Antibacterial, antifungal and antimycobacterial compounds from cyanobacteria

Malyngamide C a potential inhibitor of protein synthesis Machinery targeting peptide deformylase enzyme

Due to the rising incidence of antibiotic-resistant and bacterial illnesses, new therapeutic drugs are essential to target vital bacterial enzymes. Peptide deformylase is an attractive antibacterial target because it plays a pivotal role in protein synthesis. The present study was guided to identify the potential inhibitors of peptide deformylase (PDF), viz., computational methods such as molecular docking, molecular dynamics (MD) simulations, thermodynamic stability, free energy calculations, and ADMET analysis. Here we observed the toxicity profile and drug-likeness of the in-house cyanopeptides database. The malyngamide C showed good oral bioavailability. Molecular docking experiments revealed that malyngamide C showed a better binding affinity of -8.81 kcal/mol than reference actinonin -7.08 kcal/mol. Next, MD simulations revealed that malyngamide C, tumonoic acid A, borophycin, and actinonin were found stable in the binding pocket of PDF observed for 300 ns. The binding posture was well-retained, with negligible RMSD, and found within permissible limits observed throughout the simulations. From the MM/PBSA calculations, the free binding energy of malyngamide C was found to be -145.281 kJ/mol, significantly exceeding other selected molecules, including actinonin. The malyngamide C could be a lead antibacterial candidate with a good safety profile. These computational findings strongly support its experimental validation and further clinical investigations as a novel antibacterial agent to combat drug-resistant bacterial infections.

Fungi as a Critical Component of Lake Microbiota in Response to Cyanobacterial Harmful Algal Blooms

Cyanobacterial Harmful Algal Blooms (CyanoHABs) pose a growing threat to lake ecosystems. While microbial communities constitute the resilient power of lake ecosystems to CyanoHAB disturbances, the role of fungi remains underexplored. Here, the dynamics of size-fractionated fungal and associated bacterial communities were tracked across the peak and decline stages of a CyanoHAB event in shallow subtropical Lake Taihu. The results revealed that the composition of fungal and bacterial communities in separated size fractions varied between bloom stages, with enrichment patterns likely influenced by their reliance on algal-derived nutrients. Null model-based analysis revealed a shift in fungal community assembly, from dominance by dispersal limitation (44%) and drift (30%) at the peak stage to increased homogeneous selection (44%) at the early decline stage, whereas bacterial communities remained predominantly shaped by stochastic processes, highlighting their distinct responses to cyanobacterial biomass decomposition. Comparative topological analysis of microbial co-occurrence networks showed strengthened cross-kingdom fungi-bacteria interactions as the bloom declined, especially within decomposing cyanobacterial colonies, facilitating nutrient cycling and accelerating cyanobacterial biomass removal. These findings led to a conceptual model proposing fungi as critical members of the freshwater microbiome in eutrophic lakes, driving biogeochemical cycling and potentially contributing to the resilience of the lake ecosystem against CyanoHABs.

Insilico molecular characterization of a cyanobacterial lytic polysaccharide monooxygenase

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that catalyze the oxidative cleavage of β(1-4) glycosidic bonds and have attracted considerable attention because of their potential for enhancing efficiency in degrading recalcitrant polymeric substrates, in synergism with hydrolytic enzymes. Fungal-derived LPMOs are the most prevalent type, while other taxonomic groups have been described as potential alternative sources of these enzymes. In the present study, we aimed to identify and characterize in silico a LPMO of cyanobacterial origin with putative functions in chitin depolymerization. A similarity search of sequences and conservation of domains with characterized LPMOs identified a 289 amino acid protein from the cyanobacterium Mastigocoleus testarum (Order Nostocales), likely belonging to the CAZy-AA10 class. This protein is referred to as MtLPMO10. Phylogenetic analysis revealed that MtLPMO10 is homologous to the protein Tma12 from the fern Tectaria macrodonta, with 52.11 % sequence identity, which was the first LPMO characterized as originating from the plant kingdom. The protein tertiary structure predicted by the AlphaFold server indicates structural features common to LPMOs, such as a histidine brace formed by His31 and His132 and an immunoglobulin-like domain composed of antiparallel beta strands. Molecular dynamics (MD) simulation allowed the assessment of the enzyme-substrate affinity, using an initial pose based on literature data. The MtLPMO10-chitin complex remained stable during 100ns of MD, while the MtLPMO10-cellulose complex dissociated within 30ns of MD. Additionally, there was a shorter Cu(I)-H4 distance in the protein-substrate complex compared to the Cu(I)-H1 distance (averages of 6.0 ± 0.7 Å and 7.9 ± 0.7 Å, respectively), suggesting a C4 regioselectivity. This study highlights the existence of lytic polysaccharide monooxygenases in cyanobacteria and paves the way for further investigations related to this enigmatic class of enzymes and their potential use in biotechnological applications.

Target-specific high-throughput screening of anti-inflammatory phytosteroids for autoimmune diseases: A molecular docking-dynamics simulation approach

Without proper pathophysiology and recommended therapy, synthetic steroids are widely used as a first-line option for the management of autoimmune diseases. However, their prolonged use often leads to severe side effects such as osteoporosis, hypertension, cardiovascular, gastrointestinal complications, etc. To search for potential and safer therapeutic options, the present study aims to explore the potency and drug-ability profiles of anti-inflammatory phytosteroids (PSs). In a target-specific approach, we have selected three key molecular targets: glucocorticoid receptor/GR (PDB ID: 4P6W), cyclooxygenase-2/COX2 (PDB ID: 5F1A), and inducible nitric oxide synthase/iNOS (PDB ID: 4NOS) for a docking study of 167) selected PSs. The drug-chemistry profiles (physicochemical, toxicity, pharmacokinetic, drug-ability, etc.) of PSs were also assessed using various bioinformatics and chemoinformatics tools. The above assessment suggested that withaminilide B (PS46) is a lead candidate with higher drug-ability properties. Further, the drug stability and kinetic behaviour of the lead with the GR target 'GR-withaminilide B' in comparison with the control drug, 'GR-triamcinolone acetonide' docking complex, were studied through molecular dynamics (MD) simulation at 200 nanosecond with free energy calculation (MM/PBSA). Overall findings suggested that PSs exhibit distinct drug-ability profiles based on their functional attachments with a steroidal core moiety, where withaminilide B is a lead PSs among all to be used as alternative/ complementary candidates expected with limited adverse effects. Further experimentation is essential before mainstream application, but the study provided a platform to select drug-able candidates with a higher chance of experimental success and accelerate the drug discovery process within limited resources.

Xanthocillin X combats Burkholderia pseudomallei by targeting UDP-N-acetylglucosamine acyltransferase

Drug-resistance in Burkholderia pseudomallei (B. pseudomallei) and the limited ability of antibiotics to eradicate biofilms underscore the urgent need for alternative therapeutic options. New drugs which suppress the biofilm formation without emergence of antimicrobial resistance have clearly attracted global attention. We report a deep-sea-derived natural product xanthocillin X (Xan) for the therapeutic of B. pseudomallei 1 induced infections. Xan possesses superior antibacterial ability over commercial ceftazidime even at an ultralow concentration of 62.5 ng/mL, and can inhibit the formation of biofilm with high efficiency without drug resistance. Specially, Xan demonstrates stable binding ability with LpxA which is responsible for lipopolysaccharide synthesis, and thus disrupting the formation of biofilm. In two murine models, Xan exhibits therapeutic potency for combating B. pseudomallei 1 induced infections. Taken together, Xan that specifically interacts with LpxA impairs the formation of biofilm without drug resistance, endowing the compound with dominant antibacterial activity and accelerating tissue repair after infection.

