[Advances in the research of transformation and stabilization of soil organic carbon from plant and microbe]. / æ¤ç‰©æºå’Œå¾®ç”Ÿç‰©æºåœŸå£¤æœ‰æœºç¢³è½¬åŒ–ä¸Žç¨³å®šç ”ç©¶è¿›å±•.

Soil organic carbon (SOC) is the core component of terrestrial carbon (C) sink. Exploring the transformation and stabilization mechanism of SOC is key to understand the function of terrestrial C sink which copes with climate change. The traditional perspective is that plant residues are the initial source of SOC. The new concept of "soil microbial C pump" emphasizes that the synthesized products of soil microbial assimilation are important contributors to the stable SOC. This provides a new insight to the sequestration mechanism of SOC. Due to the complex and variable decomposition process of plant residues and the high heterogeneity of microbial residues, the transformation and stabilization mechanism of plant residues and microbial residues into SOC is still unclear. We reviewed research progress in plant and microbial residues, and introduced the characterization methods of quantification and transformation of plant residues and microbial residues, and also summarized the new findings on the transformation of plant and microbial residues into SOC. We further discussed the contribution and driving factors of microbial and plant-derived C to SOC. Finally, we prospected the future development direction and research focus in this field. This review would provide the scientific reference for the research of soil C sequestration in terrestrial ecosystem.

Structure-guided discovery of food-derived GABA-T inhibitors as hunters for anti-anxiety compounds.

With the acceleration of the pace of life, people may face all kinds of pressure, and anxiety has become a common mental issue that is seriously affecting human life. Safe and effective food-derived compounds may be used as anti-anxiety compounds. In this study, anti-anxiety compounds were collected and curated for database construction. Quantitative structure-activity relationship (QSAR) models were developed using a combination of various machine-learning approaches and chemical descriptors to predict natural compounds in food with anti-anxiety effects. High-throughput molecular docking was used to screen out compounds that could function as anti-anxiety molecules by inhibiting γ-aminobutyrate transaminase (GABA-T) enzyme, and 7 compounds were screened for in vitro activity verification. Pharmacokinetic analysis revealed three compounds (quercetin, lithocholic acid, and ferulic acid) that met Lipinski's Rule of Five and inhibited the GABA-T enzyme to alleviate anxiety in vitro. The established QSAR model combined with molecular docking and molecular dynamics was proved by the synthesis and discovery of novel food-derived anti-anxiety compounds.

[Response of Soil Bacterial Community Structure to Precipitation Change in Grassland of Loess Plateau].

As the main participants of ecosystem functions, the response of microorganisms to variations in soil moisture caused by the changes in precipitation amounts should be quantified to evaluate the impact of climate change on semi-arid ecosystems. For this purpose, a two-year simulation of the changes in the rainfall patterns was conducted on the Loess Plateau, and five precipitation treatments (80% and 40% decrease in precipitation, D80, D40; natural precipitation, NP; 40% and 80% increase in precipitation, I40, I80) were set up. The results showed that: ① Compared with NP, the carbon-to-nitrogen ratio (C/N) was lower in DP80 or IP80, while it reached the maximum value in I40. The mean C/N value of the 0-20 cm soil layer was 10.76. The microbial biomass carbon to microbial biomass nitrogen ratio (MBC/MBN) varied significantly with the soil layer in the treatments of D80 and I80, and the maximum value was 14.15 in D80. ② In the grassland soil naturally growing on the Loess Plateau, at the phylum level, the dominant phyla were Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria. At the class level, Actinobacteria, Acidobacteria, α-Proteobacteria, and Thermomicrobia were predominant. ③ RDA analysis showed that changes in soil dissolve organic carbon (DOC), dissolved organic nitrogen (DON), elemental carbon (EC), and pH values were the main factors affecting the distribution of soil bacteria under the five precipitation treatments in the study area. Overall, 80% increase or decrease in precipitation has a significant impact on soil active organic carbon content and bacterial abundance, especially D80. In conclusion, drought or extreme precipitation may considerably change the active organic matter content and bacterial community diversity and abundance in the soils of the Loess Plateau.

