Tasiamide F, a potent inhibitor of cathepsins D and E from a marine cyanobacterium

Recent progression on phytochemicals and pharmacological properties of the filamentous cyanobacterium Lyngbya sp

The distribution and phytochemistry of the non-nitrogen fixing, filamentous cyanobacterium (blue-green alga) Lyngbya sp., and the inherent antimicrobial and anticancer activities of its phycochemicals as well as of the biosynthesized nanoparticles as their pharmaceutical potencies are considered. Several phycocompounds of curio, apramide, apratoxin, benderamide, cocosamides, deoxymajusculamide, flavonoids, lagunamides, lipids, proteins, amino acids, lyngbyabellin, lyngbyastatin, majusculamide, peptides, etc. were isolated from Lyngbya sp., which had a lot of potential pharmaceutical activities; those compounds had antibacterial, antiviral, antifungal, anticancer, antioxidant, anti-inflammatory, ultraviolet protectant, and other activities. Particularly, several Lyngbya phycocompounds had potent antimicrobial potencies, seen through in vitro controlling of several frequently encountered multidrug-resistant (MDR) clinically belligerent strains of pathogenic bacteria isolated from clinical samples. The aqueous extracts of Lyngbya sp. were used for the synthesis of silver and copper oxide nanoparticles, which were used in pharmacological trials too. The nanoparticles biosynthesized with Lyngbya sp. had several uses such as biofuel, agro-based applications, in cosmetics, and industrial uses as biopolymers, and being potent antimicrobial and anticancer agents and in drug-delivery too, as medical applications. It could be concluded that the Lyngbya phycochemicals and the biosynthesized nanoparticles have future uses as antimicrobial namely as bacterial and fungal and anti-cancer agents, with promising medical and industrial uses.

Stalling the Course of Neurodegenerative Diseases: Could Cyanobacteria Constitute a New Approach toward Therapy?

Neurodegenerative diseases (NDs) are characterized by progressive and irreversible neuronal loss, accompanied by a range of pathological pathways, including aberrant protein aggregation, altered energy metabolism, excitotoxicity, inflammation, and oxidative stress. Some of the most common NDs include Alzheimer's Disease (AD), Parkinson's Disease (PD), Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), and Huntington's Disease (HD). There are currently no available cures; there are only therapeutic approaches that ameliorate the progression of symptoms, which makes the search for new drugs and therapeutic targets a constant battle. Cyanobacteria are ancient prokaryotic oxygenic phototrophs whose long evolutionary history has resulted in the production of a plethora of biomedically relevant compounds with anti-inflammatory, antioxidant, immunomodulatory, and neuroprotective properties, that can be valuable in this field. This review summarizes the major NDs and their pathophysiology, with a focus on the anti-neurodegenerative properties of cyanobacterial compounds and their main effects.

Structural Congeners of Izenamides Responsible for Cathepsin D Inhibition: Insights from Synthesis-Derived Elucidation

This study aimed to elucidate the structural congeners of natural izenamides A, B, and C (1-3) responsible for cathepsin D (CTSD) inhibition. Structurally modified izenamides were synthesized and biologically evaluated, and their biologically important core structures were identified. We confirmed that the natural statine (Sta) unit (3S,4S)-γ-amino-β-hydroxy acid is a requisite core structure of izenamides for inhibition of CTSD, which is closely related to the pathophysiological roles in numerous human diseases. Interestingly, the statine-incorporated izenamide C variant (7) and 18-epi-izenamide B variant (8) exhibited more potent CTSD-inhibitory activities than natural izenamides.

Marine Organisms as a Prolific Source of Bioactive Depsipeptides

Depsipeptides, an important group of polypeptides containing residues of hydroxy acids and amino acids linked together by amide and ester bonds, have potential applications in agriculture and medicine. A growing body of evidence demonstrates that marine organisms are prolific sources of depsipeptides, such as marine cyanobacteria, sponges, mollusks, microorganisms and algae. However, these substances have not yet been comprehensively summarized. In order to enrich our knowledge about marine depsipeptides, their biological sources and structural features, as well as bioactivities, are highlighted in this review after an extensive literature search and data analysis.

