Exogenous melatonin enhances salt stress tolerance in maize seedlings by improving antioxidant and photosynthetic capacity.

Melatonin (N-acetyl-5-methoxytryptamine) is an important biological hormone in many abiotic stress responses and developmental processes. In this study, the protective roles of melatonin were investigated by measuring the antioxidant defense system and photosynthetic characteristics in maize under salt stress. The results indicated that NaCl treatment led to the decrease in plant growth, chlorophyll contents and photochemical activity of photosystem II (PSII). However, the levels of reactive oxygen species increased significantly under salt stress. Meanwhile, we found that application of exogenous melatonin alleviated reactive oxygen species burst and protected the photosynthetic activity in maize seedlings under salt stress through the activation of antioxidant enzymes. In addition, 100 µM melatonin-treated plants showed high photosynthetic efficiency and salinity. Immunoblotting analysis of PSII proteins showed that melatonin application alleviated the decline of 34 kDa PSII reaction center protein (D1) and the increase of PSII subunit S protein. Taken together, our study promotes more comprehensive understanding in the protective effects of exogenous melatonin in maize under salt stress, and it may be involved in activation of antioxidant enzymes and regulation of PSII proteins.

[VOCs Characteristics and Sources Apportionment in Yixing City During the G20 Summit].

A continuous measurement was conducted in Yixing city urban area from 24th August to 15th September using TH-300B continuous online GC-MS instrument during G20 summit in Hangzhou, 2016. The VOCs average mass concentrations of alkane, alkene, aromatic, acetylene, haloalkane hydrocarbons, OVOC and acetonitrile were 11.00×10-9, 1.93×10-9, 5.78×10-9, 1.23×10-9, 4.16×10-9, 10.37×10-9, 0.27×10-9, respectively. The photochemical reaction activity was calculated by using the maximum potential coefficient of Ozone Formation Potential. Alkene and aromatic hydrocarbons were the most active components of OFP. By applying the positive matrix factorization(PMF)model, five major factors were extracted to identify the sources of NMHCs in Yixing city, including industry(42.2%),vehicle exhaust(17.9%), fuel evaporation(20.8%), paint/solvent usage(7.0%)and plant(12.1%). Combined with the conditional probability function(CPF) analysis, source of anthropogenic pollution was related to the distribution of industrial enterprises in the northwest and southeast, while the plant source was related to the forest hilly region of Southwest Yixing city. The effect of air pollutant emission reduction showed that the primary emission air pollutants had declined significantly during the strict control period from 1th to 6th September in G20 summit,2016, and the industry proportion was reduced to 30.5%, whereas the plant proportion increased to 16.8%.

Impact of release characteristics of sinomenine hydrochloride dosage forms on its pharmacokinetics in beagle dogs.

AIM: To investigate the effect of release behavior of sustained-release dosage forms of sinomenine hydrochloride (SM.HCl) on its pharmacokinetics in beagle dogs. METHODS: The in vitro release behavior of two SM.HCl dosage forms, including commercial 12-h sustained-release tablets and 24-h sustained-release pellets prepared in our laboratory, was examined. The two dosage forms were orally administrated to beagle dogs, and then the in vivo SM.HCl pharmacokinetics was investigated and compared. RESULTS: The optimal SM.HCl sustained-release formulation was achieved by mixing slow- and rapid-release pellets (9:1, w/w). The SM.HCl release profiles of the sustained-release pellets were scarcely influenced by the pH of the dissolution medium. Release from the 12-h sustained-release tablets was markedly quicker than that from the 24-h sustained-release pellets, the cumulative release up to 12-h was 99.9% vs 68.7%. From a pharmacokinetic standpoint, the 24-h SM.HCl sustained-release pellets had longer tmax and lower Cmax compared to the 12-h sustained-release tablets, the tmax being 2.67+/-0.52 h vs 9.83+/-0.98 h and the Cmax being 1 334.45+/-368.76 ng/mL vs 893.12+/-292.55 ng/mL, respectively. However, the AUC(0-tn) of two SM.HCl dosage forms was comparable and both preparations were statistically bioequivalent. Furthermore, the two preparations had good correlations between SM.HCl percentage absorption in vivo and the cumulative percentage release in vitro. CONCLUSION: The in vitro release properties of the dosage forms strongly affect their pharmacokinetic behavior in vivo. Therefore, managing the in vitro release behavior of dosage forms is a promising strategy for obtaining the optimal in vivo pharmacokinetic characteristics and safe therapeutic drug concentration-time curves.