Muthuvel Arumugam

This chapter centers on the novel marine metabolites from marine organisms, especially peptides and other therapeutic agents. The major component of the innate immune defense system, also regarded as the first line of defense, is the antimicrobial peptide, which not only boosts resistance but also displays promising curative properties. The isolation, potential antimicrobial activity, various properties, mechanism and sources of diversified antimicrobial peptides distributed in various phyla of marine invertebrates, along with their potential role in the therapeutic arena, are explored. The most popular conotoxin peptide Zincnotide was available as a drug (Prialt®) and entered the market as a potent analgesic agent. Ethionamide (Trecator®), a nicotinamide derivative, isolated from porifera possessing antibacterial activity, is used to treat tuberculosis. Similarly, a number of peptides have been reported for exhibiting antimicrobial activities in marine organisms. Hence, the present chapter is mainly focusing on the list of marine invertebrates’ antimicrobial peptides and their therapeutic applications.

The marine environment continues to surprise us by producing novel bioactive substances with a wide range of benefits for humans. Materials and Methods: Marine bioluminescent bacteria Photobacterium leiognathi was isolated from pony fish, Secutorruconius which was confirmed with microscopic and molecular characterization. The secondary metabolite of the isolated bacteria was extracted with dichloromethane. The chemical fingerprinting of the isolated metabolite was analyzed through TLC, FT-IR, and HPLC. The nature of the compound present in the metabolite was identified in the gas chromatography-mass spectrometry analysis (GC - MS). The isolated extract was investigated for its antibacterial property against 10 human pathogenic bacteria and also its antioxidant activity using different assays such as 1, 1-Diphenyl-2-picrylhydrazyl, Phosphomolybdenum, Metal chelating, Hydroxyl radical scavenging and hydrogen peroxide scavenging activity. Results: The Presence of functional groups including phenols, sugars, and amino acids in the extracts were identified by TLC. Totally, nine peaks were obtained for the crude extract through the FTIR spectrum range of 400 to 4000 cm-1 for the active sample. The DCM extract showed a broad spectrum of antibacterial activity against the six human bacterial pathogens. Secondary metabolites from the bioluminescent bacteria, P. leiognathi, have strong antioxidant properties. These results will be instrumental in developing novel products with biosensors and bio-imaging applications using P. leiognathi.

Green synthesis is an effective method for the synthesis of metal and metal oxide nanoparticles. The strong affinity nature of phytochemicals has been effectively utilized as a source of non-toxic nanoparticle production. The optimized pH, concentration, temperature, reaction time needed for non-aggregated and stable biosynthesis silver nanoparticles. The surface modifications of silver nanoparticles over the functionalization of natural compounds are generated unbelievable new thoughts on its properties. Biomolecules in plant extract redirect different safe and size on designed material, which cater as key instruments for harvesting the UV-region. The bio-interaction of structural integrity silver nanomaterial’s are promoted the reactive oxygen species in the wound, redox peak potential on cyclic voltammetry, spectral alteration at surface plasmon resonance (SPR) effect and redox reaction on the degradation of organic dyes. In this review, the utilization of different biological compounds and their role of mechanism in the evergreen latest application of colorimetric sensing, electrochemical analysis, wound healing and catalyst areas is discussed.

Marine microalgae such as Isochrysis sp. and Pavlova sp. are the predominant source of polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA, 20:5n–3) and docosahexaenoic acid (DHA, 22:6n–3). EPA biosynthesis pathway is predominant in lower eukaryotes, and its biosynthetic gene expressions are not well established. Till date, the C18 elongation enzymes for EPA biosynthesis have not been identified from lower eukaryote. In the present study, we describe the identification of two microalgal genes Δ6-elongase and Δ5-desaturase involved for EPA biosynthesis. By PCR-based technique, a novel elongase gene (Δ6Elo-Iso) was isolated from Isochrysis sp., and 654 bp of full-length sequence was identified, which catalysed the conversion of SDA into ETr in E. coli. The identified gene displayed unique substrate specificity for both n-3 and n-6 C18-substrates for Δ6-elongation, with no activity towards Δ9-elongase. In addition, a novel Δ5-desaturase gene (Δ5Des-Pav) was isolated from Pavlova sp. and found an ORF of 1149 bp in length, which was capable of converting ETr into EPA in omega-3 pathway. For the first time, the heterologous expressions of two novel microalgal genes were successfully expressed in Escherichia coli. EPA production from E. coli is being considered as an alternative and economic source for industrial and pharmaceutical sectors.