Expelling antibiotic molecules out of the cell wall through multiple efflux pumps is one of the potential mechanisms of developing resistance against a wide number of antibiotics in Staphylococcus aureus. The aim of this study was to investigate the association between the antibiotic susceptibility profile and the prevalence of different efflux pump genes i.e., norA, norB, norC, mepA, sepA, mdeA, qacA/B, and smr in the clinical isolates of S. aureus. Sixty clinical isolates were collected from a tertiary level hospital in Bangladesh. The disc diffusion method using ten antibiotics of different classes was used to discern the susceptibility profile. polymerase chain reaction (PCR) was employed to observe the resistance patterns and to detect the presence of plasmid and chromosomal encoded genes. Among the clinical isolates, 60% (36 out of 60) of the samples were Methicillin-resistant Staphylococcus aureus (MRSA), whereas 55% (33 out of 60) of the bacterial samples were found to be multi-drug resistant. The bacteria showed higher resistance to vancomycin (73.33%), followed by ciprofloxacin (60%), cefixime (53.33%), azithromycin (43.33%), and amoxicillin (31.67%). The prevalence of the chromosomally-encoded efflux genes norA (91.67%), norB (90%), norC (93.33%), mepA (93.33%), sepA (98.33%), and mdeA (93.33%) were extremely high with a minor portion of them carrying the plasmid-encoded genes qacA/B (20%) and smr (8.33%). Several genetic combinations of efflux pump genes were revealed, among which norA + norB + norC + mepA + sepA + mdeA was the most widely distributed combination among MRSA and MSSA bacteria that conferred resistance against ciprofloxacin and probably vancomycin. Based on the present study, it is evident that the presence of multiple efflux genes potentiated the drug extrusion activity and may play a pivotal role in the development of multidrug resistance in S. aureus.

The ocean consists of versatile domain of lives which can be exploited for human health benefits because of diversified secondary metabolites. Seaweeds, generally called macroalgae, are commonly found in the coastal region of the Bay of Bengal. But none of them were investigated properly for their biological activities. Hence, this study was performed to investigate the antioxidant, antimicrobial, cytotoxic and membrane stabilizing activities along with total phenolic content of the crude methanolic extract of three seaweeds namely, Enteromorpha intestinalis, Rhizoclonium riparium and Ceratophyllum demersum using standard protocols. Among the methanolic extracts of three seaweeds, C. demersum (52.09 ± 1.30 mg of GAE) was found to have the highest phenolic content, followed by E. intestinalis (35.98 ± 1.27 mg of GAE) and then R. riparium (29.94 ± 0.54 mg of GAE). The extractives of these seaweeds also showed promising antioxidant and membrane stabilizing properties compared to the standard. E. intestinalis extract displayed greater reducing power with increasing concentration (EC50 value 7.70 ± 0.27 μg/ml). The same seaweed E. intestinalis was found to have significant free radical (DPPH) scavenging potential (IC50 value 23.46 ± 0.54 μg/ml) compared to the reference standard ascorbic acid (IC50 value 5.76 ±0.13 μg/ml). However, the findings of antimicrobial activity test demonstrated mild antibacterial effects of these seaweeds against Escherichia coli and Aspergillus niger and none of these seaweeds exhibited cytotoxicity when tested against HeLa cell line. These findings will aid in future studies attempting to explore medicinal and therapeutic agents from these readily available seaweeds of Bangladesh. Dhaka Univ. J. Pharm. Sci. 22(1): 81-87, 2023 (June)

Green tea (Camellia sinensis) is a "non-fermented" tea popular worldwide attributed to its pleasing flavor and beneficial impact on human health. Commercially available green tea products differ in their quality, constituents and health benefits which can be attributed to the variations in the processing methods, geographical factors, and plant parts used. This study aims to compare the phytochemical constituents and biological activity of four commercial green tea brands of Bangladesh (GTE1-4). Methanolic extracts of four marketed green tea products were employed in this study. The functional groups and characteristic peaks of the known chemical entities were determined by IR and 1D-NMR spectroscopy, respectively. Gas chromatography-mass spectroscopy (GC-MS) technique was utilized for the quantitative determination of caffeine and other volatile substances. Antioxidant and antimicrobial properties were assessed using the (2,2-Diphenyl-1-picrylhydrazyl) DPPH free radical scavenging assay and the disc diffusion method, respectively. Finally, the products were tested for their potential cytotoxic effects. Caffeine, gallic acid, (-)-epicatechin, (-)-epicatechin-3-gallate, (-)-epigallocatechin, (-)-epigallocatechin-3-gallate and quinic acid were identified as the major constituents in the qualitative phytochemical analyses. GTE-1 contained the highest concentration of 1,2,3-benzenetriol while caffeine was the most abundant in GTE-2 (96.16%). Majority of the samples exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria at 1000 µg/mL concentration. Sample GTE-1 exhibited a positive cytotoxic effect at 500 µg/mL concentration when tested on HeLa cells. Taken together, the results indicate that methanol extracts of green tea in different commercial products can differ considerably.

