Activity of blue green microalgae extracts against in vitro generated Staphylococcus aureus with reduced susceptibility to vancomycin

Insight to biotechnological utility of phycochemicals from cyanobacterium Anabaena sp.: An overview

Cyanobacteria (blue-green algae) are well-known for the ability to excrete extra-cellular products, as a variety of cyanochemicals (phycocompounds) of curio with several extensive therapeutic applications. Among these phycocompound, the cyanotoxins from certain water-bloom forming taxa are toxic to biota, including crocodiles. Failure of current non-renewable source compounds in producing sustainable and non-toxic therapeutics led the urgency of discovering products from natural sources. Particularly, compounds of the filamentous N2-fixing Anabaena sp. have effective antibacterial, antifungal, antioxidant, and anticancer properties. Today, such newer compounds are the potential targets for the possible novel chemical scaffolds, suitable for mainstream-drug development cascades. Bioactive compounds of Anabaena sp. such as, anatoxins, hassallidins and phycobiliproteins have proven their inherent antibacterial, antifungal, and antineoplastic activities, respectively. Herein, the available details of the biomass production and the inherent phyco-constituents namely, alkaloids, lipids, phenols, peptides, proteins, polysaccharides, terpenoids and cyanotoxins are considered, along with geographical distributions and morphological characteristics of the cyanobacterium. The acquisitions of cyanochemicals in recent years have newly addressed several pharmaceutical aliments, and the understanding of the associated molecular interactions of phycochemicals have been considered, for plausible use in drug developments in future.

Bioprospecting microalgae and cyanobacteria for biopharmaceutical applications

Microalgae and cyanobacteria have sparked a lot of interest due to their potential in various industries like biorefineries, biopharmaceuticals, food supplements, nutraceuticals, and other high-value products. Polysaccharides, vitamins, proteins, enzymes, and steroids are valuable products isolated from microalgae and cyanobacteria and potentially used in health and biomedical applications. Bioactive compounds derived from microalgae and cyanobacteria exhibit various pharmaceutical properties like antibacterial, anticancer, antiviral, antialgal, and antioxidant. From the properties listed above, the research for novel antibiotics has become particularly appropriate. In addition, the possible emergence of resistance against pathogens, as well as the potential decline in antibiotic efficacy, has prompted researchers to look for a new source of antibiotics. Microalgae and cyanobacteria have indicated a great and unexplored potential among these sources. For this reason, microalgae and cyanobacteria have been highlighted for their efficiency in different industrial sectors, as well as for their potential uses in the betterment of human and environmental health. This review gives an overview of bioactive compounds and metabolites with several biological properties isolated from microalgae and cyanobacteria for treating different animal and human diseases.

Phycochemistry and bioactivity of cyanobacterial secondary metabolites

Microbes are a huge contributor to people's health around the world since they produce a lot of beneficial secondary metabolites. Cyanobacteria are photosynthetic prokaryotic bacteria cosmopolitan in nature. Adaptability of cyanobacteria to wide spectrum of environment can be contributed to the production of various secondary metabolites which are also therapeutic in nature. As a result, they are a good option for the development of medicinal molecules. These metabolites could be interesting COVID-19 therapeutic options because the majority of these compounds have demonstrated substantial pharmacological actions, such as neurotoxicity, cytotoxicity, and antiviral activity against HCMV, HSV-1, HHV-6, and HIV-1. They have been reported to produce a single metabolite active against wide spectrum of microbes like Fischerella ambigua produces ambigols active against bacteria, fungi and protozoa. Similarly, Moorea producens produces malygomides O and P, majusculamide C and somocystinamide which are active against bacteria, fungi and tumour cells, respectively. In addition to the above, Moorea sp. produce apratoxin A and dolastatin 15 possessing anti cancerous activity but unfortunately till date only brentuximab vedotin (trade name Adcetris), a medication derived from marine peptides, for the treatment of Hodgkin lymphoma and anaplastic large cell lymphoma has been approved by FDA. However, several publications have effectively described and categorised cyanobacterial medicines based on their biological action. In present review, an effort is made to categorize cyanobacterial metabolites on the basis of their phycochemistry. The goal of this review is to categorise cyanobacterial metabolites based on their chemical functional group, which has yet to be described.

