Liriogerphines E-U, further unique sesquiterpene-alkaloid hybrids from the rare Chinese tulip tree.

Seventeen undescribed sesquiterpene-alkaloid hybrids (liriogerphines E-U, 1-17) were isolated and identified during a further phytochemical investigation on the branches and leaves of Chinese tulip tree (Liriodendron chinense), a rare medicinal and ornamental plant endemic to China. These unique heterodimers are conjugates of germacranolide-type sesquiterpenoids with structurally diverse alkaloids [i.e., aporphine- (1-15), proaporphine- (16), and benzyltetrahydroisoquinoline-type (17)] via the formation of a C-N bond. The previously undescribed structures were elucidated by comprehensive spectroscopic data analyses and electronic circular dichroism calculations. Such a class of sesquiterpene-alkaloid hybrids presumably biosynthesized via an aza-Michael addition is quite rare from terrestrial plants. In particular, the sesquiterpene-benzyltetrahydroisoquinoline hybrid skeleton has never been reported until the present study. All the isolates were evaluated for their cytotoxic effects against a small panel of leukemia cell lines (Raji, Jeko-1, Daudi, Jurkat, MV-4-11 and HL-60), and some of them exhibited considerable activities.

Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXV. Structurally diverse triterpenoids and diterpenoids from two endangered Pinaceae plants endemic to the Chinese Qinling Mountains and their bioactivities.

A joint phytochemical investigation on the MeOH extracts of the twigs and needles of two endangered Pinaceae plants endemic to the Chinese Qinling Mountains, Picea neoveitchii (an evergreen spruce) and Larix potaninii var. chinensis (a deciduous larch), led to the isolation and characterization of 34 and 24 structurally diverse terpenoids, respectively. Among them, seven are previously undescribed, including a picane-type [i.e., 14(13 â†’ 12)abeo-12αH-serratane] (neoveitchin A) and a serratane-type (neoveitchin B) triterpenoids, and an abietane-type (neoveitchin C) as well as four labdane-type (potalarxins A-D) diterpenoids. Their structures and absolute configurations were established by extensive spectroscopic methods and/or X-ray diffraction analyses. All isolates were evaluated for their inhibitory activities against the human protein tyrosine phosphatase 1B (PTP1B). Serrat-14-en-3α,21ß-diol, betulinic acid, 3ß-hydroxy-11-ursen-13(28)-olide, ursolic acid, and oleanolic acid were found to have considerable inhibitory effects against PTP1B, with IC50 values ranging from 1.1 to 18.1 µM. The interactions of the bioactive triterpenoids with PTP1B were thereafter performed by employing molecular docking studies. In addition, 7-oxo-dehydroabietic acid (an abietane-type diterpenoid) and mangiferonic acid (a cycloartane-type triterpenoid) inhibited acetyl-coenzyme A carboxylase 1 (ACC1), with IC50 values of 3.4 and 6.6 µM, respectively.

Complete chloroplast genome of Lonicera crassifolia Batalin (Caprifoliaceae) and its phylogenetic implications.

Lonicera crassifolia is a prostrate or creeping, evergreen Lonicera species endemic to southwest China. Here, we reported the complete chloroplast (cp) genome of L. crassifolia (GenBank accession number: OK393707). The cp genome was 154,731 bp long, with a large single-copy region (LSC) of 88,619 bp and a small single-copy region (SSC) of 18,642 bp separated by a pair of inverted repeats (IRs) of 23,735 bp. It encodes 130 genes, including 85 protein-coding genes, 37 tRNA genes, and 8 ribosomal RNA genes. We also reconstructed the phylogeny of Lonicera using the maximum-likelihood (ML) method, including our data and previously reported cp genomes of related taxa. The phylogenetic analysis showed that L. crassifolia is a sister to the remaining Nintooa clade with strong bootstrap support.

[Effects of arbuscular mycorrhizal fungi inoculation on non-structural carbohydrate contents and C:N:P stoichiometry of Heptacodium miconioides under drought stress]. / å¹²æ—±èƒè¿«ä¸‹æŽ¥ç§ä¸›æžèŒæ ¹çœŸèŒå¯¹ä¸ƒå­èŠ±éžç»“æž„æ€§ç¢³æ°´åŒ–åˆç‰©ç§¯ç´¯åŠC、N、P化学计量特征的影响.