Tubercidin enhances apoptosis in serum-starved and hypoxic mouse cardiomyocytes by inducing nuclear speckle condensation

Tubercidin, known for its antimicrobial, antiparasitic, and anticancer effects, faces clinical limitations due to adverse effects, especially cardiotoxicity risks for those with ischemic cardiomyopathy. This study aims to clarify the molecular pathways of Tubercidin-induced cardiotoxicity, focusing on nuclear speckles (NSs) disruption in cardiomyocytes under serum deprivation and/or hypoxia. To simulate ischemic cardiomyopathy in vitro, we utilized FMC84 and HL-1 murine cardiomyocyte cell lines, exposing them to conditions of serum limitation and/or hypoxia to evaluate the cardiotoxic impact of Tubercidin and the contributing mechanisms. Apoptosis was quantified using flow cytometry, NSs condensation was visualized via immunofluorescence with an anti-SC35 antibody, and the expression levels of key apoptotic transcripts (RFFL, RIF1, and RNF144B) were analyzed by RT-PCR. Our findings revealed that Tubercidin significantly increased apoptosis in both HL-1 and FMC84 cell lines under conditions mimicking serum deprivation (21% O2 with 1% FBS), hypoxia (1% O2 with 10% FBS), or a combination of both. Furthermore, Tubercidin treatment led to a pronounced enlargement of NSs, as detected by immunofluorescence. Concurrently, we documented significant alterations in the expression of critical apoptotic regulatory genes, implying that Tubercidin may modulate the apoptotic pathway in stressed cardiomyocytes. It is hypothesized that Tubercidin induces NSs condensation, affecting alternative splicing of cell death genes, potentially worsening ischemic cardiomyocytes' damage. Therefore, a cautious clinical use of Tubercidin for ischemic cardiomyopathy patients is advised to reduce cardiotoxicity risks.

Antimicrobial peptides (AMPs) from microalgae as an alternative to conventional antibiotics in aquaculture

The excessive use of conventional antibiotics has resulted in significant aquatic pollution and a concerning surge in drug-resistant bacteria. Efforts have been consolidated to explore and develop environmentally friendly antimicrobial alternatives to mitigate the imminent threat posed by multi-resistant pathogens. Antimicrobial peptides (AMPs) have gained prominence due to their low propensity to induce bacterial resistance, attributed to their multiple mechanisms of action and synergistic effects. Microalgae, particularly cyanobacteria, have emerged as promising alternatives with antibiotic potential to address these challenges. The aim of this review is to present some AMPs extracted from microalgae, emphasizing their activity against common pathogens and elucidating their mechanisms of action, as well as their potential application in the aquaculture industry. Likewise, the biosynthesis, advantages and disadvantages of the use of AMPs are described. Currently, biotechnology tolls are used to enhance the action of these peptides, such as genetically modified microalgae and recombinant proteins. Cyanobacteria are also mentioned as major producers of peptides, among them, the genus Lyngbya is described as the most important producer of bioactive peptides with potential therapeutic use. The majority of cyanobacterial AMPs are of the cyclic type, meaning that they have cysteine and disulfide bridges, thanks to this, their greater antimicrobial activity and selectivity. Likewise, we found that large hydrophobic aromatic amino acid residues increase specificity, and improve antibacterial efficacy. However, based on the results of this review, it is possible to highlight that while microalgae show potential as a source of AMPs, further research in this field is necessary to achieve safe and competitive production. Therefore, the data presented here can aid in the selection of microalgal species, peptide structures, and target bacteria, with the goal of establishing biotechnological platforms for aquaculture applications.

[Production and biological activity of the triazine derivatives: focusing on antibiotics produced by bacteria]

Heterocyclic triazines and their derivatives have excellent biological activity and have been used as herbicides and anticancer drugs. A large number of derivatives were synthesized and their biological activity was investigated. Some bacteria synthesize the triazine derivatives such as Nostocine A, Toxoflavin, and Fluviol from GTP using enzymes similar to those in the synthesis pathway of Riboflavin (vitamin B2). These triazine derivatives show antibiotic activity. In particular, research on Toxoflavin has progressed as a toxin produced by bacteria that cause seedling rot and rice grain blight in rice. It has recently been revealed that Fluviol, which is produced by bacteria, acts to suppress the growth of pathogenic bacteria. This review will focus on triazine derivatives produced by bacteria.

Hidden potential of hydrazinecarboxamides (semicarbazides) as potential antimicrobial agents: A review

Hydrazinecarboxamides (semicarbazides) are increasingly recognized as a versatile scaffold in developing potential antimicrobial agents. In addition to a brief overview of the synthetic methods to prepare them, this review comprehensively analyses their antimicrobial properties. These derivatives have demonstrated potent activity against a broad spectrum of mycobacteria, bacterial and fungal pathogens, highlighting their potential to address critical human health challenges, including neglected diseases, and to combat growing antimicrobial resistance. They have also been investigated for their antiviral and antiparasitic properties. The review also summarizes structure-activity relationships, known mechanisms of action and emphasizes the crucial role of the hydrazinecarboxamide moiety in facilitating interactions with biological targets. The combination of hydrazinecarboxamides with other bioactive scaffolds (primaquine, isoniazid, etc.) has led to an identification of promising drug candidates, including those active against resistant strains, offering a promising approach for future innovations in the field of antimicrobial therapy. Attention is also drawn to limitations of hydrazinecarboxamides (poor physicochemical properties, cytotoxicity to human cells, and insufficient target selectivity), which may hinder their clinical application.

Isolation, Identification and Pigment Analysis of Novel Cyanobacterial Strains from Thermal Springs

Cyanobacterial pigments have attracted considerable attention in industry due to their bioactive potential and natural origin. In the present study, the growth dynamics and pigment composition, in terms of chlorophyll a, total carotenoids and phycobiliprotein content, of four cyanobacterial strains isolated from thermal springs, namely Oscillatoria subbrevis CZS 2201, Phormidium ambiguum CZS 2205, Nostoc calcicola TSZ 2203, and Synechococcus sp. CZS 2204, were investigated. The analysis revealed that the maximum quantity of chlorophyll a and total carotenoids was observed in Oscillatoria subbrevis CZS 2201 (26.49 and 3.44 µg mL-1), followed by Phormidium ambiguum CZS 2205 (18.64 and 2.32 µg mL-1), whereas a minimum amount was detected in Synechococcus sp. CZS 2204 (12.13 and 1.24 µg mL-1), respectively. In addition, Oscillatoria subbrevis CZS 2201 showed higher quantity of phycobiliproteins, especially C-phycocyanin (45.81 mg g-1), C-phycoerythrin (64.17 mg g-1) and C-allophycocyanin (27.45 mg g-1). Moreover, carotenoid derivatives of Oscillatoria subbrevis CZS 2201 were also identified, among which β-carotene was the dominant form (1.94 µg mL-1), while the accumulation of zeaxanthin and myxoxanthophyll was relatively high (0.53 and 0.41 µg mL-1, respectively) compared with echinenone and cryptoxanthin (0.34 and 0.23 µg mL-1, respectively). The study revealed that Oscillatoria subbrevis CZS 2201 was a potent producer of secondary carotenoids, including myxoxanthophyll.

Bioactivity of Amphidinol-Containing Extracts of Amphidinium carterae Grown Under Varying Cultivation Conditions

Microalgae are of great interest due to their ability to produce valuable compounds, such as pigments, omega-3 fatty acids, antioxidants, and antimicrobials. The dinoflagellate genus Amphidinium is particularly notable for its amphidinol-like compounds, which exhibit antibacterial and antifungal properties. This study utilized a two-stage cultivation method to grow Amphidinium carterae CCAP 1102/8 under varying conditions, such as blue LED light, increased salinity, and the addition of sodium carbonate or hydrogen peroxide. After cultivation, the biomass was extracted and fractionated using solid-phase extraction, yielding six fractions per treatment. These fractions were analyzed using Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS/MS) to identify their chemical components. Key amphidinol compounds (AM-B, AM-C, AM-22, and AM-A) were identified, with AM-B being the most abundant in Fraction 4, followed by AM-C. Fraction 5 also contained a significant amount of AM-C along with an unknown compound. Fraction 4 returned the highest antimicrobial activity against the pathogens Staphylococcus aureus, Enterococcus faecalis, and Candida albicans, with Minimal Biocidal Concentrations (MBCs) ranging from 1 to 512 µg/mL. Results indicate that the modulation of both amphidinol profile and fraction bioactivity can be induced by adjusting the cultivation parameters used to grow two-stage batch cultures of A. carterae.

