There are two viable options to produce shrimp shells as by-product waste, either within the shrimp production phases or when the shrimp are peeled before cooking by the end user. This waste is considered a double-edged sword, as it is possible to be either a source of environmental pollution, through dumping and burning, or a promising source from which to produce chitosan as a biodegradable, biocompatible biopolymer which has a variety of agricultural, industrial, and biomedical applications. Chitosan is a deacetylated form of chitin that can be chemically recovered from shrimp shells through the three sequential stages of demineralization, deproteinization, and deacetylation. The main aim of this review paper is to summarize the recent literature on the chemical extraction of chitosan from shrimp shells and to represent the physicochemical properties of chitosan extracted from shrimp shells in different articles, such as chitosan yield, moisture content, solubility, ash content, and degree of deacetylation. Another aim is to analyze the influence of the main predictors of the chemical extraction stages (demineralization, deproteinization, and deacetylation) on the chitosan yield percentage by using a multilayer perceptron artificial neural network. This study showed that the deacetylation alkali concentration is the most crucial parameter, followed by the concentrations of acid and alkali of demineralization and deproteinization, respectively. The current review was conducted to be used in prospective studies for optimizing the chemical extraction of chitosan from shrimp wastes.

Phytoremediation of heavy metal contaminated soils represents a promising technique and salt-tolerant hyperaccumulators for multiple metals are the need of time. Therefore, phytoremediation potential of four salt-tolerant grass species [Dhab (Desmostachya bipinnata), Kallar (Leptochloa fusca), Para (Brachiaria mutica) and Sporobolus (Sporobolus arabicus Boiss)] was evaluated for cadmium (Cd) and lead (Pb) in a hydroponic study. The plants were harvested after a growth period of 3 months in a nutrient solution containing different levels of Cd (0, 5, and 25 mg L⁻¹) and Pb (0, 25, and 125 mg L⁻¹). Results indicated that Dhab grass showed the highest root and shoot dry matter yield followed by Para, Kallar and Sporobolus grass irrespective of metal or its level under which they were grown. All the grass species showed considerable Cd-accumulating potential with an accumulation of >150 mg kg⁻¹of shoot dry matter at a higher level of Cd-contamination (25 mg L⁻¹). While in case of shoot Pb-accumulation only Para grass performed well and accumulated Pb >1000 mg kg⁻¹ of shoot dry matter at the higher level of Pb-contamination (125 mg L⁻¹). Moreover, Para and Dhab grasses performed better for shoot Cd-uptake, while only Para grass showed promising shoot Pb uptake potential. In conclusion, these grass species could be penitentially used for phytoremediation of salt-affected Cd and Pb contaminated soils.

This work aims to assess growth, physiology, and metal uptake response of Brachiaria mutica and Leptochloa fusca under different contamination levels of Cd (10 and 50 mg kg⁻¹) and Pb (50 and 250 mg kg⁻¹) stress. Results of pot trial showed increasing metal concentration affected B. mutica more as compared to L. fusca. In B. mutica metal stress substantially reduced shoot dry biomass, root dry biomass, total chlorophylls, and carotenoids contents by 89%, 85%, 65%, and 61%, respectively, while enhanced the SOD activity up to 62 U min⁻¹ g⁻¹ FW. L. fusca showed better growth, chlorophylls and carotenoid contents, SOD activity (up to 79 U min⁻¹ g⁻¹ FW), shoot metal uptake potential (Cd 110 µg pot⁻¹, Pb 91.57 µg pot⁻¹), and root metal concentration (Cd 126 mg kg⁻¹ dm, Pb 117 mg kg⁻¹ dm) compared to B. mutica under Pb and Cd stress. While both grass species showed metal translocation factor less than unity under all levels of metal stress. Keeping in view the above results, it is concluded that L. fusca having better growth and physiology with TF < 1 could be used for phytostabilization of Pb and Cd to reclaim the soil having moderate to lower levels of contamination.

Hemp inflorescences are a source of vital compounds, including phytocannabinoids and other biologically active compounds. Various methods are adapted for the extraction of these vital compounds such as the use of different organic solvents. This study aimed to assess the comparative extraction potential of three different solvents: deionized water, 70% methanol (MeOH), and 2% Triton X-100, for phytochemicals in hemp inflorescences. Spectrophotometric techniques were applied to investigate the total amount of polyphenolic compounds (TPC), total flavonoids contents (TF), phenolic acids (TPA), and radical scavenging activity (RSA) in hemp extracts obtained using different polarity solvents. Gas chromatography-mass spectrometry was used for cannabinoids and organic acids quantitative analysis. In the results, MeOH showed a better affinity for the recovery of TFC, TPA, and RSA in comparison to Triton X-100 and water. However, Triton X-100 performed better for TPC with 4-folds and 33% turnover compared to water and MeOH, respectively. Six cannabinoids (CBDVA, CBL, CBD, CBC, CBN, and CBG) were identified in hemp inflorescence extracts. The maximum determined concentration was as follows: CBD > CBC > CBG > CBDVA > CBL > CBN. Overall, fourteen organic acids were identified. Hemp inflorescence extracts obtained using 2% Triton X-100 showed an effect on all tested strains of microorganisms. Methanolic and aqueous extracts had antimicrobial activity against seven tested strains. On the other hand, the inhibition zones were wider for methanolic extracts compared to aqueous ones. Hemp aqua extract with antimicrobial activity might be used in various markets where toxic solvents are unwanted.