[oil microbial biomass and enzyme activities among different artificial forests in Ziwuling, Northwest China.] / å­åˆå²­äººå·¥æž—åœŸå£¤å¾®ç”Ÿç‰©ç”Ÿç‰©é‡åŠé ¶æ´»æ€§.

Decades of ecological restoration on the Loess Plateau has achieved significant on-site benefits to reduce soil erosion and improve soil quality, with remarkable off-site effects of reducing sediment delivery to Yellow River. However, regional forest community succession is still far from being adequately developed. The Ziwuling forest region and its highly developed forest community, as an advanced eco-zone, can lend practical experience to other regions on the Loess Plateau and help to identify the most suitable tree species for a better regional restoration in the future. With the aim to systematically understand the potential effects of typical local tree species to soil properties, three typical and well-established artificial forests in the Ziwuling region, Robinia pseudoacacia, Pinus tabuliformis and Platycladus orientalis were investigated in this study, with the climax community Quercus wutaishanica as a reference. All the four forest type had comparable stand age (25 years). Soil samples from 0-20 cm layers were collected from those four plantations. The soil microbial biomass (carbon and nitrogen), soil enzyme (invertase, urease and alkaline phosphatase) activities and their correlations were measured and analyzed. The results showed that: 1) soil invertase activity ranged from 16.94 to 64.49 mg·g-1·24 h-1, the soil urease activity from 0.15 to 0.26 mg·g-1·24 h-1, and the alkaline phosphatase activity from 0.65 to 1.23 mg·g-1·24 h-1. The activities of those three enzymes were significantly higher in the P. orientalis soil that in the R. pseudoacacia and P. tabuliformis soils. The geometric average values in the P. orientalis soil were even greater than that in the Q. wutaishanica soil. 2) The soil microbial biomass carbon and nitrogen varied from 247.37 to 529.84 mg·kg-1 and 41.48 to 77.91 mg·kg-1, respectively. Both of them were significantly greater in the P. orientalis soil than that in the R. pseudoacacia and P. tabu-liformis soils. Even though the soil microbial biomass carbon in the P. orientalis soil remained lower than that in the Q. wutaishanica soil, its soil microbial biomass nitrogen was greater than in the Q. wutaishanica soil. 3) The dissolved organic carbon and nitrogen in the P. tabuliformis soil were much greater than that in other species, even greater than their own soil microbial biomass carbon and nitrogen. Such a result indicated that dissolved organic matter might play a more important role in providing plant available nutrients than microbial biomass in the P. tabuliformis soil. 4) The microbial biomass carbon and nitrogen were significantly positively correlated with the total organic carbon and the total nitrogen, particularly for the R. pseudoacacia and P. tabuliformis soils. There were significantly positive relationships between the soil invertase activity, urease activity and alkaline phosphatase activity, and their soil organic carbon, total nitrogen and total phosphorus contents. 5) Based on the results of principal component analysis, we concluded that the artificial forests types had obvious effects on soil microbial carbon and nitrogen, soil organic carbon, total nitrogen, the ratio of carbon to phosphorus, the ratio of nitrogen to phosphorus and urease activity. Overall, our findings suggested that P. orientalis is better than R. pseudoacacia and P. tabuliformis in term of improving soil properties in the south forest zone on the Chinese Loess Plateau.

[Effects of vegetation and topography features on ecological stoichiometry of soil and soil microbial biomass in the hilly-gully region of the Loess Plateau, China.] / 黄土丘陵区植被与地形特征对土壤和土壤微生物生物量生态化学计量特征的影响.

