Extraction Optimization of Phenolic Compounds from Triadica sebifera Leaves: Identification, Characterization and Antioxidant Activity.

Triadica sebifera (T. sebifera) has attracted much attention because of the high oil content in its seeds, but there are few systematic studies on the phenolic compounds of T. sebifera leaves (TSP). In this study, the extraction process of TSP was optimized by response surface methodology. The phenolic components of these extracts were analyzed by high-performance liquid chromatography (HPLC). Moreover, the effects of hot air drying (HD), vacuum drying (VD) and freeze drying (FD) on the antioxidant activity and characterization of T. sebifera leaf extract (TSLE) were evaluated. Under the conditions of ethanol concentration 39.8%, liquid-solid ratio (LSR) 52.1, extraction time 20.2 min and extraction temperature 50.6 °C, the maximum TSP yield was 111.46 mg GAE/g dw. The quantitative analysis and correlation analysis of eight compounds in TSP showed that the type and content of phenolic compounds had significant correlations with antioxidant activity, indicating that tannic acid, isoquercitrin and ellagic acid were the main components of antioxidant activities. In addition, through DPPH and ABTS determination, VD-TSLE and FD-TSLE showed strong scavenging ability, with IC50 values of 138.2 µg/mL and 135.5 µg/mL and 73.5 µg/mL and 74.3 µg/mL, respectively. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) infrared spectroscopy revealed small differences in the extracts of the three drying methods. This study lays a foundation for the effective extraction process and drying methods of phenolic antioxidants from T. sebifera leaves, and is of great significance for the utilization of T. sebifera leaves.

[Characteristics of soil animal community with different garden plants and various planting periods in Wenjiang District, Chengdu, China]. / æˆéƒ½å¸‚æ¸©æ±ŸåŒºä¸åŒæ ½æ¤å¹´é™å›­æž—æ¤ç‰©åœŸå£¤åŠ¨ç‰©ç¾¤è½ç‰¹å¾.

In order to provide scientific guidance for soil quality evaluation and optimum management of flower and seedling industry, we investigated the characteristics of soil animal community with different garden plants and various planting periods in Wenjiang District, Chengdu. A total of 10258 soil animals belonging to 26 orders and 78 families were captured in four sampling times. There were significant differences in the taxonomic richness in the plots with different garden plants, generally highest in plots with Loropetalum chinense var. rubrum or Ginkgo biloba and lowest in plot with Zoysia japonica. The taxonomic richness was lower in the plots with different garden plants than the control. Taxonomic richness and abundance of soil fauna in Osmanthus fragrans plot did not change across sampling seasons. The abundance but not taxonomic richness of soil fauna in other plots had obvious seasonal variations. Different garden plants and various planting periods significantly influenced soil faunal diversity indices. Density-group index (DG) and Margalef richness index (D) in G. biloba plot, as well as Shannon diversity index (H) and D index in Z. japonica plot decreased significantly with the increases of planting period. The DG and D indices of soil animals in O. fragrans plot increased significantly with increasing planting period. The indices of soil animal diversity in L. chinense var. rubrum plot did not change regularly with planting period. The DG, D, and H indices were lowest in O. fragrans plot with different planting periods. Results of hierarchical clustering and canonical correlation analyse (CCA) indicated that garden plant species had stronger effects on the habitat than planting period. Responses of soil fauna to various habitats were different, with available P and soil pH having stronger effects on soil fauna. Our results indicated that soil animal community shifted with the changes of garden plant and planting period as well as management and cultivation methods. Excessive human interference and monoculture had negative effects on soil animal community and caused soil degradation.

[Understory plant species diversity and allelochemicals in rhizosphere soils of Eucalyptus grandis plantations with different densities]. / ä¸åŒå¯†åº¦å·¨æ¡‰äººå·¥æž—æž—ä¸‹æ¤ç‰©å¤šæ ·æ€§åŠæ ¹é™ åœŸå£¤åŒ–æ„Ÿç‰©è´¨.

