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The present study explores the antifouling potentials of ethanol extract of mangrove Avicennia officinalis. Results of antibacterial activity inferred that extract had strongly inhibited the growth of fouling bacterial strains with significant differences in halos (9-16 mm) and showed minimal bacteriostatic (12.5–100 µg ml−1) and bactericidal (25-200µg ml−1) values. It had also strenuously suppressed fouling microalgae with appreciable MIC (12.5 and 50 µg ml−1). The extract had also effectively deterred settlement of larvae of Balanus amphitrite and byssal thread of mussel Perna indica with lower EC50 (11.67 and 37.43 µg ml−1) and higher LC50 (257.33 and 817 µg ml−1) values. Further 100% recuperation of mussels from toxicity assay and therapeutic ratio of >20 substantiated its non-toxicity. GC-MS profile of bioassay guided fraction showed four (M1-M4) major bioactive metabolites. In silico biodegradability study revealed that metabolites M1 (Pentanoic acid, 5-methoxy-, phenyl ester) and M3 (Benzaldehyde, methyl-) have rapid biodegradation rates and eco-friendly in nature.

Marine bionanotechnology is one of the most promising areas of research in modern science and technology. Although there are multitude methods for the synthesis of nanoparticles (NPs), there is an increasing attention in developing high-yield, low-cost, non-toxic and eco-friendly procedures. The vital advantages of greener synthesis are cost-effective, reduced usage of toxic chemicals and abundant availability of resources. During the last ten years, there have been many biological entities used to elevate novel, greener and affordable methods for the metal NPs synthesis. Rate of synthesis and stability are higher for plant material mediated NPs. However, in comparison with terrestrial resources, marine resources have not been fully explored for synthesis of noble metal NPs. Our present review is designed to speculate the importance of usage of vast marine resources and its mediated NPs synthesis, in particular seaweed-mediated NPs synthesis to overcome the limitations involved in physical and chemical methods. Finally, recent advancements in greener synthesis of metal NPs, their size, distribution, morphology and applications such as antimicrobial, antifouling and anticancer potentials are briefly described along with portraying the prospective scope of research in this field without any negative impact on the environment.

Bionanotechnology is one of the leading research which helps to synthesize nanoparticles through biological resources. In the present study silver oxide nanoparticles (Ag2O NPs) were biosynthesized using culture supernatant of Bacillus paramycoides and evaluated for its antibiofilm activity and cytotoxic potentiality. Characteristic absorption peak for Ag2O NPs was observed at 420 nm in UV–visible spectrum. X-ray diffraction pattern shows planes of face centered cubic crystalline Ag2O NPs and narrow peak confirms their crystalline nature. High Resolution Transmission Electron Microscopy exhibited spherical particles in the range of 25–70 nm diameter. Fourier transform infrared spectroscopic analysis of Ag2O NPs represents the peaks corresponding to the functional groups of metabolites present in the supernatant. The biosynthesized Ag2O NPs showed significant antibacterial activity against marine biofilm forming bacteria (Vibrio parahaemolyticus, Salmonella sp., Enterobacter sp. and Micrococcus sp.) as observed under confocal laser scanning microscope. The present study revealed that Ag2O NPs cause release of intracellular constituents including proteins through membrane damage leading to the bacterial cell death. Silver oxide nanoparticles also showed significant cytotoxicity on A549 lung cancer cells (IC50 = 58.5 μg mL−1) by MTT assay. A549 cells treated with Ag2O NPs showed signs of apoptosis as observed under fluorescent microscope. The present study highlights the possible use of Ag2O NPs as potential antibacterial, antibiofilm and anticancer agent.

The development of novel approaches in the biosynthesis of gold nanoparticles has significantly gained tremendous attention in the medical field. In the present study, an aqueous seaweed extract of the marine brown algae S. ilicifolium has been used for the synthesis of hybrid gold nanoparticles. The gold nanoparticles were found to be near-spherical in shape and size of 20–25 nm. Altogether, phytoconstituents such as polyols, proteins, and aromatic compounds play an important role in capping and stabilizing the hybrid gold nanoparticles. The hybrid gold nanoparticles were found to be crystalline as evidence by X-ray diffraction studies. We also demonstrated that synthesized hybrid gold nanoparticles exert antibacterial activity at 48 ± 1.36 μg mL−1 and cause selective cell death of Staphylococcus aureus by generating an enhanced level of intracellular ROS. Further, upon treatment with hybrid gold nanoparticles (24 ± 1.94 μgmL−1), the breast cancer cell lines showed more apoptotic features such as loss of membrane integrity and chromatin condensation when compared to the control groups. The biocompatibility assessment of hybrid gold nanoparticles in Artemia salina revealed that it does not elicit any lethal effect even at 250 μgmL−1. Taken together, these findings suggest that a hybrid nanoparticle from S. illicifolium is eco-friendly, has selective antibacterial activity, and effectively kills breast cancer cells by inducing apoptosis.

A novel actinobacterium, Streptomyces rochei (MSA-14) was isolated from the mining sediments of Indian Rare Earth (IRE) Ltd. southwest coast of India. Secondary metabolites were extracted from S. rochei using ethyl acetate. The crude ethyl acetate extract exhibited prominent antibacterial property with wide spectral inhibitory zones (3–15 mm) having least Minimum Inhibitory Concentration (1–50 μg/ml) and Minimum Bactericidal Concentration (10–100 μg/ml) against the tested bacterial pathogens. The extract evidenced remarkable antioxidant (91%) and hemolytic (45.52%) properties at 800 μg/ml. In addition, the extract recorded good cytotoxic effect against Artemia salina nauplii with the LC50 value of 106.75 μg/ml. Further, the extract was purified by normal phase silica column chromatography using step gradient solvent method. Among the column fractions, 14th fraction rendered good biomedicinal properties. The bioassay guided 14th fraction was further purified by preparative TLC. The lead compound was analysed using FT-IR and GC-MS analysis, which ascribed a prominent bioactive compound Pyrrolidine-2,4-Dione. In silico analysis on the biodegradability of Pyrrolidine-2,4-Dione using BIOWIN and ECOSAR signified that the identified bioactive compound is more plausible for the environment, eco-friendly, easily degradable within days to week under aerobic and anaerobic conditions. Also, it is non-toxic against chosen bacterial pathogens when compared with the standard antibiotic Streptomycin.