The objectives of this study were to explore the effects of vegetation type, topographic features and their combined effects on soil microbial biomass stoichiometry, so as to better understand the interaction of soil, soil microbes and nutrient cycling under different vegetation types in the hilly-gully region of the Loess Plateau. Soils from three vegetation zones (forest zone, forest-steppe and steppe) and five slope positions (south/north backslope, south/north shoulder and summit) were chosen and the effects of vegetation types and topography features on soil and C:N:P ratios in soil microbial biomass were investigated in this study. The results showed that, among the five slope positions, the highest concentrations of soil and soil microbial biomass C, N, P were found at the backslope position and the north-facing slope. The effects of vegetation types on soil and soil microbial biomass C, N and P in the two soil layers were significantly different, whereas the effects of slope aspect and positions were only numerically different. As for different soil layers, the topsoil (0-10 cm) was more affected by slope aspect, while the subsoil (10-20 cm) was more influenced by slop position. While the effects of vegetation type on soil C:N, C:P and N:P and soil microbial biomass C:N, C:P were significant, slope aspect and slope position only influenced soil C:P and N:P. Consequently, on the Loess Plateau, the effects of vegetation type on soil and soil microbial biomass C, N, P were stronger than those of the topographic features. The standardized major axis tests showed that C:N:P stoichiometry in soil microbes was well-constrained, especially in the steppe zone. The soil microbial biomass N:P might be used as a useful tool to assess nutrient limitation of ecosystem processes in terrestrial ecosystems. If combined with plant leaf N:P, they could provide more accurate information to estimate the nutrient limitation of fragile ecosystem in hilly-gully region of the Loess Plateau.

[Ecological stoichiometry characteristics of leaf-litter-soil in different plantations on the Loess Plateau, China]. / 黄土高原不同人工林叶片-凋落叶-土壤生态化学计量特征.

In order to research into the influence of Grain to Green Project in Ziwuling forest region, this paper took three typical plantations which were Robinia pseudoacacia plantation, Pinus tabuliformis plantation, and Platycladus orientalis plantation in the Ziwuling forest region of Shaanxi Province as research objects and analyzed the carbon, nitrogen and phosphorus contents of leaf, litter and soil among the three plantations. The results showed that the contents of C, N and P in the three plantations were in order of leaf > litter > soil, the contents of N and P in leaf of R. pseu-doacacia plantation were significantly higher than that of P. tabuliformis plantation and P. orientalis. Leaf N:P was 12.21, 5.36 and 6.09 in R. pseudoacacia plantation, P. tabuliformis plantation and P. orientalis plantation, respectively. It was indicated that the three species were all subject to N deficiency. C:N and C:P showed the trend of litter > leaf > soil, and N:P demonstrated the trend of leaf > litter > soil. There were highly significant positive relationships in C:N between leaf and litter in P. tabuliformis plantation. N and P in the leaf development process of R. pseu-doacacia plantation were proportionally absorbed, and proportionally remained in the litter after N and P resorption. R. pseudoacacia was the better plantation species than P. tabuliformis and P. orientalis in the south fo-rest zone on the Loess Plateau.

Characterization of diterpenoids in the bark of Pseudolarix kaempferi by HPLC-ESI/MSn.

Fragmentation behavior of diterpenoids was investigated by ESI/MSn and the qualitative analysis of diterpenoids in the bark of Pseudolarix kaempferi was performed using high-performance liquid chromatography/ multi-stage mass spectrometry (HPLC-ESI/MSn). The characteristic fragmentation behaviors of the diterpenoids are the cleavages of the lactone ring and C4-O bond. Furthermore, the eliminations of substituent groups at C-18, C-7 and C-8 can also be observed in the MS" (n = 3-4) spectra. For C-4 acetoxy subsititued diterpenoids, [M+Na-60]+ and [M-H-104] are the base peaks of MS2 spectra in the positive and negative ionization modes, respectively. For C-4 hydroxyl subsititued diterpenoids, [M+Na-44]+ and [M-H-62] are the base peaks of MS2 in the positive and negative ionization modes, respectively. For C-18 glucosylated or esterized diterpenoids, [M+Na-44]+ is the base peak of MS2 spectra in positive ionization mode. These fragmentation rules were successfully exploited in the identification of diterpenoids in methanol/water (6:4) extract of P. kaempferi by LC-MS in positive ionization mode. A total of 9 diterpenoids were identified or tentatively characterized, and one of them is reported here for the first time. The described method could be utilized for the sensitive and rapid qualitative analysis of P. kaempferi.

HPLC-DAD-MS(n) analysis and HPLC quantitation of chemical constituents in Xian-ling-gu-bao capsules.