Four cycloartane type triterpenoids and three stigmastane type steroids were isolated from the methanolic extract of stem and root part of Pothos scandens L. (Araceae), a Bangladeshi medicinal plant by high performance liquid chromatographic technique. The compounds were characterized as 24-methylenecycloartanol (1), 24-methylenecycloartenone (2), 24-en-cycloartenone (3), 24-methylenecycloartanyl ferulate (4), stigmast-4-en-3-one (5), stigmast-4,22-diene-3-one (6) and β-sitosterol glucoside (7) through extensive 1D and 2D NMR spectroscopic studies. All the isolates were evaluated for their estrogenic/antiestrogenic activity using the estrogen-responsive breast cancer cell lines, MCF-7 and T47D. The results showed that all the compounds possess mild to strong antiestrogenic activity in both cell lines which was compared to positive control tamoxifen. 24- Methylenecycloartanol (1), which contains a hydroxyl group in its C-3 position, inhibited 90% of estradiol (E2)- induced cell proliferation in MCF-7 and T47D cell lines at a concentration of 0.01 μM only. 24- Methylenecycloartanyl ferulate (4) and stigmast-4,22-diene-3-one (6) showed 90% of estradiol (E2)-induced cell proliferation in T47D cell only at a concentration of 0.01 μM whereas 10.0 μM was required for 24- methylenecycloartanyl ferulate (4) for the same activity in MCF-7 cells. This is the first report of isolation of these compounds from the plant along with their antiestrogenic property. Dhaka Univ. J. Pharm. Sci. 18(1): 93-102, 2019 (June)

Multidrug-resistant (MDR) and Methicillin-resistant Staphylococcus aureus (MRSA) are major opportunistic pathogens, particularly in healthcare settings. Despite the importance of such strains as a priority nosocomial pathogen, genomic data on Bangladeshi isolates remain limited. This study presents whole genome sequence (WGS) analysis of three MDR-MRSA strains (SA-18, SA-36, and SA-41) isolated from wound-infected patients in a tertiary care hospital in Bangladesh. Multi-locus sequence typing (MLST) identified SA-18 and SA-36 as sequence type ST6, and SA-41 as ST1930. All isolates carried the mecA gene and SCCmec type IVa were classified as MRSA. A total of 22 antibiotic resistance genes (ARGs) were identified, including blaZ, erm(C), norA, and sdrM. Pathogenicity prediction classified all isolates as human pathogens, with SA-41 showing the highest pathogenic potential (98%). Virulence analysis revealed 75 virulence factor genes (VFGs), such as hla, spa, icaA-D, and PVL. Mobile genetic elements (MGEs), plasmids, and an intact 50.9 kb prophage region were detected, with the ebp gene identified within the prophage in SA-41. Pangenome analysis revealed 3764 gene clusters, indicating an open and diverse pangenome. The findings of the present study highlight the importance of WGS in antimicrobial stewardship programs by rapidly identifying resistant genes and spread of multidrug-resistant MRSA strains in Bangladesh which will allow better infection control, rational use of antibiotics and developing effective public health policies.

The present study was designed to develop a self-micellizing solid dispersion (SMSD) containing Thymoquinone (TQM), a phytonutrient obtained from Nigella sativa seeds, aiming to improve its biopharmaceutical and nephroprotective functions. The apparent solubility of TQM in polymer solutions was used to choose an appropriate amphiphilic polymer that could be used to make an SMSD system. Based on the apparent solubility, Soluplus® was chosen as an appropriate carrier, and mixing with TQM, SMSD-TQM with different loadings of TQM (5–15%) was made by solvent evaporation and freeze-drying techniques, respectively, and the formulations were optimized. The optimized SMSD-TQM was evaluated in terms of particle size distribution, morphology, release characteristics, pharmacokinetic behavior, and nephroprotective effects in a rat model of acute kidney injury. SMSD-TQM significantly improved the dissolution characteristics (97.8%) of TQM in water within 60 min. Oral administration of SMSD-TQM in rats exhibited a 4.9-fold higher systemic exposure than crystalline TQM. In a cisplatin-induced (6 mg/kg, i.p.) acute kidney-damaged rat model, oral SMSD-TQM (10 mg/kg) improved the nephroprotective effects of TQM based on the results of kidney biomarkers and histological abnormalities. These findings suggest that SMSD-TQM might be efficacious in enhancing the nephroprotective effect of TQM by overcoming biopharmaceutical limitations.