Marine-sourced anti-cancer and cancer pain control agents in clinical and late preclinical development

In Vivo and Clinical Studies of Natural Products Targeting the Hallmarks of Cancer

Despite more than 200 approved anticancer agents, cancer remains a leading cause of death worldwide due to disease complexity, tumour heterogeneity, drug toxicity, and the emergence of drug resistance. Accordingly, the development of chemotherapeutic agents with higher efficacy, a better safety profile, and the capability of bypassing drug resistance would be a cornerstone in cancer therapy. Natural products have played a pivotal role in the field of drug discovery, especially for the pharmacotherapy of cancer, infectious, and chronic diseases. Owing to their distinctive structures and multiple mechanistic activities, natural products and their derivatives have been utilized for decades in cancer treatment protocols. In this review, we delve into the potential of natural products as anticancer agents by targeting cancer's hallmarks, including sustained proliferative signalling, evading growth suppression, resisting apoptosis and cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. We highlight the molecular mechanisms of some natural products, in vivo studies, and promising clinical trials. This review emphasizes the significance of natural products in fighting cancer and the need for further studies to uncover their fully therapeutic potential.

Heteronemin promotes iron-dependent cell death in pancreatic cancer

The marine environment has been recognized as a prolific source of potent bioactive compounds with significant anticancer properties. Among these, heteronemin, a sesterterpenoid-type natural product, has shown promise. This study delves into the potential of heteronemin as a ferroptotic agent against pancreatic cancer, using the Panc-1 cell line as a model. The cytotoxic potential of heteronemin was assessed using cell viability assays. Furthermore, its effect on lipid peroxidation was determined spectrophotometrically, while the changes it induced in autophagy- and ferritin-related protein expressions were evaluated using immunoblotting techniques. Various cell-based tests were employed to scrutinize its anticancer efficacy. Heteronemin displayed a notable cytotoxic effect, reducing cell viability by 50% at a concentration of 55 nM. This cytotoxicity was discernibly linked to ferroptosis, as evidenced by the reversal of cell death upon treatment with the ferroptosis inhibitor, ferrostatin-1. Heteronemin treatment led to a marked increase in ferroptosis markers and malondialdehyde (MDA) levels. Conversely, the expression of glutathione peroxidase-4 (GPX4), a key anti-ferroptotic protein, was suppressed. Furthermore, significant modulations in the expression of ferritinophagy- and iron-related proteins such as Atg5, Atg7, FTL, STEAP3, and DMT-1 were evident post-treatment (p < 0.05). This study underscores the potential of heteronemin as a ferroptosis inducer in pancreatic cancer cells. Given its robust cytotoxicity, heteronemin emerges as a promising lead compound for further exploration in cancer therapeutics.

Dankasterone A induces prostate cancer cell death by inducing oxidative stress

Oxidative stress plays a dual role in tumor survival, either promoting tumor development or killing tumor cells under different conditions. Dankasterone A is a secondary metabolite derived from the fungus Talaromyces purpurogenu. It showed good potential in a screen for anti-prostate cancer compounds. In this study, MTT results showed dankasterone A was cytotoxic to prostate cancer cells, with an IC50 of 5.10 μM for PC-3 cells and 3.41 μM for 22Rv1 cells. Further studies, plate cloning assays and real-time cell analysis monitoring showed that dankasterone A significantly inhibited clonal colony formation and cell migration in 22Rv1 and PC-3 cells. In addition, flow cytometry results showed that dankasterone A induced apoptosis in prostate cancer cells while having no impact on cell cycle distribution. At the molecular level, Protein microarray experiments and western blot assays revealed that dankasterone A specifically and dramatically upregulated HO-1 protein expression; and the results of cell fluorescence staining showed that dankasterone A induced overexpression of reactive oxygen species in 22Rv1 and PC-3 cells. Taken together, dankasterone A induced prostate cancer cells to undergo intense oxidative stress, which resulted in the production of large amounts of HO-1 and the release of large amounts of reactive oxygen species, leading to apoptosis of prostate cancer cells, ultimately resulting in the inhibition of both cell proliferation and migration. We also validated the anti-prostate cancer effects of dankasterone A in vivo in a zebrafish xenograft tumor model. In conclusion, dankasterone A has the potential to be developed as an anti-prostate cancer drug.

More than just an eagle killer: The freshwater cyanobacterium Aetokthonos hydrillicola produces highly toxic dolastatin derivatives

Cyanobacteria are infamous producers of toxins. While the toxic potential of planktonic cyanobacterial blooms is well documented, the ecosystem level effects of toxigenic benthic and epiphytic cyanobacteria are an understudied threat. The freshwater epiphytic cyanobacterium Aetokthonos hydrillicola has recently been shown to produce the "eagle killer" neurotoxin aetokthonotoxin (AETX) causing the fatal neurological disease vacuolar myelinopathy. The disease affects a wide array of wildlife in the southeastern United States, most notably waterfowl and birds of prey, including the bald eagle. In an assay for cytotoxicity, we found the crude extract of the cyanobacterium to be much more potent than pure AETX, prompting further investigation. Here, we describe the isolation and structure elucidation of the aetokthonostatins (AESTs), linear peptides belonging to the dolastatin compound family, featuring a unique modification of the C-terminal phenylalanine-derived moiety. Using immunofluorescence microscopy and molecular modeling, we confirmed that AEST potently impacts microtubule dynamics and can bind to tubulin in a similar matter as dolastatin 10. We also show that AEST inhibits reproduction of the nematode Caenorhabditis elegans. Bioinformatic analysis revealed the AEST biosynthetic gene cluster encoding a nonribosomal peptide synthetase/polyketide synthase accompanied by a unique tailoring machinery. The biosynthetic activity of a specific N-terminal methyltransferase was confirmed by in vitro biochemical studies, establishing a mechanistic link between the gene cluster and its product.

