Tenacissoside H repressed the progression of glioblastoma by inhibiting the PI3K/Akt/mTOR signaling pathway.

Glioblastoma (GBM) is one of the most common intracranial primary malignancies with the highest mortality rate, and there is a lack of effective treatments. In this study, we examined the anti-GBM activity of Tenacissoside H (TH), an active component isolated from the traditional Chinese medicine Marsdenia tenacissima (Roxb.) Wight & Arn (MT), and investigated the potential mechanism. Firstly, we found that TH decreased the viability of GBM cells by inducing cell cycle arrest and apoptosis, and inhibited the migration of GBM cells. Furthermore, combined with the Gene Expression Omnibus database (GEO) and network pharmacology as well as molecular docking, TH was shown to inhibit GBM progression by directly regulating the PI3K/Akt/mTOR pathway, which was further validated in vitro. In addition, the selective PI3K agonist 740 y-p partially restored the inhibitory effects of TH on GBM cells. Finally, TH inhibited GBM progression in an orthotopic transplantation model by inactivating the PI3K/Akt/mTOR pathway in vivo. Conclusively, our results suggest that TH represses GBM progression by inhibiting the PI3K/Akt/mTOR signaling pathway in vitro and in vivo, and provides new insight for the treatment of GBM patients.

CDs-ICG@BSA nanoparticles for excellent phototherapy and in situ bioimaging.

For the diagnosis and treatment of cancer, a great challenge is the fabrication of straightforward, non-toxic, multifunctional green nanomaterials. In this study, carbon quantum dots self-assembled with indocyanine green dye at bovine serum albumin for phototherapy and in situ bioimaging are produced by a flexible hydrothermal method. We find that the synthesized nanoparticles have high tumor photothermal therapeutic activity when exposed to 808 nm light, with a photothermal conversion efficiency up to 61 %. The phototoxicity study revealed the excellent phototherapy of the nanoparticles mainly arises from photothermal therapeutic effect other than photodynamic therapy effect. Simultaneously, it allows biological imaging in the visible and near-infrared ranges because of the significant absorption at 365 nm and 840 nm. The current work offers a simple, environmentally friendly, and reasonable method for developing photothermal drugs with a high photothermal conversion efficiency in the near-infrared region, as well as good biosafety for multifunctional nanomaterials for bioimaging tumor diagnosis and direct phototherapy.

Effect of Lianhua Qingwen capsules on the positive rate of COVID-19 close contacts: A retrospective analysis of a large-scale population-based cohort study.

OBJECTIVE: Coronavirus disease 2019 (COVID-19) is still spreading worldwide. COVID-19 close contact is a key point of this epidemic. However, no medication is now available for close contact. This study aims to evaluate the beneficial effect and safety of the Lianhua Qingwen capsule (LHQW) on COVID-19 close contacts via a large, retrospective cohort study. METHODS: A total of 25,002 close contacts from 199 quarantine sites in Changchun, Jilin, who underwent medical observation, were included. The information about these close contacts were collected for further epidemiological research. Moreover, subjects were divided into an exposure group (LHQW group, oral, 4 capsules/time, t.i.d.; 18,579 subjects) and a non-exposure group (control group; 6,423 subjects). Inverse probability of treatment weighting (IPTW) with propensity score was employed to evaluate the positive rate of the SARS-CoV-2 nucleic acid test in nasal and throat swabs confirmed by polymerase chain reaction (PCR). RESULTS: A total of 22,975 subjects were included in the analysis, 17,286 cases in the LHQW group and 5,689 cases in the control group. The positive rate of nucleic acid testing in the LHQW group was 5.12%, and that in the control group was 9.70% before the adjustment of IPTW of the propensity score; the difference between the two groups was -4.58% (95% CI -5.44- -3.77%, p <  0.001). After adjusting IPTW, the positive rate of nucleic acid testing in the LHQW group and the control group was 5.10% and 9.80%, respectively; the difference between the two groups was -4.70% (95% CI -5.18- -4.23, p < 0.001). The conclusions before and after the IPTW adjustment were consistent. No test drug-related adverse reactions were observed during the study period. CONCLUSION: LHQW has a beneficial effect and safety on the close contacts of SARS-CoV-2 who are under medical observation at the quarantine sites and can be used as an optional drug for those close contacts.