Piperlongumine and its derivatives against cancer: A recent update and future prospective

Piperlongumine, or piplartine (PL), is a bioactive alkaloid isolated from Piper longum L. and a potent phytoconstituent in Indian Ayurveda and traditional Chinese medicine with a lot of therapeutic benefits. Apart from all of its biological activities, it demonstrates multimodal anticancer activity by targeting various cancer-associated pathways and being less toxic to normal cells. According to their structure-activity relationship (SAR), the trimethylphenyl ring (cinnamoyl core) and 5,6-dihydropyridin-2-(1H)-one (piperdine core) are responsible for the potent anticancer activity. However, it has poor intrinsic properties (low aqueous solubility, poor bioavailability, etc.). As a result, pharmaceutical researchers have been trying to optimise or modify the structure of PL to improve the drug-likeness profiles. The present review selected 26 eligible research articles on PL derivatives published between 2012 and 2023, followed by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) format. We have thoroughly summarised the anticancer potency, mode of action, SAR and drug chemistry of the proposed PL-derivatives against different cancer cells. Overall, SAR analyses with respect to anticancer potency and drug-ability revealed that substitution of methoxy to hydroxyl, attachment of ligustrazine and 4-hydroxycoumarin heterocyclic rings in place of phenyl rings, and attachment of heterocyclic rings like indole at the C7-C8 olefin position in native PL can help to improve anticancer activity, aqueous solubility, cell permeability, and bioavailability, making them potential leads. Hopefully, the large-scale collection and critical drug-chemistry analyses will be helpful to pharmaceutical and academic researchers in developing potential, less-toxic and cost-effective PL-derivatives that can be used against different cancers.

Chlorella vulgaris and Tetradesmus obliquus Protect Spinach (Spinacia oleracea L.) against Fusarium oxysporum

Chlorella vulgaris and Tetradesmus obliquus were tested as biocontrol agents against the phytopathogenic fungus Fusarium oxysporum. This evaluation was conducted through in vitro and in vivo trials with spinach (Spinacia oleracea L.). The in vitro trials showed that C. vulgaris and T. obliquus were able to inhibit the phytopathogen, showing a similar inhibitory effect to that of the positive controls (Rovral, BASF® and Biocontrol T34, Biocontrol Technologies® S.L.). C. vulgaris aqueous suspensions at 3.0 g L-1 led to a hyphal growth of 0.55 cm, each corresponding to a reduction of 63% of fungal growth. With T. obliquus, the hyphal growth was 0.53 cm when applied at a concentration of 0.75 g L-1, having an inhibition of fungus growth of 64%. Thereafter, these results were validated in an in vivo trial on spinach using the same controls. The results revealed a lower severity and disease incidence and a reduction in the disease's AUDPC (area under the disease progress curve) when spinach was treated with the microalgae suspensions. Overall, these findings highlight the potential of C. vulgaris and T. obliquus suspensions as promising biocontrol agents against F. oxysporum in spinach when applied through irrigation.

Antidiabetic potency and molecular insights of natural products bearing indole moiety: A systematic bioinformatics investigation targeting AKT1

Diabetic mellitus (DM) is a chronic disorder, and type 2 DM (T2DM) is the most prevalent among all categories (nearly 90%) across the globe every year. With the availability of potential drugs, the prevalence rate has remained uncontrollable, while natural resources showed a promising potency, and exploring such potential candidates at the preclinical stage is essential. An extensive literature search selected 89 marine and plant-derived indole derivatives with anti-inflammatory, antioxidant, lipid-lowering, etc., activities. However, as we know, drugs have not been able to convert from 'lead' to 'mainstream' due to inadequate drug-ability profiles, as our systematic investigation proved and selected herdmanine_A (HERD_A) and penerpene_D (PENE_D) as the most potential antidiabetic candidates from the library of indole derivatives. Based on our previous network pharmacology study, we selected three new target enzymes: Acetyl-CoA carboxylase 2 (ACACB; PDB ID: 3JRX), cyclin-dependent kinase 4 (CDK4; PDB ID: 3G33), and alpha serine/threonine-protein kinase 1 (AKT1; PDB ID: 3O96) to assess the antidiabetic potency of selected indole derivatives through binding energy or docking score. To conduct molecular docking studies with these enzymes, we used the PyRx-AutoDock platform. Furthermore, molecular dynamic simulation at 100 ns, physicochemical analysis, pharmacokinetics, toxicity assessment, and drug-likeness evaluation suggested that HERD_A and penerpene PENE_D were the most potent inhibitors against AKT1 compared to koenimbine (most potential based on the recorded IC50 value) and murrayakonine_A (most potential based on the docking score). In summary, HERD_A and/or PENE_D have the potential to be used as alternative therapeutic agent for the treatment of diabetes after some pharmacological investigation.

Cinchonine: A Versatile Pharmacological Agent Derived from Natural Cinchona Alkaloids

BACKGROUND

Cinchonine is one of the Cinchona alkaloids that is commercially extracted from the Peruvian bark of Cinchona officinalis L. (Family: Rubiaceae). It is also obtained in much lower quantities from other species of Cinchona, such as Cinchona calisaya, Cinchona succirubra, and Cinchona pubescens, and in some other plants, such as Remijia peruviana. Cinchonine has been historically used as an anti-malarial agent. It also has a wide range of other biological properties, including anti-cancer, anti-obesity, anti-inflammatory, anti-parasitic, antimicrobial, anti-platelet aggregation, and anti-osteoclast differentiation.

AIM AND OBJECTIVE

This review discusses the pharmacological activity of cinchonine under different experimental conditions, including in silico, in vitro, and in vivo. It also covers the compound's physicochemical properties, toxicological aspects, and pharmacokinetics.

METHODOLOGY

A comprehensive literature search was conducted on multiple online databases, such as PubMed, Scopus, and Google Scholar. The aim was to retrieve a wide range of review/research papers and bibliographic sources. The process involved applying exclusion and inclusion criteria to ensure the selection of relevant and high-quality papers.

RESULTS

Cinchonine has numerous pharmacological properties, making it a promising compound for various therapeutic applications. It induces anti-cancer activity by activating caspase-3 and PARP-1, and triggers the endoplasmic reticulum stress response. It up-regulates GRP78 and promotes the phosphorylation of PERK and ETIF-2α. Cinchonine also inhibits osteoclastogenesis, inhibiting TAK1 activation and suppressing NFATc1 expression by regulating AP-1 and NF-κB. Its potential anti-inflammatory effects reduce the impact of high-fat diets, making it suitable for targeting obesity-related diseases. However, research on cinchonine is limited, and further studies are needed to fully understand its therapeutic potential. Further investigation is needed to ensure its safety and efficacy in clinical applications.

CONCLUSION

Overall, this review article explains the pharmacological activity of cinchonine, its synthesis, and physicochemical properties, toxicological aspects, and pharmacokinetics.

Eco-friendly biopesticides derived from CO2-Fixing cyanobacteria

There is currently an escalating global demand for the utilization of plant and natural extracts as pesticides due to their minimal health risks. Cyanobacteria are highly valuable organisms with significant potential in agriculture and are of great interest for the development of agrochemical agents as biopesticides. The flexibility and adaptability of Cyanobacteria to various environmental conditions are facilitated by the presence of specialized enzymes involved in the production of biologically active diverse secondary metabolites, including alkaloids, lipopolysaccharides, non-protein amino acids, non-ribosomal peptides, polyketides, terpenoids, and others. This review focuses on the metabolites synthesized from cyanobacteria that have demonstrated effectiveness as antibacterial, antiviral, antifungal agents, insecticides, herbicides, and more. The potential role of cyanobacteria as an alternative to chemical pesticides for environmental conservation is discussed.

