, this could successfully suppress endosulfan uptake, and reduced the BAFs by 66.5-67.7% in the freshly contaminated soil and 32.3-41.4% in the aged soil. Thus, this adsorbent treatment could be an effective, financially viable, and sustainable option to protect human health by reducing plant uptake of endosulfan from contaminated soils.

Effect of soil organic matter on the plant uptake of perfluorooctanoic acid (PFOA) and perfluorooctanesulphonic acid (PFOS) in lettuce on granular activated carbon-applied soil.

The presence of perfluorooctanoic acid (PFOA) and perfluorooctanesulphonic acid (PFOS) in crops is an important consideration for food safety. The soil organic matter (SOM) content may affect the adsorption potential of PFOA and PFOS in water and soil and their subsequent uptake in crops. To better understand these dynamics, the adsorption and uptake of PFOA and PFOS in lettuce were investigated using granular activated carbon (GAC)-treated soils with varying SOM content. The adsorption potential of GAC was investigated, with maximum adsorption capacities for PFOA and PFOS calculated to be 9.091 mg g-1 and 27.778 mg g-1, respectively. These values decreased to 5.208 mg g-1 and 17.241 mg g-1, respectively, after the addition of 0.04 wt% humic acid. The average plant uptake factor (PUF) in low and high perfluoroalkyl and polyfluoroalkyl acid (PFAA)-contaminated soils with 4.0 wt% SOM was restricted to 0.353 for PFOA and 0.108 for PFOS. The PUFs were approximately two times lower than those for soil with 2.6 wt% SOM. Addition of 1 wt% GAC to the soil successfully reduced the PUF by up to 99.4%, with values of 0.006 (PFOA) and 0.005 (PFOS) in 2.6 wt% SOM-treated soil and 0.079 (PFOA) and 0.023 (PFOS) in 4.0 wt% SOM-treated soil. Although the PUF in the GAC-treated soil was drastically decreased, the PUF of the soil with 4.0 wt% SOM was at least four times higher than that with 2.6 wt% SOM. Therefore, SOM content is an important consideration in the remediation of PFOA- and PFOS-contaminated farmland soil using carbonaceous adsorbent.

Bacillus aryabhattai SRB02 tolerates oxidative and nitrosative stress and promotes the growth of soybean by modulating the production of phytohormones.

Plant growth promoting rhizobacteria (PGPR) are diverse, naturally occurring bacteria that establish a close association with plant roots and promote the growth and immunity of plants. Established mechanisms involved in PGPR-mediated plant growth promotion include regulation of phytohormones, improved nutrient availability, and antagonistic effects on plant pathogens. In this study, we isolated a bacterium from the rhizospheric soil of a soybean field in Chungcheong buk-do, South Korea. Using 16S rRNA sequencing, the bacterium was identified as Bacillus aryabhattai strain SRB02. Here we show that this strain significantly promotes the growth of soybean. Gas chromatography-mass spectrometry analysis showed that SRB02 produced significant amounts of abscisic acid, indole acetic acid, cytokinin and different gibberellic acids in culture. SRB02-treated soybean plants showed significantly better heat stress tolerance than did untreated plants. These plants also produced consistent levels of ABA under heat stress and exhibited ABA-mediated stomatal closure. High levels of IAA, JA, GA12, GA4, and GA7, were recorded in SRB02-treated plants. These plants produced longer roots and shoots than those of control plants. B. aryabhattai SRB02 was found to be highly tolerant to oxidative stress induced by H2O2 and MV potentiated by high catalase (CAT) and superoxide dismutase (SOD) activities. SRB02 also tolerated high nitrosative stress induced by the nitric oxide donors GSNO and CysNO. Because of these attributes, B. aryabhattai SRB02 may prove to be a valuable resource for incorporation in biofertilizers and other soil amendments that seek to improve crop productivity.

Phenolic phytochemical displaying SARS-CoV papain-like protease inhibition from the seeds of Psoralea corylifolia.

Severe acute respiratory syndrome coronavirus (SARS-CoV) papain-like protease (PLpro) is a key enzyme that plays an important role in SARS virus replication. The ethanol extract of the seeds of Psoralea corylifolia showed high activity against the SARS-CoV PLpro with an IC50 of value of 15 µg/ml. Due to its potency, subsequent bioactivity-guided fractionation of the ethanol extract led to six aromatic compounds (1-6), which were identified as bavachinin (1), neobavaisoflavone (2), isobavachalcone (3), 4'-O-methylbavachalcone (4), psoralidin (5) and corylifol A (6). All isolated flavonoids (1-6) inhibited PLpro in a dose-dependent manner with IC50 ranging between 4.2 and 38.4 µM. Lineweaver-Burk and Dixon plots and their secondary replots indicated that inhibitors (1-6) were mixed inhibitors of PLpro. The analysis of KI and KIS values proved that the two most promising compounds (3 and 5) had reversible mixed type I mechanisms.

Caffeic acid and quercitrin purified from Houttuynia cordata inhibit DNA topoisomerase I activity.

A methanol extract of Houttuynia cordata showed an inhibitory effect on mammalian DNA topoisomerase I. Two topoisomerase I inhibitory compounds were purified and identified as caffeic acid and quercitrin. Caffeic acid and quercitrin inhibited the activity of topoisomerase I with IC(50) values of about 0.15 and 0.05 mM, respectively. A concentration of 45 µM caffeic acid caused 50% growth inhibition in human leukaemia U937 cells, but not on those of normal fibroblast NIH3T3 cells. However, quercitrin mysteriously stimulated proliferation of U937 and NIH3T3 cells. Caffeic acid-induced cell death was characterised with the cleavage of poly (ADP-ribose) polymerase and procaspase-3, indicating that this inhibitor triggered apoptosis. The apoptotic induction by caffeic acid was also confirmed using flow cytometry analysis. Because DNA topoisomerase I is an important target for tumour chemotherapy, the present study suggests that caffeic acid, but not quercitrin, may function by suppressing oncogenic disease through the inhibition of cellular topoisomerase I activity.