Lead/Drug Discovery from Natural Resources

Natural products and their derivatives have been shown to be effective drug candidates against various diseases for many years. Over a long period of time, nature has produced an abundant and prosperous source pool for novel therapeutic agents with distinctive structures. Major natural-product-based drugs approved for clinical use include anti-infectives and anticancer agents. This paper will review some natural-product-related potent anticancer, anti-HIV, antibacterial and antimalarial drugs or lead compounds mainly discovered from 2016 to 2022. Structurally typical marine bioactive products are also included. Molecular modeling, machine learning, bioinformatics and other computer-assisted techniques that are very important in narrowing down bioactive core structural scaffolds and helping to design new structures to fight against key disease-associated molecular targets based on available natural products are considered and briefly reviewed.

Natural Products from Plants and Algae for Treatment of Alzheimer’s Disease: A Review

Neurodegenerative disorders including Parkinson’s disease (PD), Huntington’s disease (HD) and the most frequent, Alzheimer’s disease (AD), represent one of the most urgent medical needs worldwide. Despite a significantly developed understanding of disease development and pathology, treatments that stop AD progression are not yet available. The recent approval of sodium oligomannate (GV-971) for AD treatment in China emphasized the potential value of natural products for the treatment of neurodegenerative disorders. Many current clinical studies include the administration of a natural compound as a single and combination treatment. The most prominent mechanisms of action are anti-inflammatory and anti-oxidative activities, thus preserving cellular survival. Here, we review current natural products that are either approved or are in testing for a treatment of neurodegeneration in AD. In addition to the most important compounds of plant origin, we also put special emphasis on compounds from algae, given their neuroprotective activity and their underlying mechanisms of neuroprotection.

Marine-Derived Compounds with Anti-Alzheimer's Disease Activities

Alzheimer's disease (AD) is an irreversible and progressive brain disorder that slowly destroys memory and thinking skills, and, eventually, the ability to perform simple tasks. As the aging population continues to increase exponentially, AD has become a big concern for society. Therefore, neuroprotective compounds are in the spotlight, as a means to tackle this problem. On the other hand, since it is believed-in many cultures-that marine organisms in an individual diet cannot only improve brain functioning, but also slow down its dysfunction, many researchers have focused on identifying neuroprotective compounds from marine resources. The fact that the marine environment is a rich source of structurally unique and biologically and pharmacologically active compounds, with unprecedented mechanisms of action, marine macroorganisms, such as tunicates, corals, sponges, algae, as well as microorganisms, such as marine-derived bacteria, actinomycetes, and fungi, have been the target sources of these compounds. Therefore, this literature review summarizes and categorizes various classes of marine-derived compounds that are able to inhibit key enzymes involved in AD, including acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), β-secretase (BACE-1), and different kinases, together with the related pathways involved in the pathogenesis of AD. The compounds discussed herein are emerging as promising anti-AD activities for further in-depth in vitro and in vivo investigations, to gain more insight of their mechanisms of action and for the development of potential anti-AD drug leads.

Bridging Cyanobacteria to Neurodegenerative Diseases: A New Potential Source of Bioactive Compounds against Alzheimer's Disease

Neurodegenerative diseases (NDs) represent a drawback in society given the ageing population. Dementias are the most prevalent NDs, with Alzheimer’s disease (AD) representing around 70% of all cases. The current pharmaceuticals for AD are symptomatic and with no effects on the progression of the disease. Thus, research on molecules with therapeutic relevance has become a major focus for the scientific community. Cyanobacteria are a group of photosynthetic prokaryotes rich in biomolecules with confirmed activity in pathologies such as cancer, and with feasible potential in NDs such as AD. In this review, we aimed to compile the research works focused in the anti-AD potential of cyanobacteria, namely regarding the inhibition of the enzyme β-secretase (BACE1) as a fundamental enzyme in the generation of β-amyloid (Aβ), the inhibition of the enzyme acetylcholinesterase (AChE) lead to an increase in the availability of the neurotransmitter acetylcholine in the synaptic cleft and the antioxidant and anti-inflammatory effects, as phenomena associated with neurodegeneration mechanisms.

Diversity, molecular mechanisms and structure-activity relationships of marine protease inhibitors-A review

Marine habitats are well-known for their diverse life forms that are potential sources of novel bioactive compounds. Evidence from existing studies suggests that these compounds contribute significantly to the field of pharmaceuticals, nutraceuticals, and cosmeceuticals. The isolation of natural compounds from a marine environment with protease inhibitory activity has gained importance due to drug discovery potential. Despite the increasing research endeavours focusing on protease inhibitors' design and characterization, many of these compounds have failed to reach final phases of clinical trials. As a result, the search for new sources for the development of protease inhibitors remains pertinent. This review focuses on the diverse marine protease inhibitors and their structure-activity relationships. Furthermore, the potential of marine protease inhibitors in drug discovery and molecular mechanism inhibitor binding are critically discussed.