A pot experiment was conducted to investigate the effects of drought stress and arbuscular mycorrhizal fungi (AMF) inoculation on C:N:P stoichiometry and non-structural carbohydrate (NSC) contents in two-year-old Heptacodium miconioides seedlings. There were four treatments, including control (CK), drought stress (D), AMF inoculation (AMF), and combined drought stress and AMF inoculation (D+AMF). The results showed that drought stress significantly reduced AMF colonization rate, whereas plant height and leaf number of inoculated treatment were significantly higher than the non-inoculated treatment. Inoculation with AMF significantly increased soluble sugar and NSC content in root and leaf, as well as starch content in stem and leaf. The inoculation significantly decreased the stem and leaf soluble sugar to starch ratio under drought stress. Drought stress caused a significant increase in C content in roots and leaves, and a significant decrease in P content in stems. Compared with no inoculation drought stress, P content in roots, stems, leaves, and C content in leaves of mycorrhizal seedlings were significantly increased by inoculation under drought stress, whereas root C and N content and stem C content were significantly reduced. Under drought stress, AMF inoculation significantly decreased C:N, C:P, and N:P ratios in roots and stems, and N:P ratios in leaves of H. miconioides. P content in roots and leaves were significantly positively correlated with soluble sugar and NSC content. Stem P content was significantly positively correlated with starch and NSC content. N:P ratios in each organ was significantly negatively correlated with NSC content. In all, inoculation with AMF can improve the drought tolerance of H. miconioides seedling by increasing soluble sugar content in roots and leaves and the soluble sugar/starch ratio in roots, improving starch content in above-ground organs, promoting the P absorption, and reducing N:P ratios in each organ. Therefore, AMF colonization could improve the survival rate of H. miconioides seedling in dry environments.

Liriogerphines A-D, a Class of Sesquiterpene-Alkaloid Hybrids from the Rare Chinese Tulip Tree Plant.

Liriogerphines A-D (1-4, respectively), an unprecedented class of hybrids of germacranolide-type sesquiterpenoids and aporphine-type alkaloids, were isolated from the rare medicinal plant Liriodendron chinense. Their structures were elucidated by comprehensive spectroscopic analyses combined with electronic circular dichroism calculations and X-ray crystallographic data. Biosynthetically, an aza-Michael addition reaction is proposed to be involved in the assemblies of this class of hybrids. Compound 4 exhibited cytotoxicity against leukemia cells via inducing apoptosis and inhibiting Bcl-2 expression.

Structurally diverse mono-/dimeric triterpenoids from the vulnerable conifer Pseudotsuga gaussenii and their PTP1B inhibitory effects. The role of protecting species diversity in support of chemical diversity.

A preliminary phytochemical investigation on the MeOH extract of the twigs and needles of Pseudotsuga gaussenii (a 'vulnerable' plant endemic to China) led to the isolation and characterization of 25 structurally diverse mono- and dimeric triterpenoids. 19 of them are previously undescribed, including eight cucurbitane-type triterpenoids (gaussenols A-H, 1-8, resp.), one serratene-type triterpene (gaussenol I, 9), and 10 triterpenic dimers (gaussenols J-S, 10-19, resp.). Their chemical structures were elucidated by means of spectroscopic data, some chemical transformations, the modified Mosher's method, and single crystal X-ray diffraction analyses. Compound 9 is the first 13R diastereoisomeric serratene-type triterpenoid derivative from nature. The unprecedented dimeric triterpenoids are constructed either through ester linkage (10-18) or via ether bond (19) among the side chains of same or different types of triterpenoid skeletons (e.g., cucurbitane-type, lanostane-type, and/or cycloartane-type). Compounds 9, 15, 21, and 25 exhibited inhibitory effects against the human protein tyrosine phosphatase 1B (PTP1B, a potential drug target for the treatment of type-II diabetes and obesity), with IC50 values of 3.1, 8.6, 9.0, and 5.6 µM, respectively. The interactions of the bioactive compounds with PTP1B were thereafter performed by employing molecular docking studies, with binding affinities ranging from - 6.9 to - 7.3 kcal/mol. The above findings could reveal the important role of protecting plant species diversity in support of chemical diversity and potential sources of new therapeutics.

Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities.