Cyanobacterial extracellular antibacterial substances could promote the spread of antibiotic resistance: impacts and reasons

Many studies have shown that antibiotic resistance genes (ARGs) can be facilitated by a variety of antibacterial substances. Cyanobacteria are photosynthetic bacteria that are widely distributed in the ocean. Some extracellular substances produced by marine cyanobacteria have been found to possess antibacterial activity. However, the impact of these extracellular substances on ARGs is unclear. Therefore, we established groups of seawater microcosms that contained different concentrations (1000, 100, 10, 1, 0.1, 0.01, and 0 μg mL-1) of cyanobacterial extracellular substances (CES), and tracked the changes of 17 types of ARGs, the integron gene (intI1), as well as the bacterial community at different time points. The results showed that CES could enrich most ARGs (15/17) in the initial stage, particularly at low concentrations (10 and 100 μg mL-1). The correlation analysis showed a positive correlation between several ARGs and intI1. It is suggested that the abundance of intI1 increased with CES may contribute to the changes of these ARGs, and co-resistance of CES may be the underlying reason for the similar variation pattern of some ARGs. Moreover, the results of qPCR and high-throughput sequencing of 16S rRNA showed that CES had an inhibitory impact on the growth of bacterial communities. High concentrations of CES were found to alter the structure of bacterial communities. Co-occurrence networks showed that bacteria elevated in the high concentration group of CES and might serve as the potential hosts for a variety of ARGs. In general, marine cyanobacteria could play an important role in the global dissemination of ARGs and antibiotic-resistant bacteria (ARBs).

Prospective Phycocompounds for Developing Therapeutics for Urinary Tract Infection

Antibiotic resistance of bacteria is causing clinical and public health concerns that are challenging to treat. Infections are becoming more common in the present era, and patients admitted to hospitals often have drug-resistant bacteria that can spread nosocomial infections. Urinary tract infections (UTIs) are among the most common infectious diseases affecting all age groups. There has been an increase in the proportion of bacteria that are resistant to multiple drugs. Herein is a comprehensive update on UTI-associated diseases: cystitis, urethritis, acute urethral syndrome, pyelonephritis, and recurrent UTIs. Further emphasis on the global statistical incidence and recent advancement of the role of natural products in treating notorious infections are described. This updated compendium will inspire the development of novel phycocompounds as the prospective antibacterial candidate.

A new easy method for determination of surface adhesion of phototrophic biofilms

Terrestrial cyanobacteria grow as phototrophic biofilms and offer a wide spectrum of interesting products. For cultivation of phototrophic biofilms different reactor concepts have been developed in the last years. One of the main influencing factors is the surface material and the adhesion strength of the chosen production strain. In this work a flow chamber was developed, in which, in combination with optical coherence tomography and computational fluid dynamics simulation, an easy analysis of adhesion forces between different biofilms and varied surface materials is possible. Hereby, differences between two cyanobacteria strains and two surface materials were shown. With longer cultivation time of biofilms adhesion increased in all experiments. Additionally, the content of extracellular polymeric substances was analyzed and its role in surface adhesion was evaluated. To test the comparability of obtained results from the flow chamber with other methods, analogous experiments were conducted with a rotational rheometer, which proved to be successful. Thus, with the presented flow chamber an easy to implement method for analysis of biofilm adhesion was developed, which can be used in future research for determination of suitable combinations of microorganisms with cultivation surfaces on lab scale in advance of larger processes.

Harmful and beneficial properties of cyanotoxins: Two sides of the same coin

Cyanotoxins are by definition "harmful agents" produced by cyanobacteria. Their toxicity has been extensively studied and reviewed over the years. Cyanotoxins have been commonly classified, based on their poisonous effects on mammals, into three main classes, neurotoxins, hepatotoxins and dermatotoxins, and, considering their chemical features, mainly identified as peptides, alkaloids and lipopolysaccharides. Here we propose a broader subdivision of cyanotoxins into eight distinct classes, taking into account their molecular structures, biosynthesis and modes of action: alkaloids, non-ribosomal peptides, polyketides, non-protein amino acids, indole alkaloids, organophosphates, lipopeptides and lipoglycans. For each class, the structures and primary mechanisms of toxicity of the main representative cyanotoxins are reported. Despite their powerful biological activities, only recently scientists have considered the biotechnological potential of cyanotoxins, and their applications both in medical and in industrial settings, even if only a few of these have reached the biotech market. In this perspective, we discuss the potential uses of cyanotoxins as anticancer, antimicrobial, and biocidal agents, as common applications for cytotoxic compounds. Furthermore, taking into account their mechanisms of action, we describe peculiar potential bioactivities for several cyanotoxin classes, such as local anaesthetics, antithrombotics, neuroplasticity promoters, immunomodulating and antifouling agents. In this review, we aim to stimulate research on the potential beneficial roles of cyanotoxins, which require interdisciplinary cooperation to facilitate the discovery of innovative biotechnologies.

Cyanobacteria: A Promising Source of Antifungal Metabolites

Cyanobacteria are a rich source of secondary metabolites, and they have received a great deal of attention due to their applicability in different industrial sectors. Some of these substances are known for their notorious ability to inhibit fungal growth. Such metabolites are very chemically and biologically diverse. They can belong to different chemical classes, including peptides, fatty acids, alkaloids, polyketides, and macrolides. Moreover, they can also target different cell components. Filamentous cyanobacteria have been the main source of these compounds. This review aims to identify the key features of these antifungal agents, as well as the sources from which they are obtained, their major targets, and the environmental factors involved when they are being produced. For the preparation of this work, a total of 642 documents dating from 1980 to 2022 were consulted, including patents, original research, review articles, and theses.

The Potential of Allelochemicals from Microalgae for Biopesticides

Improvements in agricultural productivity are required to meet the demand of a growing world population. Phytopathogens, weeds, and insects are challenges to agricultural production. The toxicity and widespread application of persistent synthetic pesticides poses a major threat to human and ecosystem health. Therefore, sustainable strategies to control pests are essential for agricultural systems to enhance productivity within a green paradigm. Allelochemicals are a less persistent, safer, and friendly alternative to efficient pest management, as they tend to be less toxic to non-target organisms and more easily degradable. Microalgae produce a great variety of allelopathic substances whose biocontrol potential against weeds, insects, and phytopathogenic fungi and bacteria has received much attention. This review provides up-to-date information and a critical perspective on allelochemicals from microalgae and their potential as biopesticides.

Antimicrobial peptides derived from microalgae for combating antibiotic resistance: Current status and prospects

Microalgae are photosynthetic cell factories that produce a spectrum of bioactive compounds extensively used for various applications. Owing to the increase in antibiotic resistance among microbial pathogens, there is a significant thrust for identifying new treatment strategies, and antimicrobial peptides (AMPs) generation is one such method. These AMPs have multiple roles and are active against bacteria, fungi, and viruses. Such peptides synthesized in microalgae have a significant role in medical application, managing aquaculture-associated diseases, and the food industry. To increase their effectiveness and novel peptides, genetically modified microalgae are used as cell factories. With the advancement of new technologies like the CRISPR-Cas system, new avenues are opened for developing novel AMPs using microalgae. This review gives us insight into the various AMPs produced by microalgae and multiple technologies involved in creating such therapeutically essential molecules.

Antifungal and Antibacterial Activities of Isolated Marine Compounds

To combat the ineffectiveness of currently available pharmaceutical medications, caused by the emergence of increasingly resistant bacterial and fungal strains, novel antibacterial and antifungal medications are urgently needed. Novel natural compounds with antimicrobial activities can be obtained by exploring underexplored habitats such as the world's oceans. The oceans represent the largest ecosystem on earth, with a high diversity of organisms. Oceans have received some attention in the past few years, and promising compounds with antimicrobial activities were isolated from marine organisms such as bacteria, fungi, algae, sea cucumbers, sea sponges, etc. This review covers 56 antifungal and 40 antibacterial compounds from marine organisms. These compounds are categorized according to their chemical structure groups, including polyketides, alkaloids, ribosomal peptides, and terpenes, and their organismal origin. The review provides the minimum inhibitory concentration MIC values and the bacterial/fungal strains against which these chemical compounds show activity. This study shows strong potential for witnessing the development of new novel antimicrobial drugs from these natural compounds isolated and evaluated for their antimicrobial activities.

