Platyphylloside: Metabolism and digestibility reductionin vitro

The metabolism of platyphylloside [(5S)-5-hydroxy-1,7-bis-(4-hydroxyphenyl)-3-heptanone-5-O--d-glucopyranosidel]—known to reduce digestibility—was studiedin vitro in sheep rumen liquor. Platyphylloside is hydrolyzed to 5-hydroxy-3-platyphyllone [(5S)-5-hydroxy-1,7-bis-(4-hydroxyphenyl)-3-heptanone], which is reduced to centrolobol [1,7-bis-(4-hydroxyphenyl)-3-heptanol], via 3-platyphyllone [7-bis-(4-hydroxyphenyl)-3-heptanone]. The digestibility-reducing effect was shown to be correlated with the concentration of centrolobol.     

艳山姜一内生菌SRT2次级代谢产物的初步研究

对一株艳山姜内生菌的发酵菌丝体提取物的化学成分进行研究。实验方法:为柱色谱分离,现代物理和光谱分析鉴定化合物的结构。结果:分离鉴定了4个化合物,分别为三十二烷酸(dotricontanoicacid),十六烷酸(Hexadeeanoicacid),蔗椒(sltl～rosc)胡萝卜苷(Daucosten01)。结论:除十六烷酸外,所有化合物均首次从该菌丝体中分离得到。     

Molecular and Physiological Responses of Citrus sinensis Leaves to Long-Term Low pH Revealed by RNA-Seq Integrated with Targeted Metabolomics

Low pH-induced alterations in gene expression profiles and organic acids (OA) and free amino acid (FAA) abundances were investigated in sweet orange [Citrus sinensis (L.) Osbeck cv. Xuegan] leaves. We identified 503 downregulated and 349 upregulated genes in low pH-treated leaves. Further analysis indicated that low pH impaired light reaction and carbon fixation in photosynthetic organisms, thereby lowering photosynthesis in leaves. Low pH reduced carbon and carbohydrate metabolisms, OA biosynthesis and ATP production in leaves. Low pH downregulated the biosynthesis of nitrogen compounds, proteins, and FAAs in leaves, which might be conducive to maintaining energy homeostasis during ATP deprivation. Low pH-treated leaves displayed some adaptive responses to phosphate starvation, including phosphate recycling, lipid remodeling, and phosphate transport, thus enhancing leaf acid-tolerance. Low pH upregulated the expression of some reactive oxygen species (ROS) and aldehyde detoxifying enzyme (peroxidase and superoxidase) genes and the concentrations of some antioxidants (L-tryptophan, L-proline, nicotinic acid, pantothenic acid, and pyroglutamic acid), but it impaired the pentose phosphate pathway and V_E and secondary metabolite biosynthesis and downregulated the expression of some ROS and aldehyde detoxifying enzyme (ascorbate peroxidase, aldo-keto reductase, and 2-alkenal reductase) genes and the concentrations of some antioxidants (pyridoxine and γ-aminobutyric acid), thus disturbing the balance between production and detoxification of ROS and aldehydes and causing oxidative damage to leaves.     

吴茱萸致肝毒性部位在大鼠体内的多样性分析

利用超高效液相色谱-四极杆-飞行时间质谱（UPLC-Q-TOF MS）技术对吴茱萸肝毒性部位给药后大鼠胆汁、尿液、粪便中的原型成分及其代谢产物进行分析,共检测到23个原型成分和10个代谢产物。采用正离子MSE扫描模式采集质量范围m/z 50~1 200的数据,通过与UNIFI软件数据库比对,以及各成分的保留时间、精确的一级和二级质谱信息,结合化合物的裂解规律和已有文献报道,共鉴定出29个化学成分,包括23个原型成分和6个代谢产物。进一步由代谢产物逆向追踪原型成分,推测出可能的代谢途径。这些成分在体内的主要代谢途径有葡萄糖醛酸结合、硫酸酯化、甲酰基化、羟基化、去甲基化等。基本明确了吴茱萸肝毒性部位在大鼠胆汁、尿液和粪便中的主要存在形式及代谢途径,为揭示吴茱萸肝毒性物质基础提供了参考依据。     

膜生物反应器 CCCF 过程中酵母细胞生长特性研究

渗透汽化膜生物反应器CCCF过程乙醇发酵中酵母细胞的生长表现出五个不同的阶段,即：快速生长期、乙醇抑制期、二次生长期、平衡期和衰亡期。采用摇瓶实验对发酵副产物（主要为有机酸和甘油）的抑制行为进行检测,结果表明随着副产物浓度的增加,抑制作用越来越强,细胞生长表现出较长的迟滞期和较低的细胞浓度。当副产物浓度达到膜生物反应器中发酵后期的浓度时,细胞的比生长速率和得率仅分别为0．061和0．024。     

ORP调控对葡萄糖和果糖混合底物丁醇发酵的影响

采用氧化还原电位(oxidoreduction potential,ORP)调控以模拟菊芋块茎酸解液(葡萄糖和果糖混合糖)为底物进行的丙酮丁醇发酵过程,能够有效控制"酸崩溃"现象的发生。已通过实验确定最佳调控策略为控制整个发酵过程的ORP不低于-460mV。本研究在最佳调控策略下,发酵终点丁醇浓度从3.39g/L提高到11.65g/L,残糖浓度从30.82g/L降低到1.38g/L。对比ORP调控组和对照组发现,ORP调控能够改变发酵过程中细胞内还原力水平,能量状态和代谢流向,因此ORP调控能有效防止"酸崩溃"现象发生,调节菌体生长和溶剂产量。ORP调控策略应用于以葡萄糖和果糖混合糖为底物的丁醇发酵具有操作可行性,是一种简便而有效的工艺优化手段。     

Identification of In Vitro Metabolites of Synthetic Phenolic Antioxidants BHT,BHA, and TBHQ by LC-HRMS/MS

Butylated hydroxytoluene (BHT) and its analogs, butylated hydroxyanisole (BHA) and tert-butyl-hydroquinone (TBHQ), are widely used synthetic preservatives to inhibit lipid oxidation in the food, cosmetic and pharmaceutical industries. Despite their widespread use, little is known about their human exposure and related biotransformation products. The metabolism of these compounds was investigated using in vitro incubations with human and rat liver fractions. Liquid chromatography coupled to high-resolution tandem mass spectrometry was employed to detect and characterize stable and reactive species formed via oxidative metabolism, as well as phase II conjugates. Several oxidative metabolites have been detected, as well as glutathione, glucuronide, and sulfate conjugates, many of which were not previously reported. A combination of accurate mass measurements, MS/MS fragmentation behavior, and isotope-labeling studies were used to elucidate metabolite structures.