A phytochemical investigation on the MeOH extract of the leaves and twigs of the endangered conifer Torreya jackii Chun led to the isolation and characterization of 21 structurally diverse diterpenoids. Among them, six are previously undescribed, including four abietane-type (torreyins A-D, resp.) and two labdane-type diterpenoids (torreyins E and F). Their structures and absolute configurations were determined by a combination of spectroscopic methods, calculated/experimental electronic circular dichroism (ECD) data, and single-crystal X-ray diffraction analyses. In particular, torreyins A-C are rare 11,12-seco-abietane type diterpenoids possessing a dilactone moiety, and their biosynthetic pathway starting from a co-occurring abietane derivative (i.e., cyrtophyllone B) was briefly proposed. Among the isolates, 7-oxo-dehydroabietic acid and 15-methoxy-7,13-abietadien-18-oic acid showed considerable inhibitory effects against acetyl-coenzyme A carboxylase 1 (ACC1) and protein tyrosine phosphatase 1 B (PTP1B), with IC50 values of 3.1 and 6.8 µM, respectively.

Structurally diverse glycosides of secoiridoid, bisiridoid, and triterpene-bisiridoid conjugates from the flower buds of two Caprifoliaceae plants and their ATP-citrate lyase inhibitory activities.

The ethanolic extracts of the dried flower buds of two Caprifoliaceae plants, Lonicera japonica and Abelia × grandiflora, showed considerable inhibitory activities against adenosine triphosphate (ATP)-citrate lyase (ACL), a new promising drug target for the treatment of metabolic disorders. Bioassay-guided purification in conjunction with HPLC-PDA profiling led to the isolation and characterization of thirty-five (1-35) and fourteen (1'-14') structurally diverse compounds from the above two plant extracts, respectively. Compounds 1-9 and 1'-6' are previously undescribed glycosides. Their structures were elucidated on the basis of spectroscopic data, electronic circular dichroism (ECD), and single crystal X-ray diffraction analyses. In particular, lonicejaposide A (1) has an unprecedented skeleton generated through the coupling of C-7 in secologanin with C-2'' in phenylacetaldehyde via an aldol condensation. Abeliflorosides A (1') and B (2') are hitherto unknown glycosides of triterpene and bisiridoid conjugates constructed through the formation of a 1,3-dioxane moiety. All the isolates were evaluated for their inhibitory activities against ACL. Compounds 9, 25-28, 31, 1', 2', and 14' displayed significant inhibitory effects, with IC50 values ranging from 0.1 to 14.2 µM. The interactions of selected compounds possessing different structure features (e.g., 9, 25, 31, and 2') with ACL were thereafter performed by employing molecular docking studies. In addition, compound 2', the most complex triterpene-bisiridoid conjugate glycoside reported herein, also inhibited acetyl-CoA carboxylase 1 (ACC1), with an IC50 value of 7.9 µM. The dried material of the flower buds of L. japonica (honeysuckle) is a well-known traditional oriental medicine (i.e., Flos Lonicerae Japonicae, FLJ) and has long been used in large quantities. The above findings not only provide new insights for the development of multipurpose utilization of FLJ in healthcare community, but also provide profitable clues indicating that the flower buds of A. × grandiflora might be a potential alternative to FLJ in the traditional Chinese medicine market.

A new coumarin derivative from the stems of the endangered plant Ulmus elongata.

A preliminary phytochemical investigation of the stems of the endangered plant Ulmus elongata led to the isolation of a new coumarin derivative (named ulmuselactone A, 1) and eight known compounds (2-9). The new structure was elucidated by detailed analysis of comprehensive spectroscopic methods, and its absolute configuration was established by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The isolated compounds were evaluated for their antibacterial activities.

Cytotoxic secondary metabolites from the vulnerable conifer Cephalotaxus oliveri and its associated endophytic fungus Alternaria alternate Y-4-2.

Rare and endangered plants (REPs) and their associated endophytes survived in unique habitats are promising sources for natural product-derived drug discovery. In this study, six new (cephaloverines A-F, 1-6, resp.) and 16 known (11-26) cephalotaxine-type alkaloids, together with three new (oliverbiflavones A-C, 7-9, resp.) and 11 known (27-37) biflavonoids were isolated and characterized from the twigs and leaves of Cephalotaxus oliveri, an endangered plant endemic to China. Meanwhile, a preliminary investigation on the secondary metabolites from a selected fungal endophyte (i.e., Alternaria alternate Y-4-2) associated with the title plant led to the isolation of 21 structurally distinct polyketides including one new dimeric xanthone (10). The new structures (1-10) with the absolute configurations were determined by detailed spectroscopic analyses, electronic circular dichroism (ECD) or Na2MoO4-induced ECD, the modified Mosher's method, and some chemical transformations. Compounds 1-4 are the first representatives of naturally occurring N-oxides of cephalotaxine esters, while compounds 7-9 have a special structural feature of having a C-methylated biflavonoid skeleton. The Cephalotaxus alkaloids with ester side-chains at C-3 (1-6, 13-22, and 26) and four biflavonoids (27-29 and 34) were found to show pronounced cytotoxicities against a small panel of human cancer cell lines (A549, NCI-H460, HL60, NCI-H929, and RPMI-8226), with IC50 values mainly ranging from 0.003 to 9.34 µM. The most potent compound, deoxyharringtonine (16), generally exhibited IC50 values less than 10 nM. The structure-activity relationship (SAR) of the aforementioned Cephalotaxus alkaloids was briefly discussed.