To explore the influencing factors of understory plant species diversity of Eucalyptus grandis, we examined understory plant species diversity and phenolic allelochemicals in the rhizosphere soils of four-year-old and eight-year-old E. grandis plantations with different densities (1200, 1600, 2000 ind·hm-2) in Danling County of Sichuan Province. The results showed that a total of 45 plant species were recorded, belonging to 33 families and 44 genera. With the increases of stand age and decreases of stand density, plant species richness increased and their importance values were evenly distributed. Phanerophytes was the dominant life form across all stands. Shannon index and Margalef index of shrub in the four-year-old E. grandis plantations increased significantly at the density of 1600 ind·hm-2. All herbage plant diversity index except for Margalef index in four-year-old ones and Pielou index in eight-year-old plantations increased significantly with the decreases of density. Shannon index and Margalef index of shrub in 1200 ind·hm-2 were significantly higher in eight-year-old E. grandis stands than those in four-year-old ones. Five phenolic allelochemicals in the rhizosphere soils of E. grandis plantations were identified. In four-year-old stands, salicylic acid concentrations decreased significantly at the density of 1600 ind·hm-2. The concentrations of chrysin in four-year-old stands reduced significantly with the decreases of density. The concentrations of salicylic acid in eight-year-old stands increased significantly with the decreases of tree density. Salicylic acid concentrations in 2000 ind·hm-2 were significantly higher in four-year-old stands than that in eight-year-old ones, but the result was opposite in stands with density of 1600 ind·hm-2. The concentrations of chrysin in stand with density of 1200 ind·hm-2 were significantly higher in eight-year-old stands than that in four-year-old ones. Rundancy analysis (RDA) result showed that soil pH, bulk density, and the concentrations of soil organic matter, total nitrogen, total phospho-rus, and allelochemicals were the main environmental factors influencing understory plant species diversity. Therefore, prolonging rotation period and reducing stand density would improve micro-environmental condition of forests and buffer the allelopathy of E. grandis, which could facilitate the development of understory vegetation.

[Changes of total phenols and condensed tannins during the decomposition of mixed leaf litter of Pinus massoniana and broad-leaved trees.] / é©¬å°¾æ¾ä¸Žé˜”å¶æ ‘ç§æ··åˆå‡‹è½å¶åˆ†è§£è¿‡ç¨‹ä¸­æ€»é šå’Œç¼©åˆå•å®çš„å˜åŒ–.

A field litterbag experiment was conducted to investigate dynamics of total phenols and condensed tannin in the mixed leaf litter of Pinus massoniana (P) with other three broad-leaved species, i.e., Sassafras trumu (S), Cinnamomum camphora (C), Toona sinensis (T) during decomposition in low hilly lands, Sichuan Province, China. The mass ratio of P. massoniana : S. trumu (PS) was 6:4, 7:3, 8:2, P. massoniana : C. camphora (PC) was 6:4, 7:3, 8:2 and P. massoniana : T. sinensis (PT) was 6:4, 7:3, 8:2, respectively. The results showed that the degradation rate of condensed tannin in pure P. massoniana litter was 84.4%, being significantly lower than that in the mixed litters after 180 d. The degradation rate of condensed tannin and total phenols were the highest in PC 6:4, with 90.3% and 68.6%, respectively. The mixed litters promoted the decomposition of condensed tannin and total phenols in the P. massoniana litter. With decomposition time, the degradation rate of condensed tannin in mixed litters between P. massoniana and broad-leaved species initial increased, and then remained stable. The degradation rate of total phenols in pure P. massoniana litter, PT 7:3 and all the PC treatments increased significantly and then decreased during the 90 d decomposition. The degradation rate of total phenols in all the PS, PT 6:4 and 8:2 treatments increased with the decomposition time. The dynamics of total phenols and condensed tannin were closely related to litter quality, and the enzyme activities of polyphenol oxidase, peroxidase and leucine aminopeptidase.

Large-scale purification and characterization of recombinant human stem cell factor in Escherichia coli.

The pharmacological importance of recombinant human stem cell factor (rhSCF) has increased the demand to establish effective and large-scale production and purification processes. A good source of bioactive recombinant protein with capability of being scaled-up without losing activity has always been a challenge. The objectives of the study were the rapid and efficient pilot-scale expression and purification of rhSCF. The gene encoding stem cell factor (SCF) was cloned into pBV220 and transformed into Escherichia coli. The recombinant SCF was expressed and isolated using a procedure consisting of isolation of inclusion bodies (IBs), denaturation, and refolding followed by chromatographic steps toward purification. The yield of rhSCF reached 835.6 g/20 L, and the expression levels of rhSCF were about 33.9% of the total E. coli protein content. rhSCF was purified by isolation of IBs, denaturation, and refolding, followed by SP-Sepharose chromatography, Source 30 reversed-phase chromatography, and Q-Sepharose chromatography. This procedure was developed to isolate 5.5 g of rhSCF (99.5% purity) with specific activity at 0.96 × 106  IU/mg, endotoxin levels of pyrogen at 1.0 EU/mg, and bacterial DNA at 10 ng/mg. Pilot-scale fermentations and purifications were set up for the production of rhSCF that can be upscaled for industry.

[Effects of canopy density on the functional group of soil macro fauna in Pinus massoniana plantations]. / 马尾松人工林郁闭度对大型土壤动物功能群的影响.