Transcriptomic and proteomic analyses reveal the first occurrence of diverse toxin groups in Millepora alcicornis

Millepora alcicornis is a reef-forming cnidarian widely distributed in the Mexican Caribbean. Millepora species or "fire corals" inflict a painful stinging reaction in humans when touched. Even though hundreds of organic and polypeptide toxins have been characterized from sea anemones and jellyfish, there are few reports regarding the diversity of toxins synthesized by fire corals. Here, based on transcriptomic analysis of M. alcicornis, several predicted proteins that show amino acid sequence similarity to toxins were identified, including neurotoxins, metalloproteases, hemostasis-impairing toxins, serin proteases, cysteine-rich venom proteins, phospholipases, complement system-impairing toxins, phosphodiesterases, pore-forming toxins, and L-aminoacid oxidases. The soluble nematocyst proteome of this organism was shown to induce hemolytic, proteolytic, and phospholipase A2 effects by gel zymography. Protein bands or spots on 1D- and 2D-PAGE gels corresponding to zones of hemolytic and enzymatic activities were excised, subjected to in-gel digestion with trypsin, and analyzed by mass spectrometry. These proteins exhibited sequence homology to PLA2s, metalloproteinases, pore-forming toxins, and neurotoxins, such as actitoxins and CrTX-A. The complex array of venom-related transcripts that were identified in M. alcicornis, some of which are first reported in "fire corals", provide novel insight into the structural richness of Cnidarian toxins and their distribution among species. SIGNIFICANCE: Marine organisms are a promising source of bioactive compounds with valuable contributions in diverse fields such as human health, pharmaceuticals, and industrial application. Currently, not much attention has been paid to the study of fire corals, which possess a variety of molecules that exhibit diverse toxic effects and therefore have great pharmaceutical and biotechnological potential. The isolation and identification of novel marine-derived toxins by classical approaches are time-consuming and have low yields. Thus, next-generation strategies, like base-'omics technologies, are essential for the high-throughput characterization of venom compounds such as those synthesized by fire corals. This study moves the field forward because it provides new insights regarding the first occurrence of diverse toxin groups in Millepora alcicornis. The findings presented here will contribute to the current understanding of the mechanisms of action of Millepora toxins. This research also reveals important information related to the potential role of toxins in the defense and capture of prey mechanisms and for designing appropriate treatments for fire coral envenomation. Moreover, due to the lack of information on the taxonomic identification of Millepora, the insights presented here can advise the taxonomic classification of the species of this genus.

A network pharmacology-based investigation of brugine reveals its multi-target molecular mechanism against Breast Cancer

Breast cancer represents the leading cause of mortality among women worldwide. Since the complexity of breast cancer as a disease resides in its heterogeneity as it consists of several subtypes such as hormone receptor-positive subtypes: Luminal A, Luminal B, Her2- overexpressed, basal-like and hormone receptor-negative subtype: TNBC. Among all the subtypes, triple negative breast cancer (TNBC) is the most lethal and complex subtype. Moreover, the available treatment options like surgery, radiation therapy, and chemotherapy are not sufficient because of the associated side effects and drug resistance development. Therefore, discovery of new effective natural compounds with anti-tumor activity is required. In this pursuit, marine organisms provide a plentiful supply of such chemicals compounds. A marine compound Brugine found in the bark and stem of mangrove species Bruguiera sexangula is a potential anti-cancer compound. It has shown its cytotoxic activity against sarcoma 180 and lewis lung cancer. The molecular processes, however, are currently unknown. So, in order to research the molecular pathways this compound utilizes, we sought to apply a network pharmacology approach. The network pharmacology strategy we used in this investigation to identify and evaluate possible molecular pathways involved in the treatment of breast cancer with brugine was supported by simulation and molecular docking experiments. The study was conducted using various databases such as the cancer genome atlas (TCGA) for the genetic profile study of breast cancer, Swiss ADME for studying the pharmacodynamic study of brugine, Gene cards for collection of information of genes, STRING was used to study the interaction among proteins, AutoDock vina was to study the binding efficacy of brugine with the best fit protein. The results showed that the compound and breast cancer target network shared 90 common targets. According to the functional enrichment analysis brugine exhibited its effects in breast cancer via modulating certain pathways such as cAMP signaling pathway, JAK/STAT pathway, HIF-1 signaling pathway PI3K-Akt pathway, calcium signaling pathway, and Necroptosis. Molecular docking investigations demonstrated that the investigated marine compound has a high affinity for the key target, protein kinase A (PKA). A stable protein-ligand combination was created by the best hit molecule, according to molecular dynamics modeling. The purpose of this research was to examine the importance of brugine as a potentially effective treatment for breast cancer and to obtain knowledge of the molecular mechanism used by this substance in breast cancer.

Further undescribed cembranoids from South China Sea soft coral Sarcophyton ehrenbergi: Structural elucidation and biological evaluation

A detailed chemical investigation of the South China Sea soft coral Sarcophyton ehrenbergi has yield seven undescribed cembranoids, namely isoehrenbergol D and sarcoehrenolides F-K embodying a rare α,β-unsaturated-lactone moiety at C-6 to C-19, along with two known related compounds, ehrenbergol D and sarcoehrenolide A. Their structures and absolute configurations were unambiguously established in the light of extensive spectroscopic data analysis, modified Mosher's method, X-ray diffraction analysis, and quantum chemical computation method. In a bioassay for α-glucosidase inhibition, ehrenbergol D was evaluated as α-glucosidase inhibitor with an IC₅₀ value of 13.57 μM.

Callyspongia spp.: Secondary Metabolites, Pharmacological Activities, and Mechanisms

One of the most widespread biotas in the sea is the sponge. Callyspongia is a sponge genus found in the seas, making it easily available. In this review, the pharmacological activity and mechanism of action of the secondary metabolites of Callyspongia spp. are addressed, which may lead to the development of new drugs and targeted therapeutic approaches. Several scientific databases, such as Google Scholar, PubMed, ResearchGate, Science Direct, Springer Link, and Wiley Online Library, were mined to obtain relevant information. In the 41 articles reviewed, Callyspongia spp. was reported to possess pharmacological activities such as cytotoxicity against cancer cell lines (36%), antifungal (10%), anti-inflammatory (10%), immunomodulatory (10%), antidiabetic and antiobesity (6%), antimicrobial (8%), antioxidant (4%), antineurodegenerative (4%), antihypercholesterolemic (2%), antihypertensive (2%), antiparasitic (2%), antiallergic (2%), antiviral (2%), antiosteoporotic (2%), and antituberculosis (2%) activities. Of these, the antioxidant, antituberculosis, and anti-inflammatory activities of Callyspongia extract were weaker compared with that of the control drugs; however, other activities, particularly cytotoxicity, show promise, and the compounds responsible may be developed into new drugs.

Marine Natural Products from the Beibu Gulf: Sources, Chemistry, and Bioactivities

Marine natural products (MNPs) play an important role in the discovery and development of new drugs. The Beibu Gulf of South China Sea harbors four representative marine ecosystems, including coral reefs, mangroves, seaweed beds, and coastal wetlands, which are rich in underexplored marine biological resources that produce a plethora of diversified MNPs. In our ongoing efforts to discover novel and biologically active MNPs from the Beibu Gulf, we provide a systematic overview of the sources, chemical structures, and bioactive properties of a total of 477 new MNPs derived from the Beibu Gulf, citing 133 references and covering the literature from the first report in November 2003 up to September 2022. These reviewed MNPs were structurally classified into polyketides (43%), terpenoids (40%), nitrogen-containing compounds (12%), and glucosides (5%), which mainly originated from microorganisms (52%) and macroorganisms (48%). Notably, they were predominantly found with cytotoxic, antibacterial, and anti-inflammatory activities. This review will shed light on these untapped Beibu Gulf-derived MNPs as promising lead compounds for the development of new drugs.

