Nanotechnology is a dynamic field comprising chemistry, physics, biology, and engineering, with a high proficiency in disease treatment delivery methods. Metallic precursors (e.g.,AgNO₃) are widely used to synthesize NPs. But, owing to their harmful nature and the cost of these metallic nanoparticles, the focus is shifting toward "green synthesis" of nanoparticles using fungi, bacteria, plants, and algae. Hence, we used Padina commersonii to green synthesize NPs. We focused on the antioxidant, hypoglycemic, and antimicrobial efficacy of biologically synthesized AgNPs from P. commersonii. Silver NPs (AgNPs) were synthesized using 80% methanol extract of P. commersonii upon removal of pigments and polysaccharides. Methanol (80%) was selected for higher polyphenol yield (∼30% w/w) compared to aqueous extracts (∼12% w/w), critical for efficient Ag⁺ reduction. Major phytochemicals, including fucoidan, phlorotannins, flavonoids (quercetin), and terpenes, are present in 80% methanol extract of P. Commersonii The NPs were characterized using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, dynamic light scattering, energy dispersive X-ray (X-ray diffraction (XRD), and scanning electron microscopy (SEM). Antioxidant potential was determined using DPPH and ABTS scavenging assays, while hypoglycemic activity was conducted using alpha-glucosidase and alpha-amylase enzyme inhibitory assays. Finally, antimicrobial activities were conducted against S. aureus, E. coli (bacteria), and the fungal strains Candida albicans and Aspergillus niger. The AgNPs were confirmed by the colour change from yellow to brown. Further, the UV and Raman spectrophotometry peaks, respectively, at 424 nm and 335 cm^-1, confirmed the presence of AgNPs. The average AgNPs size of 73.19 nm was obtained using the dynamic light scattering(DLS) technique, while the zeta potential indicated its stability at -21.5 mV. The SEM imaging confirmed a smooth surface with no aggregation, whereas the XRD pattern perceived the crystalline nature of these AgNPs. The antioxidant potential of AgNPs was higher than (DPPH: IC₅₀: 271.17 ± 3.992 and ABTS: IC50 195.03 ± 5.7535 µg/mL) the methanol extract. Similar patterns were observed with the hypoglycemic potential with α-glucosidase (IC50:161.74 ± 3.992 µg/mL) and α-amylase inhibitions (IC50: 176.70 ± 5.7535 µg/mL). The antimicrobial efficacy of AgNPs was evident for studied bacterial species (S.aureus:12.77 ± 0.58 mm; E.coli:15.27 ± 0.58 mm) and fungi (A. niger: 18.10 ± 0.15 mm; C.albicans: 17.4 ± 0.57 mm). The AgNPs displayed potent antidiabetic and antimicrobial efficacy, suggesting their potential as viable alternatives to conventional antibiotic and antidiabetic drugs.

The relative lack of marine venom could be attributed to the difficulty in dealing with venomous marine animals. Moreover, the venom of marine animals consists of various bioactive molecules, many of which are proteins with unique properties. In this study, we investigated the potential toxic proteins of jellyfish collected for ligand screening to understand the mechanism of the toxic effects of jellyfish. Since taxonomic identification is problematic due to the lack of proper keys, we conducted morphological and molecular mitochondrial DNA sequencing from COI and ITS regions. The venom extract from nematocysts found along the bell margins was used for protein characterization using SDS-gel electrophoresis and nano-liquid chromatography-tandem mass spectrometry. Ligand screening for the most potent toxin and antibacterial and cytotoxicity assays were carried out. The phylogenetic tree showed distinct clustering from other Catostylus sp. The proteomic analysis revealed venom with many bioactive proteins. Only 13 venom proteins were identified with molecular weights ranging from 4318 to 184,923 Da, exhibiting the venom’s complexity. The overall toxin protein composition of Catostylus sp. venom was dominated by potassium channel toxin alpha-KTx. Molecular docking of toxin alpha-KTx 1.13 revealed high specificity towards the human voltage-gated potassium channel Kv3 with a high fitness score and a minimum energy barrier of −17.9 kcal/mol. Disc diffusion and cytotoxicity assays revealed potent antibacterial activity against Klebsiella pneumoniae with no cytotoxicity. Further studies on detailed characterization and therapeutic potentials are warranted.