Aegiceras corniculatum (L.) Blanco, a mangrove shrub species in the Myrsine family, often grows at the seaward edge of the mangrove zone in China. In the present study, seasonal dynamics of nutrient resorption and phenolics concentration associated with leaf senescence of A. corniculatum were investigated in order to evaluate its possible nutrient conservation strategies in the subtropical Zhangjiang river estuary. It was found that the nitrogen (N) and phosphorus (P) concentrations in mature leaves showed similar seasonal changes with the highest concentrations in winter and the lowest in summer, and were significantly higher than those in senescent leaves. The N:P ratios of mature leaves through the year were found to be less than 14, indicating that the A. corniculatum forest was N-limited. The nitrogen resorption efficiency (NRE) was higher than phosphorus resorption efficiency (PRE), and N resorption was complete. In addition, A. corniculatum leaves contained high total phenolics (TPs) and total condensed tannin (TCT) levels (both above 20%). TPs concentrations in mature and senescent leaves were all inversely related to their N or P concentrations. TPs:N and TCT:N ratios in senescent leaves were significantly higher than those in mature leaves. The obtained results suggested that high NRE during leaf senescence and high TPs:N and TCT:N ratios in senescent leaves might be important nutrient conservation strategies for the mangrove shrub A. corniculatum forest growing in N-limited conditions.

Avicennia marina is a typical mangrove species of subtropical coastlines of China. However, little is known about the retention of nutrients by this species in oligotrophic, coastal environments. In this study, seasonal changes in nitrogen (N) and phosphorus (P) concentrations, N: P ratio and total phenolic concentration in A. marina leaves during senescence were studied. Avicennia marina leaves had high N and P concentrations but the seasonal pattern of N concentration was different from that of P concentration. The A. marina forest was N-limited as the N: P ratio of mature leaves was less than 14. Nitrogen resorption efficiency was higher than P resorption efficiency, and the concentrations of N and P in senescent leaves indicated that N resorption was mostly complete whereas P resorption was incomplete. Avicennia marina leaves contained low tannin concentrations, particularly condensed tannins, as the leaf extracts did not react with acid butanol. Total phenolic concentrations were not correlated with N concentrations in mature and senescent leaves of A. marina. These findings suggest that the high N resorption efficiency and low nutrient losses play an important role in nutrient conservation strategies for A. marina forests, whereas low tannin concentations have limited effects on nutrient cycling.

In this study, the condensed tannins in 70% acetone extracts of leaf, twig, and stem bark of Calliandra haematocephala were purified by a Sephadex LH-20 column, and their structures were identified using MALDI-TOF-MS and thiolysis-HPLC-ESI-MS analyses. The results showed that the condensed tannin structures varied significantly among C. haematocephala organs. The condensed tannins from leaf were essentially of prodelphinidins, consisting mainly of (epi)gallocatechin and (epi)gallocatechin-3-O-gallate units; the condensed tannins from twig and stem bark were predominately of procyanidins, with catechin, epicatechin, and (epi)catechin-3-O-gallate as the main constitutive units for the former and epicatechin as the main constitutive unit for the latter, respectively. Furthermore, in vitro antioxidant activities of these condensed tannins were evaluated using the ABTS·+ and FRAP methods. All of the condensed tannins exhibited stronger antioxidant activities compared to those of synthetic antioxidant BHA. For all organs, the two tested activities were found to be the highest in leaf condensed tannins, followed by that in twig condensed tannins and stem-bark condensed tannins. The results suggested that the number of hydroxyl groups on the B-ring and the level of 3-O-galloylation in condensed tannins were closely related with their antioxidant activities, and that the condensed tannins from different parts of C. haematocephala could be used as a natural additive in the food and cosmetic industries.

Seasonal dynamics of total phenolics (TP), extractable condensed tannins (ECT), protein-bound condensed tannins (PBCT), fiber-bound condensed tannins (FBCT), total condensed tannins (TCT) and nitrogen contents in sun and shade leaves of Aegiceras corniculatum were studied in the Zhangjiang Estuary, Fujian Province, China. The contents of TP, ECT and TCT in the sun leaves were significantly higher than those in the shade leaves through the season. The N content in sun leaves was higher than that in shade leaves in the autumn, while it was lower in the summer, and there was no significant difference in the winter and spring. With the respect to the P through the year, P content in the sun leaves was different between seasons, with the highest in winter and the lowest in summer. In addition, the TP:N and ECT:N ratios in sun leaves were significantly higher than those in shade leaves except in autumn. High tannin levels and TP:N and ECT:N ratios in the sun leaves not only can reduce oxidative stress, but also improve the ability of resisting plant diseases and insect pests.

