Current Green Chemistry - Volume 9, Issue 1, 2022

Pollution by plastics is a major concern in this era. This paper discusses the research achievements concerning the degradation of polymers using different microbes. The bacterial and fungal populations that reside in waste or dumped plastics decompose plastics naturally by enzymatic aerobic or anaerobic biodegradation. Bacteria and fungi with polymer-degrading ability are isolated through various technologies. The specific bacterial species like Bacillus sp., Rhodococcus sp., Pseudomonas sp., Staphylococcus sp., Arthrobacter sp., Microbacterium sp. and Phanerochaete sp. etc. and specific fungal species like Aspergillus sp. or Penicillium sp. etc. degrade polymers in the relevant rate of duration. The microbial polymer degradation reforms soil properties, soil ecology, soil ecosystem and agricultural crop production, and improves the quality of surface and subsurface water. It restricts the pollution in the soil layer and mitigates the release of waste polymer from the polymer industry. Eventually, it will help to sustain the ecology and natural ecosystem. Furthermore, the scientific investigation may build standard materials and methods for producing biodegradable fertilizers for polymer degradation. Overall assessment of the study indicates that there is a possibility of developing effective bacterial or fungal consortia suited for external application on plastic debris for faster degradation, as well as to tackle waste management in polymer industries.

Extensive use of pesticides and herbicides in the agricultural fields for the safeguard of crops engenders huge concern regarding pollution of these agricultural fields as well as directly or indirectly linked to an aquatic environment. In order to find out the apt bioremediation techniques that could be potentially used against these highly noxious agricultural pollutants, utilization of fungi and their associated enzymes like laccases and others may be an imperative tool against these pesticides, insecticides, and herbicides. A fungal system, including fungal enzymes, has proved their efficacy in the degradation studies of malathion (1), acetamiprid (2), 2, 4-D (3), chlorimuron-ethyl, imidacloprid (4), flubendiamide (5), thiamethoxam (6), pyrimethanil (7), cypermethrin (8), nicosulfuron (9), chlorpyrifos (10), isoproturon (11), chlorothalonil (12), DDT (13), atrazine (14), and alachlor (15) like agricultural organic pollutants which have been meritoriously and succinctly conferred here. There are limited recent works on fungal system-mediated bioremediation of pesticides and herbicides compared to a bacterial system, that is why, authors have objectively decided to compile the recent promising researches on the topic to provide an effective and informative update on the significant applicability of the fungal system in the removal of such organic pollutants. Herein, authors have best tried to present a clear, subject-centric and compact picture of the operative contribution of fungal systems (fungi and associated enzymes) in the biodegradation of different pesticides/insecticides or herbicides.

Aims and Background: Curcumin's poor water solubility still presents a challenge. Because of Curcumin's instability in solubilizing solvents, using a non-sustainable solvent and dissolved oxygen in the solution might be the problem. Thus, considering all facts, looking for a promising alternative solvent medium is in need. Indeed, a solution of hydrotropic agent has been assessed recently. Hydrotropic agents are the best replacements for organic solvents. These are eco-friendly, safe, and non-toxic agents. Hence, the presented research focuses on improving the solubility of Curcumin through a hydrotropic solid dispersion approach. Amazingly, Curcumin showed a significant solubility enhancement in sodium salicylate hydrotropic Solution. Sodium salicylate hydrotrope ensured the stability of Curcumin in Solution, maintained homogeneity, and exhibited antioxidant properties. Hydrotropy combined with the solid dispersion technique is a simple and effective way to improve the bioavailability of Curcumin. Hydrotropic solid dispersion-loaded curcumin topical gel was developed to achieve transdermal delivery of Curcumin. Solid dispersion was prepared by solvent evaporation method and evaluated for in-vitro performance. Invitro drug dissolution, drug content, FTIR, and XRD were carried out for the prepared HSD. Objective: The selected HSD (1:4) was loaded into a topical gel by dispersion method, and in-vitro parameters like drug content, Spreadability, pH, rate of drug dissolution, and drug content were performed. Methods: The solubility study has substantially enhanced the solubility of Curcumin in a 2M sodium salicylate hydrotropic solution. Sodium salicylate was compatible with formulating the solid dispersion. Hydrotropic solid dispersion was successfully prepared in 1:4 ratios. XRD results have shown the amorphous nature of Curcumin in the presence of sodium benzoate. The dissolution studies have shown improved release compared to pure Curcumin and PM (1:4). The prepared HSD was then incorporated into a gel by dispersion method using carbopol 934 and hydroxypropyl methylcellulose as a gelling agent. The Cur-HSD gel was homogeneous and transparent in appearance. Results: The gel showed excellent Spreadability and drug content of 94.2 with 90.21% of percent drug release for 120 min and showed improved release in the presence of hydrotrope for improved topical delivery of Curcumin. Conclusions: Thus, to enhance the topical delivery of poorly soluble phytoconstituents, hydrotropes are suggested as a greener approach and to be applied for other poorly soluble phytoconstituents.

Aims and Background: The low rainwater recharge rate and high seawater intrusion into the water aquifer present a dilemma of high ground-water salinity for the narrow coastal Gaza Strip. Thus, extremely saline water causes impairment to household appliances and deteriorates the performance of the reverse-osmosis desalination units. Methods: Accordingly, xylem discs of different plants, such as Mulberry, Pomegranate, Olives, Centroza, and Ficus, were investigated for desalination of tap water by flow-through experimentation. Various parameters such as the total dissolved salt of the inflow water, disc thickness, flow rate and the type of plant were investigated. Finally, the morphology of the xylem discs of the five plants was screened using an optical microscope. Results and Discussion: It was found that the xylem of different plants showed dissimilar efficiencies in water desalination. Thus, Centroza established the highest desalination efficiency of 31%, followed by Olive and Ficus as 26 and 25%, respectively, while Pomegranate and Mulberry established the poorest salt removal at 17 and 14%, respectively. Successive three-disc set up established ~ 50% desalination of inflow-water of ~5000 ppm. Conclusion: Hence, a disposable cost-effective xylem desalination unit is proposed as a guard filter to be installed between the faucet and household desalination units and washing machines or dishwashers, in order to improve the performance and extend the life-time of these appliances.

Aim and Background: Introducing deuterium to a molecule is of interest to a wide variety of research, including investigation of reaction mechanisms or kinetics, analysis of drug metabolism, structural elucidation of molecules, and syntheses of isotopically labeled materials used for NMR spectroscopy and medicinal research. Objective: The transition-metal-free regioselective deuteration of 2-methylquinolin-8-ol (1a) and 2,5- dimethylquinolin-8-ol (2a) with ambient reaction conditions and low-cost reagents is described in the paper. Methods: Regioselective H/D isotope exchange has been presented by combining the following techniques ¹H NMR, ¹³C NMR, GC-MS, and X-ray crystallography. The molecular orbitals of the deuterated molecule 1a have been calculated by density functional theory (DFT) to provide an elucidation of the isotope exchange. Results: The metal-free regioselective green deuteration based on modified Skraup-Doebner-Von Miller synthesis and water-d2 KOD solution or water-d2 D2SO4 solution of hydroxyquinolines was elaborated. Conclusion: The metal-free regioselective green deuteration of hydroxyquinoline-type compounds with ambient reaction conditions and low-cost reagents provided valuable tools for isotopic labeling. The modified Skraup-Doebner-Von Miller synthesis of deuterated hydroxyquinolines has the potential to allow higher deuteration capacity. The presented isotopic exchange reactions also possess synthetic values as the source of deuterated compounds for the studies of NMR spectroscopy, medicinal research, and drug discovery processes.