Process Technologies of Cyanobacteria

Although the handling and exploitation of cyanobacteria is associated with some challenges, these phototrophic bacteria offer great opportunities for innovative biotechnological processes. This chapter covers versatile aspects of working with cyanobacteria, starting with up-to-date in silico and in vitro screening methods for bioactive substances. Subsequently, common conservation techniques and vitality/viability estimation methods are compared and supplemented by own data regarding the non-invasive vitality evaluation via pulse amplitude modulated fluorometry. Moreover, novel findings about the influence the state of the pre-cultures have on main cultures are presented. The following sub-chapters deal with different photobioreactor-designs, with special regard to biofilm photobioreactors, as well as with heterotrophic and mixotrophic cultivation modes. The latter topic provides information from literature on successfully enhanced cyanobacterial production processes, augmented by own data.

Revisiting the role of cyanobacteria-derived metabolites as antimicrobial agent: A 21st century perspective

Cyanobacterial species are ancient photodiazotrophs prevalent in freshwater bodies and a natural reservoir of many metabolites (low to high molecular weight) such as non-ribosomal peptides, polyketides, ribosomal peptides, alkaloids, cyanotoxins, and isoprenoids with a well-established bioactivity potential. These metabolites enable cyanobacterial survival in extreme environments such as high salinity, heavy metals, cold, UV-B, etc. Recently, these metabolites are gaining the attention of researchers across the globe because of their tremendous applications as antimicrobial agents. Many reports claim the antimicrobial nature of these metabolites; unfortunately, the mode of action of such metabolites is not well understood and/or known limited. Henceforth, this review focuses on the properties and potential application, also critically highlighting the possible mechanism of action of these metabolites to offer further translational research. The review also aims to provide a comprehensive insight into current gaps in research on cyanobacterial biology as antimicrobials and hopes to shed light on the importance of continuing research on cyanobacteria metabolites in the search for novel antimicrobials.

Combined Bioinformatics and Combinatorial Chemistry Tools to Locate Drug-Able Anti-TB Phytochemicals: A Cost-Effective Platform for Natural Product-Based Drug Discovery

Based on extensive experimental studies, a huge number of phytochemicals showed potential activity against tuberculosis (TB) at a lower minimum inhibitory concentration (MIC) and fewer toxicity profiles. However, these promising drugs have not been able to convert from 'lead' to 'mainstream' due to inadequate drug-ability profiles. Thus, early drug-prospective analyses are required at the primary stage to accelerate natural-product-based drug discovery with limited resources and time. In the present study, we have selected seventy-three potential anti-TB phytochemicals (MIC value ≤10 μg/mL) and assessed the drug-ability profiles using bioinformatics and combinatorial chemistry tools, systematically. Primarily, the molecular docking study was done against two putative drug targets, catalase-peroxidase enzyme (katG) and RNA polymerase subunit-β (rpoB) of Mycobacterium tuberculosis (Mtb) using AutoDock 4.2 software. Further, assessed the drug-ability score from Molsoft, toxicity profiles from ProTox, pharmacokinetics from SwisADME, hierarchical cluster analysis (HCA) by ChemMine tools and frontier molecular orbitals (FMOs) with Avogadro and structural activity relationships (SAR) analysis with ChemDraw 18.0 software. Above analyses indicated that, lower MIC exhibited anti-TB phytochemicals, abietane, 12-demethylmulticaulin exhibited poor docking and drug-ability scores, while tiliacorinine, 2-nortiliacorinine showed higher binding energy and drug-ability profiles. Overall, tiliacorinine, 2-nortiliacorinine, 7α-acetoxy-6β-hydroxyroyleanone (AHR), (2S)-naringenin and isovachhalcone were found as the most active and drug-able anti-TB candidates from 73 candidates. Phytochemicals are always a vital source of mainstream drugs, but the MIC value of a phytochemical is not sufficient for it to be promoted. An ideal drug-ability profile is therefore essential for achieving clinical success, where advanced bioinformatics tools help to assess and analyse that profile. Additionally, several natural pharmacophores found in existing anti-TB drugs in SAR analyses also provide crucial information for developing potential anti-TB drug. As a conclusion, combined bioinformatics and combinatorial chemistry are the most effective strategies to locate potent-cum-drug-able candidates in the current drug-development module.

Therapeutic potential of marine macrolides: An overview from 1990 to 2022

The sea is a vast ecosystem that has remained primarily unexploited and untapped, resulting in numerous organisms. Consequently, marine organisms have piqued the interest of scientists as an abundant source of natural resources with unique structural features and fascinating biological activities. Marine macrolide is a top-class natural product with a heavily oxygenated polyene backbone containing macrocyclic lactone. In the last few decades, significant efforts have been made to isolate and characterize macrolides' chemical and biological properties. Numerous macrolides are extracted from different marine organisms such as marine microorganisms, sponges, zooplankton, molluscs, cnidarians, red algae, tunicates, and bryozoans. Notably, the prominent macrolide sources are fungi, dinoflagellates, and sponges. Marine macrolides have several bioactive characteristics such as antimicrobial (antibacterial, antifungal, antimalarial, antiviral), anti-inflammatory, antidiabetic, cytotoxic, and neuroprotective activities. In brief, marine organisms are plentiful in naturally occurring macrolides, which can become the source of efficient and effective therapeutics for many diseases. This current review summarizes these exciting and promising novel marine macrolides in biological activities and possible therapeutic applications.

Dietary supplementation with Cyberlindnera jadinii improved growth performance, serum biochemical Indices, antioxidant status, and intestinal health in growing raccoon dogs (Nyctereutes procyonoides)

This study was conducted to investigate whether different dietary Cyberlindnera jadinii levels affect growth performance, serum immunity, antioxidant capacity, and intestinal microbiota in growing raccoon dogs. Forty-five healthy male raccoon dogs were randomly assigned to three treatment groups, with 15 raccoon dogs per group. Each raccoon dog was housed in an individual cage. The raccoon dogs in the three groups were fed diets supplemented with Cyberlindnera jadinii at dosages of 0 (N group), 1 × 10⁹ (L group) and 5 × 10⁹ CFU/g (H group). A 7-day pretest period preceded a formal test period of 30 days. The results showed that Cyberlindnera jadinii in the L and H groups improved average daily gain (ADG) (P < 0.05) and decreased the ratio of feed to weight (F/G) (P < 0.05). Serum immunoglobulins A and G levels were increased in the L and H groups compared to the N group (P < 0.05). Cyberlindnera jadinii in the L and H groups increased serum superoxide dismutase activity (P < 0.05), and serum glutathione peroxidase activity was increased in the L group compared to the N group (P < 0.05). The relative abundance of Firmicutes and Actinobacteriota were increased, and the relative abundance of Bacteroidota was decreased in the L and H groups compared to the N group (P < 0.05). The relative abundance of Proteobacteria and Cyanobacteria was increased in the H group compared to the other two groups (P < 0.05). The ratio of Firmicutes to Bacteroidetes in the Cyberlindnera jadinii supplementation groups increased compared with the N group (P < 0.05). The relative abundance of Megasphaera and Bifidobacterium were increased, and the relative abundance of Prevotella was decreased in the L and H groups compared to the N group (P < 0.05). The relative abundance of Dialister was increased, while the relative abundance of Blautia was decreased in the H group compared to the other two groups (P < 0.05). The relative abundance of Agathobacter was decreased in the H group compared to the N group (P < 0.05). In conclusion, dietary supplementation with Cyberlindnera jadinii increased growth performance, serum immunity, antioxidant capacity, and improved intestinal microbiota in growing raccoon dogs. Cyberlindnera jadinii can therefore be used as a growth promoter in raccoon dogs.