Tannins from the leaves of a medicinal mangrove plant, Ceriops tagal, were purified and fractionated on Sephadex LH-20 columns. C-13 nuclear magnetic resonance (C-13-NMR), reversed/normal high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDT-TOF MS) analysis showed that the tannins were predominantly B-type procyanidins with minor A-type linkages, galloyl and glucosyl substitutions, and a degree of polymerization (DP) up to 33. Thirteen subfractions of the procyanidins were successfully obtained by a modified fractionation method, and their antioxidant activities were investigated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity and ferric reducing antioxidant power (FRAP) method. All these subfractions exhibited potent antioxidant activities, and eleven of them showed significantly different mean DP (mDP) ranging from 1.43 +/- 0.04 to 31.77 +/- 1.15. Regression analysis demonstrated that antioxidant activities were positively correlative with mDP when around mDP <10, while dropped and then remained at a level similar to mDP = 5 with around 95 mu g ml(-1) for DPPH scavenging activity and 4 mmol AAE g(-1) for FRAP value.

The antioxidant compounds of leaves and fruits from Averrhoa carambola were extracted with acetone:water (7:3, v/v) and distilled water. The acetone:water extracts (AWE) were separated into five different subfractions, three obtained by liquid liquid extraction using n-hexane (HF), ethyl acetate (EAF) and water (WF), and the other two obtained by further fractionation of the WF on a Sephadex LH-20 column (WS1 and WS2). The antioxidant activities, total phenolics and total flavonoids of these extracts and fractions were investigated. Results showed that all the extracts and fractions possessed potent antioxidant activities, as measured by DPPH, ABTS and FRAP methods, with the strongest for WS2 fractions accompanied with the highest total phenolics and total flavonoids. Reversed-phase HPLC, normal-phase HPLC, MALDI-TOF-MS and C-13 NMR analyses identified that the main antioxidant components present in WS2 fractions were essentially of procyanidin-type proanthocyanidins, consisting mainly of epicatechin units linked by B-type interflavan bonds. In addition, GC-MS analysis revealed that the most abundant fatty acids were alpha-linolenic acid (62.04 +/- 1.65%) for leaves and oleic acid (55.44 +/- 1.37%) for fruits. The amount of total unsaturated fatty acids in leaves and fruits comprised more than 77% of total fatty acid. (C) 2013 Elsevier Ltd. All rights reserved.

Ions in Matrix-Assisted Laser Desorption/Ionization (MALDI) are predominantly singly charged for small analyte molecules. With the estimated high number density and low temperature of electrons, the three-body recombination mechanism is attractive and should be considered as an important cause for the charge reduction in the plume. Theoretical calculations indicate that the rate coefficient of the three-body recombination is about 50 times higher than that of the two-body recombination if the analyte molecule has insufficient degrees of freedom. Experimental results show that, for small analyte molecules, the ratio of AH22+/AH+ is close to the theoretical 5% value from the three-body recombination modeling and this ratio declines with the increasing electron and matrix molecule number density caused by greater laser irradiance. The ratio of [A + 2]+/[A + 1]+ is higher than the theoretical isotopic value, and the excess [A + 2]+ could exclusively result from the three-body recombination collisions. Further evidence demonstrates that [A + 2]+/[A + 1]+ increases with electron number density, which is in correspondence with the model. All of these theoretical and experimental results indicate that three-body recombination is an essential charge reduction mechanism for small molecules in the MALDI plume.

: Casuarina equisetifolia is characterised by high primary productivity in coastal sandy soils ， which are generally low in nutrient contents． High tannin production and nutrient resorption may be important strategies for C． equisetifolia in coastal environments． Despite the widespread planting and known ecological and physiological properties of C． equisetifolia ， there is scant information about the nutrient resorption patterns mature stand and did not change in juvenile and senescent stands． Total condensed tannin ( TCT ) followed similar pattern as ECT during stand development． Protein precipitation capacity ( PPC ) in mature and senescent branchlets were significantly higher in juvenile stand than in mature and senescent stands． PPC decreased during branchlet senescence in the three stands． Significant positive linear correlations were found between PPC and TP or TCT． Nitrogen ( N ) concentrations both in mature and senescent branchlets obviously increased during stand development． Phosphorus ( P ) concentrations in mature branchlets were similar in juvenile and mature stands but lower in senescent stand． Phosphorus concentrations in senescent branchlets of juvenile stand were significantly higher than those of mature and senescent stands． Nitrogen : phosphorus ratios ( N ∶ P ratios ) of mature branchlets ， were all above 20 ， also increased during stand development． Nitrogen resorption efficiencies ( NＲE ) in three stands were basically below 50% ， the lowest in senescent stand． Phosphorus resorption efficiencies ( PＲE ) were above 70% with the highest in mature stand ( 78． 08% ) ． There were significant negative correlations between N and P concentrations in mature and senescent branchlets． Nitrogen resorption efficiency had a particular strong relationship with the N ∶P ratios of branchlets． On the other hand ， PＲE was not significantly related to N ∶P ratios of branchlets． There were significant correlations between TP or TCT and N or P concentrations in branchlets except for the relationship between TCT and P concentrations in senescent branchlets． The above results indicated that the tannin level ， nutrient concentration and resorption were affected by stand age． C． equisetifolia could adjust their nutrient conservation with stand development at intraspecific level．