Phragmites rhizoma polysaccharide-based nanocarriers for synergistic treatment of ulcerative colitis.

The purpose of this study was to construct Phragmites rhizoma polysaccharide-based nano-drug delivery systems (PRP2-SeNPs-H/Aza-Lips) for synergistically alleviating ulcerative colitis and to investigate the important roles of Phragmites rhizoma polysaccharide-based nanocarriers in PRP2-SeNPs-H/Aza-Lips. Phragmites rhizoma polysaccharide (PRP2) was isolated and used for the preparation of Phragmites rhizoma polysaccharide selenium nanoparticles with low selenium content (PRP2-SeNPs-L) and high selenium content (PRP2-SeNPs-H). Based on the electrostatic attraction between PRP2-SeNPs-H and azathioprine liposomes (Aza-Lips), PRP2-SeNPs-H/Aza-Lips were constructed for precise delivery of the model drug azathioprine (Aza) to colon lesions. Results showed that PRP2 significantly alleviated the clinical symptoms and colon tissue damage and down-regulated the levels of inflammatory factors in serum and colon, demonstrating beneficial effects on mice with ulcerative colitis. PRP2-SeNPs-L had better relieving effects on ulcerative colitis. Phragmites rhizoma polysaccharide-based nanocarriers may protect azathioprine liposomes against gastrointestinal digestion, enhance the therapeutic effects on ulcerative colitis, and significantly reduce liver damage from azathioprine, which helps to improve the efficacy and toxicity of clinical drugs.

Cationic amphiphilic dendrons with effective antibacterial performance.

Bacterial infections and antibiotic resistance have become a global healthcare crisis. Herein, we designed and synthesized a series of cationic amphiphilic dendrons with cationic dendrons and hydrophobic alkyl chains for potential antibacterial applications. Our results showed that the antimicrobial activities of the cationic amphiphilic dendrons were highly dependent upon the length of the hydrophobic alkyl chain, whereas the number of cationic charges was less important. Among these cationic amphiphilic dendrons, a prime candidate was identified, which possessed excellent antimicrobial activity against various pathogens (minimum inhibitory concentrations of 9, 3, and 3 µg mL-1 for Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus, respectively). Scanning electron microscopy and fluorescence microscopy analyses showed that it could disrupt the integrity of a pathogen's membrane, leading to cell lysis and death. In addition, in vitro bacteria-killing kinetics showed that it had rapid bactericidal efficiency. It also had excellent antimicrobial activities against MRSA in vivo and promoted wound healing. In general, the synthesized cationic amphiphilic dendrons, which exhibited rapid and broad-spectrum bactericidal activity, may have great potential in antimicrobial applications.

Effects of two dietary crude protein levels on finishing performance, meat quality, and gene expression of market lambs.

Seventeen crossbred lambs were assigned randomly to low-protein (LP; 8% crude protein [CP]; n = 9) and high-protein (HP; 13% CP; n = 8) diets for 9 weeks. The final body weight, average daily feed intake (ADFI), and average daily gain (ADG) of the HP lambs were significantly higher (P < 0.05) than the LP lambs; however, gain to feed ratio (G:F) for the LP lambs was significantly higher (P < 0.05) than the HP lambs. Hot carcass weight (HCW), adjusted fat thickness, and drip loss of longissimus dorsi (LD) muscle were significantly higher (P < 0.05) for the HP than LP lambs. In contrast, instrumental color values L*, a*, b*, C*, and hue angle (H) of meat from the LP lambs scored significantly higher (P < 0.05) than the HP lambs. The LD muscle from HP lambs had significantly greater CLA of cis-9 trans-11 isomer (P < 0.05) than the LP lambs. The gene expression of metabolism and meat quality-related genes of LP was significantly higher than HP (P < 0.05). These results suggest that a higher dietary CP level promotes growth performance for finishing lambs, whereas lower dietary CP level is beneficial for meat quality, especially when evaluating color characteristics in the final product.