In order to understand the effects of canopy density on the functional group characteristics of soil macrofauna in Pinus massoniana plantations, we divided the captured soil fauna into five types including xylophages, predators, saprophages, omnivores and fungal feeders. The results showed that 1) Saprozoic feeders had the highest percentage of total individuals, and the omnivores and xylophages occupied higher percentages of total taxa. 2) The individual and group number of the predators, and the group number of xylophages did not change significantly under 0.5-0.6 and then decreased significantly under 0.6-0.9 canopy density. 3) With the increasing canopy density, the individual an dgroup number of predators in litter layer decreased significantly, the saprozoic individual number in 5-10 cm soil layer represented irregular trends. The individual number of xylophage increased with the depth of soil, and the group number in litter layer, the individual and group number in 5-10 cm soil layer decreased significantly. 4) Pielou evenness of xylophage had no significant changes with the canopy density, all the other diversity index of xylophage and saprophage were various with the increasing canopy density. The predatory Simpson index was stable under 0.5-0.8, and then decreased significantly under 0.8-0.9 canopy density. 5) The CCA (canonical correlation analysis) indicated that soil bulk density and moisture content were the main environmental factors affecting functional groups of soil macro fauna. Moisture content greatly impacted on the number of saprophagous individuals. But xylophage and predators were mostly affected by soil bulk density, and the predatory Simpson index was mainly affected by soil pH value and total phosphorus. Our research indicated that the structure of soil macro faunal functional group under 0.7 canopy density was comparatively stable, which would facilitate the maintenance of soil fertility and ecological function in Pinus massoniana plantation.

[Edge effects of forest gap in Pinus massoniana plantations on the decomposition of leaf litter recalcitrant components of Cinnamomum camphora and Toona ciliata.] / 马尾松人工林林窗边缘效应对樟和红椿凋落叶难降解物质分解的影响.

The objective of the study was to evaluate the dynamics of recalcitrant components during foliar litter decomposition under edge effects of forest gap in Pinus massoniana plantations in the low hilly land, Sichuan basin. A field litterbag experiment was conducted in seven forest gaps with different sizes (100, 225, 400, 625, 900, 1225, 1600 m2) which were generated by thinning P. massoniana plantations. The degradation rate of four recalcitrant components, i.e., condensed tannins, total phenol, lignin and cellulose in foliar litter of two native species (Cinnamomum camphora and Toona ciliata) at the gap edge and under the closed canopy were measured. The results showed that the degradation rate of recalcitrant components in T. ciliata litter except for cellulose at the gap edge were significantly higher than that under the closed canopy. For C. camphora litter, only the degradation of lignin at the gap edge was higher than that under the closed canopy. After one-year decomposition, four recalcitrant components in two types of foliar litter exhibited an increment of degradation rate, and the degradation rate of condensed tannin was the fastest, followed by total phenol and cellulose, but the lignin degradation rate was the slowest. With the increase of gap size, except for cellulose, the degradation rate ofthe other three recalcitrant components of the T. ciliata at the edge of medium sized gaps (400 and 625 m2) were significantly higher than at the edge of other gaps. However, lignin in the C. camphora litter at the 625 m2 gap edge showed the greatest degradation rate. Both temperature and litter initial content were significantly correlated with litter recalcitrant component degradation. Our results suggested that medium sized gaps (400-625 m2) had a more significant edge effect on the degradation of litter recalcitrant components in the two native species in P. massoniana plantations, however, the effect also depended on species.

[Effects of gaps on distribution of soil aggregates and organic carbon in Pinus massoniana plantation].

The effects of forest gap size on the distribution of soil aggregates, organic carbon and labile organic carbon were investigated in a 39-year-old Pinus massoniana plantation in Yibin, Sichuan Province. The results showed that the composition of soil aggregates was dominated by particles > 2 mm, which accounted for 51.7%-78.7% of the whole soil samples under different sized forest gaps and beneath P. massoniana plantation. Soil organic carbon content and labile organic carbon content in > 5 mm aggregates were significantly positively correlated with the soil organic carbon and labile organic carbon contents. Furthermore, the amounts of organic carbon and labile organic carbon storage > 5 mm particles were higher than those in other size particles. Therefore, particles > 5 mm of aggregates dominated the soil carbon pool. Compared with those P. massoniana plantations, the contents of organic carbon in aggregates and total topsoil decreased during the formation of forest gaps, whereas the soil organic carbon storage under 1225 m2 gap was higher. In addition, the soil labile organic carbon content under 225 and 400 m2 gaps and the labile organic carbon storage under 225, 400, 900 and 1225 m2 gaps were higher than those the plantations, but were lower than under the other gaps. It was suggested that an appropriate size of forest gap would increase the accumulation of soil organic carbon and labile organic carbon content. The size of forest gap had significant effects on the distribution of soil aggregates, organic carbon and labile organic carbon. The soil sample under 1225 m2 gap had the highest organic carbon content and storage and a better aggregate proportion, and the higher labile organic carbon storage. Therefore, it was suggested that 1225 m2 gap might be an optimal logging gap size.