超声波法提取大黄胰蛋白酶抑制剂

目的研究大黄中胰蛋白酶抑制剂活性成分的最佳提取条件。方法以提取液对胰蛋白酶的抑制率为指标,采用正交实验法对提取溶剂用量(A)、提取温度(B)、提取时间(C)、提取次数(D)4个因素进行优选研究,并以优选出的提取方案进行验证实验。结果因素B,D对提取效果有显著的影响,因素C影响不显著。结论大黄中胰蛋白酶抑制活性成分有效部位的最佳提取工艺为A3B1C3D2。

Resident Willingness to Pay for Ecotourism Resources and Associated Factors in Sanjiangyuan National Park,China

Willingness to Pay(WTP),Willingness to Work(WTW)and Willingness to Accept Compensation(WTA)are the three quantitative criteria for assessing local ecological asset values for the social aspects of ecosystem services and residents’willingness to contribute to and receive compensation for tourism ecology.The objectives of this study are to estimate the residents’willingness to pay,work and accept compensation for conservation at Sanjiangyuan National Park,and to analyze the relationship between residents’attitude towards tourism ecology and the ecological assets of the National Park based on a standard questionnaire survey.The dichotomous choice Contingent Valuation Method(CVM)was employed to determine the willingness.The survey conducted in 2018 collected WTP,WTW,WTA,socio-demFographical information,social trust and resident perceptions toward tourism impacts and relevant management strategies from 244 residents in two counties.Based on generalized linear modeling,income and education level are important for residents’WTP and WTA,but other social characteristics,such as gender and age,do not have significant effects.The social trust is found to be a significant factor on residents’willingness,despite the limitation on education level.Also,government funding is associated with residents’inclination to WTP,WTW and WTA,but the support levels differ among the two counties due to geographical and social heterogeneities.The estimated WTP,WTW and WTA for the Sanjiangyuan National Park in 2018 were 1.2448×10^(7) yuan,1.247×10^(6) hours and 2.3232×10^(7) yuan yr^(-1) based on the survey and published demographics.This study,for the first time,estimates the WTP,WTW and WTA for the Sanjiangyuan National Park and informs ecological conservation managers and policy makers.Ultimately,to maintain the long-term benefits arising from sustainable development,compensation should be specifically tailored and site-dependent,and development measures based on local resources should be adopted by governments to actively support eco-tourism activities.

Père David’s Deer(Elaphurus davidianus)in China:Population Dynamics and Challenges

The reintroduction of rare and endangered species is one of the most important approaches to conservation and ecosystem restoration,but it has still proven to be an adventurous undertaking and most reintroduction programmes fail,so successful demonstrations are needed.Père David’s deer(Elaphurus davidianus,Milu in Chinese)could be considered one of conservation’s great success stories,as this species’path on the road to extinction has been reversed by a combination of ex-situ conservation and successful re-introduction in China.The species had been consigned to an imperial hunting ground when the last Chinese herds were exterminated during the fall of the Qing Dynasty(1644-1912).Fortunately,a few of the last remaining individuals were sent to European zoos.From these animals,a herd was bred on the 14;Duke of Bedford’s estate,Woburn Abbey,and between 1985and 1987,and 38 Milu were donated back to China for re-introduction in Beijing Milu Park(BMP),the former imperial hunting ground.An additional 39 deer were released at Dafeng National Nature Reserve(DFNNR),Jiangsu Province in 1986.In both of these safe and protected locations,the Milu thrived allowing for over 700 Milu to be sent to a further 82 sites throughout the species’original Chinese range over the last 36 years.As a result,the Milu population totaled 9136 by 2021,with 2855 individuals now living back in the wild;while another 5681 individuals inhabit the DFNNR,and 186 reside in BMP.Wild Milu,however,still face significant conservation challenges.The population lacks genetic diversity,leading to severe inbreeding depression and carrying multiple risks,such as high miscarriage rates,a reduced lifespan,and susceptibility to disease.Environmental constraints such as pollution and habitat fragmentation further result in small,fragmented wild populations.Moreover,the species currently lacks a national level conservation master plan,the associated coordinated monitoring platforms,and breeding plans for China’s captive populations.Finally,there is now a lack of international cooperation in the conservation of this species.We therefore call for both a national-level conservation master plan in China and international cooperation to develop a shared database and germplasm databank covering Milu across all countries with ex-situ populations,as crucial steps for securing the long-term conservation of Milu and preventing it from ever becoming“extinct in the wild”again.

Biocatalytic bis-C-alkylation of phenolics using one-pot cascades with promiscuous C-glycosyltransferase and prenyltransferase

C-glycosylation and C-prenylation are two important C-C-bond forming reactions for preparation,diversification and structural modification of natural/unnatural products with pharmacological activities.Here,we described unprecedented enzymatic cascades to C-glycosylate/prenylate different acyl resorcinol derivatives in stepwise,one-pot reactions by combining two promiscuous enzymes,MiCGT,a C-glycosyltransferase,and AtaPT,a prenyltransferase.Five novel bis-C-alkylated products were obtained and structurally identified by MS and NMR spectroscopic data as well as comparison with the literature.This study provided a potential synthetic strategy for synthesizing structurally novel and diverse compounds bearing both C-glycosyl and C-prenyl moieties by a two-step,enzymatic bis-C-alkylation.