A combination index and glycoproteomics-based approach revealed synergistic anticancer effects of curcuminoids of turmeric against prostate cancer PC3 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Herbal medicines (HMs) often exert integration effects, including synergistic, additive and antagonistic effects, in such ways that they act on multiple targets and multiple pathways on account of their multiple components. Turmeric, made from the rhizome of Curcuma longa L., is a well-known HM prescribed in the polyherbal formulas for cancer treatment in traditional Chinese medicines (TCMs). However, neither the multiple anticancer compounds of turmeric nor the integration effects of these components are fully known. AIM OF THE STUDY: This work aims to develop a systematic approach to reveal the integration effect mechanisms of multiple anticancer compounds in turmeric against prostate cancer PC3 cells. MATERIALS AND METHODS: Combination index and omics technologies were applied to profile the integration effect mechanisms of bioactive compounds in proportions naturally found in turmeric. PC3 cell line (a prostate cancer cell line) fishing and high resolution mass spectrometry were employed to screen and identify the anticancer compounds from turmeric. The combinations which contain different cell-bound compounds in natural proportions were prepared for further evaluation of anti-cancer activity by using cell viability assays, and assessment of cell apoptosis and cell cycle analysis. Combination index analysis was applied to study the integration effects of the anticancer compounds in their natural proportions. Finally, quantitative glycoproteomics/proteomics and Western blot were implemented to reveal the potential synergistic effect mechanisms of the anticancer compounds based on their natural proportions in turmeric. RESULTS: Three curcuminoids (curcumin, CUR; demethoxycurcumin, DMC; bisdemethoxycurcumin, BDMC) in turmeric were discovered and shown to possess significant synergistic anticancer activities. Combination index analysis revealed an additive effect of CUR combined with DMC or BDMC and a slight synergistic effect of DMC combined with BDMC in natural proportions in turmeric, while a combination of all three curcuminoids (CUR, DMC and BDMC) at a ratio of 1:1:1 yielded superior synergistic effects. Interestingly, the presence of BDMC and DMC are essential for synergistic effect. Glycoproteomics and proteomics demonstrated that different curcuminoids regulate various protein pathways, such as ribosome, glycolysis/gluconeogenesis, biosynthesis of amino acids, and combination of CUR + DMC + BDMC showed the most powerful effects on down-regulation of protein expression. CONCLUSIONS: Our analytical approach provides a systematic understanding of the holistic activity and integration effects of the anti-cancer compounds in turmeric and three curcuminoids of turmeric showed a synergistic effect on PC3 cells.

Beneficial effects of sulfated polysaccharides from the red seaweed Gelidium pacificum Okamura on mice with antibiotic-associated diarrhea.

The purpose of this study was to investigate whether Gelidium pacificum Okamura polysaccharides (sulfated polysaccharide, GPOP-1) had beneficial effects on mice with antibiotic-associated diarrhea (AAD). Compared with the natural recovery group, GPOP-1 increased the richness and diversity of the gut microbiome, as well as altered the composition of the gut microbiota. At the genus level, GPOP-1 significantly increased the relative abundance of Bacteroides, Oscillospira, and Bifidobacterium and decreased the relative abundance of Parabacteroides, Sutterella, and AF12. The metabolic pathway differences according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that the metabolic function of the gut microbiota could be significantly improved by GPOP-1. Furthermore, GPOP-1 downregulated the concentrations of inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) and interleukin-2 (IL-2), alleviated the pathological features of the cecum, and increased the contents of acetates, propionates, butyrates, and total short-chain fatty acids (SCFAs). Results indicated that GPOP-1 had beneficial effects on mice with AAD by promoting the recovery of the gut microbiota and mucosal barrier function, reversing metabolic disorders, downregulating the levels of inflammatory cytokines and improving the content of SCFAs.