Marine Pharmacology in 2016-2017: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The review of the 2016-2017 marine pharmacology literature was prepared in a manner similar as the 10 prior reviews of this series. Preclinical marine pharmacology research during 2016-2017 assessed 313 marine compounds with novel pharmacology reported by a growing number of investigators from 54 countries. The peer-reviewed literature reported antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral activities for 123 marine natural products, 111 marine compounds with antidiabetic and anti-inflammatory activities as well as affecting the immune and nervous system, while in contrast 79 marine compounds displayed miscellaneous mechanisms of action which upon further investigation may contribute to several pharmacological classes. Therefore, in 2016-2017, the preclinical marine natural product pharmacology pipeline generated both novel pharmacology as well as potentially new lead compounds for the growing clinical marine pharmaceutical pipeline, and thus sustained with its contributions the global research for novel and effective therapeutic strategies for multiple disease categories.

Targeting eukaryotic proteases for natural products-based drug development

Covering: up to April 2020 Proteases are involved in the regulation of many physiological processes. Their overexpression and dysregulated activity are linked to diseases such as hypertension, diabetes, viral infections, blood clotting disorders, respiratory diseases, and cancer. Therefore, they represent an important class of therapeutic targets. Several protease inhibitors have reached the market and >60% of them are directly related to natural products, even when excluding synthetic natural product mimics. Historically, natural products have been a valuable and validated source of therapeutic agents, as over half of the marketed drugs across targets and diseases are inspired by natural product structures. In the past two decades the number of new protease inhibitors discovered from nature has sharply increased. Additionally, the availability of 3D structural information for proteases has permitted structure-based design and accelerated the synthesis of optimized lead structures with improved potency and selectivity profiles, resulting in some of the most-potent-in-class inhibitors. These discoveries were oftentimes maximized by in-depth biological assessments of lead inhibitors, linking them to a relevant disease state. This review will discuss some of the current and emerging drug targets and their involvement in various disease processes, highlighting selected success stories behind several FDA-approved protease inhibitors that have natural products scaffolds as well as recent selected pharmacologically well-characterized inhibitors derived from marine or terrestrial sources.

Marine Cyanobacteria: A Source of Lead Compounds and their Clinically-Relevant Molecular Targets

The prokaryotic filamentous marine cyanobacteria are photosynthetic microbes that are found in diverse marine habitats, ranging from epiphytic to endolithic communities. Their successful colonization in nature is largely attributed to genetic diversity as well as the production of ecologically important natural products. These cyanobacterial natural products are also a source of potential drug leads for the development of therapeutic agents used in the treatment of diseases, such as cancer, parasitic infections and inflammation. Major sources of these biomedically important natural compounds are found predominately from marine cyanobacterial orders Oscillatoriales, Nostocales, Chroococcales and Synechococcales. Moreover, technological advances in genomic and metabolomics approaches, such as mass spectrometry and NMR spectroscopy, revealed that marine cyanobacteria are a treasure trove of structurally unique natural products. The high potency of a number of natural products are due to their specific interference with validated drug targets, such as proteasomes, proteases, histone deacetylases, microtubules, actin filaments and membrane receptors/channels. In this review, the chemistry and biology of selected potent cyanobacterial compounds as well as their synthetic analogues are presented based on their molecular targets. These molecules are discussed to reflect current research trends in drug discovery from marine cyanobacterial natural products.

Cathepsin E expression and activity: Role in the detection and treatment of pancreatic cancer

Cathepsin E (CTSE) is an intracellular, hydrolytic aspartic protease found to be expressed in cells of the immune and gastrointestinal systems, lymphoid tissues, erythrocytes, and cancer cells. The precise functions are not fully understood; however, various studies have investigated its numerous cell-type specific roles. CTSE expression has been shown to be a potential early biomarker for pancreatic ductal adenocarcinoma (PDAC). PDAC patients have low survival rates mostly due to the lack of early detection methods. CTSE-specific activity probes have been developed and tested to assist in tumor imaging and functional studies investigating the role of CTSE expression in PDAC tumors. Furthermore, a CTSE protease-specific, photodynamic therapy pro-drug was developed to explore its potential use to treat tumors that express CTSE. Since CTSE is expressed in pancreatic diseases that are risk factors for PDAC, such as pancreatic cysts and chronic pancreatitis, learning about its function in these disease types could assist in early PDAC detection and in understanding the biology of PDAC progression. Overall, CTSE expression and activity shows potential to detect PDAC and other pancreatic diseases. Further research is needed to fully understand its functions and potential translational applicability.