Marine Natural Products with Activities against Prostate Cancer: Recent Discoveries

Prostate cancer is the most common cancer in men, with over 52,000 new cases diagnosed every year. Diagnostics and early treatment are potentially hindered by variations in screening protocols, still largely reliant on serum levels of acid phosphatase and prostate-specific antigen, with tumour diagnosis and grading relying on histopathological examination. Current treatment interventions vary in terms of efficacy, cost and severity of side effects, and relapse can be aggressive and resistant to the current standard of care. For these reasons, the scientific community is looking for new chemotherapeutic agents. This review reports compounds and extracts derived from marine organisms as a potential source of new drugs against prostate cancer. Whilst there are several marine-derived compounds against other cancers, such as multiple myeloma, leukemia, breast and lung cancer, already available in the market, the presently collated findings show how the marine environment can be considered to hold potential as a new drug source for prostate cancer, as well. This review presents information on compounds presently in clinical trials, as well as new compounds/extracts that may enter trials in the future. We summarise information regarding mechanisms of action and active concentrations.

Unveiling Microbial Chemical Interactions Based on Metabolomics Approaches

Microorganisms are ubiquitous in diverse habitats and studying their chemical interactions with the environment and comprehend its complex relations with both hosts and environment, are crucial for the development of strategies to control microbial diseases. This chapter discusses the importance of studying microorganisms with agricultural benefits, using specialized metabolites as examples. Herein we highlight the challenges and opportunities in utilizing microorganisms as alternatives to synthetic pesticides and fertilizers in agriculture. Genome-guided investigations and improved analytical methodologies are necessary to characterize diverse and complex biomolecules produced by microorganisms. Predicting and isolating bioproducts based on genetic information have become a focus for researchers, aided by tools like antiSMASH, BiG-SCAPE, PRISM, and others. However, translating genomic data into practical applications can be complex. Therefore, integrating genomics, transcriptomics, and metabolomics enhances chemical characterization, aiding in discovering new metabolic pathways and specialized metabolites. Additionally, elicitation is one promising strategy to enhance beneficial metabolite production. Finally, identify and characterize microbial secondary metabolites remain challenging due to their low production, complex chemical structure characterization and different environmental factors necessary for metabolite in vitro production.

Non-coding RNA-related antitumor mechanisms of marine-derived agents

In the last two decades, natural active substances have attracted great attention in developing new antitumor drugs, especially in the marine environment. A series of marine-derived compounds or derivatives with potential antitumor effects have been discovered and developed, but their mechanisms of action are not well understood. Emerging studies have found that several tumor-related signaling pathways and molecules are involved in the antitumor mechanisms of marine-derived agents, including noncoding RNAs (ncRNAs). In this review, we provide an update on the regulation of marine-derived agents associated with ncRNAs on tumor cell proliferation, apoptosis, cell cycle, invasion, migration, drug sensitivity and resistance. Herein, we also describe recent advances in marine food-derived ncRNAs as antitumor agents that modulate cross-species gene expression. A better understanding of the antitumor mechanisms of marine-derived agents mediated, regulated, or sourced by ncRNAs will provide new biomarkers or targets for potential antitumor drugs from preclinical discovery and development to clinical application.

Can Natural Products Targeting EMT Serve as the Future Anticancer Therapeutics?

Cancer is the leading cause of death and has remained a big challenge for the scientific community. Because of the growing concerns, new therapeutic regimens are highly demanded to decrease the global burden. Despite advancements in chemotherapy, drug resistance is still a major hurdle to successful treatment. The primary challenge should be identifying and developing appropriate therapeutics for cancer patients to improve their survival. Multiple pathways are dysregulated in cancers, including disturbance in cellular metabolism, cell cycle, apoptosis, or epigenetic alterations. Over the last two decades, natural products have been a major research interest due to their therapeutic potential in various ailments. Natural compounds seem to be an alternative option for cancer management. Natural substances derived from plants and marine sources have been shown to have anti-cancer activity in preclinical settings. They might be proved as a sword to kill cancerous cells. The present review attempted to consolidate the available information on natural compounds derived from plants and marine sources and their anti-cancer potential underlying EMT mechanisms.

Marine Cyanobacteria as Sources of Lead Anticancer Compounds: A Review of Families of Metabolites with Cytotoxic, Antiproliferative, and Antineoplastic Effects

The marine environment is highly diverse, each living creature fighting to establish and proliferate. Among marine organisms, cyanobacteria are astounding secondary metabolite producers representing a wonderful source of biologically active molecules aimed to communicate, defend from predators, or compete. Studies on these molecules’ origins and activities have been systematic, although much is still to be discovered. Their broad chemical diversity results from integrating peptide and polyketide synthetases and synthases, along with cascades of biosynthetic transformations resulting in new chemical structures. Cyanobacteria are glycolipid, macrolide, peptide, and polyketide producers, and to date, hundreds of these molecules have been isolated and tested. Many of these compounds have demonstrated important bioactivities such as cytotoxicity, antineoplastic, and antiproliferative activity with potential pharmacological uses. Some are currently under clinical investigation. Additionally, conventional chemotherapeutic treatments include drugs with a well-known range of side effects, making anticancer drug research from new sources, such as marine cyanobacteria, necessary. This review is focused on the anticancer bioactivities of metabolites produced by marine cyanobacteria, emphasizing the identification of each variant of the metabolite family, their chemical structures, and the mechanisms of action underlying their biological and pharmacological activities.

Evaluation of Phytochemistry and Pharmacological Properties of Alnus nitida

In the current study, the anti-inflammatory and analgesic potential of Alnus nitida (leaves and fruits) was evaluated in the Sprague-Dawley rat. Traditionally, A. nitida was used for the treatment of inflammatory ailments. However, A. nitida leaves and fruits have not been yet reported regarding any potential medicinal effects. Leaves/fruits of A. nitida were extracted with methanol and fractionated to attain n-hexane, chloroform, ethyl acetate and aqueous fractions. These extracts were then evaluated for in vivo analgesic and anti-inflammatory potential. For in vivo anti-inflammatory activity, carrageenan-induced paw edema assay, Freunds’ complete adjuvant-induced edema, xylene-induced ear edema and histamine-induced paw edema models were used in rats, which showed significant (p < 0.01) reduction (70−80%) in edema in comparison of inflammatory controls. On other hand, for the analgesic assessment, hot plate assay and acetic acid-induced writhing tests were used, which showed a significant (p < 0.01) rise in latency time (40−60%) as compared with pain-induced controls. These results were comparable with standard drugs in a concentration-dependent manner and no mortality or toxicity was observed during all experiments. Then, for the identification of chemical constituents gas chromatography−mass spectrometry (GC-MS) analysis was performed, which indicated the presence of neophytadiene, 3,7,11,15-Tetramethyl-2-hexadecen-1-ol, phytol and vitamin E, justifying the use of A. nitida to treat inflammatory disorders.