[Effect and mechanism of essential oil from Zanthoxylum bungeanum in microemulsion gel preparation on percutaneous delivery of complex components].

This study aimed to investigate the transdermal enhancing effect of essential oil from Zanthoxylum bungeanum(Z. bungeanum oil) in microemulsion gel(ZO-ME-gel) on permeation of different components,and reveal the transdermal enhancing mechanism of ZO-ME-gel. A series of components with different log P values were selected as model drugs and encapsulated in ZO-ME-gel to simplify and characterize the complex components of traditional Chinese medicine. The transdermal behavior of the model drugs was further examined using the improved Franz diffusion cell method. Then attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR),differential scanning calorimetry(DSC) studies and hematoxylin-eosin(HE) staining were used to investigate the effects of Z. bungeanum oil and ZO-ME-gel on keratin,intercellular lipids and microstructure of the stratum corneum(SC). The results showed that Z. bungeanum oil and ZO-ME-gel had a good transdermal enhancing effect on both hydrophilic and lipophilic drugs,and the best effect was achieved when log P value was-0. 5. The transdermal enhancing mechanism of Z. bungeanum oil and ZO-ME-gel was related to affecting the order of the SC lipids,changing lipid fluidity and protein conformation,and disrupting the integrity of the SC structure. 5% Z. bungeanum oil had greater transdermal enhancing effect and destruction of SC structure than ZO-ME-gel. These results suggested that Z. bungeanum oil loaded in microemulsion gel still had a good transdermal enhancing effect although the effect was not as great as Z. bungeanum oil itself,in addition,ZO-ME-gel was less irritating to the skin and safer to use,which had a guiding role in the development and clinical application of Z. bungeanum oil-containing traditional Chinese medicine topical preparations.

Qualitative and quantitative analysis of Yifei Tongluo granules to identify main bioactive components using LC-DAD/MS and pharmacokinetic studies.

A standard fingerprint containing twelve common peaks was constructed from ten batches of Yifei Tongluo granules to evaluate batch-to-batch consistency by using HPLC-DAD. Additionally, the corresponding medicinal material attributes of these chemical constituents were analyzed according to the data acquired from the HPLC method and the identification was further carried out using the LC-MS/MS method. Comparing the retention time or accurate mass with previous studies or standards, the common components were tentatively identified in 50 min for ten batches of samples. At the same time, a reliable LC-MS/MS method was established to quantify marker substances simultaneously in 25 min, and the linear relationship of the standard curves was good in the experimental range. The validations of the method were successfully applied to the quality control and pharmacokinetic study. The results obtained from this study suggest that militarine was most abundant and the components in the granules caused pharmacokinetic herb-drug interactions in rats. This study provides a meaningful basis for evaluating the viability of Yifei Tongluo granules for clinical applications.

Research progress of music therapy in lung cancer surgery / 中国胸心血管外科临床杂志

@#Music has a powerful influence on people’s psychology and emotions. Many clinical research reports confirm that music therapy can directly affect and improve people’s psychological and physiological status, alleviate patients’anxiety and other adverse physiological emotions, improve the effectiveness of surgical treatment, and promote rapid recovery. Lung cancer surgery has the characteristics of great trauma, high incidence of postoperative complications and poor prognosis. Therefore, music therapy has its unique advantages for lung cancer. With the rapid development of thoracic surgery (ERAS), as an important part of psychological intervention, music therapy plays an irreplaceable role in the surgical treatment of lung cancer. This article reviews the impact of music therapy on anxiety in lung cancer surgery.

[Optimize preparation of compound licorice microemulsion with D-optimal design].

