Asian Journal of Green Chemistry
Volume:6 Issue: 4, Autumn 2022

Synthesis of silver nanoparticles (AgNPs) are one of the most vital and fascinating nanomaterials among several metallic nanoparticles that are picking up significantly worldwide as a result of their importance in biomedical applications. This study aimed to investigate the antibacterial activities of green synthesized silver nanoparticles by using three Nigerian fresh leaf extracts (Justicia secunda, Telfairia occidentalis, and Jatropha tanjorensis) on clinical and environmental bacterial isolates. The green synthesized AgNPs were characterized by using UV-Vis spectrophotometry, Fourier transform infrared (FT-IR), and Scanning electron microscopy (SEM), and screened for their antibacterial activity by using Agar diffusion method. Our result showed that the green synthesized AgNPs from the three Nigerian vegetables exhibited the moderate antibacterial potentials against selected clinical and environmental bacterial isolates.  In conclusion, the green synthesized AgNPs by using fresh Justicia secunda, Telfairia occidentalis, and Jatropha tanjorensis leaf extracts have antibacterial properties with therapeutic potential in treatment, management, and/or prevention of bacterial infections, and may be promising source for the development of chemotherapeutic (antibiotic) agents in the future.

A simple, efficient, and environmentally benign green approach was developed for the synthesis of 3-alkenyl oxindole derivatives with effective antifungal properties. The targeted compounds (3a-3g) were synthesized by using Knoevenagel condensation with oxindole and substituted aromatic aldehydes in the solvent-free, microwave-assisted reaction conditions. Silica extracted from rice husk waste was functionalized with (3-aminopropyl) triethoxysilane (APTES) to use as an eco-friendly, reusable, and solvent-free reaction medium. The structures of the final products were confirmed by their melting points, IR, 1H-NMR, 13C-NMR, and elemental analysis. The desired products were isolated with 72-88% yields in 12 minutes. The in vitro antimicrobial activity against ATCC standard cultures of human pathogenic Candida species, clinical isolates of Candida albicans, and several Gram-positive and Gram-negative bacteria were investigated and reported. All the synthesized 3-alkenyl oxindole derivatives exhibited the selective antifungal properties with the minimum inhibitory concentration (MIC) values ranging from 2 µg/mL to 125 µg/mL against tested Candida species. The findings of this study emphasized that green synthesized 3-alkenyl oxindole derivatives can be considered as the potential lead compounds to develop the effective antifungals against human pathogenic Candida species.

Herbal medicines have been in use before conventional drugs in Nigeria and Ebonyi state in particular. Their uses have been on the increase due to its efficacy. The knowledge on the concentrations of trace metals is important for determining the effectiveness of the plants in treating various diseases. In this study, the concentration of trace metals in herbal medicine sold in Abakaliki metropolis was determined using varian spectra AA55B atomic absorption Spectrophotometer. The results obtained from the sample gotten from the international market showed that sample A ranged from 0.3±0.06 Cu to 7.15±0.145 Fe. Sample B ranged from 0.9±0.018 Cd to 5.8±0.116 Fe, while sample C, D, E, and F ranges from 0.75±0.015 Cd to 24.1±0.482 Fe, 5.65±0.113 Cd to 15.4±0.308 Fe, 1.2±0.024 Cd to 18.2±0.364 Fe, and 0.15±0.01 Cd to 5.2±0.112 Fe, respectively. Among all the studied samples, Fe has the highest concentrations. The Fe concentration in samples C, D, and E were above the permissible limit of W.H.O, while the Zn concentrations were within the acceptable limit of W.H.O. The Cd concentrations in the samples were above the standard limit except sample F. The Zn concentrations in all the studied samples fell within the acceptable limit of WHO. From kpirikpiri sample, the obtained results showed that the Cd concentrations of all the samples studied were within the acceptable limit of WHO except in samples A, B,C, and D which ranged from 0.1±0.01 sample F to 1.3±0.02 sample A. The World Health Organization acceptable limits for the concentration of Cd, Zn, and Fe in herbal medicine are 0.3, 100, and 15 µg/g, respectively.

Tuberculosis is a long-term infection caused by the bacteria Mycobacterium tuberculosis. Long-term TB treatment has several drawbacks, including medication resistance, noncompliance with therapy, and a scarcity of therapeutic options. It is critical to find new medications that are both safer and more effective. Molecular modification is a valuable method for identifying novel chemicals that can overcome these obstacles. The primary tactics to obtain a novel anti-tubercular medication are summarized in this paper.

Schiff base transition metal complexes using benzil and its derivatives as a diketone with different amines in 1:1 or 1:2 ratio can be synthesized by simple condensation reaction or mild conditions. They may contain donor atoms such as oxygen, sulphur, and nitrogen which make the ligand a better chelating ligand to coordinate strongly with different metal ions to form Schiff base metal complexes. Here, in this review, the synthesis of different types of Schiff bases customized from benzil and corresponding bidentate, tridentate, and tetradentate metal complexes has been summarized.

This review is mainly focused on the recent development of rice husk utilization for the efficient immobilization of organic molecules. It was pointed out that sodium silicate precursor was prepared in large amounts from rice husk ash. Moreover, a new route was designed for the extracted sodium silicate through a purely homogenous method in-situ reaction of 3-(chloropropyl)triethoxysilane (CPTES) with silica. The product was solid silica with chloride end groups. The silica-chloride end groups are the cornerstone for the design of heterogeneous catalyses with the specific functional groups for different purposes. These functionalized silica catalysts have attracted widespread attention due to their good physical and catalytic properties in a large variety of chemical reactions.

Environmental pollution viz water, air, sound, and land pollution, etc. have been a threat to mankind for a long. Water pollution is a major worldwide problem, but in a desert area where already a scarcity of water is there, solid and liquid wastes from different sources make the conditions ugly. Entry of toxic metals in water above a particular concentration is extremely harmful and sometimes lethal, too. In the recent years, the use of bio-adsorbents for the removal of hazardous metal ions from wastewater has been reported, few of these were found suitable whereas many were not, and further improvements and modifications are required to increase the adsorption capacity. In the present paper, the use of microwave radiation for the quick preparation of Aerva javanica based bio-adsorbent and its application for the removal of cadmium(II) and lead(II) ions from the aqueous solutions have been described. The Aerva javanica Flower adsorbent's metal absorption capability or metal uptake was investigated by batch and column experiments. The experimental stock solutions' initial metal ion concentration, agitation period, temperature, and pH were all examined factors. It investigated how these parameters affected the removal of metal ions. The results of pre-concentration and recovery of metal ions using the column method be 97.8% and 97.2% for cadmium and lead, respectively.