In this study, a systematic method was established for the global quality control of Xian-ling-gu-bao capsules (XLGB), a popular six-herb Traditional Chinese Patent Medicine (TCPM) for the treatment of osteoporosis. Both qualitative and quantitative analyses were conducted. In qualitative analysis part, a fast and sensitive method based on high-performance liquid chromatography coupled with diode-array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-MS(n)) was established for rapid separation and sensitive identification. Samples were separated on a Waters Symmetry C(18) column (250mm×4.6mm, 5µm) by gradient elution using acetonitrile (A) and water-formic acid (B; 0.03%, v/v) as mobile phase at a flow rate of 1.0ml/min. Based on the mass spectra, UV spectra and retention time, 47 compounds were identified or tentatively characterized, including 27 flavonols (all from Epimedii Herba, the major component herb), 4 coumarins, 3 flavonones, 1 chalcone, 3 isoflavones, 1 coumestrol, 3 triterpenoid saponins, 1 iridoid, 3 steroidal saponins, and 1 phenolic acid. Among them, 18 compounds were confirmed by comparing with reference standards. In quantitative analysis part, 10 major compounds in 18 batches of XLGB were simultaneously determined by HPLC/UV detected at 270nm. The method was validated with respect to intra- and inter-day precision, repeatability and stability, with RSD less than 1.0%, 1.5%, 2.9% and 1.8%, respectively. All the 10 analytes showed good linearity in wide linear ranges (r(2)=0.9999), and their average recoveries varied between 97.8% and 104.9%.

[Two new phenolic acids from Drynariae rhizoma].

To study the chemical constituents of Drynariae Rhizoma, nine phenolic acids were isolated from a 70% ethanol extract by using a combination of various chromatographic techniques including column chromatography over silica gel, ODS, Sephadex LH-20, and semi-preparative HPLC. By spectroscopic techniques including 1H NMR, 13C NMR, 2D NMR, and HR-ESI-MS, these compounds were identified as 4, 4'-dihydroxy-3, 3'-imino-di-benzoic acid (1), protocatechuic acid (2), gallic acid (3), p-hydroxybenzoic acid (4), (E)-caffeic acid (5), ethyl trans-3, 4-dihydroxycinnamate (6), caffeic acid 4-O-beta-D-glucopyranoside (7), p-coumaric acid 4-O-beta-D-glucopyranoside (8), and 23(S)-12-O-caffeoyl-12-hydroxyllauric acid glycerol ester (9), separately. Among them, 1 and 9 are new compounds, and 3, 4, and 6 were isolated from Drynaria species for the first time.

Neuroprotective xanthone glycosides from Swertia punicea.

Two new dimeric xanthone O-glycosides, puniceasides A (1) and B (2), a new trimeric O-glycoside, puniceaside C (3), and two new trimeric C-glycosides, puniceasides D (4) and E (5), together with 12 known xanthones were isolated from the entire plant of Swertia punicea. The structures of 1-5 were determined by HRESIMS and NMR spectroscopic methods. Compounds 2, 6, and 7 exhibited potent neuroprotective activity against H(2)O(2)-induced PC12 cell damage.

Chemical fingerprint of commercial Radix Echinopsis and quantitative analysis of alpha-terthienyl.

New TLC, HPLC and LC/MS methods were developed for the rapid separation, characterization and quantitation of thiophenes in Radix Echinopsis, a herbal medicine, which has been used in China for long history. Nineteen commercial batches of this herb were analyzed by TLC and HPLC. Only five batches were derived from correct species. The other 14 batches were identified as its adulterating species, Radix Rhapontici, as they did not contain characteristic thiophenes of Echinopsis species. By LC/MS, 16 thiophenes were identified from the methanol extracts of Radix Echinopsis and Radix Rhapontici according to their fragmentation behaviors in MS/MS. In addition, a fully validated HPLC method was established to determine the contents of alpha-terthienyl in Radix Echinopsis. The contents ranged from 2.7 to 5.2 mg/g for five tested samples. The methods in this paper were simple and reliable, and could be used for the comprehensive quality control of Radix Echinopsis.

Analysis of chemical constituents and taxonomic similarity of Salvia species in China using LC/MS.