In modern bioanalytics, elemental analysis of single cells is important yet challenging due to the complicated biological matrices and elemental contents. We have developed the high irradiance femtosecond laser ionization orthogonal time-of-flight mass spectrometry (fs-LI-O-TOFMS) to determine the elemental composition of individual cells. The sample preparation procedure is simple and fast through heating and drying the cells. Under typical operating conditions, elements above femtogram levels in a single cell can be clearly observed in the spectrum with reasonable isotope ratios. Some of the nonmetallic elements that are difficult to measure by ICPMS, such as P, S, and Cl, can be easily determined by fs-LI-O-TOFMS. Replicate analyses show that signal variations are 15-35% for metallic elements and 25-50% for nonmetallic elements. The results demonstrate that fs-LI-O-TOFMS is a simple, rapid, and practical tool for the elemental determination of single cells.

Casuarina equisetifolia is a major species planted in protection forest along the coast of southeast China.At present,how to sustain and enhance its environmental regulation functions has become important science question for local protection forest management.This paper reviewed the research at home and abroad on nutrient cycling,energy flow and protective functions of C.equisetifolia ecosystem in coastal zone as well as on the effects of forest management measures on forest ecosystem,indicating that C.equisetifolia plantations have the characteristics of high production,high photosynthesis rate and better adaptive abilities.The relationship between disturbance and the degraded C.equisetifolia ecosystem was discussed.Then the suggestions were made for the restoration and reconstruction of the damaged C.equisetifolia protection forest and the management of its ecosystem.

The characteristics of laser ionization in low pressure background gas have been investigated through the measurement of temporal and kinetic energy distributions of Al+, Mn+, Nb+, In+, Ta+, and Bi+ produced from a disk comprised of these metallic elements. A Q-switched Nd:YAG laser was utilized with a laser beam at 532nm of wavelength and 1.0×1010W/cm2 of laser irradiance. The kinetic energy was found to be the same for all ablated species at the given pressure, regardless of the atomic mass. The plume propagation translates from a free expansion at 0.5Pa to a collisional and shockwave-like hydrodynamic expansion at 50Pa. A plume splitting exists at 500–1500Pa where only the fast component can be observed with a grounded nozzle voltage. As the nozzle voltage grows up, the thermalized component with increased kinetic energy is found depending on the nozzle voltage.

In this study, we investigated the changes in total phenolics, extractable condensed tannins (ECT), protein noncovalent bound condensed tannins (PNBCT) and irreversible covalent bound condensed tannins (ICBCT) in the hypocotyls and pericarps of Aegiceras corniculatum fruits during dry storage. The loss of moisture content and survival rate, as indicators of the viability and quality of plant tissues, were also monitored during the dry storage. Great amount of free condensed tannins combined with proteins in the senescent pericarps during the process of deteriorative reactions associated with dry storage, which contributed to the rapid increase of PNBCT characterized by the sigmoid model. However, there was a rapid loss of total phenolics and ECT from pericarps during the first 9 days of the dry storage, with 37.3% loss of ECT due to the transformation of PNBCT. PNBCT of the hypocotyls also fitted a sigmoid model with dry storage time, and was related to the viability of the hypocotyls. During the dry storage, most of the disappeared ECT of hypocotyls formed complexes with protein, and the total condensed tannins (TCT) did not decline during the 27 days dry storage. The distribution of the oligomers and polymers in the condensed tannins was significantly different between the fresh and dried hypocotyls of A. corniculatum. The oligermers with lower degree of polymerization (DP) appeared to have higher capacity of binding to proteins than the polymers with high DP in plant tissues during the dry storage. The changes of hydroxy pattern of tetramers in the fresh and dried hypocotyls showed that the proteins would be selective binding those flavan-3-ol oligomers with more hydroxyl in plant tissues with deteriorative reactions during dry storage. However, the hydroxy pattern of nomamers was not significantly different between the fresh and dried hypocotyls. Our results indicated that few flavan3-ol polymers reacted with proteins in hypocotyls of A. corniculatum associated with the deteriorative reactions during the dry storage.