Integrated bioinformatics-cheminformatics approach toward locating pseudo-potential antiviral marine alkaloids against SARS-CoV-2-Mpro

The emergence of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) with the most contagious variants, alpha (B.1.1.7), beta (B.1.351), delta (B.1.617.2), and Omicron (B.1.1.529) has continuously added a higher number of morbidity and mortality, globally. The present integrated bioinformatics-cheminformatics approach was employed to locate potent antiviral marine alkaloids that could be used against SARS-CoV-2. Initially, 57 antiviral marine alkaloids and two repurposing drugs were selected from an extensive literature review. Then, the putative target enzyme SARS-CoV-2 main protease (SARS-CoV-2-Mpro) was retrieved from the protein data bank and carried out a virtual screening-cum-molecular docking study with all candidates using PyRx 0.8 and AutoDock 4.2 software. Further, the molecular dynamics (MD) simulation of the two most potential alkaloids and a drug docking complex at 100 ns (with two ligand topology files from PRODRG and ATB server, separately), the molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) free energy, and contributions of entropy were investigated. Then, the physicochemical-toxicity-pharmacokinetics-drug-likeness profiles, the frontier molecular orbitals energies (highest occupied molecular orbital, lowest unoccupied molecular orbital, and ΔE), and structural-activity relationship were assessed and analyzed. Based on binding energy, 8-hydroxymanzamine (-10.5 kcal/mol) and manzamine A (-10.1 kcal/mol) from all alkaloids with darunavir (-7.9 kcal/mol) and lopinavir (-7.4 kcal/mol) against SARS-CoV-2-Mpro were recorded. The MD simulation (RMSD, RMSF, Rg, H-bond, MM/PBSA binding energy) illustrated that the 8-hydroxymanzamine exhibits a static thermodynamic feature than the other two complexes. The predicted physicochemical, toxicity, pharmacokinetics, and drug-likeness profiles also revealed that the 8-hydroxymanzamine could be used as a potential lead candidate individually and/or synergistically with darunavir or lopinavir to combat SARS-CoV-2 infection after some pharmacological validation.

Identification and characterization of the novel bioactive compounds from microalgae and cyanobacteria for pharmaceutical and nutraceutical applications

Microalgae and cyanobacteria (blue-green algae) are used as food by humans. They have gained a lot of attention in recent years because of their potential applications in biotechnology. Microalgae and cyanobacteria are good sources of many valuable compounds, including important biologically active compounds with antiviral, antibacterial, antifungal, and anticancer activities. Under optimal growth condition and stress factors, algal biomass produce varieties of potential bioactive compounds. In the current review, bioactive compounds production and their remarkable applications such as pharmaceutical and nutraceutical applications along with processes involved in identification and characterization of the novel bioactive compounds are discussed. Comprehensive knowledge about the exploration, extraction, screening, and trading of bioactive products from microalgae and cyanobacteria and their pharmaceutical and other applications will open up new avenues for drug discovery and bioprospecting.

Cyanopeptides restriction and degradation co-mediate microbiota assembly during a freshwater cyanobacterial harmful algal bloom (CyanoHAB)

Cyanobacterial harmful algal blooms (CyanoHABs) are globally intensifying and exacerbated by climate change and eutrophication. However, microbiota assembly mechanisms underlying CyanoHABs remain elusive. Especially, cyanopeptides, as a group of bioactive secondary metabolites of cyanobacteria, could affect microbiota assembly and ecosystem function. Here, the trajectory of cyanopeptides was followed and linked to microbiota during Microcystis-dominated CyanoHABs in Lake Taihu, China. The most abundant cyanopeptide classes detected included microginin, spumigin, microcystin, nodularin and cyanopeptolin with total MC-LR-equivalent concentrations between 0.23 and 2051.54 ppb, of which cyanotoxins beyond microcystins (e.g., cyanostatin B and nodularin_R) far exceeded reported organismal IC₅₀ and negatively correlated with microbiota diversity, exerting potential collective eco-toxicities stronger than microcystins alone. The microbial communities were differentiated by size fraction and sampling date throughout CyanoHABs, and surprisingly, their variances were better explained by cyanopeptides (19-38%) than nutrients (0-16%). Cyanopeptides restriction (e.g., inhibition) and degradation were first quantitatively verified as the deterministic drivers governing community assembly, with stochastic processes being associated with the interplay between cyanopeptide dynamics and lake microbiota. This study presents an emerging paradigm in which cyanopeptides restriction and degradation co-mediate lake water microbiota assembly, unveiling new insights into the ecotoxicological significance of CyanoHABs to freshwater ecosystems.

The use of algae for environmental sustainability: trends and future prospects

Algae are photosynthetic prokaryotic or eukaryotic ubiquitously found group of organisms. Their enormous potentiality in coping up with various environmental crises has been well documented. Algae have proven to be ideal for biomonitoring of water pollution and help in removing the pollutants with their process of bioremediation apart from the production of eco-friendly sources of energy. Industries like food and pharmaceuticals are exploiting algae for producing several value-added products. The agricultural sector is also highly benefited from microalgae, as they are the good promoters of crop growth. The CO₂-removing potential of algae proves to be an asset in fighting climate change. Moreover, the relatively easy and inexpensive methods of sampling and culturing of algae make them more popular. In this paper, we review the sustainable application aspects of algae in various areas like pollution control, energy production, agriculture, and fighting climate change. Critical discussions have been made on the recent trends and advances of algal technologies indicating future prospects.

Study from microcosms and mesocosms reveals Escherichia coli removal in high rate algae ponds during domestic wastewater treatment is primarily caused by dark decay

While high rate algal ponds (HRAPs) can provide efficient pathogen removal from wastewater, the mechanisms involved remain unclear. To address this knowledge gap, the mechanisms potentially causing Escherichia coli (E. coli) removal during microalgae-based wastewater treatment were successively assessed using laboratory microcosms designed to isolate known mechanisms, and bench scale assays performed in real HRAP broth. During laboratory assays, E. coli decay was only significantly increased by alkaline pH (above temperature-dependent thresholds) due to pH induced toxicity, and direct sunlight exposure via UV-B damage and/or endogenous photo-oxidation. Bench assays confirmed alkaline pH toxicity caused significant decay but sunlight-mediated decay was not significant, likely due to light attenuation in the HRAP broth. Bench assays also evidenced the existence of uncharacterized ‘dark’ decay mechanism(s) not observed in laboratory microcosms. To numerically evaluate the contribution of each mechanism and the uncertainty associated, E. coli decay was modelled assuming dark decay, alkaline pH induced toxicity, and direct sunlight-mediated decay were independent mechanisms. The simulations confirmed E. coli decay was mainly caused by dark decay during bench assays (48.2–89.5% estimated contribution to overall decay at the 95% confidence level), followed by alkaline-pH induced toxicity (8.3–46.5%), and sunlight-mediated decay (0.0–21.9%).

In vivo and in silico screening for antimicrobial compounds from cyanobacteria

Due to the emerging rise of multi‐drug resistant bacteria, the discovery of novel antibiotics is of high scientific interest. Through their high chemodiversity of bioactive secondary metabolites, cyanobacteria have proven to be promising microorganisms for the discovery of antibacterial compounds. These aspects make appropriate antibacterial screening approaches for cyanobacteria crucial. Up to date, screenings are mostly carried out using a phenotypic methodology, consisting of cyanobacterial cultivation, extraction, and inhibitory assays. However, the parameters of these methods highly vary within the literature. Therefore, the common choices of parameters and inhibitory assays are summarized in this review. Nevertheless, less frequently used method variants are highlighted, which lead to hits from antimicrobial compounds. In addition to the considerations of phenotypic methods, this study provides an overview of developments in the genome‐based screening area, be it in vivo using PCR technique or in silico using the recent genome‐mining method. Though, up to date, these techniques are not applied as much as phenotypic screening.

