Synthesis and biological activities of three-molecule conjugates with para-aminosalicylic acid as parent nucleus / 药学学报

Based on the idea of multi-target drug design, taking p-aminosalicylic acid (PAS) as the parent nucleus, the unreported target molecules TM1 and TM2 were designed with PAS, isonicotinic acid and fluoroquinolone as three structural units conjugated by different linkers. Sixteen target molecules were synthesized by multi-step reaction, and their activities against Mycobacterium tuberculosis and human pathogenic bacteria were evaluated. The results showed that the anti-tuberculosis activity of TM2a was stronger than those of the assayed fluoroquinolones, while TM1a was comparable to that of clinafloxacin, the most active compound of the positive control fluoroquinolones; TM1a showed the strongest inhibitory activity to all almost tested strains, TM1b and TM2a showed very strong inhibitory activity to most strains, and TM1h/2h had strong inhibitory activity to some strains; The inhibitory activities of TM1a/1h on Staphylococcus aureus ATCC14125 are much stronger than those of fluoroquinolones, which eminently deserves further study. The hemolysis test results showed that the highly active molecules TM1a and TM2a exhibited relative safety below the concentrations of 8 and 32 μg·mL-1, respectively. In this study, a new hybrid molecule of three molecular pharmacophores with PAS as the parent nucleus was synthesized for the first time, and some of which have highly strong antibacterial activity, which provides a new idea for the research and development of antibiotics.

Synthesis and antibacterial activity of synephrine sulfonamide derivatives containing tetrazole and sulfuryl groups / 药学学报

Synephrine is a natural small-molecule alkaloid found in Aurantii fructus immaturus with versatile biological activities, but its derivatives have been rarely studied so far. Based on the multi-target drug design strategy, the phenolic hydroxyl and secondary amino group of synephrine were modified structurally by the molecular splicing method in this study and thus five intermediates and fifteen target molecules were designed and synthesized. These compounds were evaluated with certain human pathogenic bacteria and fungi, and found that the inhibitory activities of IM4 and IM5 against E.coli are comparable to those of eight fluoroquinolones; TM1n showed stronger inhibitory activity against drug-resistant C. trobicans and drug-resistant C. albicans than the positive control drug fluconazole. TM1d and TM1f against C. albicans ATCC90023, TM1o and TM1f against drug-resistant C. albicans, and TM1f against C. parapsilosis ATCC22019 are all comparable to fluconazole, all of which have the potential for in-depth research. In this study, synephrine derivatives with strong inhibitory activities against human pathogenic fungi were discovered for the first time, which provided a new idea for the further study of synephrine.

Synthesis and antibacterial activity of C-7 haloacyl cephalosporins / 药学学报

Cephalosporins are widely used in the treatment of infectious diseases. The structural differences in cephalosporin drugs mainly lie in the C-7 amino side chain and the C-3 substituent. In this study, twenty-five haloacylated cephalosporins of five series were designed by using a strategy of introducing simple substituents at the C-7 amino group in four cephalosporin parent nucleus with different C-3 substituents and efficiently synthesized under optimized conditions. Their activities against human pathogenic bacteria, Pichia pastoris, citrus canker and citrus pathogenic fungi were evaluated. The results showed that most of the molecules had activity against human pathogenic bacteria, of which seven compounds including TM1f had stronger or equivalent inhibitory activities against eight human pathogens than the marketed drugs cefalotin, cefoxitin sodium and ceftizoxime sodium. The inhibitory activity of TM1s against Alternaria alternate Al.6 was stronger than that of cephalosporins and comparable to that of the positive control prochloraz. TM1f and TM1s are worthy of further study.

Antibacterial potential of a basic phospholipase A2(VRV-PL-VIIIa) from Daboia russelii pulchella (Russell's viper) venom