The aim of this study was to investigate polymeric proanthocyanidin (PA) composition and free radical scavenging activity of leaf, stem bark and fine root of Grevillea robusta. The spectra obtained through MALDI-TOF MS analysis revealed that the examined PAs were built up a mixture of procyanidins and prodelphinidins. Acid-catalyzed cleavage of the PAs coupled with reversed-phase HPLC-ESI-MS showed that the main constituents of cleavage products were (epi) gallocatechin benzylthioether and (epi) catechin benzylthioether for leaf and stem bark, and was (epi) gallocatechin benzylthioether for fine root, respectively. The mean degrees of polymerization (mDP) of PAs of leaf, stem bark and fine root were 9.6, 19.0 and 10.1, respectively. The PAs extracted from leaf, stem bark and fine root exhibited higher antioxidant activity than those of ascorbic acid and synthetic antioxidant butylated hydroxyanisole (BHA), as measured by 2,2'-azinobis( 3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging method.

Freeze-dried leaf, stem bark, and root bark powders of Aegiceras corniculatum were extracted with three different types of polar solvents: methanol, ethyl acetate, and water. The methanol extracts had the highest concentrations in total phenolics and extractable condensed tannins, followed by water and ethyl acetate extracts. Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) suggested that condensed tannins from leaf, stem bark, and root bark contained prodelphinidins and procyanidins, with the predominance of prodelphinidins and high level of galloylation. Acid-catalyzed degradation in the presence of benzyl mercaptan indicated that gallocatechin, epigallocatechin, epigallocatechin-3-O-gallate, and epicatechin-3-O-gallate occurred as the terminal units and (epi)gallocatechin, (epi)gallocatechin-3-O-gallate, (epi)catechin, and (epi)catechin-3-O-gallate occurred as the extension units. The mean degrees of polymerization (mDP) of condensed tannins from leaf, stem bark, and root bark were 13.5, 7.4, and 12.3, respectively. The condensed tannins from leaf and stem bark exhibited a higher DPPH radical scavenging activity and ferric reducing/antioxidant power compared to that of synthetic antioxidant butylated hydroxyanisole (BHA). (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Nutrient, water, and their interactions influence the allocation of investment by plants to resistance and tolerance traits. We used a completely crossed randomized-block design experiment to examine the independent and interactive effects of nutrients and water availability on tannin production of C. equisetifolia seedlings. The results showed that nitrogen and phosphorus fertilizer have significant effects on total phenolics (TP) and extractable condensed tannins (ECT) concentrations of branchlets. TP and ECT concentrations decreased with fertilizer addition and increased in arid condition. This pattern lends to support source-sink hypothesis such as the carbon-nutrient balance (CNB) hypothesis and the growth-differentiation balance (GDB) hypothesis. Soluble sugars or starch concentrations were both inversely related to TP concentrations. However, there was no significant correlation between them and ECT concentrations. In addition, chlorophyll concentration had a positive linear correlation with TP and no significant correlation with ECT. On the contrary, chlorophyll a/b ratios were negatively correlated with TP and positively correlated with ECT. The discrepancy of relationship between carbohydrates and TP or ECT showed that the biosynthetic routes of different tannins were different. In this study, no significant correlation between TP and N, or ECT and N, did not support protein competition model (PCM). TP:N and ECT:N ratios were higher in nutrient deficiency and arid conditions, which were one of the important nutrient conservation strategies for C. equisetifolia.

Kandelia obovata, with abundant condensed tannins (CTs), is a typical mangrove species in China, but little is known about the chemical alterations and ecological roles of CTs during leaf litter decomposition. A litterbag experiment was conducted to investigate the changes of CTs in a subtropical mangrove swamp along Zhangjiang River Estuary, China, using the colorimetric assays, reversed/normal-phase HPLC–ESI-MS and MALDI–TOF-MS techniques. Total phenolics (TP), extractable CTs (ECT) and total CTs (TCT) decreased rapidly, while bound CTs (BCT), including protein- and fibre-bound CTs in leaves, increased during decomposition, and these temporal changes were well-expressed by exponential functions. Negative correlations between nitrogen (N) and TP, as well as N and ECT were found; however, a positive correlation between N and BCT was detected, suggesting that CTs played an important role in humification during N immobilization. The HPLC–ESI-MS analyses showed that the polymerization degree of CTs had an initial increase, due to leaching, followed by a decrease in the subsequent shift towards abiotic or/and biotic degradation. MALDI–TOF-MS confirmed the degradation processes for CTs. A decrease in the degree of hydroxylation, along with an increase in glycosylation-CTs, was obtained during litter decomposition. These chemical changes enhanced the current knowledge on the potential ecological role of N transformation in CTs in mangrove swamps.