In order to increase the solubility of essential oil in compound licorice microemulsion and improve the efficacy of the decoction for treating chronic eczema, this experiment intends to prepare the decoction into microemulsion. The essential oil was used as the oil phase of the microemulsion and the extract was used as the water phase. Then the microemulsion area and maximum ratio of water capacity was obtained by plotting pseudo-ternary phase diagram, to determine the appropriate types of surfactant and cosurfactant, and Km value-the mass ratio between surfactant and cosurfactant. With particle size and skin retention of active ingredients as the index, microemulsion prescription was optimized by D-optimal design method, to investigate the in vitro release behavior of the optimized prescription. The results showed that the microemulsion was optimal with tween-80 as the surfactant and anhydrous ethanol as the cosurfactant. When the Km value was 1, the area of the microemulsion region was largest while when the concentration of extract was 0.5 g·mL⁻¹, it had lowest effect on the particle size distribution of microemulsion. The final optimized formulation was as follows: 9.4% tween-80, 9.4% anhydrous ethanol, 1.0% peppermint oil and 80.2% 0.5 g·mL⁻¹ extract. The microemulsion prepared under these conditions had a small viscosity, good stability and high skin retention of drug; in vitro release experiment showed that microemulsion had a sustained-release effect on glycyrrhizic acid and liquiritin, basically achieving the expected purpose of the project.

Protective Effect of Flavonoids from Ziziphus jujuba cv. Jinsixiaozao against Acetaminophen-Induced Liver Injury by Inhibiting Oxidative Stress and Inflammation in Mice.

This study was aimed to investigate the chemical composition, antioxidant activities and hepatoprotective effect of flavonoids from Ziziphus jujuba cv. Jinsixiaozao (ZJF). The composition of ZJF was analyzed by high performance liquid chromatography (HPLC) and Liquid chromatography-mass spectrometry (LC-MS), and antioxidant properties were investigated by biological assays in vitro. The hepatoprotective activity of ZJF was evaluated in acetaminophen (APAP)-treated BALB/c mice. Results indicate that ZJF displayed significant antioxidant capacity. Pretreatment with ZJF significantly decreased APAP-elevated serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total bilirubin (TB). Activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were enhanced with ZJF administration, while malondialdehyde (MDA) level and glutathione (GSH) depletion were reduced. Meanwhile, ZJF reversed the suppression of nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, and up-regulated the protein expression of NAD(P)H: quinone oxidoreductase 1(NQO1) in liver damage mice. Furthermore, ZJF attenuated APAP-induced inflammatory mediator production, such as nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1ß (IL-1ß). Expression of p65 showed that ZJF dampened nuclear factor-κB (NF-κB) activation. The results strongly indicate that the hepatoprotective role of ZJF in APAP-induced hepatotoxicity might result from its induction of antioxidant defense via activation of Nrf2 and reduction of inflammation via inhibition of NF-κB.

In vitro antioxidative and immunological activities of polysaccharides from Zizyphus Jujuba cv. Muzao.

Zizyphus jujuba has been used as a traditional Chinese medicinal herb since ancient time. Polysaccharides have been found to be important bioactive compounds in the jujube. This work was designed to investigate the physicochemical characteristics and bioactivities of polysaccharides purified from Zizyphus jujuba cv. Muzao. Water-soluble polysaccharides were extracted using an ultrasonically assisted extraction method. The purified polysaccharides (HJP) were obtained by deproteinization and decoloration. Three main fractions (HJP1, HJP2 and HJP3) were isolated using DEAE-Sepharose fast flow ion-exchange chromatography. The purified polysaccharides were found to consist of mannose, rhamnose, galactose, galacturonic acid, glucose and arabinose at various levels for different fractions. The HJP and its three main fractions displayed DPPH radical scavenging activities as well as relatively strong reducing power and HJP had stronger activities than homogeneous compositions. Moreover, the results from in vitro immunological activities studies indicated that HJP could improve the phagocytosis activity of THP-l cells and had effect on the expression of pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6). In conclusion, the polysaccharides from Zizyphus jujuba cv. Muzao were discovered to have antioxidative and immunological activities.