Background:Microbial/bacterial resistance against antibiotics poses a serious threat to public health. Furthermore, the side effects of these antibiotics have stimulated tremendous interest in developing new molecules from diverse organisms as therapeutic agents. This study evaluates the antibacterial potential of a basic protein, Vipera russellii venom phospholipase A2 fraction VIIIa (VRV-PL-VIIIa), from Daboia russelii pulchella venom against gram-positive and gram-negative bacteria.Methods:The antibacterial potential of VRV-PL-VIIIa in the presence and absence of an inhibitor (p-bromophenacyl bromide) was tested against gram-positive and gram-negative bacteria and the minimum inhibitory concentration was determined by microdilution tests.Results:VRV-PL-VIIIa demonstrated potent antibacterial activities against all the human pathogenic strains tested. It more effectively inhibited such gram-positive bacteria as Staphylococcus aureus and Bacillus subtilis, when compared to the gram-negative bacteria Escherichia coli, Vibrio cholerae, Klebsiella pneumoniae and Salmonella paratyphi. It inhibited bacterial growth at minimum inhibitory concentration values ranging from 11.1 to 19.2 μg/mL. The anti-bacterial potential of VRV-PL-VIIIa was comparable to the standards gentamycin, chlorophenicol and streptomycin. The PLA2's hemolytic and antibacterial activities were strongly correlated. Furthermore, even in the presence of p-bromophenacyl bromide, intense antibacterial activity was observed, suggesting a dissociation or partial overlapping of the bactericidal/antimicrobial domains.Conclusion:VRV-PL-VIIIa demonstrated potent antibacterial activities against all the human pathogenic strains tested. The study shows that despite a strong correlation between enzymatic and antimicrobial activities of VRV-PL-VIIIa, it may possess additional properties that mimic the bactericidal/membrane permeability-increasing protein. This study encourages further in-depth studies on the molecular mechanisms of antibacterial properties of VRV-PL-VIIIa, which would thereby facilitate development of this protein into a possible therapeutic lead molecule for treating bacterial infections.(AU)

Antibacterial potential of a basic phospholipase A (VRV-PL-VIIIa) from Daboia russelii pulchella (Russell's viper) venom

Background: Microbial/bacterial resistance against antibiotics poses a serious threat to public health. Furthermore, the side effects of these antibiotics have stimulated tremendous interest in developing new molecules from diverse organisms as therapeutic agents. This study evaluates the antibacterial potential of a basic protein, Vipera russellii venom phospholipase A2 fraction VIIIa (VRV-PL-VIIIa), from Daboia russelii pulchella venom against gram-positive and gram-negative bacteria. Methods: The antibacterial potential of VRV-PL-VIIIa in the presence and absence of an inhibitor (p-bromophenacyl bromide) was tested against gram-positive and gram-negative bacteria and the minimum inhibitory concentration was determined by microdilution tests. Results: VRV-PL-VIIIa demonstrated potent antibacterial activities against all the human pathogenic strains tested. It more effectively inhibited such gram-positive bacteria as Staphylococcus aureus and Bacillus subtilis, when compared to the gram-negative bacteria Escherichia coli, Vibrio cholerae, Klebsiella pneumoniae and Salmonella paratyphi. It inhibited bacterial growth at minimum inhibitory concentration values ranging from 11.1 to 19.2 μg/mL. The anti-bacterial potential of VRV-PL-VIIIa was comparable to the standards gentamycin, chlorophenicol and streptomycin. The PLA2's hemolytic and antibacterial activities were strongly correlated. Furthermore, even in the presence of p-bromophenacyl bromide, intense antibacterial activity was observed, suggesting a dissociation or partial overlapping of the bactericidal/antimicrobial domains. Conclusion: VRV-PL-VIIIa demonstrated potent antibacterial activities against all the human pathogenic strains tested. The study shows that despite a strong correlation between enzymatic and antimicrobial activities of VRV-PL-VIIIa, it may possess additional properties that mimic the bactericidal/membrane permeability-increasing protein. This study encourages further in-depth studies on the molecular mechanisms of antibacterial properties of VRV-PL-VIIIa, which would thereby facilitate development of this protein into a possible therapeutic lead molecule for treating bacterial infections.

Screening for antimicrobial activity of crude extracts of Skeletonema costatum.

Various organic and aqueous extracts of Skeletonema costatum were screened for their antibacterial activities. The extracts were tested against different species of human pathogenic bacteria by the agar-solid diffusion method. Water extract of Skeletonema costatum showed maximum antimicrobial activity of 19.0 mm against Klebsiella pneumoniae and a minimum activity of 9 mm against Proteus vulgaris. All the tested microorganisms were resistant to methanol, ethanol and propanol extracts except Escherichia coli and Staphylococcus aureus which exhibited a least inhibition zone of 6.0 and 7.0 mm respectively in propanol. Acetone extract of Skeletonema costatum also showed the highest biological activity of 19.0 mm against Klebsiella pneumoniae, moderate activity of 12.0 mm against Salmonella typhi, and 11.0 mm against Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. Sequential extract of Spirulina exhibited maximum antimicrobial activity. Inhibition zone of 23.2 mm was observed for Klebsiella pneumoniae and 14.0 mm for Proteus vulgaris.