Salvia species have an extensive distribution and a long history of medical use in China. In this study, chemical differences between different Salvia species were thoroughly investigated, and 86 constituents were characterized through a sensitive HPLC-DAD-ESI-MS (n) method. In total, 19 Salvia species were screened. Our study suggested that Ser. Brachylomae, Ser. Digitaloidites, Ser. Castaneae, and Ser. Miltiorrhizae were the sibling series (Ser. is short for series) and that Ser. Brachylomae, Ser. Maximowicziana, and Ser. Campanulatae were unique with regard to their constituents in addition to having componential affinity. This study offered a simple chemotaxonomy approach and a reasonable bioactivity interpretation of Salvia species.

Qualitative evaluation and quantitative determination of 10 major active components in Carthamus tinctorius L. by high-performance liquid chromatography coupled with diode array detector.

Flavonoids in the water extract of Carthamus tinctorius L. exhibit potent biological activities such as anti-coagulant, vasodilation, anti-oxidant, neuroprotection and immunosuppressant. A high-performance liquid chromatographic method was established to evaluate the quality of Carthamus tinctorius through a simultaneous quantitation of eight flavonoids, hydroxysafflor yellow A (2), 6-hydroxykaempferol 3,6-di-O-beta-glucoside-7-O-beta-glucuronide (3), 6-hydroxykaempferol 3,6,7-tri-O-beta-glucoside (4), 6-hydroxykaempferol 3-O-beta-rutinoside-6-O-beta-glucoside (6), 6-hydroxykaempferol 3,6-di-O-beta-glucoside (7), 6-hydroxyapigenin 6-O-glucoside-7-O-glucuronide (8), anhydrosafflor yellow B (9), and kaempferol 3-O-beta-rutinoside (10), together with two other compounds named guanosine (1) and syringin (5). Among them, compound 8 was identified as a new compound. The compounds were separated on an Alltech Alltima-C(18) column with gradient elution of acetonitrile and 0.01% trifluoroacetic acid. The detection wavelength was 280 nm. All the compounds showed good linearity (r(2) >or= 0.9989). The recoveries, measured at three concentration levels, varied from 94.9% to 105.2%. This method was also validated with respect to precision, repeatability and accuracy, and was successfully applied to quantify the 10 components in 46 batches of C. tinctorius samples from different areas. Significant variations were found in the contents of these compounds in these samples. Compared with the reported analytical methods of C. tinctorius, this simple and reliable method provided a new basis for overall assessment on quality of C. tinctorius and should be considered as a suitable quality control method.

Microbial transformation of alantolactone by Mucor polymorphosporus.

Two new transformed sesquiterpenes of alantolactone by Mucor polymorphosporus were obtained. They were characterized as 3beta-hydroxy-11betaH-eudesm-5-en-8beta,12-olide (2) and 3beta,11alpha-dihydroxy-eudesm-5-en-8beta,12-olide (3), on the basis of spectral methods including 2D NMR. And product 3 was an unusual hydroxylation derivative of alantolactone at C-11.

Three new compounds from the roots of Saposhnikovia divaricata.

From the roots of Saposhnikovia divaricata, three new compounds, divaricataesters A (1), B (2), and C (3) were isolated, along with three known compounds, cimifugin (4), (3S)-2,2-dimethyl-3,5-dihydroxy-8-hydroxymethyl-3,4-dihydro-2H,6H-benzo[1,2-b:5,4-b']dipyran-6-one (5) and 5-hydroxymethyl-furfurol (6). Their structures were established by spectral analysis and comparison with the reported data in literatures.

Characterization of chemical constituents in Guan Xin II decoction by liquid chromatography coupled with electrospray ionization-mass spectrometry.

Guan Xin II decoction (GX II) is a widely used traditional Chinese medicine (TCM) formula for the treatment of coronary heart diseases. However, the comprehensive chemical analysis of the formulated GX II is not clarified yet. An HPLC-DAD-ESI-MSn method was established to analyze GX II and its five component herbs, respectively. A total of 57 compounds, including phenolic acids, glycosides, flavonoids, and alkaloids were identified or tentatively characterized on the basis of their mass spectra or by comparison with reference standards. This is the first time that the chemical composition of GX II was elucidated by LC/MS. The established method will be used for quality control and pharmacokinetic studies of GX II.

