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Microwaves in Lactam Chemistry
Published in Banik Bimal Krishna, Bandyopadhyay Debasish, Advances in Microwave Chemistry, 2018
Dr. Debasish Bandyopadhyay, Bimal Krishna Banik
1,3-Dipolar cycloaddition constitutes a proficient approach for the synthesis of five-membered heterocycles. An efficient solvent-free synthesis of anti-tubercular diversely substituted spiro-γ-lactams was reported under microwave irradiation [97]. It is well known that tuberculosis (TB) is contagious and airborne. After the human immunodeficiency virus (HIV), it is the 2nd leading cause of death from a single infectious agent worldwide. In 2014 alone, 9.6 million people fell ill with TB and 1.5 million died. More than 95% of TB deaths occur in low- and middle-income countries. With growing bacterial resistance against even new generation antibiotics, multi-drug resistant M. tuberculosis (MDR-TB) is becoming a major health issue [96]. The spiro-γ-lactams that synthesized in the reaction [97] were screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB), MDR-TB, and Mycobacterium smegmatis (MC2) using an agar dilution method. One of these compounds was found to be the most active with a minimum inhibitory concentration (MIC) of 1.76 and 0.88 mM against MTB and MDR-TB respectively.
Dendrimers: Emerging Anti-Infective Nanomedicines
Published in Bhupinder Singh, Rodney J. Y. Ho, Jagat R. Kanwar, NanoBioMaterials, 2018
Scientists have also designed some other types of dendrimers using different core or branching units like tricarboxylato dendrimers, and Jeffamine®-based dendrimers. Tulu et al. (2009) designed water-soluble dendrimers using poly(oxypropylene) triamine (Jeffamine®) as the core and methacrylate as the branching units (Figure 6.5). The antimicrobial activity of these dendrimers was determined using disk diffusion method which was compared with references including vancomycin, tetracycline, penicillin-G, ampicillin, ofloxacin and cefotaxime. MIC was determined using dilution method and compared with gentamycin and nystatin as antibacterial and antifungal reference antibiotics, respectively. The microorganisms used for this study were five gram-positive bacteria strains (S. aureus, Bacillus cereus, Mycobacterium smegmatis, Listeria monocytogenes, Micrococcus luteus), five gram-negative bacteria (E. coli, K. pneumoniae, P. aeruginosa, Proteus vulgaris, Enterobacter aerogenes) and five yeast cultures (including C. albicans, Kluyveromyces fragilis, Rhodotorula rubra, Debaryomyces hansenii and Hanseniaspora guilliermondii). The antifungal activity of dendrimers was referenced with the antifungal antibiotics including clotrimazole, ketaconazole, and nystatin. The results of these studies suggested that the developed dendrimeric constructs showed broad spectrum activity i.e. found active against gram-positive, gram-negative and yeast cultures.
Catabolite Regulation of the Main Metabolism
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
On the other hand, this mechanism may not be seen in Gram-positive bacteria such as B. subtilis (Diesterhaft and Freese 1972), B. stearothermophilus (Sakai et al. 1986, Walker et al. 1992, Lowell et al. 1998), C. glutamicum (Jetten et al. 1994), pathogens such as Mycobacterium smegmatis (Kapoor and Venkitasubramanian 1983), and Z. moblis (Pawluk et al. 1986). In the case of B. subtilis, the FBP pool size correlates with the glycolytic flux (Chubukov et al. 2013), where FBP may modulate the glycolysis not by Pyk, but by the transcriptional regulation via such transcription factors as CcpA and CggR (Deutscher et al. 1995, Doan et al. 2003). The Pyk of B. subtilis is activated by adenosine monophosphate (AMP) and ribose 5-phosphate (R5P) (Dieterhaft and Frees 1972), while that of Z. mobilis lacks any allosteric regulation (Pawluk et al. 1986). The reason for the latter may be that the Entner-Doudoroff (ED) pathway is dominant instead of EMP pathway in Z. mobilis. The Pyk activity of photosynthestic organism such as cyanobacteria is also activated by R5P and AMP as well as glycerol 3-phosphate (GL3P), while inhibited by FBP, inorganic phosphate (P,), and ATP, etc. (Knowles et al. 2001).
Production of highly soluble native human paraoxonase 2 with potential anti-biofilm property
Published in Preparative Biochemistry & Biotechnology, 2023
Fauzia Parween, Priyamedha Yadav, Kalyani Singh, Rinkoo Devi Gupta
HuPON2 has been characterized as a highly promiscuous enzyme in vitro and non-enzymatic functions as an antioxidant in vivo.[11,12] The role of HuPON2 as an anti-biofilm agent in gram-negative bacteria is known owing to its lactonase activity for the hydrolysis of Acyl-HSL.[6] However, the primary QS molecules in Mycobacteria is poorly explored.[13,14] Hence in this study, we aim to further extend the anti-biofilm property of HuPON2 due to its promiscuous nature. Herein, we studied the biofilm inhibition in Mycobacterium smegmatis (M. smeg.), which is a model organism to study Mycobacteria in general, due to its nonpathogenic nature and a short generation time.[15]
In vitro antibacterial activities of selected TB drugs in the presence of clay minerals against multidrug-resistant strain of Mycobacterium smegmatis
Published in Cogent Engineering, 2020
Patrick K. Arthur, Vincent Amarh, Ethel J. S. Blessie, Rebecca Yeboah, Benjamin W. Kankpeyeng, Samuel N. Nkumbaan, Elvis K Tiburu
We have previously reported two MDR strains of Mycobacterium smegmatis that could be useful model organisms for screening novel drugs against drug-resistant strains of Mycobacterium tuberculosis (Arthur et al., 2019). The drug-susceptible Mycobacterium smegmatis mc2 155 and a corresponding MDR strain were used in this study to obtain insight on the effect of healing clay on the antimycobacterial activity of selected antibiotics. One of the notable observations was the ability of healing clay to resuscitate the in vitro antimycobacterial activity of pyrazinamide against the drug-susceptible strain. Even though pyrazinamide exhibits poor antimycobacterial activity in vitro, it has been shown to exhibit enhanced in vitro activity against Mycobacterium tuberculosis following addition of iron to the growth media (Somoskovi et al., 2004). Iron-mediated toxicity in bacterial pathogens is achieved via formation of free radicals that destroy essential cellular components of these pathogens (Schoonen et al., 2006). Aluminum in clay materials also exhibits antibacterial activity by compromising the integrity of bacterial membranes (Londono et al., 2017). Thus, the toxic effects of iron and aluminum in the healing clay might have synergized with pyrazinamide to cause the detectable antimicrobial activity against the Mycobacterium smegmatis mc2 155 strain. Despite the increased in vitro activity of pyrazinamide against Mycobacterium smegmatis mc2 155 in the presence of healing clay, the MDR strain was unaffected by the combination of pyrazinamide and healing clay. We demonstrated that this phenomenon might be attributed to the high metabolic activity of the MDR strain relative to the drug-susceptible Mycobacterium smegmatis mc2 155 strain and is consistent with a study which showed that pyrazinamide effectively eliminates tubercular bacilli with low metabolic activity (Mitchison, 1985). Subsequent studies would ascertain whether the healing clay synergizes the in vivo activity of pyrazinamide against Mycobacterium tuberculosis.