Octapeptin has strong antibacterial activity against Gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii, while it also has activity against some Gram-positive bacteria. This study used natural octapeptin A3 and B3 as lead compounds for structural modification. Twenty-one peptide derivatives (including A3 and B3) containing eight amino acid residues were prepared by solid-phase synthesis, and evaluated for antibacterial activity and renal cytotoxicity. Among them, three compounds 6, 7 and 17 exhibited broad-spectrum antibacterial activity and significantly enhanced the activity for Gram-positive bacteria while maintaining the activity of Gram-negative bacteria. Several compounds improved the activity for Pseudomonas aeruginosa. Compound 7 was active against all test strains and had relatively low renal cytotoxicity. The results provide a basis for the further development of novel polypeptide antibiotics.

Inosine 5′-monophosphate dehydrogenase (IMPDH) is a key enzyme catalyzing the rate-limiting step of de novo nucleotide synthesis in vivo. In recent years, it has become a therapeutic target for anti-virus, anti-bacterial, anti-cancer, anti-parasitic and other diseases. IMPDH inhibitors have been shown to inhibit viral prolife-ration in host cells by depleting guanosine 5′-monophosphate (GMP), the raw material required for viral replication in host cells, with broad-spectrum antiviral properties. In order to find novel anti-coronavirus drugs, this study screened 22 potential IMPDH inhibitors from 70 000 natural small molecule libraries based on IMPDH protein structure using molecular docking and ROC calculation for virtual screening. With ribavirin as the positive control drug, Huh7 cell and H460 cell models were used to verify the anti-coronavirus HCoV-229E and HCoV-OC43 activities of 22 selected target compounds. Among them, compounds 11, 12, 15 and 16 showed inhibitory activity against coronavirus HCoV-229E. The compounds 4, 12, 13 and 15 showed inhibitory activities against coronavirus HCoV-OC43. 12 and 15 showed significant inhibitory activity against both two coronaviruses, and their efficacy was similar to ribavirin at the same dose, which can be further studied as a lead compound for IMPDH inhibitors.

Objective To investigate the effects of Zhoufei Pingchuan Capsules on the balance of peripheral blood helper T lymphocyte 17 cell/regulatory T lymphocyte cell(Th17/Treg)and related inflammatory factors in peripheral blood of patients with stable chronic obstructive pulmonary disease(COPD)with lung-kidney qi deficiency syndrome.Methods Totally 40 COPD patients were randomly divided into the study group and the control group,with 20 cases in each group.Another 20 cases were in the healthy group.The control group was given tiotropium bromide powder inhalation,18 μg/time,1 time/d,inhalation;on the basis of the control group,the study group was given Zhoufei Pingchuan Capsules,3 pills/time,3 times/d,orally.All patients were treated for 8 weeks.The healthy group was not given any intervention.Forced expiratory volume in one second(FEV1),FEV1/forced vital capacity(FEV1/FVC),maximum mid-expiratory flow(MMEF),carbon monoxide diffusing capacity/alveolar ventilation(DLCO/VA),arterial partial pressure of oxygen(PaO2),arterial partial pressure of carbon dioxide(PaCO2),COPD assessment test(CAT)score,Th17/Treg ratio,cytokines interleukin(IL)-17,IL-22,IL-10,and transforming growth factor-β1(TGF-β1)were compared before and after treatment.Results Compared with before treatment,the lung function indexes(FEV1,FEV1/FVC,MMEF,DLCO/VA),blood gas indexes(PaO2,PaCO2)and CAT score in the study group after treatment were significantly improved(P<0.05).After treatment,the mean values of MMEF,DLCO/VA,PaCO2 and CAT score in the study group were better than those in the control group(P<0.05).Compared with before treatment,the levels of Th17,IL-17 and IL-22 in the study group were significantly lower,and the levels of Treg,IL-10 and TGF-β1 were significantly higher(P<0.05).After treatment,there were significant differences in Th17,Treg,IL-17,IL-22,IL-10 and TGF-β1 among the three groups(P<0.01).Further pairwise comparison showed that Th17 ranked in the order of high and low was control group>study group>healthy group,Treg in the order of high and low was healthy group>study group>control group,the levels of IL-17 and IL-22 in the order of high and low were control group>study group>healthy group,and the levels of IL-10 and TGF-β1 in the order of high and low were healthy group>study group>control group,with statistical significance(P<0.05).Conclusion Zhoufei Pingchuan Capsules can improve the lung function,arterial blood gas and symptom score of patients with lung-kidney qi deficiency syndrome in stable stage of COPD.Its mechanism may be related to regulating the balance of Th17/Treg,down-regulating the levels of Th17,IL-17 and IL-22,and up-regulating the levels of Treg,IL-10 and TGF-β1,in order to reduce airway inflammation and regulate immune homeostasis.

Monoterpenes are widely used in cosmetics, food, medicine, agriculture and other fields. With the development of synthetic biology, it is considered as a potential way to create microbial cell factories to produce monoterpenes. Engineering Saccharomyces cerevisiae to produce monoterpenes has been a research hotspot in synthetic biology. In S. cerevisiae, the production of geranyl pyrophosphate(GPP) and farnesyl pyrophosphate(FPP) is catalyzed by a bifunctional enzyme farnesyl pyrophosphate synthetase(encoded by ERG20 gene) which is inclined to synthesize FPP essential for yeast growth. Therefore, reasonable control of FPP synthesis is the basis for efficient monoterpene synthesis in yeast cell factories. In order to achieve dynamic control from GPP to FPP biosynthesis in S. cerevisiae, we obtained a novel chassis strain HP001-pERG1-ERG20 by replacing the ERG20 promoter of the chassis strain HP001 with the promoter of cyclosqualene cyclase(ERG1) gene. Further, we reconstructed the metabolic pathway by using GPP and neryl diphosphate(NPP), cis-GPP as substrates in HP001-pERG1-ERG20. The yield of GPP-derived linalool increased by 42.5% to 7.6 mg·L~(-1), and that of NPP-derived nerol increased by 1 436.4% to 8.3 mg·L~(-1). This study provides a basis for the production of monoterpenes by microbial fermentation.
Fermentation ; Geranyltranstransferase/genetics* ; Monoterpenes/metabolism* ; Saccharomyces cerevisiae/metabolism* ; Saccharomyces cerevisiae Proteins/metabolism*