Metabolic analysis of four phenolic acids in rat by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-diode array detection-electrospray ionization ion trap mass spectrometry (LC-DAD-ESI-MS(n)) method was established for the analysis of danshensu, caffeic acid, ferulic acid and isoferulic acid in rat plasma, bile, urine and feces after oral administration or intravenous injection. Liquid-liquid extraction was employed for the preparation of biosamples, and the chromatographic separation was carried out using an Agilent Zorbax Extend C(18) reversed phase column and acetonitrile-0.1% formic acid as the mobile phase. Totally nineteen metabolites were detected and identified as prototype, methylated, hydroxylated, sulfated and glucuronized conjugates. The metabolism of the individual phenolic acids in biosamples was investigated, and the metabolic pathway was proposed. By comparing the metabolism of different compounds which shared similar structures, we were able to find that methylation was the main pathway of danshensu metabolism, and the double bond on the side chain was critical for the drug excretion via bile and the formation of glucuronized conjugates. The results proved that the established method was simple, sensitive and reliable, which could be used to detect and identify the structures of metabolites and to better understand their in vivo metabolism.

[Biotransformation of podophyllotoxin by cell suspension culture and root culture of Rheum palmatum].

OBJECTIVE: To study the biotransformation of podophyllotoxin by the cell suspension culture and root culture systems of Rheum palmatum. METHOD: Using plant tissue culture technology and HPLC techniques to isolate products. The structures were elucidated by spectroscopic means. RESULT: Cell suspension culture of R. palmatum could convert podophyllotoxin to produce picropodophyllotoxin with the yield of 73.8%, while root culture of R. palmatum could convert podophyllotoxin to produce epipodophyllotoxin and apopodophyllotoxin. CONCLUSION: Podophyllotoxin did not affect the pH value of the media used in tissue cultures. Both cell suspension culture and root culture of R. palmatum can convert podophyllotoxin.

Characterization of compounds from the roots of Saposhnikovia divaricata by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

In this study, four types of compounds including coumarins, chromones, furoylmethyl amino acid derivative and benzofuran glycoside were isolated from the roots of Saposhnikovia divaricata. The electrospray ionization (ESI) mass spectral fragmentation pathways of these compounds were proposed. In particular, the ESI-MS(n) fragmentation behavior of linear dihydrofurocoumarins, dihydrofuro- and dihydropyranochromones were deduced in detail. For the linear dihydrofurocoumarins, the fragmentation was triggered by the initial loss of the C-4' substituting group. Then, the characteristic ions were observed followed by the losses of 15, 18, 28 and 46 Da. It is noteworthy that the elimination of H(2)O (18 Da) from the cleavage of the dihydrofuran ring is reported for the first time. For the linear dihydrofurochromones, characteristic eliminations of 18, 48 and 72 Da were observed. The loss of 18 Da could arise from two different fragmentation pathways, and the observed ion was composed of a mixture of two different structural ions. For the linear dihydropyranochromones, it was found that the dihydropyran ring was converted into the pyran ring by the elimination of the C-3' substituting group. This fragmentation was followed by the diagnostic losses of 18, 28, 42 and 54 Da in tandem mass spectrometry. The above fragmentation rules were successfully applied for the analysis of the chemical constituents of the roots of Saposhnikovia divaricata. A total of 32 compounds were identified or tentatively characterized by HPLC/DAD/ESI-MS(n). Among them, eight compounds were new and seven compounds were reported from that genus for the first time.

Analysis of phenolic compounds in Epimedium plants using liquid chromatography coupled with electrospray ionization mass spectrometry.

A new method based on HPLC coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) has been established for the analysis of phenolic compounds in Epimedium plants. The characteristic fragmentation pathways of 29 phenolic compounds were studied, and 126 compounds were identified or tentatively characterized based on their mass spectra from fourteen samples including the aerial samples and the underground parts of the seven species. Furthermore, the differences in phenolic compound profiles between different Epimedium plants and two parts of the seven species were reported for the first time. Due to their significant chemical differences, these Epimedium species should be used separately in clinical practice.