Biosynthesis of Vitroprocines by α-Oxoamine Synthase and Oxidoreductase Identified from Vibrio sp. QWI-06

A specific α-oxoamine synthase (VsAOS-2) and an oxidoreductase (VsOR) identified from marine Vibrio sp. QWI-06 were involved in the decarboxylative condensation of l-tyrosine to lauroyl-CoA following the reduction of the ketone group to form vitroprocine-type compound 1. The intermediates and products were characterized through HR-MS and their MS/MS fragmentations. This study reveals the biosynthetic pathway of vitroprocines and provides a useful model for elucidating the reaction mechanism underlying the production of amino acid-polyketide derivatives in microorganisms.

Discovery and Development of Dolastatin 10-Derived Antibody Drug Conjugate Anticancer Drugs

Dolastatin 10 is an extremely potent broad-spectrum antitubulin anticancer pentapeptide isolated from Dolabella auricularia. The two-dimensional structure was elucidated by NMR and mass spectrometric analyses. The absolute configuration was determined by a convergent total synthesis. SAR studies established that modifications at C- and N-terminals were tolerated for cytotoxic activity. Human clinical trials of dolastatin 10 and auristatin PE (a C-terminal analog) showed occasional signs of efficacy but failed due to lack of separation of toxicity and efficacy. Nanomolar cytotoxicity helped transition this class of pentapeptides to the next phase of development as antibody drug conjugates (ADCs) by reducing systemic toxicity. Four ADC drugs (Adcetris, Padcev, Polivy, and Blenrep) carrying monomethyl auristatin E (MMAE, vedotin) and monomethyl auristatin F (MMAF, mafodotin) payloads have been approved for treatment of a number of cancers expressing antibody-specific antigens. More than 36 ADCs carrying a variety of pentapeptide analogues are undergoing preclinical and clinical developments. They are being evaluated in more than 200 human trials. A comprehensive review of the discovery, total synthesis of dolastatin 10 and new amino acids, SAR studies of dolastatin 10 and auristatins, conjugations to antibodies, and preclinical and clinical development of ADCs have been presented.

Anti-lung Cancer Marine Compounds: A Review

Lung cancer is one of the most common and lethal cancers in human beings. Lung cancer has been divided into two major types: small cell lung cancer (SCLC) and non-small cell lung carcinoma (NSCLC). Current drugs suffer from various side effects, and the insufficient efficacy of present treatments creates a desire for better more efficient new drugs. This review compares the diversity of marine-derived bioactive compounds from different marine species. Some of the natural products from marine resources are in different stages of clinical trials. By the way, most of them have been studied in vitro and in vivo. Additionally, in this review, the mechanisms of action of marine-derived anti-lung cancer components on lung cancer cell lines have been reviewed. In addition, considering growing rate and the high costs of cancer research, attention must be paid to some aspects of targeting and developing anti-lung cancer drug. In better words, like the other therapeutic strategies that have their particular challenges and weak points, several challenges about marine-derived anti-lung cancer components which exist for scientists for doing research are explained. Moreover, as the attentions in the field of cancer therapy are focused on designing and developing new anticancer strategies for the treatment of cancer in the future, the application of marine-derived anti-lung cancer components in the field of future cancer therapy and their role in future anticancer strategies are briefly discussed.

Computational peptidology approach to the study of the chemical reactivity and bioactivity properties of Aspergillipeptide D, a cyclopentapeptide of marine origin

Aspergillipeptide D is a cyclic pentapeptide isolated from the marine gorgonian Melitodes squamata-derived fungus Aspergillus sp. SCSIO 41501 that it has been shown to present moderate activity against herpes virus simplex type 1 (HSV-1). Thus, this paper presents the results of a computational study of this cyclopentapeptide's chemical reactivity and bioactivity properties using a CDFT-based computational peptidology (CDFT-CP) methodology, which is derived from combining chemical reactivity descriptors derived from Conceptual Density Functional Theory (CDFT) and some Cheminformatics tools which may be used. This results in an improvement of the virtual screening procedure by a similarity search allowing the identification and validation of the known ability of the peptide to act as a possible useful drug. This was followed by an examination of the drug's bioactivity and pharmacokinetics indices in relation to the ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) characteristics. The findings provide further evidence of the MN12SX density functional's superiority in proving the Janak and Ionization Energy theorems using the proposed KID approach. This has proven to be beneficial in accurately predicting CDFT reactivity characteristics, which aid in the understanding of chemical reactivity. The Computational Pharmacokinetics study revealed the potential ability of Aspergillipeptide D as a therapeutic drug through the interaction with different target receptors. The ADMET indices confirm this assertion through the absence of toxicity and good absorption and distribution properties.

Bioactive Molecules from Ciliates: Structure, Activity, and Applicative Potential

Ciliates are a rich source of molecules synthesized to socialize, compete ecologically, and interact with prey and predators. Their isolation from laboratory cultures is often straightforward, permitting the study of their mechanisms of action and their assessment for applied research. This review focuses on three classes of these bioactive molecules: (i) water‐borne, cysteine‐rich proteins that are used as signaling pheromones in self/nonself recognition phenomena; (ii) cell membrane‐associated lipophilic terpenoids that are used in interspecies competitions for habitat colonization; (iii) cortical granule‐associated molecules of various chemical nature that primarily serve offence/defense functions.

Can be marine bioactive peptides (MBAs) lead the future of foodomics for human health?

Marine organisms are considered a cache of biologically active metabolites with pharmaceutical, functional, and nutraceutical properties. Among these, marine bioactive peptides (MBAs) present in diverse marine species (fish, sponges, cyanobacteria, fungi, ascidians, seaweeds, & mollusks) have acquired attention owing to their broad-spectrum health-promoting benefits. Nowadays, scientists are keener exploring marine bioactive peptides precisely due to their unique structural and biological properties. These MBAs have reported ameliorating potential against different diseases like hypertension, diabetes, obesity, HIV, cancer, oxidation, and inflammation. Furthermore, MBAs isolated from various marine organisms may also have a beneficial role in the cosmetic, nutraceutical, and food industries. Few marine peptides and their derivative are approved for commercial use, while many MBAs are in various pre-clinical and clinical trials. This review mainly focuses on the diversity of marine bioactive peptides in marine organisms and their production procedures, such as chemical and enzymatic hydrolysis. Moreover, MBAs' therapeutic and biological potential has also been critically discussed herein, along with their status in drug discovery, pre-clinical and clinical trials.