Stewartiacids A-N, C-23 carboxylated triterpenoids from Chinese Stewartia and their inhibitory effects against ATP-citrate lyase and NF-κB.

Fourteen previously undescribed naturally occurring C-23 carboxylated triterpenoids, stewartiacids A-N (1-14), were isolated and characterized from the twigs and leaves of the ornamental and medicinal plant Stewartia sinensis (Chinese Stewartia), a 'vulnerable' species endemic to China. The new structures were elucidated on the basis of spectroscopic data, single crystal X-ray diffraction, and electronic circular dichroism (ECD) analyses. Stewartiacids A (1) and B (2) are isoursenol derivatives. Stewartiacid C (3) is a 12-oxo-γ-amyrin analogue. Both isoursenol and γ-amyrin derivatives are quite rare in nature. Stewartiacids D (4) and E (5) are 13,27-cycloursane-type compounds. Stewartiacids K (11) and L (12) are ursane-type triterpene and phenylpropanol adducts built through a 1,4-dioxane ring, which are also seldom reported in the literature. The rest are common C-23 carboxylated ursane-type (6-10) and oleanane-type (13, 14) pentacyclic triterpenoids. Stewartiacids G (7), K (11), and L (12) showed moderate inhibitory effects against ATP-citrate lyase (ACL), with IC50 values of 12.5, 2.8, and 10.6 µM, respectively. Stewartiacid K (11) also exhibited moderate inhibition (IC50: 16.8 µM) of NF-κB.

LC-MS guided isolation and dereplication of Lycopodium alkaloids from Lycopodium cernuum var. sikkimense of different geographical origins.

Lycopodium alkaloids (LAs) are the characteristic metabolites of club mosses. Chemical differences often exist in different specimens of a single plant species collected from different geographic origins. In this study, a preliminary LC-MS detection and dereplication analyses of alkaloidal constituents of Lycopodium cernuum var. sikkimense (Müll. Hal.) C.B. Clarke (LCVS2) collected from Fujian province led to the isolation and characterization of three undescribed LAs, lycocernuskines A-C, and six known cernuane-type LAs. The known compounds were previously isolated from the same plant species (LCVS1) collected from Chongqing, and so their dereplication in LCVS2 was accomplished based on their retention times (tR) and the quasi-molecular ion peaks in the LC-MS fingerprint. Chemical structures were identified by spectroscopic methods, single-crystal X-ray diffraction analysis, and electronic circular dichroism calculations. Lycocernuskines A and B are the first two examples of C-12 hydroxylated phlegmarane-type LAs bearing a nitrone residue at the quinoline ring. The isolates were evaluated for their anti-AChE and neuroprotective effects.

Characterization of 31 microsatellite markers for Sinocalycanthus chinensis (Calycanthaceae), an endemic endangered species.

PREMISE OF THE STUDY: Thirty-one microsatellite markers were developed for Sinocalycanthus chinensis (Calycanthaceae), an endemic endangered species in China. METHODS AND RESULTS: Twenty-one polymorphic and 10 monomorphic microsatellite markers of S. chinensis were developed using methods of biotin-streptavidin capture and capillary electrophoresis. The number of alleles per locus was one to 20 with an average of 4.677 in 90 individuals taken from two populations in Zhejiang Province and one population in Anhui Province in China. Mean observed and expected heterozygosity across all three populations were 0.403 ± 0.061 (0.033-1.000 per locus) and 0.510 ± 0.043 (0.032-0.797 per locus), respectively. Of these 31 loci, 29 were successfully amplified in Calycanthus floridus. CONCLUSIONS: These microsatellite markers will be useful for studies of population genetic diversity and phylogeny of S. chinensis and C. floridus.

Short-term parasite-infection alters already the biomass, activity and functional diversity of soil microbial communities.

