Comparison of volatile profiles and bioactive components of sun-dried Pu-erh tea leaves from ancient tea plants on Bulang Mountain measured by GC-MS and HPLC

To explore the volatile profiles and the contents of ten bioactive components(polyphenols and caffeine) of sun-dried Pu-erh tea leaves from ancient tea plants on Bulang Mountain,17 samples of three tea varieties were analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry(HS-SPME-GC-MS) and high-performance liquid chromatography(HPLC).A total of 75 volatile components were tentatively identified.Laomaner(LME),Laobanzhang(LBZ),and other teas on Bulang Mountain(BL) contained 70,53,and 71 volatile compounds,respectively.Among the volatile compounds,alcohols(30.2%-45.8%),hydrocarbons(13.7%-17.5%),and ketones(12.4%-23.4%) were qualitatively the most dominant volatile compounds in the different tea varieties.The average content of polyphenol was highest in LME(102.1 mg/g),followed by BL(98.7 mg/g) and LBZ(88.0 mg/g),while caffeine showed the opposite trend,27.3 mg/g in LME,33.5 mg/g in BL,and 38.1 mg/g in LBZ.Principal component analysis applied to both the volatile compounds and ten bioactive components showed a poor separation of samples according to varieties,while partial least squares-discriminant analysis(PLS-DA) showed satisfactory discrimination.Thirty-four volatile components and five bioactive compounds were selected as major discriminators(variable importance in projection(VIP)>1) among the tea varieties.These results suggest that chromatographic data combined with multivariate analysis could provide a useful technique to characterize and distinguish the sun-dried Pu-erh tea leaves from ancient tea varieties on Bulang Mountain.

Cathepsin L plays a key role in SARS-CoV-2 infection in humans and humanized mice and is a promising target for new drug development

To discover new drugs to combat COVID-19,an understanding of the molecular basis of SARS-CoV-2 infection is urgently needed.Here,for the first time,we report the crucial role of cathepsin L(CTSL)in patients with COVID-19.The circulating level of CTSL was elevated after SARS-CoV-2 infection and was positively correlated with disease course and severity.Correspondingly,SARS-CoV-2 pseudovirus infection increased CTSL expression in human cells in vitro and human ACE2 transgenic mice in vivo,while CTSL overexpression,in turn,enhanced pseudovirus infection in human cells.CTSL functionally cleaved the SARS-CoV-2 spike protein and enhanced virus entry,as evidenced by CTSL overexpression and knockdown in vitro and application of CTSL inhibitor drugs in vivo.Furthermore,amantadine,a licensed anti-influenza drug,significantly inhibited CTSL activity after SARS-CoV-2 pseudovirus infection and prevented infection both in vitro and in vivo.Therefore,CTSL is a promising target for new anti-COVID-19 drug development.

Optomechanical properties of a degenera te nonperiodic cavity chain

The absorption of single-cav计y and double-cavity optomechanical systems and periodic optomechanical lattices has previously been investigated extensively. In this paper, we present the absorption of a nonperiodic cavity chain. where the absorption value on the resonance point shows switchable dips or peaks, according to whether the optomechanical interaction is at an odd or even-numbered position in the chain. Meanwhile, the value of absorption due to the optomechanical interaction varies with the number of the bare cavities. The calculated results may have some novel applications, such as detecting the position of the movable mirror in a long cavity chain, which would be useful in quantum information processing based on optomechanical systems.

Emerging relationship between RNA helicases and autophagy

RNA helicases,the largest family of proteins that participate in RNA metabolism,stabilize the intracellular environment through various processes,such as translation and pre-RNA splicing.These proteins are also involved in some diseases,such as cancers and viral diseases.Autophagy,a self-digestive and cytoprotective trafficking process in which superfluous organelles and cellular garbage are degraded to stabilize the internal environment or maintain basic cellular survival,is associated with human diseases.Interestingly,similar to autophagy,RNA helicases play important roles in maintaining cellular homeostasis and are related to many types of diseases.According to recent studies,RNA helicases are closely related to autophagy,participate in regulating autophagy,or serve as a bridge between autophagy and other cellular activities that widely regulate some pathophysiological processes or the development and progress!on of diseases.Here,we summarize the most recent studies to understand how RNA helicases function as regulatory proteins and determine their association with autophagy in various diseases.