Evaluation of In Vitro Antioxidant, Anti-Obesity, and Anti-Diabetic Activities of Opuntia ficus Cladodes Gel and Its Application as a Preservative Coating for Shrimp during Refrigerated Storage

Opuntia ficus cladodes (OFC) are considered one of the wastes that result from opuntia cultivation, and their disposal by traditional methods results in many environmental problems. Therefore, this study was conducted with two aims. The first was the production of OFC gel, and the evaluation of its in vitro antioxidant (by two methods, DPPH and ABTS), anti-obesity, and anti-diabetic activities. The second was an investigation of the effects of different concentrations of this gel (0, 50, and 100%) as an edible coating on the quality of shrimp during 8 days of refrigerated storage. The results showed that this gel was characterised by a high content of ash (10.42%), total carbohydrates (75.17%), and total phenols (19.79 mg GAE/g). OFC gel contained six types of sugars: arabinose, xylose, galactose, rhamnose, glucose, and uronic acid, and the most abundant was xylose (36.72%). It is also clear from the results that the OFC gel had high antioxidant properties, which were higher against DPPH than ABTS at the same concentration. OFC gel showed a high inhibition activity against lipase, α-glycosidase, and α-amylase enzymes, and their IC50 values were 1.43 mg/mL, 0.78 mg/mL, and 0.57 mg/mL, respectively. The results also stated that shrimp coated with OFC gel had lower pH, drip loss, TVB-N, and TBA values through the days of refrigerated storage. Moreover, the shrimp coated with 100% OFC gel were better than those coated with 50% OFC gel. In conclusion, OFC gel showed high potency as active antioxidant, for its enzyme anti-activities, and as an edible coating for shrimp.

Silver Nanoparticle Synthesis by Rumex vesicarius Extract and Its Applicability against Foodborne Pathogens

The consumption of foods polluted with different foodborne pathogens such as fungus, viruses, and bacteria is considered a serious cause of foodborne disease in both humans and animals. Multidrug-resistant foodborne pathogens (MRFP) cause morbidity, death, and substantial economic loss, as well as prolonged hospitalization. This study reports on the use of aqueous Rumex leaf extract (ARLE) in the synthesis of silver nanoparticles (ARLE-AgNPs) with versatile biological activities. The synthesized ARLE-AgNPs had spherical shapes with smooth surfaces and an average hydrodynamic size of 27 nm. ARLE-AgNPs inhibited the growth of Escherichia coli ATCC25721, Pseudomonas aeruginosa ATCC27843, Streptococcus gordonii ATCC49716, Enterococcus faecalis ATCC700813, and Staphylococcus aureus ATCC4342. The ARLE-AgNPs were more active against Escherichia coli ATCC25721 than other harmful bacterial strains (26 ± 3 mm). The zone of inhibition for antibacterial activity ranged between 18 ± 3 mm and 26 ± 3 mm in diameter. The nanoparticles' MIC values varied from 5.19 µg/mL to 61 µg/mL, while their MBC values ranged from 46 µg/mL to 119 µg/mL. The nanoparticles that were created had antioxidant potential. The cytotoxic activity was tested using normal fibroblast cell lines (L-929), and the enhanced IC50 value (764.3 ± 3.9 g/mL) demonstrated good biological compatibility. These nanoparticles could be evolved into new antibacterial compounds for MRFP prevention.