Total Syntheses of Cathepsin D Inhibitory Izenamides A, B, and C and Structural Confirmation of Izenamide B

The first total syntheses of izenamides A, B, and C, which are depsipeptides inhibitor of cathepsin D, were accomplished. In addition, the stereochemistry of izenamide B was confirmed by our syntheses. The key features of our synthetic route involve the avoidance of critical 2,5-diketopiperazine (DKP) formation and the minimization of epimerization during the coupling of amino acids for the target peptides.

Recent Advances in Exploration and Biotechnological Production of Bioactive Compounds in Three Cyanobacterial Genera: Nostoc, Lyngbya, and Microcystis

Cyanobacteria, are only Gram-negative bacteria with the capacity of oxygenic photosynthesis, so termed as “Cyanophyta” or “blue-green algae.” Their habitat is ubiquitous, which includes the diverse environments, such as soil, water, rock and other organisms (symbiosis, commensalism, or parasitism, etc.,). They are characterized as prominent producers of numerous types of important compounds with anti-microbial, anti-viral, anti-inflammatory and anti-tumor properties. Among the various cyanobacterial genera, members belonging to genera Nostoc, Lyngbya, and Microcystis possess greater attention. The major reason for that is the strains belonging to these genera produce the compounds with diverse activities/structures, including compounds in preclinical and/or clinical trials (cryptophycin and curacin), or the compounds retaining unique activities such as protease inhibitor (micropeptins and aeruginosins). Most of these compounds were tested for their efficacy and mechanism of action(MOA) through in vitro and/or in vivo studies. Recently, the advances in culture techniques of these cyanobacteria, and isolation, purification, and chromatographic analysis of their compounds have revealed insurmountable novel bioactive compounds from these cyanobacteria. This review provides comprehensive update on the origin, isolation and purification methods, chemical structures and biological activities of the major compounds from Nostoc, Lyngbya, and Microcystis. In addition, multi-omics approaches and biotechnological production of compounds from selected cyanobacterial genera have been discussed.

Cyanobacterial bioactive metabolites-A review of their chemistry and biology

Cyanobacterial blooms occur when algal densities exceed baseline population concentrations. Cyanobacteria can produce a large number of secondary metabolites. Odorous metabolites affect the smell and flavor of aquatic animals, whereas bioactive metabolites cause a range of lethal and sub-lethal effects in plants, invertebrates, and vertebrates, including humans. Herein, the bioactivity, chemistry, origin, and biosynthesis of these cyanobacterial secondary metabolites were reviewed. With recent revision of cyanobacterial taxonomy by Anagnostidis and Komárek as part of the Süβwasserflora von Mitteleuropa volumes 19(1-3), names of many cyanobacteria that produce bioactive compounds have changed, thereby confusing readers. The original and new nomenclature are included in this review to clarify the origins of cyanobacterial bioactive compounds. Due to structural similarity, the 157 known bioactive classes produced by cyanobacteria have been condensed to 55 classes. This review will provide a basis for more formal procedures to adopt a logical naming system. This review is needed for efficient management of water resources to understand, identify, and manage cyanobacterial harmful algal bloom impacts.