Mitochondrial Pro-Apoptotic Properties of Sinularia compressa from Persian Gulf against Breast Cancer Cells and Its Chemical Composition

Locals in the Persian Gulf islands traditionally use Sinularia compressa to treat cancer. Therefore, this study deals with the cytotoxic activity of the soft coral Sinularia compressa chloroform extract (SCE), its pro-apoptotic activity, and the determination of its secondary metabolites. Cytotoxicity was done against MCF-7 and MDA-MB-231 and MCF‑10A cells. Apoptosis induction was checked by flow cytometry. The DCFDA and JC-1 probes were used to assess the production of reactive oxygen species (ROS) and the mitochondrial transmembrane potential. Caspase-9, Bax, and Bcl-2 proteins were determined with ELISA Kit, and by western blot analysis. SCE exhibited cytotoxic activity with an IC₅₀ value of 32.51 ± 0.70 μg/ml against MCF-7, and 8.53 ± 0.97 μg/ml against MDA-MB-231 cancer cells. The induction of the intrinsic apoptosis pathway was found by ROS generation, attenuation of Bcl-2 and induction of Bax proteins. It was supported by activation of caspase-9, increased apoptotic cells, as well as decrease of ΔΨm. In the acute toxicity, there was no detectable sign of hepatic or renal toxicity in the SCE 100 mg/kg. GC mass and NMR identified bioactive compounds as one monoterpene, one sesquiterpene, five fatty acids, one phthalate, and two steroidal compounds.

Structural insights into the substrate selectivity of α-oxoamine synthases from marine Vibrio sp. QWI-06

Pyridoxal phosphate (PLP)-dependent α-oxoamine synthases are generally believed to be responsible for offloading and elongating polyketides or catalyzing the condensation of amino acids and acyl-CoA thioester substrates, such as serine into sphingolipids and cysteate into sulfonolipids. Previously, we discovered vitroprocines, which are tyrosine- and phenylalanine-polyketide derivatives, as potential new antibiotics from the genus Vibrio. Using bioinformatics analysis, we identified putative genes of PLP-dependent enzyme from marine Vibrio sp. QWI-06, implying a capability to produce amino-polyketide derivatives. One of these genes was cloned, and the recombinant protein, termed Vibrio sp. QWI-06 α-oxoamine synthases-1 (VsAOS1), was overexpressed for structural and biochemical characterization. The crystal structure of the dimeric VsAOS1 was determined at 1.8-Å resolution in the presence of L-glycine. The electron density map indicated a glycine molecule occupying the pyridoxal binding site in one monomer, suggesting a snapshot of the initiation process upon the loading of amino acid substrate. In mass spectrometry analysis, VsAOS1 strictly acted to condense L-glycine with C12 or C16 acyl-CoA, including unsaturated acyl analog. Furthermore, a single residue replacement of VsAOS1 (G243S) allowed the enzyme to generate sphingoid derivative when L-serine and lauroyl-CoA were used as substrates. Our data elucidate the mechanism of substrate binding and selectivity by the VsAOS1 and provide a thorough understanding of the molecular basis for the amino acid preference of AOS members.

Computational Pharmacokinetics Report, ADMET Study and Conceptual DFT-Based Estimation of the Chemical Reactivity Properties of Marine Cyclopeptides

Homophymines A-E and A1-E1 are bioactive natural cyclodepsipeptides with a complex molecular architecture. These molecules could have a potential use as antimicrobial, antiviral, and anticancer substances. We have carried out a computational study of the properties of this family of marine peptides using a CDFT-based Computational Peptidology (CDFT-CP) methodology that results from the combination of the chemical reactivity descriptors that arise from conceptual Density Functional Theory (CDFT) together with cheminformatics tools. The latter can be used to estimate the associated physicochemical parameters and to improve the process of virtual screening through a similarity search. Using this approach, the ability of the peptides to behave as a potentially useful drugs can be investigated. An analysis of their bioactivity and pharmacokinetics indices related to the ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) features has also been carried out.

Hydroquinone 5-O-Cinnamoyl Ester of Renieramycin M Suppresses Lung Cancer Stem Cells by Targeting Akt and Destabilizes c-Myc

Cancer stem cells (CSCs) are distinct cancer populations with tumorigenic and self-renewal abilities. CSCs are drivers of cancer initiation, progression, therapeutic failure, and disease recurrence. Thereby, novel compounds targeting CSCs offer a promising way to control cancer. In this study, the hydroquinone 5-O-cinnamoyl ester of renieramycin M (CIN-RM) was demonstrated to suppress lung cancer CSCs. CIN-RM was toxic to lung cancer cells with a half-maximal inhibitory concentration of around 15 µM. CIN-RM suppressed CSCs by inhibiting colony and tumor spheroid formation. In addition, the CSC population was isolated and treated and the CSCs were dispatched in response to CIN-RM within 24 h. CIN-RM was shown to abolish cellular c-Myc, a central survival and stem cell regulatory protein, with the depletion of CSC markers and stem cell transcription factors ALDH1A1, Oct4, Nanog, and Sox2. For up-stream regulation, we found that CIN-RM significantly inhibited Akt and consequently decreased the pluripotent transcription factors. CIN-RM also inhibited mTOR, while slightly decreasing p-GSK3β (Ser9) but rarely affected the protein kinase C (PKC) signal. Inhibiting Akt/mTOR induced ubiquitination of c-Myc and promoted degradation. The mechanism of how Akt regulates the stability of c-Myc was validated with the Akt inhibitor wortmannin. The computational analysis further confirmed the strong interaction between CIN-RM and the Akt protein with a binding affinity of −10.9 kcal/mol at its critical active site. Taken together, we utilized molecular experiments, the CSC phenotype, and molecular docking methods to reveal the novel suppressing the activity of this compound on CSCs to benefit CSC-targeted therapy for lung cancer treatment.

Marine-derived pipeline anticancer natural products: a review of their pharmacotherapeutic potential and molecular mechanisms

Background

Cancer is a complex and most widespread disease and its prevalence is increasing worldwide, more in countries that are witnessing urbanization and rapid industrialization changes. Although tremendous progress has been made, the interest in targeting cancer has grown rapidly every year. This review underscores the importance of preventive and therapeutic strategies.

