Chitin, being the second most abundant biopolymer after cellulose, has been gaining popularity since its initial discovery by Braconot in 1811. However, fundamental knowledge and literature on chitin and its derivatives from insects are difficult to obtain. The most common and sought-after sources of chitin are shellfish (especially crustaceans) and other aquatic invertebrates. The amount of shellfish available is obviously restricted by the amount of food waste that is allowed; hence, it is a limited resource. Therefore, insects are the best choices since, out of 1.3 million species in the world, 900,000 are insects, making them the most abundant species in the world. In this review, a total of 82 samples from shellfish—crustaceans and mollusks (n = 46), insects (n = 23), and others (n = 13)—have been collected and studied for their chemical extraction of chitin and its derivatives. The aim of this paper is to review the extraction method of chitin and chitosan for a comparison of the optimal demineralization and deproteinization processes, with a consideration of insects as alternative sources of chitin. The methods employed in this review are based on comprehensive bibliographic research. Based on previous data, the chitin and chitosan contents of insects in past studies favorably compare and compete with those of commercial chitin and chitosan—for example, 45% in Bombyx eri, 36.6% in Periostracum cicadae (cicada sloughs), and 26.2% in Chyrysomya megacephala. Therefore, according to the data reported by previous researchers, demonstrating comparable yield values to those of crustacean chitin and the great interest in insects as alternative sources, efforts towards comprehensive knowledge in this field are relevant.

The use of metal nanoparticles (MNPs) in various fields is increasing day-by-day leading to a genuine concern about the issues related to their environmental and biological safety. The major approaches for the synthesis of NPs include physical and chemical methods which are expensive and hazardous to health in addition to being toxic to the environment. This review highlights the potential of plant extracts to carry out the synthesis of MNPs with a special emphasis on the role of flavonoids in nanosynthesis. This green and clean approach have been actively utilized in recent years as an alternative to conventional hazardous approaches. It has proved as cost-effective, non-toxic, less time and labor consuming, efficient, and eco-friendly method for the synthesis of MNPs with specific biological actions. This review also focuses on the role of polyphenols, including the flavonoids as bioreductants of metal salts for the synthesis of NPs along with their biomedical applications. Various examples of the MNPs, along with their biological actions, have also been summarized.

Turmeric (Curcuma longa) is extensively used as a spice and a coloring agent in Southeast Asia. Turmeric is used as a traditional remedy for cough, diabetic wounds, hepatic disorders, and rheumatism due to its antiseptic, antibacterial, and anti-inflammatory properties. Since the last few decades, extensive work has been done on turmeric and its constituents to explore its pharmacological actions. Curcumin is the main constituent of turmeric and is well demonstrated for its anti-inflammatory, hypoglycaemic, antioxidant, wound-healing, and antimicrobial activities. The functional neurons of the brain and synapses are lost in neurodegenerative disorders for which there is no permanent cure. Oxidative damage and inflammation play a role in age-related neurological disorders. The antioxidants have the ability to prevent different neurological disorders. Recent studies have shown that both turmeric and curcumin possess neuroprotective and cognitiveenhancing properties that help to prevent neurodegenerative diseases like Alzheimer's disease and Parkinson’s disease. Different experimental studies have indicated the antioxidant and anti-ageing properties of turmeric and curcumin. Various studies have shown that curcumin acts as a strong barrier against neurological disorders and, hence, it may be a potential drug candidate for the prevention of neurodegenerative diseases. The aim of this review was to present the current pieces of evidence in the literature regarding the neuroprotective effects of turmeric and curcumin.

In this study it was investigated the incorporation of different starches, such as sago starch, corn starch, potato starch, tapioca starch and wheat starch, in low-density polyethylene matrix (LDPE) to enhanced mechanical properties and to obtain partially biodegradable product with the aim to reduce the plastics wastes in the environment. For comparison, virgin LDPE, LDPE with different sources of starch blends were prepared and characterized under the same conditions. The starches were mixed to the LDPE using a twin screw extruder to guarantee the homogeneity of the formulations. The compound were shaping processed by injection moulding. The characterization of those compounds was done by physical (density, MFI), mechanical (Universal tensile machine). The addition of starch to LDPE reduced the MFI values, the tensile strength, elongation at break and impact strength, whereas the elastic modulus, flexural modulus and flexural strength increased. LDPE/SS show the good mechanical behavior compared to other formulation. The physical and mechanical properties were evident when 5 and 30 wt% were added. Water uptake increased with increased starch content and immersion time. The time taken for the composites to equilibrate was about one month even when they were immersed completely in water.

This study aimed to evaluate the physicochemical characteristics and mineral contents of dried extract of Averrhoa bilimbi and its antioxidant and antibacterial properties. Dried extracts leaves powder of A. bilimbi were analysed for its physicochemical properties and mineral compositions. The antioxidant and antibacterial capacities of extracts were determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the disc diffusion method respectively. The functional groups from active compounds were identified by Fourier Transforms Infrared Spectrophotometer (FTIR). Physicochemical characteristics of A. bilimbi dried extracts, including pH and total acids dissolved in water and ethanol solvents, showed negligible differences. The dried leaves powder of A. bilimbi was rich in carbohydrate, protein, and ash contents. It also exhibited essential minerals in which potassium was the highest content. Compared to water, ethanol extract showed more scavenging property against DPPH (82.82 mg GAE/ g DW) and gave a more inhibitory effect on the growth of Salmonella sp., Escherichia coli, and Staphylococcus aureus. The FTIR spectra showed phenolic compounds might be associated with the antioxidant and antibacterial activities of this extract. A. Bilimbi leaves are promising a source for the development of functional food to prevent diseases related to stress oxidative and bacterial infections.

This study aims to evaluate the effects of different drying methods on the physical properties, total phenolic content, total flavonoid content, and antioxidant activity of extracts from Moringa oliefera L. (MO) leaf waste. The effects of two drying techniques, namely, sun drying (A1) and tray drying (A2), on the physical and antioxidant properties of the extracts obtained using three extracting solvents, i.e., water (b1), ethanol (b2), and ethyl acetate (b3), were investigated. These extracts were analyzed for their physicochemical and antioxidant properties. The antioxidant properties were determined with the Folin Ciocalteau, aluminum chloride, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays. Fourier transform infrared spectrophotometry (FTIR) was used to identify functional groups in the active compounds. It was found that the physical properties of the MO extract, including yield, pH, total solids, and color, showed significant differences for the two drying methods (p < 0.05). The b3 extract had the highest value for total phenolic contents, total flavonoid contents, and antioxidant activities, followed by b2 and b1, respectively, for both the sun drying and tray drying methods. There was a significant correlation between the total phenolic and flavonoid contents and antioxidant activity (IC₅₀). This study reveals that waste material from MO leaves could be utilized as an antioxidant agent, which is expected to reduce environmental pollution from the MO processing industry.