A Novel Approach for Fast Screening of a Complex Cyanobacterial Extract for Immunomodulatory Properties and Antibacterial Activity

The filamentous cyanobacteria from genus Phormidium are rich natural sources of bioactive compounds that could be exploited as pharmaceuticals or nutraceuticals. In this study, we suggest a novel approach for assessing the immunomodulatory properties of the products derived from cyanobacteria. The influence of Phormidium papyraceum extract on the human leukocyte immunophenotype was evaluated by attempting to link this activity to certain putative compounds identified in the extract. By using three staining panels and flow cytometry, we found that the cyanobacterial extract affected mainly CD4+ T cells upregulating activated CD4+CD152+ T cells (15.75 ± 1.93% treated vs. 4.65 ± 1.41% control) and regulatory CD4+CD25+ T cells (5.36 ± 0.64% treated vs. 1.03 ± 0.08% control). Furthermore, P. papyraceum extract can modulate T cell subpopulations with a CD4+ effector/memory phenotype. Extract-treated cells showed increased production of IL-2 (55 ± 12 pg/mL) and IL-6 (493 ± 64 pg/mL) compared to the untreated, 21 ± 7 pg/mL and 250 ± 39 pg/mL, respectively. No significant changes were observed in the secretion of TNF-α. In addition, P. papyraceum extract displayed antibacterial activity against both Gram-negative (inhibition zone from 18.25 ± 0.50 mm to 20.28 ± 1.50 mm) and Gram-positive (inhibition zone from 10.86 ± 0.85 mm to 17.00 ± 0.82 mm) bacteria. The chemical profile of the cyanobacterial extract was determined using LC–ESI–MS/MS analysis, where at least 112 putative compounds were detected. Many of these compounds have proven different biological activities. We speculated that compounds such as betulin and the macrolide azithromycin (or their analogues) could be responsible for the immunomodulatory potential of the investigated extract. More studies are needed to determine and validate the biological activities of the determined putative compounds.

Passively immobilized cyanobacteria Nostoc species BB 92.2 in a moving bed photobioreactor (MBPBR): design, cultivation and characterization

The cyanobacterium Nostoc sp. BB 92.3. had shown antibacterial activity. A cultivation as biofilm, a self-forming matrix of cells and extracellular polymeric substances, increased the antibacterial effect. A new photobioreactor system was developed that allows a surface-associated cultivation of Nostoc sp. as biofilm. High-density polyethylene carriers operated as a moving bed were selected as surface for biomass immobilization. This system, well established in heterotrophic wastewater treatment, was for the first time used for phototrophic biofilms. The aim was a cultivation on a large scale without inhibiting growth while maximizing immobilization. Cultivation in a small photobioreactor (1.5 L) with different volumetric filling degrees of carriers (13.4-53.8 %) in a batch process achieved immobilization rates of 70-85 % and growth was similar to a no-carrier-control. In a larger photobioreactor (65-liter) essentially all of the biomass was immobilized on the carriers and the space-time yield of biomass (0.018 g_{cell dry weight} L^-1 day^-1 ) was competitive compared to phototrophic biofilm cultivations from literature. The use of carriers increased the gas exchange in the reactor by a factor of 2.5-3, but doubled the mixing time. Enriched gassing with carbon dioxide resulted in a short-term increase in growth rate, but unexpectedly it also adversely changed the growth morphology. This article is protected by copyright. All rights reserved.

Lactylated acidic exopolysaccharide produced by the cyanobacterium Nostoc cf. linckia

Cyanobacteria produce a wide range of metabolites of interest for industrial or medical use. The cultivation of freshwater Nostoc cf. linckia yielded 5.4 g/L of a crude exopolysaccharide (cEPS) with a molecular weight of 1.31 × 10⁵ g/mol. Ion-exchange chromatography of cEPS yielded two dominant fractions, EPS-1 and EPS-2, differing in molecular weight. The lower molecular weight fraction (EPS-1) was subjected to structural studies. Results of chemical and spectroscopic analyses showed that three of the four dominant sugars, glucose, galactose and xylose are 1,4-linked in the backbone in the following order: [→4)-β-D-Xylp-(1 → 4)-β-D-Glcp-(1 → 4)-α-D-Galp-(1 → 4)-β-D-Glcp-(1→]_n. Terminal mannose residues were identified as side chains linked at C3 of every third backbone xylose and every second glucose is branched at C6 by 3-O-lactyl-β-D-glucuronic acid (nosturonic acid). Antioxidant properties of EPS were tested using two in vitro methods. Both assays showed that the cEPS was more active than purified EPS-1 and EPS-2 fractions and deproteinized EPS.

Potential of Marine Terpenoids against SARS-CoV-2: An In Silico Drug Development Approach

In an emergency, drug repurposing is the best alternative option against newly emerged severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. However, several bioactive natural products have shown potential against SARS-CoV-2 in recent studies. The present study selected sixty-eight broad-spectrum antiviral marine terpenoids and performed molecular docking against two novel SARS-CoV-2 enzymes (main protease or Mpro or 3CLpro) and RNA-dependent RNA polymerase (RdRp). In addition, the present study analysed the physiochemical-toxicity-pharmacokinetic profile, structural activity relationship, and phylogenetic tree with various computational tools to select the 'lead' candidate. The genomic diversity study with multiple sequence analyses and phylogenetic tree confirmed that the newly emerged SARS-CoV-2 strain was up to 96% structurally similar to existing CoV-strains. Furthermore, the anti-SARS-CoV-2 potency based on a protein-ligand docking score (kcal/mol) exposed that the marine terpenoid brevione F (-8.4) and stachyflin (-8.4) exhibited similar activity with the reference antiviral drugs lopinavir (-8.4) and darunavir (-7.5) against the target SARS-CoV-Mpro. Similarly, marine terpenoids such as xiamycin (-9.3), thyrsiferol (-9.2), liouvilloside B (-8.9), liouvilloside A (-8.8), and stachyflin (-8.7) exhibited comparatively higher docking scores than the referral drug remdesivir (-7.4), and favipiravir (-5.7) against the target SARS-CoV-2-RdRp. The above in silico investigations concluded that stachyflin is the most 'lead' candidate with the most potential against SARS-CoV-2. Previously, stachyflin also exhibited potential activity against HSV-1 and CoV-A59 within IC50, 0.16-0.82 µM. Therefore, some additional pharmacological studies are needed to develop 'stachyflin' as a drug against SARS-CoV-2.

Total syntheses and antiproliferative activities of prenostodione and its analogues

A high-yielding total synthesis of the indole alkaloid prenostodione was completed in 4 steps and 44% overall yield from 1H-indole-3-carboxylic acid. The expedient syntheses of prenostodiones containing distinct substituents at the para position of the phenyl frame underscored the scope of this methodology. The cytotoxic activities of the tert-butyl esters of prenostodione analogues were tested using six tumor cell lines. Preliminary structure-activity studies revealed the importance of the identity of the aromatic substituent at the C-4 position for cytotoxic activity. The IC50 values of these compounds were found to compare satisfactorily with those of the commercially available drugs etoposide and cisplatin. Furthermore, the compounds with, respectively, -OMe (14d) and -NO2 (14f) groups at C-4 were more selective than these control compounds in PC-3, K-562, and MCF-7 cells. Also, computational studies were carried out to determine the ADMET profiles and passive membrane permeabilities of the compounds. The results suggested the promise of 14d and 14f as hit compounds for the development of new anticancer agents.

