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Ethyl‐2‐(4‐methyl‐2‐oxo‐2‐coumarin‐7‐yloxy)acetate 1 has been prepared from 7‐hydroxy‐4‐methyl‐2‐coumarin, which on further treatment with hydrazine hydrate in boiling ethanol gave the hydrazide compound 2. The resulting hydrazide was reacted with substituted aryl isothiocyanates to form thiosemicarbazides compounds 3a, 3b, 3c, 3d, 3e. 1‐(2‐(4‐Methyl‐2‐oxo‐2‐coumarin‐7‐yloxy)acetyl)‐4‐aryl thiosemicarbazides 3 underwent cyclization with different reagents under different reaction conditions to furnish coumarin derivatives possessing triazoles 4a, 4b, 4c, 4d, 4e, thiadiazoles 5a, 5b, 5c, 5d, 5e, and oxadiazoles 6a, 6b, 6c, 6d, 6e, respectively. The structures of all the compounds have been assigned by elemental analysis and spectral studies. The synthesized compounds were screened for their antimicrobial analgesic activities. The nonconventional controlled microwave irradiation synthesis is carried out at (200 W) at 70°C. This approach offers a number of advantages in terms of methodology, high‐product yield, short reaction time, mild reaction conditions, environmentally benign, and easy workup.

Cyanobacteria-mediated silver nanoparticles synthesis approach has proven to be more efficient and eco-friendly in achieving biomedical applications compared to physical and chemical prototypes. In the present work, the silver nanoparticles were successfully synthesized by cell-free extract of freshwater cyanobacteria, i.e., Chroococcus turgidus and Characium typicum. The cyanobacterial silver nanoparticles (CSNPs) were characterized by UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) analysis and were further tested for antibacterial and cytotoxic efficiency. The synthesis of CSNPs was confirmed through visible color change and shift of peaks at 430-445 nm by the UV-Vis spectroscopy. The size of CSNPs was between 22 and 34 nm and oval-shaped which were confirmed by SEM and TEM analyses. The FTIR spectra showed a new peak at the range of 3,400-3,460 cm −1 compared to control, confirming the reduction of silver nitrate. Furthermore, the antibacterial activity of CSNPs showed highest zone of inhibition with 6.9, 4.0, 2.0, and 3.0 mm against Salmonella paratyphi, Escherichia coli, Klebsiella pneumonia, and Staphylococus aureus, respectively, whereas in vitro cytotoxic activity of C. typicum and C. turgidus silver nanoparticles showed remarkable IC 50 values with 43.3 and 40.9 ug/ml against MCF-7 breast cancer cell line and 20.8 and 55.7 ug/ml against HepG2 cancer cell, simultaneously.

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Synthesis and Antimicrobial Activities of Some Triazole, Thiadiazole, and Oxadiazole Substituted Coumarins. -Thiosemicarbazides undergo cyclization reactions with different reagents using conventional heating, microwave irradiation and grinding as synthetic methods. The compounds synthesized are screened for their antibacterial activity against K. pneumonia and E. coli as well as for their antifungal activity against A. niger, A. fumigates, and A. terrs. Some compounds show good antibacterial activity against K. pneumonia and good antifungal activity. -(REDDY, K. R.; MAMATHA, R.; BABU*, M. S. S.; SHIVA KUMAR, K.; JAYAVEERA, K. N.; NARAYANASWAMY, G.; J. Heterocycl. Chem. 51 (2014) 1, 132-137, http://dx.