Immuno-enhancement effects of Yifei Tongluo Granules on cyclophosphamide-induced immunosuppression in Balb/c mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional Chinese medicine Yifei Tongluo Granules has been employed clinically with the combination of chemotherapy agents to treat patients with multidrug-resistant tuberculosis. However, the mechanisms underlying the therapeutic potential have not been well elucidated. The present study was employed to verify immunomodulatory effect and to investigate the underlying mechanisms which have not been explored. MATERIALS AND METHODS: The study samples of total extracts (FB-E) and polysaccharides (FB-P) were prepared by the extraction of the Yifei Tongluo Granules using appropriate techniques. A simple immunodeficient mice model was established by challenging Balb/c mice with cyclophosphamide in order to avoid the handling of tuberculosis viruses. The in vivo study was thus designed to systematically elucidate the immuno-enhancement effects of Yifei Tongluo Granules extracts in immunosuppressed mice induced by cyclophosphamide. Balb/c mice were orally ingested once daily with the low and high doses of two different extracts for ten consecutive days, respectively, accompanied by intraperitoneal injection of cyclophosphamide (60mg/kg) on days 1-3 and 10. RESULTS: Compared with the model group, the treatment of immunodeficient mice with the low and high doses of the extracts FB-E or FB-P enhanced spleen and thymus indices, T- and B-cell proliferation as well as increased the activities of splenic natural killer, lymphokine activated killer, cytotoxic T lymphocyte cells and peritoneal macrophage phagocytosis. In addition, the FB-E or FB-P treatment balanced the ratio of Th1/Th2 and up-regulated the CD4+/CD8+ ratio in the serum. CONCLUSIONS: These results demonstrate, for the first time, that the treatment of the cyclophosphamide-challenged mice with the Yifei Tongluo Granules extracts resulted in accelerated recovery of immunosuppression, sugguesting that the immunomodulation might be the mechanism for the observed clinical benefits of Yifei Tongluo Granules. Our findings provide preliminary mechanistic study evidences for clinical application of Yifei Tongluo Granules in patients with immunodeficient diseases such as tuberculosis.

S-allylmercapto-l-cysteine modulates MUC5AC and AQP5 secretions in a COPD model via NF-кB signaling pathway.

Garlic has shown versatile medicinal activities in the prevention and treatment of diseases such as chronic obstructive pulmonary disease (COPD). However, no individual garlic bioactive components have yet been determined in the COPD treatment effects. In this work, S-allylmercapto-l-cysteine (SAMC) identified in the aged garlic was selected as a model compound to determine its COPD therapeutic potential. The COPD model was established by using lipopolysaccharides (LPS) to stimulate the human airway submucosal gland cell line SPC-A1. Previous studies show that both MUC5AC up-regulation and AQP5 down-regulation play an important role in viscous COPD mucus secretions. The modulation effects of SAMC on LPS-induced MUC5AC and AQP5 productions in SPC-A1 cells were then evaluated. Pretreatment of the SPC-A1 cells with SAMC attenuated MUC5AC secretion and increased AQP5 expression in a dose-dependent manner in the non-cytotoxic concentration range of 20 to 100µM. Mechanistic studies suggested that SAMC could suppress the accumulation of MUC5AC mRNA and inhibit IкBα degradation and NF-кB p65 translocation. These results suggest that SAMC could be a promising candidate in the prevention and treatment of MUC5AC-associated disorders such as COPD.

ent-Eudesmane-Type Sesquiterpenoids from the Chinese Liverwort Chiloscyphus polyanthus var. rivularis.

