Chitosan is obtained from chitin that in turn is recovered from marine crustacean wastes. The recovery methods and their varying types and the advantages of the recovery methods are briefly discussed. The bioactive properties of chitosan, which emphasize the unequivocal deliverables contained by this biopolymer, have been concisely presented. The variations of chitosan and its derivatives and their unique properties are discussed. The antioxidant properties of chitosan have been presented and the need for more work targeted towards harnessing the antioxidant property of chitosan has been emphasized. Some portions of the crustacean waste are being converted to chitosan; the possibility that all of the waste can be used for harnessing this versatile multifaceted product chitosan is projected in this review. The future of chitosan recovery from marine crustacean wastes and the need to improve in this area of research, through the inclusion of nanotechnological inputs have been listed under future perspective.

Mushrooms have been long accomplished for their medicinal properties and bioactivity. The ancients benefitted from it, even before they knew that there was more to mushrooms than just the culinary aspect. This review addresses the benefits of mushrooms and specifically dwells on the positive attributes of mushroom polysaccharides. Compared to mushroom research, mushroom polysaccharide-based reports were observed to be significantly less frequent. This review highlights the antioxidant properties and mechanisms as well as consolidates the various antioxidant applications of mushroom polysaccharides. The biological activities of mushroom polysaccharides are also briefly discussed. The antiviral properties of mushrooms and their polysaccharides have been reviewed and presented. The lacunae in implementation of the antiviral benefits into antiCOVID-19 pursuits has been highlighted. The need for expansion and extrapolation of the knowns of mushrooms to extend into the unknown is emphasized.

Extensive growth of microscopic algae and cyanobacteria results in harmful algal blooms (HABs) in marine, brackish, and freshwater environments. HABs can harm humans and animals through their toxicity or by producing ecological conditions such as oxygen depletion, which can kill fish and other economically or ecologically important organisms. This review summarizes the reports on various HABs that are able to bring about marine fish kills. The predominant HABs, their toxins, and their effects on fishes spread across various parts of the globe are discussed. The mechanism of HAB-driven fish kills is discussed based on the available reports, and existing mitigation methods are presented. Lapses in the large-scale implementation of mitigation methods demonstrated under laboratory conditions are projected. Clay-related technologies and nano-sorption-based nanotechnologies, although proven to make significant contributions, have not been put to use in real-world conditions. The gaps in the technology transfer of the accomplished mitigation prototypes are highlighted. Further uses of remote sensing and machine learning state-of-the-art techniques for the detection and identification of HABs are recommended.

Chitosan has become a highlighted polymer, gaining paramount importance and research attention. The fact that this valuable polymer can be extracted from food industry-generated shell waste gives it immense value. Chitosan, owing to its biological and physicochemical properties, has become an attractive option for biomedical applications. This review briefly runs through the various methods involved in the preparation of chitosan and chitosan nanoforms. For the first time, we consolidate the available scattered reports on the various attempts towards greens synthesis of chitosan, chitosan nanomaterials, and chitosan nanocomposites. The drug delivery applications of chitosan and its nanoforms have been reviewed. This review points to the lack of systematic research in the area of green synthesis of chitosan. Researchers have been concentrating more on recovering chitosan from marine shell waste through chemical and synthetic processes that generate toxic wastes, rather than working on eco-friendly green processes—this is projected in this review. This review draws the attention of researchers to turn to novel and innovative green processes. More so, there are scarce reports on the application of green synthesized chitosan nanoforms and nanocomposites towards drug delivery applications. This is another area that deserves research focus. These have been speculated and highlighted as future perspectives in this review.

After decades of research and development concerning cancer treatment, cancer is still at large and very much a threat to the global human population. Cancer remedies have been sought from all possible directions, including chemicals, irradiation, nanomaterials, natural compounds, and the like. In this current review, we surveyed the milestones achieved by green tea catechins and what has been accomplished in cancer therapy. Specifically, we have assessed the synergistic anticarcinogenic effects when green tea catechins (GTCs) are combined with other antioxidant-rich natural compounds. Living in an age of inadequacies, combinatorial approaches are gaining momentum, and GTCs have progressed much, yet there are insufficiencies that can be improvised when combined with natural antioxidant compounds. This review highlights that there are not many reports in this specific area and encourages and recommends research attention in this direction. The antioxidant/prooxidant mechanisms of GTCs have also been highlighted. The current scenario and the future of such combinatorial approaches have been addressed, and the lacunae in this aspect have been discussed.

With population explosion, automobiles have also exploded and so has pollution due to vehicular emissions. Road-side plants and highway vegetation are the first targets of these vehicular emissions. This review briefly presents a snapshot of how vehicular emission can affect plants. On the contrary, the positive perspective of how road-side plants may be able to affect and influence the harmful effects of vehicular emissions has also been discussed. Ways and means by which plants can become potential bio indicators of air pollution have also been speculated. The fact that the nanocarbon particulate aspect of automobile pollutants and their interactions with road-side plants and more so on road-side agricultural crops, has not been appropriately investigated has been raised as a key concern. The need to arrive at mitigation methods to identify permanent solutions to these rising concerns has been highlighted.