Antibacterial, antifungal and antimycobacterial compounds from cyanobacteria

Infections from multidrug resistant (MDR) pathogenic bacteria, fungi and Mycobacterium tuberculosis remain progressively intractable. The search of effective antimicrobials from other possible non-conventional sources against MDR pathogenic bacteria, fungi and mycobacteria is call of the day. This review considers 121 cyanobacterial compounds or cyano-compounds with antimicrobial activities. Chemical structures of cyano-compounds were retrieved from ChemSpider and PubChem databases and were visualized by the software ChemDraw Ultra. Chemical information on cyano-compounds pertaining to Lipinski rules of five was assessed. The reviewed cyano-compounds belong to the following chemical classes (with examples): alkaloids (ambiguine isonitriles and 12-epi-hapalindole E isonitrile), aromatic compounds (benzoic acid and cyanobacterin), cyclic depsipeptides (cryptophycin 52 and lyngbyabellin A), cyclic peptides (calophycin and tenuecyclamides), cyclic undecapeptides (kawaguchipeptins and lyngbyazothrin A), cyclophane (carbamidocyclophane), extracellular pigment (nostocine A), fatty acids (alpha-dimorphecolic acid and majusculonic acid), linear peptides (muscoride A), lipopeptides (fischerellins and scytonemin A), nucleosides (tolytoxin and tubercidin), phenols (ambigols and 4-4'-hydroxybiphenyl), macrolides (scytophycin A and tolytoxin), polyketides (malyngolide and nostocyclyne), polyphenyl ethers (crossbyanol A), porphinoids (tolyporphin J) and terpenoids (noscomin and scytoscalarol). Cyanobacteria appear to be a diverse source of compounds with antimicrobial activity. Further attention is required to elucidate whether those could be applied as pharmaceuticals.

Current perspectives on the dynamics of antibiotic resistance in different reservoirs

Antibiotic resistance consists of a dynamic web. In this review, we describe the path by which different antibiotic residues and antibiotic resistance genes disseminate among relevant reservoirs (human, animal, and environmental settings), evaluating how these events contribute to the current scenario of antibiotic resistance. The relationship between the spread of resistance and the contribution of different genetic elements and events is revisited, exploring examples of the processes by which successful mobile resistance genes spread across different niches. The importance of classic and next generation molecular approaches, as well as action plans and policies which might aid in the fight against antibiotic resistance, are also reviewed.

Unraveling cyanobacteria ecology in wastewater treatment plants (WWTP)

Cyanobacteria may be important components of wastewater treatment plants' (WWTP) biological treatment, reaching levels of 100% of the total phytoplankton density in some systems. The occurrence of cyanobacteria and their associated toxins in these systems present a risk to the aquatic environments and to public health, changing drastically the ecology of microbial communities and associated organisms. Many studies reveal that cyanotoxins, namely microcystins may not act as antibacterial compounds but they might have negative impacts on protozoans, inhibiting their growing and respiration rates and leading to changes in cellular morphology, decreasing consequently the treatment efficacy in WWTP. On the other side, flagellates and ciliates may ingest some cyanobacteria species while the formation of colonies by these prokaryotes may be seen as a defense mechanism against predation. Problems regarding the occurrence of cyanobacteria in WWTP are not limited to toxin production. Other cyanobacterial secondary metabolites may act as antibacterial compounds leading to the disruption of bacterial communities that biologically convert organic materials in WWTP being fundamental to the efficacy of the process. Studies reveal that the potential antibacterial capacity differs according to cyanobacteria specie and it seems to be more effective in Gram (+) bacteria. Thus, to understand the effects of cyanobacterial communities in the efficiency of the waste water treatment it will be necessary to unravel the complex interactions between cyanobacterial populations, bacteria, and protozoa in WWTP in situ studies.

Cyanobacteria: an emerging source for drug discovery

The c group of Gram-negative gliding bacteria, has a long history of cosmopolitan occurrence. It has great biodiversity despite the absence of sexual reproduction. This wide biodiversity may be reflected in the wide spectrum of its secondary metabolites. These cyanobacterial secondary metabolites are biosynthesized by a variety of routes, notably by non-ribosomal peptide synthetase or polyketide synthetase systems, and show a wide range of biological activities including anticancer, antibacterial, antiviral and protease inhibition activities. This high degree of chemical diversity in cyanobacterial secondary metabolites may thus constitute a prolific source of new entities leading to the development of new pharmaceuticals.