Main text

Natural products (NPs) from various sources including plants have always played a crucial role in cancer treatment. In this growing list, numerous unique secondary metabolites from marine sources have added and gaining attention and became potential players in drug discovery and development for various biomedical applications. Many NPs found in nature that normally contain both pharmacological and biological activity employed in pharmaceutical industry predominantly in anticancer pharmaceuticals because of their enormous range of structure entities with unique functional groups that attract and inspire for the creation of several new drug leads through synthetic chemistry. Although terrestrial medicinal plants have been the focus for the development of NPs, however, in the last three decades, marine origins that include invertebrates, plants, algae, and bacteria have unearthed numerous novel pharmaceutical compounds, generally referred as marine NPs and are evolving continuously as discipline in the molecular targeted drug discovery with the inclusion of advanced screening tools which revolutionized and became the component of antitumor modern research.

Conclusions

This comprehensive review summarizes some important and interesting pipeline marine NPs such as Salinosporamide A, Dolastatin derivatives, Aplidine/plitidepsin (Aplidin®) and Coibamide A, their anticancer properties and describes their mechanisms of action (MoA) with their efficacy and clinical potential as they have attracted interest for potential use in the treatment of various types of cancers.

A CDFT-Based Computational Peptidology (CDFT-CP) Study of the Chemical Reactivity and Bioactivity of the Marine-Derived Alternaramide Cyclopentadepsipeptide

Alternaramide is a cyclic pentadepsipeptide isolated from marine sources that has been shown to present weak antibiotic activity against Bacillus subtilis and Staphylococcus aureus as well as inhibitory effects on inflammatory mediator expressions. Thus, this work reports the results of a computational study of the chemical reactivity and bioactivity properties of this cyclopentadepsipeptide considering a CDFT-based computational peptidology (CDFT-CP) methodology that results from the combination of the chemical reactivity descriptors that arise from conceptual density functional theory (CDFT) together with some cheminformatics tools that can be used to estimate the associated physicochemical parameters, to improve the process of virtual screening through a similarity search, and to identify the ability of the peptide to behave as a potential useful drug, complemented with an analysis of its bioactivity and pharmacokinetics indices related to the ADMET (absorption, distribution, metabolism, excretion, and toxicity) features. The results represent a new confirmation of the superiority of the MN12SX density functional in the fulfilment of the Janak and ionization energy theorems through the proposed KID procedure. This has been useful for the accurate prediction of the CDFT reactivity descriptors that help in understanding the chemical reactivity. The computational pharmacokinetics study revealed the potential ability of alternaramide as a therapeutic drug by interacting with GPCR ligands and protease inhibitors. The ADMET indices confirm this assertion through the absence of toxicity and good absorption and distribution properties.

Marine Natural Products: A Potential Source of Anti-hepatocellular Carcinoma Drugs

Hepatocellular carcinoma (HCC) has high associated morbidity and mortality rates. Although chemical medication represents a primary HCC treatment strategy, low response rates and therapeutic resistance serve to reduce its efficacy. Hence, identifying novel effective drugs is urgently needed, and many researchers have sought to identify new anti-cancer drugs from marine organisms. The marine population is considered a "blue drug bank" of unique anti-cancer compounds with diverse groups of chemical structures. Here, we discuss marine-derived compounds, including PM060184 and bryostatin-1, with demonstrated anti-cancer activity in vitro or in vivo. Based on the marine source (sponges, algae, coral, bacteria, and fungi), we introduce pharmacological parameters, compound-induced cytotoxicity, effects on apoptosis and metastasis, and potential molecular mechanisms. Cumulatively, this review provides insights into anti-HCC research conducted to date in the field of marine natural products and marine-derived compounds, as well as the potential pharmacological mechanisms of these compounds and their status in drug development.

Computer-Aided Drug Design Applied to Secondary Metabolites as Anticancer Agents

Computer-Aided Drug Design (CADD) techniques have garnered a great deal of attention in academia and industry because of their great versatility, low costs, possibilities of cost reduction in in vitro screening and in the development of synthetic steps; these techniques are compared with highthroughput screening, in particular for candidate drugs. The secondary metabolism of plants and other organisms provide substantial amounts of new chemical structures, many of which have numerous biological and pharmacological properties for virtually every existing disease, including cancer. In oncology, compounds such as vimblastine, vincristine, taxol, podophyllotoxin, captothecin and cytarabine are examples of how important natural products enhance the cancer-fighting therapeutic arsenal. In this context, this review presents an update of Ligand-Based Drug Design and Structure-Based Drug Design techniques applied to flavonoids, alkaloids and coumarins in the search of new compounds or fragments that can be used in oncology. A systematical search using various databases was performed. The search was limited to articles published in the last 10 years. The great diversity of chemical structures (coumarin, flavonoids and alkaloids) with cancer properties, associated with infinite synthetic possibilities for obtaining analogous compounds, creates a huge chemical environment with potential to be explored, and creates a major difficulty, for screening studies to select compounds with more promising activity for a selected target. CADD techniques appear to be the least expensive and most efficient alternatives to perform virtual screening studies, aiming to selected compounds with better activity profiles and better "drugability".

Anticancer Perspectives on the Fungal-Derived Polyphenolic Hispolon

BACKGROUND

Cancer is a dreadful disease causing thousands of deaths per year worldwide, which requires precision diagnostics and therapy. Although the selection of therapeutic regimens depends on the cancer type, chemotherapy remains a sustainable treatment strategy despite some of its known side-effects. To date, a number of natural products and their derivatives or analogues have been investigated as potent anticancer drugs. These drug discoveries have aimed for targeted therapy and reduced side-effects, including natural therapeutic regimens.

OBJECTIVE

This review introduces a prospective fungal-derived polyphenol, Hispolon (HIS), as an anticancer agent. Accordingly, this review focuses on exploring the anticancer effect of hispolon based on information extracted from databases such as PubMed, ScienceDirect, MedLine, Web of Science, and Google Scholar.

METHODS

A literature search in PubMed, ScienceDirect, MedLine, Web of Science, and Google Scholar was accomplished, using the keyword 'Hispolon', pairing with 'cancer', 'cytotoxicity', 'cell cycle arrest', 'apoptosis', 'metastasis', 'migration', 'invasion', 'proliferation', 'genotoxicity', 'mutagenicity', 'drug-resistant cancer', 'autophagy', and 'estrogen receptor.

RESULTS

Database-dependent findings from reported research works suggest that HIS can exert anticancer effects by modulating multiple molecular and biochemical pathways, including cell cycle arrest, apoptosis, autophagy, inhibition of proliferation, metastasis, migration, and invasion. Moreover, HIS inhibits the estrogenic activity and exhibits chemoprevention prospects, possibly due to its protective effects such as anticancer and anti-inflammatory mechanisms. To date, a number of HIS derivatives and analogues have been introduced for their anticancer effects in numerous cancer cell lines.