Synthesis and Biological Evaluation of New N-Acyl-α-amino Ketones and 1,3-Oxazoles Derivatives

In order to develop novel bioactive substances with potent activities, some new valine-derived compounds incorporating a 4-(phenylsulfonyl)phenyl fragment, namely, acyclic precursors from N-acyl-α-amino acids and N-acyl-α-amino ketones classes, and heterocycles from the large family of 1,3-oxazole-based compounds, were synthesized. The structures of the new compounds were established using elemental analysis and spectral (UV-Vis, FT-IR, MS, NMR) data, and their purity was checked by reversed-phase HPLC. The newly synthesized compounds were evaluated for their antimicrobial and antibiofilm activities, for toxicity on D. magna, and by in silico studies regarding their potential mechanism of action and toxicity. The 2-aza-3-isopropyl-1-[4-(phenylsulfonyl)phenyl]-1,4-butanedione 4b bearing a p-tolyl group in 4-position exhibited the best antibacterial activity against the planktonic growth of both Gram-positive and Gram-negative strains, while the N-acyl-α-amino acid 2 and 1,3-oxazol-5(4H)-one 3 inhibited the Enterococcus faecium biofilms. Despite not all newly synthesized compounds showing significant biological activity, the general scaffold allows several future optimizations for obtaining better novel antimicrobial agents by the introduction of various substituents on the phenyl moiety at position 5 of the 1,3-oxazole nucleus.

Phytoplankton of the Curonian Lagoon as a New Interesting Source for Bioactive Natural Products. Special Impact on Cyanobacterial Metabolites

The bioprospecting of marine and brackish water systems has increased during the last decades. In this respect, microalgae, including cyanobacteria, and their metabolites are one of the most widely explored resources. Most of the bioactive compounds are isolated from ex situ cultures of microorganisms; however, analysis of field samples could also supply valuable information about the metabolic and biotechnological potential of microalgae communities. In this work, the activity of phytoplankton samples from the Curonian Lagoon was studied. The samples were active against antibiotic resistant clinical and environmental bacterial strains as well as against serine proteases and T47D human breast adenocarcinoma cells. No significant effect was found on Daphnia magna. In addition, using LC-MS/MS, we documented the diversity of metabolites present in field samples. A list of 117 detected cyanopeptides was presented. Cyanopeptolins constituted the largest class of cyanopeptides. As complex bloom samples were analyzed, no link between the observed activity and a specific sample component can be established. However, the results of the study showed a biotechnological potential of natural products from the Curonian Lagoon.

Phycocyanin Extracted from Oscillatoria minima Shows Antimicrobial, Algicidal, and Antiradical Activities: In silico and In vitro Analysis

BACKGROUND

Phycocyanin is an algae-derived protein, which binds to pigment for harvesting light. It has been reported in various different species, including that of red algae, dinoflagellates, and cryptophyta. Importantly, phycocyanin has enormous applications, including cosmetic colorant, food additive, biotechnology, diagnostics, fluorescence detection probe, an anticancer agent, anti-inflammatory, immune enhancer, etc. In addition, several different algae were utilized for the isolation of cyano-phycocyanin (C-PC), but most of the purification methods consist of several steps of crude extraction.

AIM

To isolate C-PC from a new source of microalgae with better purity level and to evaluate its antimicrobial, algicidal, and antiradical activities.

METHODS

Biological activity, permeability, pharmacokinetics, and toxicity profile of C-PC were predicted by in silico studies. C-PC was purified and isolated by using ammonium sulphate precipitation, ion-exchange chromatography and gel-filtration chromatography. C-PC was characterized by SDS-PAGE and elution profile (purity ratio) analysis. Antimicrobial and algicial activities of C-PC were evaluated by the microtitre plate based assays. Antiradical activity of C-PC was evaluated by DPPH- and ABTS*+ radical scavenging assays.

CONCLUSION

C-PC was extracted from Oscillatoria minima for the first time, followed by its quantitative as well qualitative evaluation, indicating a new alternative source of this important protein. Furthermore, the antimicrobial, algicidal, and antiradical activities of the isolated C-PC extract have been demonstrated by both in silico as well as in vitro methods.

On the application of 3d metals for C-H activation toward bioactive compounds: The key step for the synthesis of silver bullets

Several valuable biologically active molecules can be obtained through C-H activation processes. However, the use of expensive and not readily accessible catalysts complicates the process of pharmacological application of these compounds. A plausible way to overcome this issue is developing and using cheaper, more accessible, and equally effective catalysts. First-row transition (3d) metals have shown to be important catalysts in this matter. This review summarizes the use of 3d metal catalysts in C-H activation processes to obtain potentially (or proved) biologically active compounds.

Toxic or Otherwise Harmful Algae and the Built Environment

This article gives a comprehensive overview on potentially harmful algae occurring in the built environment. Man-made structures provide diverse habitats where algae can grow, mainly aerophytic in nature. Literature reveals that algae that is potentially harmful to humans do occur in the anthropogenic environment in the air, on surfaces or in water bodies. Algae may negatively affect humans in different ways: they may be toxic, allergenic and pathogenic to humans or attack human structures. Toxin-producing alga are represented in the built environment mainly by blue green algae (Cyanoprokaryota). In special occasions, other toxic algae may also be involved. Green algae (Chlorophyta) found airborne or growing on manmade surfaces may be allergenic whereas Cyanoprokaryota and other forms may not only be toxic but also allergenic. Pathogenicity is found only in a special group of algae, especially in the genus Prototheca. In addition, rare cases with infections due to algae with green chloroplasts are reported. Algal action may be involved in the biodeterioration of buildings and works of art, which is still discussed controversially. Whereas in many cases the disfigurement of surfaces and even the corrosion of materials is encountered, in other cases a protective effect on the materials is reported. A comprehensive list of 79 taxa of potentially harmful, airborne algae supplemented with their counterparts occurring in the built environment, is given. Due to global climate change, it is not unlikely that the built environment will suffer from more and higher amounts of harmful algal species in the future. Therefore, intensified research in composition, ecophysiology and development of algal growth in the built environment is indicated.

Biosynthesis of Sinapigladioside, an Antifungal Isothiocyanate from Burkholderia Symbionts

Sinapigladioside is a rare isothiocyanate-bearing natural product from beetle-associated bacteria (Burkholderia gladioli) that might protect beetle offspring against entomopathogenic fungi. The biosynthetic origin of sinapigladioside has been elusive, and little is known about bacterial isothiocyanate biosynthesis in general. On the basis of stable-isotope labeling, bioinformatics, and mutagenesis, we identified the sinapigladioside biosynthesis gene cluster in the symbiont and found that an isonitrile synthase plays a key role in the biosynthetic pathway. Genome mining and network analyses indicate that related gene clusters are distributed across various bacterial phyla including producers of both nitriles and isothiocyanates. Our findings support a model for bacterial isothiocyanate biosynthesis by sulfur transfer into isonitrile precursors.

CyanoMetDB, a comprehensive public database of secondary metabolites from cyanobacteria

Harmful cyanobacterial blooms, which frequently contain toxic secondary metabolites, are reported in aquatic environments around the world. More than two thousand cyanobacterial secondary metabolites have been reported from diverse sources over the past fifty years. A comprehensive, publically-accessible database detailing these secondary metabolites would facilitate research into their occurrence, functions and toxicological risks. To address this need we created CyanoMetDB, a highly curated, flat-file, openly-accessible database of cyanobacterial secondary metabolites collated from 850 peer-reviewed articles published between 1967 and 2020. CyanoMetDB contains 2010 cyanobacterial metabolites and 99 structurally related compounds. This has nearly doubled the number of entries with complete literature metadata and structural composition information compared to previously available open access databases. The dataset includes microcytsins, cyanopeptolins, other depsipeptides, anabaenopeptins, microginins, aeruginosins, cyclamides, cryptophycins, saxitoxins, spumigins, microviridins, and anatoxins among other metabolite classes. A comprehensive database dedicated to cyanobacterial secondary metabolites facilitates: (1) the detection and dereplication of known cyanobacterial toxins and secondary metabolites; (2) the identification of novel natural products from cyanobacteria; (3) research on biosynthesis of cyanobacterial secondary metabolites, including substructure searches; and (4) the investigation of their abundance, persistence, and toxicity in natural environments.