Search

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.

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.

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.

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.

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.

As part of ongoing research on natural products derived from medicinal plants for enzyme inhibition, known dibenzoyl derivatives (1–3, 11 and 20), pterocarpans (4, 15 and 19), flavanones (5, 7, 10, 12–14, 18, 21–24, 26, 27, 29, 31–33, 35, 36, and 38–46), flavones (6, 16, 28, 30 and 37), isoflavones (8 and 17), furocoumarins (9), and chalcones (25 and 34) have been tentatively identified within fractions of Sophora flavescens roots (SFR) using the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTof-MS) technique. The extract and column fractions inhibited indoleamine 2,3-dioxygenase (IDO) and monoamine oxidases (MAOs) differently depending on the metabolite groups. The majority of rich fractions were shown to have residual activities of 49–59% at 10 μg/mL (IDO) and 11.7–34.9% at 50 μg/mL (MAOs) or below. In the total ion current (TIC) chromatogram, significant markers for the metabolites of the bioactive-guided fractions were identified; pterocarpans (4, 15 and 19), flavanones (5, 10, 12–14, 18, 21–23, 26, 29 31–33, 35, 36, and 38–46), isoflavones (8 and 17), furocoumarins (9), dibenzoyl derivatives (11 and 20), flavones (16, 28, 30 and 37), and chalcones (25 and 34) were evaluated among forty-six analyzed metabolites. Possible bioactive markers could be deduced using a data library and previous references, and information regarding spectroscopic characterization and optimal target metabolites was obtained.

The seeds of Psoralea corylifolia were extracted into five different polar solvents: chloroform, 50% ethanol in water, ethanol, methanol and water. All extracts were evaluated for glycosidase inhibitory activity. The chloroform extract (CE) showed the lowest IC 50 values against α-glucosidase (82.9 μg/ml) and α-mannosidase (132 μg/ml). Chromatography of CE yielded nine phenolic compounds which were identified as isovabachalcone ( 1 ), 4′- O -methylbavachalcone ( 2 ), isobavachromene ( 3 ), corylifolin ( 4 ), bavachinin ( 5 ), psoralidin ( 6 ), neobavaisoflavone ( 7 ), corylifol A ( 8 ), and bakuchiol ( 9 ). All isolated compounds, apart from compound 5 , possessed α-glucosidase inhibitory activities. Among them, compounds 6 – 8 exhibited potent inhibition with IC 50 s of 13.7, 27.7 and 11.3 μM, respectively. Furthermore, compounds 2 and 6 showed α-mannosidase inhibitory activity. Mechanistic analysis of their inhibition modes against α-glucosidase showed that compounds ( 6 and 7 ) were noncompetitive, whereas compound 8 was mixed. Furthermore, the most active glycosidase inhibitors ( 2 , 6 – 8 ) were proven to be present in the native seed in high quantities by an HPLC chromatogram.

Three chalcones and two flavanones displaying tyrosinase inhibitory activity were isolated from the seed of Psoralea corylifolia, a cultivated edible plant. The isolated compounds were elucidated as known isovabachalcone, 4′-O-methylbavachalcone, isobavachromene, corylifolin, and bavachinin. The inhibitory potencies of the polyphenols toward monophenolase activity of mushroom tyrosinase were investigated. The inhibitory concentration (IC50) values of compounds 1–5 for monophenolase activity were determined to be 12.3, 48.8, 15.8, 23.6, and 143.9 μM, respectively. The potent inhibitors 1–4 exhibited the competitive inhibition characteristics in analysis of Lineweaver-Burks and Dixon-plot.

(2S,3R)-3-Hydroxy-2-(hydroxymethyl)-3,6-dihydro-2H-pyridine 8, an important precursor for the synthesis of polyhydroxylated piperidine azasugars, has been prepared from L -serine. Highly stereoselective nucleophilic addition to amino aldehyde 5 gave the corresponding allylic alcohol 6 which proceeded to give dihydro-2H-piridine 7a via a Grubbs 11 catalyzed RCM. Stereoselective H-bond directed epoxidation of allylic alcohol led to the oxiranyl alcohol 9 which was easily converted to L-deoxyaltronojirimycin by regioselective ring opening.

Glycosidase inhibitors are major targets in the treatment of type Ⅱ diabetes, cancer and viral infections. This study was carried out to investigate the glycosidase inhibitory substances from bamboo (Phyllostachys bambusoides). Bamboo was extracted with methanol and then further fractionated with n-hexane, chloroform, n-BuOH and aqueous to get an active fraction. All extracts were evaluated for α-glucosidase inhibitory activities to identify the n-hexane fraction with 33.5 ㎍/ml of IC50 value. Active compound 1 in the n-hexane fraction was identified as linoleic acid, which exhibited inhibitory activity with 12.4 ㎛ of IC 50 value. Mechanistic analysis showed that linoleic acid exhibited noncompective inhibition. This is the first study in which bamboo is reported to show α-glucosidase inhibitory activity.

Although Hypericum species are best known as plants that produce hypericin and are used in folk medicine, their other chemical constituents are poorly understood. Polyphenolic secondary metabolites from whole plants of representative Korean Hypericum species ( H. laxum Koidz., H. erectum Thunb., and H. ascyron L.) were analyzed using a ultra performance liquid chromatography-quadrupole time-of-flight/mass spectrometry (UPLC-Q-TOF/MS)-based approach combined with unsupervised principal component analysis (PCA) multivariate analysis. On the loading scatter plot, significant changes in metabolites were found between species, and three flavonol glycosides (8: quercetin-3- O-galactoside, 12: kaempferol-3- O-glucoside, and 13: quercetin-3- O-rhamnoside) were evaluated as key markers among 17 isolated metabolites. The extracts of H. laxum Koidz. exhibited significant quenching effects on DPPH and ABTS radicals, with IC50 values of 10–20 μg/mL, and were slightly higher in total phenol (TP) and total flavonoid (TF) contents than other species. Additionally, anti-inflammatory activity was observed by reduced nitric oxide (NO) and interleukin-6 (IL-6) production from lipopolysaccharide (LPS)-stimulated macrophages (RAW 264.7 cells). This is the first study to report the presence of bioactive metabolites and their correlating biological activities in H. laxum Koidz.