Seven new ent-eudesmane-type sesquiterpenoids (1-7) and six known analogues (8-13) were isolated from the Chinese liverwort Chiloscyphus polyanthus var. rivularis. Their structures were determined from analysis of MS and NMR spectroscopic data and single-crystal X-ray diffraction. A cytotoxic evaluation showed that compound 1 exhibited weak inhibitory activity against the A549 cancer cell line with an IC50 value of 27.7 µM.

Selenium inhibits sulfate-mediated methylmercury production in rice paddy soil.

There is increasing interest in understanding factors controlling methylmercury (MeHg) production in mercury-contaminated rice paddy soil. Sulfate has been reported to affect MeHg biogeochemistry under anoxic conditions, and recent studies revealed that selenium (Se) could evidently reduce MeHg production in paddy soil. However, the controls of sulfate and Se on net MeHg production in paddy soil under fluctuating redox conditions remain largely unknown. Microcosm experiments were conducted to explore the effects of sulfate and Se on net MeHg production in rice paddy soil. Soil was added with 0-960 mg/kg sulfate, in the presence or absence of 3.0 mg/kg selenium (selenite or selenate), and incubated under anoxic (40 days) or suboxic conditions (5 days), simulating fluctuating redox conditions in rice paddy field. Sulfate addition moderately affected soil MeHg concentrations under anoxic conditions, while reoxidation resulted in evidently higher (18-40%) MeHg levels in sulfate amended soils than the control. The observed changes in net MeHg production were related to dynamics of sulfate and iron. However, Se could inhibit sulfate-mediated MeHg production in the soils: Se addition largely reduced net MeHg production in the soils (23-86%, compared to the control), despite of sulfate addition. Similarly, results of the pot experiments (i.e., rice cultivation in amended soils) indicated that soil MeHg levels were rather comparable in Se-amended soils during rice growth period, irrespective of added sulfate doses. The more important role of Se than sulfate in controlling MeHg production was explained by the formation of HgSe nanoparticles irrespective of the presence of sulfate, confirmed by TEM-EDX and XANES analysis. Our findings regarding the effects of sulfate and Se on net MeHg production in rice paddy soil together with the mechanistic explanation of the processes advance our understanding of MeHg dynamics and risk in soil-rice systems.

Mechanistic understanding of MeHg-Se antagonism in soil-rice systems: the key role of antagonism in soil.

Methylmercury (MeHg) accumulation in rice has great implications for human health. Here, effects of selenium (Se) on MeHg availability to rice are explored by growing rice under soil or foliar fertilization with Se. Results indicate that soil amendment with Se could reduce MeHg levels in soil and grain (maximally 73%). In contrast, foliar fertilization with Se enhanced plant Se levels (3-12 folds) without affecting grain MeHg concentrations. This evidence, along with the distinct distribution of MeHg and Se within the plant, demonstrate for the first time that Se-induced reduction in soil MeHg levels (i.e., MeHg-Se antagonism in soil) rather than MeHg-Se interactions within the plant might be the key process triggering the decreased grain MeHg levels under Se amendment. The reduction in soil MeHg concentrations could be mainly attributed to the formation of Hg-Se complexes (detected by TEM-EDX and XANES) and thus reduced microbial MeHg production. Moreover, selenite and selenate were equally effective in reducing soil MeHg concentrations, possibly because of rapid changes in Se speciation. The dominant role of Se-induced reduction in soil MeHg levels, which has been largely underestimated previously, together with the possible mechanisms advance our mechanistic understanding about MeHg dynamics in soil-rice systems.

Scapairrins A-Q, Labdane-Type Diterpenoids from the Chinese Liverwort Scapania irrigua and Their Cytotoxic Activity.

Seventeen new labdane-type diterpenoids, scapairrins A-Q (1-17), including six pairs of diastereoisomers, and three known analogues (18-20) were isolated from the Chinese liverwort Scapania irrigua. The structures of 1-17 were determined based on a combination of the analysis of their MS and NMR spectroscopic data, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Cytotoxicity testing showed that compounds 7-10 exhibited inhibitory activities against a small panel of human cancer cell lines.