The acetone-water (1:1, v/v) was more effective solvent for extracting total phenolics and extractable condensed tannins from Machilus pauhoi leaves than methanol, ethanol, acetone, water, methanol-water (1:1, v/v), and ethanol-water (1:1, v/v). The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis revealed that catechin/epicatechin was the basic units occurring in M. pauhoi leaf condensed tannins, and A-type and B-type linkages were most common among the structural units of polymers. Thiol degradation with cysteamine indicated that the polymer was constituted of (+)-catechin and (-)-epicatechin as the terminal units and (-)-epicatechin as the extension units. The mean degree of polymerization (mDP) of the condensed tannins was 6.96. The condensed tannins from M. pauhoi leaves had more effective 2,2-diphenyl-1-picrylhydrazyl (DPPH) and diammonium salt (ABTS) free radicals scavenging abilities than the ascorbic acid and butylated hydroxyanisole (BHA), and may be considered as a new source of natural antioxidants for food and nutraceutical products.   Key words: Machilus pauhoi, condensed tannins, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, reversed phase high performance liquid chromatography, antioxidant activity.

In insects, tyrosinase plays important roles in normal developmental processes, such as cuticular tanning, scleration, wound healing, production of opsonins, encapsulation and nodule formation for defense against foreign pathogens. Thus, tyrosinase may be regarded as a potential candidate for novel bioinsecticide development. A family of alkyl 3,4-dihydroxybenzoates (C₆-C₉), new tyrosinsase inhibitors, were synthesized. Their inhibitory effects on the activity of tyrosinase have been investigated. The results showed all of them could inhibit the activity of tyrosianse effectively. The order of potency was nonyl 3,4-dihydroxybenzoate (C₉DB) > octyl 3,4-dihydroxybenzoate(C₈DB) > heptyl 3,4-dihydroxybenzoate(C₇DB) > hexyl 3,4-dihydroxybenzoate (C₆DB). The kinetic analysis of these four compounds on tyrosinase was taken to expound their inhibitory mechanism. The research of the control of insects in agriculture was taken as C₆DB for example. C₆DB could inhibit the development and molting of Plutella xylostella effectively. To clarify its insecticidal mechanism, we researched the expression of tyrosinase in the P. xylostella treated with C₆DB by real-time quantitative PCR. The results showed C₆DB could inhibit the expression of tyrosinase in the P. xylostella as expected.

The extract from mangosteen pericarp was separated into eight fractions, four by solvent extraction (hexane, FH; petroleum ether, FP; ethyl acetate, FE; water, FW) and the other four by fractionation on Sephadex LH-20 column (fractions F1, F2, F3, and F4). Phenolic compounds were identified as the major antioxidant components in each fraction. UV–VIS spectrum, reversed-phase HPLC–ESI-MS coupled with thiolysis, normal-phase HPLC–ESI-MS and MALDI-TOF-MS analyses complementally showed that the phenolic-rich fractions were condensed tannins with structural heterogeneity in monomer units, degree of polymerization and interflavan linkages. Mangosteen condensed tannins predominately contained procyanidins with a significant amount of propelargonidin but much lower signals of prodelphinidin. Eicosapentamers of condensed tannins were detected by MALDI-TOF-MS. Both B-type and A-type linkages were present. Condensed tannins fractions from mangosteen pericarp, especially fractions F3 and FE, can be explored as beneficial food antioxidants because of their high yields and potent antioxidant activities.

Characteristics of laser ionization in vacuum and low pressure background gas (He) have been investigated through the measurement of kinetic energy and spatial distributions of copper and tungsten ions. A Q-switched Nd:YAG laser with 532 nm wavelength was utilized and the laser irradiance was fixed at 9 × 109 W cm−2. A plume splitting was observed in the low pressure regime investigated (from 100 Pa to 2000 Pa). The plume propagation translates from a free expansion in vacuum to shockwave-like expansion at relative low pressure and finally diffusion into background gas at relative high pressure environment. A measurement of ion spatial distribution in the ion source has also been carried out for characterizing ions at different pressures and the behaviors of doubly charged, singly charged, and polyatomic ions to reveal the effect of plume–background gas interaction.