Native parasitic plants may be used to infect and control invasive plants. We established microcosms with invasive Mikania micrantha and native Coix lacryma-jobi growing in mixture on native soils, with M. micrantha being infected by parasitic Cuscuta campestris at four intensity levels for seven weeks to estimate the top-down effects of plant parasitism on the biomass and functional diversity of soil microbial communities. Parasitism significantly decreased root biomass and altered soil microbial communities. Soil microbial biomass decreased, but soil respiration increased at the two higher infection levels, indicating a strong stimulation of soil microbial metabolic activity (+180%). Moreover, a Biolog assay showed that the infection resulted in a significant change in the functional diversity indices of soil microbial communities. Pearson correlation analysis indicated that microbial biomass declined significantly with decreasing root biomass, particularly of the invasive M. micrantha. Also, the functional diversity indices of soil microbial communities were positively correlated with soil microbial biomass. Therefore, the negative effects on the biomass, activity and functional diversity of soil microbial community by the seven week long plant parasitism was very likely caused by decreased root biomass and root exudation of the invasive M. micrantha.

[Response of photosynthesis traits of dominant plant species to different light regimes in the secondary forest in the area of Qiandao Lake, Zhejiang, China].

To understand the mechanisms driving community succession in the secondary forest surrounding Qiandao Lake, Zhejiang, China, we investigated seasonal dynamics of the diurnal variations of net photosynthetic rates, their responses to both light and CO2, and chlorophyll fluorescence parameters of four dominant plant species, i. e., Pinus massoniana, Castanopsis sclerophylla, Lithocarpus glaber and Cyclobalanopsis glauca in three natural light habitats, i. e., gap, edge and understory. In the three different light regimes, the daily mean values of the net photosynthetic rate (Pn) of P. massoniana and C. sclerophylla were significantly higher in summer than in the other seasons, while Pn of L. glaber and C. glauca was significantly higher in autumn than in the other seasons. In the forest gap and edge habitats, the annual mean values of the maximum net photosynthetic rate (Amax), the light saturation point (LSP), light compensation point (LCP) and dark respiration rate (Rd) of P. massoniana were the highest, followed by C. sclerophylla, and those of L. glaber and C. glauca were the lowest. In the understory habitat, the annual mean values of Amax and the apparent quantum yield (AQY) of C. glauca were the highest, followed by L. glaber and C. sclerophylla, and those of P. massoniana were the lowest. The annual mean values of the maximum rate of carboxylation (Vc max), maximum rate of electron transport (Jmax) and triose phosphate use rate (TPU) of P. massoniana were significantly higher than those of the other three plant species in the three different light regimes. During the four seasons, the photochemical maximum efficiency of PSII (Fv/Fm) of P. massoniana and C. sclerophylla in the forest gap habitat was significantly higher, while those of L. glaber and C. glauca in the understory habitat were significantly higher than in the other light regimes. The maximum values of Fv/Fm of P. massoniana and C. sclerophylla were the highest in summer, and those of L. glaber and C. glauca were the highest in autumn. It suggested that P. massoniana and C. sclerophylla were more suitable for habitats with high light intensities such as forest gaps, and L. glaber and C. glauca were more suitable for habitats with low light intensities such as the understory. During ecological succession, P. massoniana and C. sclerophylla would withdraw from the community with the increasing canopy density, and L. glaber and C. glauca would be the dominant species in the climax community.

A donor-acceptor-donor conjugated molecule: twist intramolecular charge transfer and piezochromic luminescent properties.

A donor-acceptor-donor molecule, , showed typical twist intramolecular charge transfer at the excited state and piezochromic property. XRD, DSC and computational researches revealed that the collapse of the crystalline structure upon applying pressure caused the piezochromic phenomenon, while the fluorescence was recovered by heating and solvent fuming.

T-shaped donor-acceptor molecules for low-loss red-emission optical waveguide.

A series of T-shaped polycyclic molecules with high fluorescence were developed as optical waveguide materials. Their emissions covered almost the whole visible range from 450 to 800 nm. Compound 3-1 showed an optical loss coefficient about 0.29 dB/µm in red-emission waveguide. Our investigations demonstrated that these molecules held great potential for organic optical waveguide due to the high fluorescence quantum efficiency and large Stokes' shift.

[Effects of nitrogen deposition on leaf physiological and ecological characteristics of Lindera aggregata seedlings].

