Effect of UV-B Radiation and Desiccation Stress on Photoprotective Compounds Accumulation in Marine <Emphasis Type="Italic">Leptolyngbya</Emphasis> sp.

Increased awareness regarding the harmful effects of ultraviolet (UV)-B radiation has led to the search for new sources of natural UV-B protecting compounds. Mycosporine-like amino acids are one of such promising compounds found in several organisms. Cyanobacteria are ideal organisms for isolation of these compounds due to their compatibility and adaptability to thrive under harsh environmental conditions. In the following investigation, we report the production of shinorine in Leptolyngbya sp. isolated from the intertidal region. Based on the spectral characteristics and liquid chromatography-mass spectrometry analysis, the UV-absorbing compound was identified as shinorine. To the best of our knowledge, this is the first report on the occurrence of shinorine in Leptolyngbya sp. We also investigated the effect of artificial UV-B radiation and periodic desiccation on chlorophyll-a, total carotenoids, and mycosporine-like amino acids (MAAs) production. The UV-B radiation had a negative effect on growth and chlorophyll concentration, whereas it showed an inductive effect on the production of total carotenoids and MAAs. Desiccation along with UV-B radiation led to an increase in the concentration of photoprotective compounds. These results indicate that carotenoids and MAAs thus facilitate cyanobacteria to avoid and protect themselves from the deleterious effects of UV-B and desiccation.     

Spectral and Molecular Modeling Studies on Hydroxybenzaldehydes with Native and Modified Cyclodextrins

The inclusion complexation of 2-hydroxy-3-methoxybenzaldehyde (2HMB), 4-hydroxy-3-methoxybenzaldehyde (4HMB), 3,4-dimethoxybenzaldehyde (DMB) and 4-hydroxy-3,5-dimethoxybenzaldehyde (HDMB) with α-CD, β-CD, HP-α-CD and HP-β-CD were carried out by UV-Visible, steady-state and time-resolved fluorescence and PM3 methods. All the benzaldehydes shows dual fluorescence in aqueous and CD mediums and 1:1 inclusion complexes were formed with CDs. PM3 geometry optimizations results indicate that the HDMB/CD complex is significantly more favorable than the other complexes. The negative enthalpy changes suggest that the inclusion complexation processes are spontaneous. The geometry of the most stable complex shows that methoxy/OH group of HMBs is entrapped in the less polar CD cavities, while the aldehyde group present in the upper part of the CDs cavities.     

Biosynthesis of silver nanoparticles using citrus sinensis peel extract and its antibacterial activity

Biosynthesis of silver nanoparticles (AgNPs) was achieved by a novel, simple green chemistry procedure using citrus sinensis peel extract as a reducing and a capping agent. The effect of temperature on the synthesis of silver nanoparticles was carried out at room temperature (25°C) and 60°C. The successful formation of silver nanoparticles has been confirmed by UV-vis, FTIR, XRD, EDAX, FESEM and TEM analysis and their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa (gram-negative), and Staphylococcus aureus (gram-positive) has been studied. The results suggest that the synthesized AgNPs act as an effective antibacterial agent.     

Medicinal Plants,Phytochemicals, and Herbs to Combat Viral Pathogens Including SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome corona virus-2 (SARS-CoV-2), is the most important health issue, internationally. With no specific and effective antiviral therapy for COVID-19, new or repurposed antiviral are urgently needed. Phytochemicals pose a ray of hope for human health during this pandemic, and a great deal of research is concentrated on it. Phytochemicals have been used as antiviral agents against several viruses since they could inhibit several viruses via different mechanisms of direct inhibition either at the viral entry point or the replication stages and via immunomodulation potentials. Recent evidence also suggests that some plants and its components have shown promising antiviral properties against SARS-CoV-2. This review summarizes certain phytochemical agents along with their mode of actions and potential antiviral activities against important viral pathogens. A special focus has been given on medicinal plants and their extracts as well as herbs which have shown promising results to combat SARS-CoV-2 infection and can be useful in treating patients with COVID-19 as alternatives for treatment under phytotherapy approaches during this devastating pandemic situation.