Natural Products from Cyanobacteria: Focus on Beneficial Activities

Cyanobacteria are photosynthetic microorganisms that colonize diverse environments worldwide, ranging from ocean to freshwaters, soils, and extreme environments. Their adaptation capacities and the diversity of natural products that they synthesize, support cyanobacterial success in colonization of their respective ecological niches. Although cyanobacteria are well-known for their toxin production and their relative deleterious consequences, they also produce a large variety of molecules that exhibit beneficial properties with high potential in various fields (e.g., a synthetic analog of dolastatin 10 is used against Hodgkin's lymphoma). The present review focuses on the beneficial activities of cyanobacterial molecules described so far. Based on an analysis of 670 papers, it appears that more than 90 genera of cyanobacteria have been observed to produce compounds with potentially beneficial activities in which most of them belong to the orders Oscillatoriales, Nostocales, Chroococcales, and Synechococcales. The rest of the cyanobacterial orders (i.e., Pleurocapsales, Chroococcidiopsales, and Gloeobacterales) remain poorly explored in terms of their molecular diversity and relative bioactivity. The diverse cyanobacterial metabolites possessing beneficial bioactivities belong to 10 different chemical classes (alkaloids, depsipeptides, lipopeptides, macrolides/lactones, peptides, terpenes, polysaccharides, lipids, polyketides, and others) that exhibit 14 major kinds of bioactivity. However, no direct relationship between the chemical class and the respective bioactivity of these molecules has been demonstrated. We further selected and specifically described 47 molecule families according to their respective bioactivities and their potential uses in pharmacology, cosmetology, agriculture, or other specific fields of interest. With this up-to-date review, we attempt to present new perspectives for the rational discovery of novel cyanobacterial metabolites with beneficial bioactivity.

Cyanobacterial bioactive metabolites-A review of their chemistry and biology

Cyanobacterial blooms occur when algal densities exceed baseline population concentrations. Cyanobacteria can produce a large number of secondary metabolites. Odorous metabolites affect the smell and flavor of aquatic animals, whereas bioactive metabolites cause a range of lethal and sub-lethal effects in plants, invertebrates, and vertebrates, including humans. Herein, the bioactivity, chemistry, origin, and biosynthesis of these cyanobacterial secondary metabolites were reviewed. With recent revision of cyanobacterial taxonomy by Anagnostidis and Komárek as part of the Süβwasserflora von Mitteleuropa volumes 19(1-3), names of many cyanobacteria that produce bioactive compounds have changed, thereby confusing readers. The original and new nomenclature are included in this review to clarify the origins of cyanobacterial bioactive compounds. Due to structural similarity, the 157 known bioactive classes produced by cyanobacteria have been condensed to 55 classes. This review will provide a basis for more formal procedures to adopt a logical naming system. This review is needed for efficient management of water resources to understand, identify, and manage cyanobacterial harmful algal bloom impacts.

Discovery of Amantamide, a Selective CXCR7 Agonist from Marine Cyanobacteria

CXCR7 plays an emerging role in several physiological processes. A linear peptide, amantamide (1), was isolated from marine cyanobacteria, and the structure was determined by NMR and mass spectrometry. The total synthesis was achieved by solid-phase method. After screening two biological target libraries, 1 was identified as a selective CXCR7 agonist. The selective activation of CXCR7 by 1 could provide the basis for developing CXCR7-targeted therapeutics and deciphering the role of CXCR7 in different diseases.

Izenamides A and B, Statine-Containing Depsipeptides, and an Analogue from a Marine Cyanobacterium

Izenamides A, B, and C (1-3), new linear depsipeptides, were isolated from a taxonomically distinct marine cyanobacterium. Izenamides A and B contain a statine moiety [(3 S,4 S)-4-amino-3-hydroxy-6-methylheptanoic acid] and inhibited the activity of cathepsin D, an aspartic peptidase. Meanwhile, izenamides did not show growth-inhibitory activity against HeLa, HL60, or MCF-7 cells at up to 10 μM.

Discovery, Synthesis, Pharmacological Profiling, and Biological Characterization of Brintonamides A-E, Novel Dual Protease and GPCR Modulators from a Marine Cyanobacterium

Five novel modified linear peptides named brintonamides A-E (1-5) were discovered from a marine cyanobacterial sample collected from Brinton Channel, Florida Keys. The total synthesis of 1-5 in addition to two other structurally related analogues (6 and 7) was achieved, which provided more material to allow rigorous biological evaluation and SAR studies. Compounds were subjected to cancer-focused phenotypic cell viability and migration assays and orthogonal target-based pharmacological screening platforms to identify their protease and GPCR modulatory activity profiles. The cancer related serine protease kallikrein 7 (KLK7) was inhibited to similar extents with an IC50 near 20 μM by both representative members 1 and 4, which differed in the presence or lack of the N-terminal unit. In contrast to the biochemical protease profiling study, clear SAR was observed in the functional GPCR screens, where five GPCRs in antagonist mode (CCR10, OXTR, SSTR3, TACR2) and agonist mode (CXCR7) were modulated by compounds 1-7 to varying extents. Chemokine receptor type 10 (CCR10) was potently modulated by brintonamide D (4) with an IC50 of 0.44 μM. We performed in silico modeling to understand the structural basis underlying the differences in the antagonistic activity among brintonamides toward CCR10. Because of the significance of KLK7 and CCR10 in cancer progression and metastasis, we demonstrated the ability of brintonamide D (4) at 10 μM to significantly target downstream cellular substrates of KLK7 (Dsg-2 and E-cad) in vitro and to inhibit CCL27-induced CCR10-mediated proliferation and the migration of highly invasive breast cancer cells.