CONCLUSION

Data obtained from this review suggest that hispolon and some of its derivatives can be promising anticancer agents, and may become plant-based cancer chemotherapeutic leads for the development of potent anticancer drugs, alone or in combination with other chemotherapeutic agents.

In vitro and in silico anticancer potential analysis of Streptomyces sp. extract against human lung cancer cell line, A549

During our previous investigation, bioactive compounds present in the extract of Streptomyces sp. strain 196 were characterized using LC-MS/MS and 1H NMR studies. These compounds were K-252-C aglycone indolocarbazole alkaloid, decoyinine, and cycloheximide; the study of these natural drugs against lung carcinoma is still limited. Focus of the current investigation was to study the anticancer effect of strain 196 extract on lung cancer cells (A549). During in vitro studies, anti-proliferative effect of extract was studied using MTT assay in A549 cells. Effect of extract on cell survival was further evaluated using colony assay. Cell death was qualitatively assessed using apoptosis assay. The aftereffect of extract treatment on metastatic potential of cancerous cells was studied using wound closure assay. Effect of extract on the morphology and cytoskeletal arrangement of A549 cells was studied using phalloidin staining. The extract demonstrated concentration and time-dependent cytotoxicity with IC50 value at 0.5 mg/ml (6 h) and 0.15 mg/ml (24 h). The proliferation and metastatic potential of cells, as characterized by MTT and migration assay, decreased over time in a concentration-dependent manner. Discrete changes in cellular morphology were noted as a result of the induced cytotoxicity. Apoptosis assay demonstrated 98.7% cell death at highest concentration of extract (1 mg/ml). During in silico studies, molecular docking revealed that strain 196 compounds are efficiently binding to mutant EGFR form (T790M/L858R) with release of binding energy (∆G) between - 5 and - 6.9 kcal/Mol. In conclusion, strain 196 extract could be a source of therapeutic drugs to treat lung carcinoma.

Anti-tumour drugs of marine origin currently at various stages of clinical trials (review)

Oncological diseases for a long time have remained one of the most significant health problems of modern society, which causes great losses in its labour and vital potential. Contemporary oncology still faces unsolved issues as insufficient efficacy of treatment of progressing and metastatic cancer, chemoresistance, and side-effects of the traditional therapy which lead to disabilities among or death of a high number of patients. Development of new anti-tumour preparations with a broad range of pharmaceutical properties and low toxicity is becoming increasingly relevant every year. The objective of the study was to provide a review of the recent data about anti-tumour preparations of marine origin currently being at various phases of clinical trials in order to present the biological value of marine organisms – producers of cytotoxic compounds, and the perspectives of their use in modern biomedical technologies. Unlike the synthetic oncological preparations, natural compounds are safer, have broader range of cytotoxic activity, can inhibit the processes of tumour development and metastasis, and at the same time have effects on several etiopathogenic links of carcinogenesis. Currently, practical oncology uses 12 anti-tumour preparations of marine origin (Fludarabine, Cytarabine, Midostaurin, Nelarabine, Eribulin mesylate, Brentuximab vedotin, Trabectedin, Plitidepsin, Enfortumab vedotin, Polatuzumab vedotin, Belantamab mafodotin, Lurbinectedin), 27 substances are at different stages of clinical trials. Contemporary approaches to the treatment of oncological diseases are based on targeted methods such as immune and genetic therapies, antibody-drug conjugates, nanoparticles of biopolymers, and metals. All those methods employ bioactive compounds of marine origin. Numerous literature data from recent years indicate heightened attention to the marine pharmacology and the high potential of marine organisms for the biomedicinal and pharmaceutic industries.

Holospiniferoside: A New Antitumor Cerebroside from The Red Sea Cucumber Holothuria spinifera: In Vitro and In Silico Studies

Chemical investigation of the methanolic extract of the Red Sea cucumber Holothuria spinifera led to the isolation of a new cerebroside, holospiniferoside (1), together with thymidine (2), methyl-α-d-glucopyranoside (3), a new triacylglycerol (4), and cholesterol (5). Their chemical structures were established by NMR and mass spectrometric analysis, including gas chromatography-mass spectrometry (GC-MS) and high-resolution mass spectrometry (HRMS). All the isolated compounds are reported in this species for the first time. Moreover, compound 1 exhibited promising in vitro antiproliferative effect on the human breast cancer cell line (MCF-7) with IC50 of 20.6 µM compared to the IC50 of 15.3 µM for the drug cisplatin. To predict the possible mechanism underlying the cytotoxicity of compound 1, a docking study was performed to elucidate its binding interactions with the active site of the protein Mdm2-p53. Compound 1 displayed an apoptotic activity via strong interaction with the active site of the target protein. This study highlights the importance of marine natural products in the design of new anticancer agents.

Ellagic Acid and Schisandrins: Natural Biaryl Polyphenols with Therapeutic Potential to Overcome Multidrug Resistance in Cancer

Multidrug resistance (MDR) is one of the major clinical challenges in cancer treatment and compromises the effectiveness of conventional anticancer chemotherapeutics. Among known mechanisms of drug resistance, drug efflux via ATP binding cassette (ABC) transporters, namely P-glycoprotein (P-gp) has been characterized as a major mechanism of MDR. The primary function of ABC transporters is to regulate the transport of endogenous and exogenous small molecules across the membrane barrier in various tissues. P-gp and similar efflux pumps are associated with MDR because of their overexpression in many cancer types. One of the intensively studied approaches to overcome this mode of MDR involves development of small molecules to modulate P-gp activity. This strategy improves the sensitivity of cancer cells to anticancer drugs that are otherwise ineffective. Although multiple generations of P-gp inhibitors have been identified to date, reported compounds have demonstrated low clinical efficacy and adverse effects. More recently, natural polyphenols have emerged as a promising class of compounds to address P-gp linked MDR. This review highlights the chemical structure and anticancer activities of selected members of a structurally unique class of 'biaryl' polyphenols. The discussion focuses on the anticancer properties of ellagic acid, ellagic acid derivatives, and schisandrins. Research reports regarding their inherent anticancer activities and their ability to sensitize MDR cell lines towards conventional anticancer drugs are highlighted here. Additionally, a brief discussion about the axial chirality (i.e., atropisomerism) that may be introduced into these natural products for medicinal chemistry studies is also provided.

Application of marine natural products in drug research

New diseases are emerging as the environment changes, so drug manufacturers are always on the lookout for new resources to develop effective and safe drugs. In recent years, many bioactive substances have been produced in the marine environment, which represents an alternative resource for new drugs used to combat major diseases such as cancer or inflammation. Many marine-derived medicinal substances are in preclinical or early stage of clinical development, and some marine drugs have been put on the market, such as ET743 (Yondelis®). This review presents the sources, activities, mechanisms of action and syntheses of bioactive substances based on marine natural products in clinical trials and on the market, which is helpful to understand the progress of drug research by application of marine natural products.

