Microwave-assisted solvent-free synthesis of some novel thiazole-substituted thiosemicarbazone analogues: antimicrobial and anticancer studies

The increased resistance to antibiotics has compelled researchers to devise novel active compounds targeting multidrug-resistant pathogenic microorganisms. A series of thiosemicarbazone derivatives was synthesized by reacting thiosemicarbazide with 2-aryl-4-formylthiazole, 2-aryl-5-formyl-4-methylthiazole, and/or 5-acetyl-2-aryl-4-methylthiazole compounds. These thiosemicarbazone-based thiazole adducts were evaluated for their inhibitory activities against tuberculosis H37Ra and Bovis BCG mycobacteria. Their cytotoxicity was assessed against two cancer cell lines: colonic carcinoma (HCT-116) and cervical cancer (HeLa). Notably, these thiosemicarbazones exhibited minimal cytotoxic effects on these cell lines even at their highest concentrations. Furthermore, the prepared thiosemicarbazone derivatives demonstrated significant antimicrobial efficacy against Bacillus subtilis and Staphylococcus aureus (Gram-positive bacterial pathogens) as well as Escherichia coli and Pseudomonas fluorescens (Gram-negative bacterial pathogens). While most of the prepared thiosemicarbazone derivatives exhibited moderate activity against Candida albicans (a fungal strain), their performance was notable. The thiosemicarbazone-based thiazole adducts were also successfully synthesized using a solvent-free approach under microwave irradiation. Compared with conventional reflux methods, the microwave-assisted technique yielded high thiazole yields within just 5 min, obviating the need for catalysis. This study signifies significant strides toward the rational design of more potent antimycobacterial agents.

Subconjunctival Delivery of Sorafenib-Tosylate-Loaded Cubosomes for Facilitated Diabetic Retinopathy Treatment: Formulation Development, Evaluation, Pharmacokinetic and Pharmacodynamic (PKPD) Studies

Diabetic retinopathy (DR) is a microvascular complication associated with vascular endothelial growth factor (VEGF) overexpression. Therapeutic delivery to the retina is a challenging phenomenon due to ocular biological barriers. Sorafenib tosylate (ST) is a lipophilic drug with low molecular weight, making it ineffective at bypassing the blood-retinal barrier (BRB) to reach the target site. Cubosomes are potential nanocarriers for encapsulating and releasing such drugs in a sustained manner. The present research aimed to compare the effects of sorafenib-tosylate-loaded cubosome nanocarriers (ST-CUBs) and a sorafenib tosylate suspension (ST-Suspension) via subconjunctival route in an experimental DR model. In this research, ST-CUBs were prepared using the melt dispersion emulsification technique. The distribution of prepared nanoparticles into the posterior eye segments was studied with confocal microscopy. The ST-CUBs were introduced into rats' left eye via subconjunctival injection (SCJ) and compared with ST-Suspension to estimate the single-dose pharmacokinetic profile. Streptozotocin (STZ)-induced diabetic albino rats were treated with ST-CUBs and ST-Suspension through the SCJ route once a week for 28 days to measure the inhibitory effect of ST on the diabetic retina using histopathology and immunohistochemistry (IHC) examinations. Confocal microscopy and pharmacokinetic studies showed an improved concentration of ST from ST-CUBs in the retina. In the DR model, ST-CUB treatment using the SCJ route exhibited decreased expression levels of VEGF, pro-inflammatory cytokines, and adhesion molecules compared to ST-Suspension. From the noted research findings, it was concluded that the CUBs potentially enhanced the ST bioavailability. The study outcomes established that the developed nanocarriers were ideal for delivering the ST-CUBs via the SCJ route to target the retina for facilitated DR management.