Marine natural products

Covering: 2016. Previous review: Nat. Prod. Rep., 2017, 34, 235-294This review covers the literature published in 2016 for marine natural products (MNPs), with 757 citations (643 for the period January to December 2016) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1277 in 432 papers for 2016), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included.

Marine natural product peptides with therapeutic potential: Chemistry, biosynthesis, and pharmacology

The oceans are a uniquely rich source of bioactive metabolites, of which sponges have been shown to be among the most prolific producers of diverse bioactive secondary metabolites with valuable therapeutic potential. Much attention has been focused on marine bioactive peptides due to their novel chemistry and diverse biological properties. As summarized in this review, marine peptides are known to exhibit various biological activities such as antiviral, anti-proliferative, antioxidant, anti-coagulant, anti-hypertensive, anti-cancer, antidiabetic, antiobesity, and calcium-binding activities. This review focuses on the chemistry and biology of peptides isolated from sponges, bacteria, cyanobacteria, fungi, ascidians, and other marine sources. The role of marine invertebrate microbiomes in natural products biosynthesis is discussed in this review along with the biosynthesis of modified peptides from different marine sources. The status of peptides in various phases of clinical trials is presented, as well as the development of modified peptides including optimization of PK and bioavailability.

Grassystatins D-F, Potent Aspartic Protease Inhibitors from Marine Cyanobacteria as Potential Antimetastatic Agents Targeting Invasive Breast Cancer

Three new modified peptides named grassystatins D-F (1-3) were discovered from a marine cyanobacterium from Guam. Their structures were elucidated using NMR spectroscopy and mass spectrometry. The hallmark structural feature in the peptides is a statine unit, which contributes to their aspartic protease inhibitory activity preferentially targeting cathepsins D and E. Grassystatin F (3) was the most potent analogue, with IC50 values of 50 and 0.5 nM against cathepsins D and E, respectively. The acidic tumor microenvironment is known to increase the activation of some of the lysosomal proteases associated with tumor metastasis such as cathepsins. Because cathepsin D is a biomarker in aggressive forms of breast cancer and linked to poor prognosis, the effects of cathepsin D inhibition by 1 and 3 on the downstream cellular substrates cystatin C and PAI-1 were investigated. Furthermore, the functional relevance of targeting cathepsin D substrates was evaluated by examining the effect of 1 and 3 on the migration of MDA-MD-231 cells. Grassystatin F (3) inhibited the cleavage of cystatin C and PAI-1, the activities of their downstream targets cysteine cathepsins and tPA, and the migration of the highly aggressive triple negative breast cancer cells, phenocopying the effect of siRNA-mediated knockdown of cathepsin D.

Structural Diversity, Biological Properties and Applications of Natural Products from Cyanobacteria. A Review

Nowadays, various drugs on the market are becoming more and more resistant to numerous diseases, thus declining their efficacy for treatment purposes in human beings. Antibiotic resistance is one among the top listed threat around the world which eventually urged the discovery of new potent drugs followed by an increase in the number of deaths caused by cancer due to chemotherapy resistance as well. Accordingly, marine cyanobacteria, being the oldest prokaryotic microorganisms belonging to a monophyletic group, have proven themselves as being able to generate pharmaceutically important natural products. They have long been known to produce distinct and structurally complex secondary metabolites including peptides, polyketides, alkaloids, lipids, and terpenes with potent biological properties and applications. As such, this review will focus on recently published novel compounds isolated from marine cyanobacteria along with their potential bioactivities such as antibacterial, antifungal, anticancer, anti-tuberculosis, immunosuppressive and anti-inflammatory capacities. Moreover, various structural classes, as well as their technological uses will also be discussed.