From June 2010 to July 2011, a pot experiment was conducted to explore the effects of nitrogen deposition on the leaf physiological and ecological characteristics of Lindera aggregate seedlings. Three levels of NH4NO3, i. e., low-N (2 g x m(-2) x a(-1)), medium-N (8 g x m(-2) x a(-1)), and high-N (32 g x m(-2) x a(-1)) , were added to simulate nitrogen deposition, and the seedling leaf photosynthesis, relative chlorophyll content, chlorophyll fluorescence parameters, membrane lipid peroxidation, and antioxidant enzyme activities were determined. After one-year treatment, the daily mean values of the net photosynthetic rate (P)n)) and the maximum net photosynthetic rate (P(n max)) at low, medium and high levels of NH4 NO3 addition were 47.0%, 117.8% and 41.2%, and 82.6%, 191.3% and 152.2% higher than those of the control (no NH4 NO3 addition), respectively, with the highest values at medium level of NH4NO3 addition. The intercellular CO2 concentration, daily mean stomatal conductance, light saturation point, and apparent quantum yield in the three treatments of NH4NO3 addition were all higher than those of the control, and the dark respiration rate was the highest in treatment high-N. The relative chlorophyll content was the highest in treatment medium-N, followed by in treatment high-N, and had no significant difference between treatment low-N and the control. The chlorophyll fluorescence parameters varied with the levels of NH4NO3 addition. The PS II primary chemical efficiency (F(v)/F(m)) and PS II potential activity (F(v)/F(o)) were the lowest in treatment high-N, the superoxide dismutase activity was higher in nitrogen addition treatments than in the control, and the peroxidase activity, malonydialdehyde content, and membrane permeability were the highest in treatment high-N. All the results suggested that nitrogen deposition enhanced the photosynthetic ability of L. aggregata seedlings, with the most obvious effects in treatment medium-N, and altered the other physiological traits of the seedlings to different degrees.

[Contents of secondary metabolites and anti-bacterial activity of compound Caulis Sargentodoxae decoction].

OBJECTIVE: To compare the contents of secondary metabolites and the anti-bacterial activity of seven different compound Caulis Sargentodoxae decoctions. METHODS: Kirby-Bauer disk agar diffusion method was used for measuring anti-bacterial activity. The contents of secondary metabolites were determined by spectrometry. The correlation and path analysis were used to identify the goal compound. RESULT: The secondary metabolites contents and anti-bacterial activity of seven different compound Caulis Sargentodoxae decoctions varied significantly. The total contents of six secondary metabolites of Shushao Caulis Sargentodoxae decoction was the highest, while that of Caihu Caulis Sargentodoxae decoction was the second highest and that of Yiyi Caulis Sargentodoxae decoction was the lowest. The anti-bacterial activity of Shushao Caulis Sargentodoxae decoction was the highest and that of Cangbai Caulis Sargentodoxae decoction was the lowest. The correlation and path analysis showed that the total tannin and total chlorogenic acid might be the major factors related to the anti-bacterial activity of compound Caulis Sargentodoxae decoctions. CONCLUSION: The total contents of six secondary metabolites and the anti-bacterial activity of Shushao Caulis Sargentodoxae decoction are the highest among seven different decoctions and there is a significant correlation of the anti-bacterial activity with the contents of total tannin and total chlorogenic acid.

[Effects of water stress and temperature on gas exchange and chlorophyll fluorescence of Sinocalycanthus chinensis leaves].

Sinocalycanthus chinensis is an endangered species in Sinocalycanthus, and only distributed in Zhejiang Province of China. This paper studied the photosynthetic responses of 2-year-old pot-cultured S. chinensis to different levels of water stress and temperature. The results indicated that under mild and moderate water stress, the net photosynthetic rate (Pn) of S. chinensis leaves was decreased to 92.3% and 74.3% of the control, respectively, which was mainly attributed to stomatal limitation; and under severe water stress, the Pn was decreased to 44.4% of the control, which might be mainly linked to non-stomatal limitation. The appropriate temperature for S. chinensis photosynthesis was from 20 degrees C to 28 degrees C. At 39 degrees C, the Pn, water use efficiency (WUE), and maximal photochemistry efficiency (Fv/Fm) were decreased significantly, while the dark respiration rate (Rd) and transpiration rate (Tr) were enhanced significantly. With increasing water stress and temperature, some photosynthetic parameters including light saturation point (LSP), apparent quantum yield (AQY) and maximal CO2 assimilation rate (Pmax) decreased to certain extents, while light compensation point (LCP) increased, suggesting that both severe water stress and higher temperature were the important environmental factors affecting the survival of S. chinensis.