Saringosterol acetate isolated from Hizikia fusiforme, an edible brown alga, suppressed hepatocellular carcinoma growth and metastasis in a zebrafish xenograft model

Saringosterol acetate (SSA) was isolated from an edible brown alga Hizikia fusiforme. In this study, we developed an adult zebrafish human hepatocellular carcinoma (HCC) xenograft model to confirm that SSA inhibits tumor growth and metastasis. Established Hep3B cells labeled with the fluorescent tracker CM-Dil were xenografted into the abdominal cavity of zebrafish once every three days for one month. Compared with the control group, the fish injected with Hep3B showed a significant increase in α-fetoprotein (AFP) and factors related to tumor growth and metastasis (IL-6, TNF-α, TGFβ, MMP2, and MMP9). Using the model, it was proven that SSA affected survival rate, AFP production, and the levels of factors related to tumor growth and metastasis via the PI3K/AKT/mTOR and TGFβ/Smad pathways. In conclusion, this HCC model can be used for in vivo experiments to investigate the inhibition of cancer, and SSA may be useful for the treatment of cancer.

Bioactive Compounds from Marine Heterobranchs

The natural products of heterobranch molluscs display a huge variability both in structure and in their bioactivity. Despite the considerable lack of information, it can be observed from the recent literature that this group of animals possesses an astonishing arsenal of molecules from different origins that provide the molluscs with potent chemicals that are ecologically and pharmacologically relevant. In this review, we analyze the bioactivity of more than 450 compounds from ca. 400 species of heterobranch molluscs that are useful for the snails to protect themselves in different ways and/or that may be useful to us because of their pharmacological activities. Their ecological activities include predator avoidance, toxicity, antimicrobials, antifouling, trail-following and alarm pheromones, sunscreens and UV protection, tissue regeneration, and others. The most studied ecological activity is predation avoidance, followed by toxicity. Their pharmacological activities consist of cytotoxicity and antitumoral activity; antibiotic, antiparasitic, antiviral, and anti-inflammatory activity; and activity against neurodegenerative diseases and others. The most studied pharmacological activities are cytotoxicity and anticancer activities, followed by antibiotic activity. Overall, it can be observed that heterobranch molluscs are extremely interesting in regard to the study of marine natural products in terms of both chemical ecology and biotechnology studies, providing many leads for further detailed research in these fields in the near future.

Seaweed-associated heterotrophic bacteria: new paradigm of prospective anti-infective and anticancer agents

Ever since the development of the first antibiotic compound with anticancer potential, researchers focused on isolation and characterization of prospective microbial natural products with potential anti-infective and anticancer activities. The present work describes the production of bioactive metabolites by heterotrophic bacteria associated with intertidal seaweeds with potential anti-infective and anticancer activities. The bacteria were isolated in a culture-dependent method and were identified as Shewanella algae MTCC 12715 (KX272635) and Bacillus amyloliquefaciens MTCC 12716 (KX272634) based on combined phenotypic and genotypic methods. Further, the bacteria were screened for their ability to inhibit drug-resistant infectious pathogens and prevent cell proliferation of human liver carcinoma (HepG2) and breast cancer (MCF7) cell lines, without affecting the normal cells. Significant anti-infective activity was observed with bacterial cells and their organic extracts against broad-spectrum multidrug-resistant pathogens, such as vancomycin-resistant Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, Klebsiella pneumonia and Pseudomonas aeruginosa with minimum inhibitory concentration ≤ 3.0 µg mL^-1 as compared to the antibiotic agents' chloramphenicol and ampicillin, which were active at ≥ 6.25 mg mL^-1. The extracts also exhibited anticancer activity in a dose-responsive pattern against HepG2 (with IC₅₀, half maximal inhibitory concentration ~ 78-83 µg mL^-1) and MCF7 (IC₅₀ ~ 45-48 µg mL^-1) on tetrazolium bromide screening assay with lesser cytotoxic effects on normal fibroblast (L929) cell lines (IC₅₀ > 100 µg mL^-1). The results revealed that seaweed-associated heterotrophic bacteria could occupy a predominant role for a paradigm shift towards the development of prospective anti-infective and anticancer agents.

Marine-Derived Penicillium purpurogenum Reduces Tumor Size and Ameliorates Inflammation in an Erlich Mice Model

Background: This study addresses the antitumoral properties of Penicillium purpurogenum isolated from a polluted lagoon in Northeastern Brazil. Methods: Ethyl Acetate Extracellular Extract (EAE) was used. The metabolites were studied using direct infusion mass spectrometry. The solid Ehrlich tumor model was used for antitumor activity. Female Swiss mice were divided into groups (n = 10/group) as follows: The negative control (CTL−), treated with a phosphate buffered solution; the positive control (CTL+), treated with cyclophosphamide (25 mg/kg); extract treatments at doses of 4, 20, and 100 mg/kg; animals without tumors or treatments (Sham); and animals without tumors treated with an intermediate dose (EAE20). All treatments were performed intraperitoneally, daily, for 15 days. Subsequently, the animals were euthanized, and the tumor, lymphoid organs, and serum were used for immunological, histological, and biochemical parameter evaluations. Results: The extract was rich in meroterpenoids. All doses significantly reduced tumor size, and the 20 and 100 mg/kg doses reduced tumor-associated inflammation and tumor necrosis. The extract also reduced the cellular infiltration of lymphoid organs and circulating TNF-α levels. The extract did not induce weight loss or renal and hepatic toxic changes. Conclusions: These results indicate that P. purpurogenum exhibits immunomodulatory and antitumor properties in vivo. Thus, fungal fermentation is a valid biotechnological approach to the production of antitumor agents.

Blue-Print Autophagy in 2020: A Critical Review

Autophagy is an elegant and complex biological process that has recently attracted much attention from the scientific community. The compounds which are capable of control and modulation of this process have a promising potential as therapeutics for a number of pathological conditions, including cancer and neurodegenerative disorders. At the same time, due to the relatively young age of the field, there are still some pitfalls in the autophagy monitoring assays and interpretation of the experimental data. This critical review provides an overview of the marine natural compounds, which have been reported to affect autophagy. The time period from the beginning of 2016 to the middle of 2020 is covered. Additionally, the published data and conclusions based on the experimental results are re-analyzed with regard to the guidelines developed by Klionsky and colleagues (Autophagy. 2016; 12(1): 1–222), which are widely accepted by the autophagy research community. Remarkably and surprisingly, more than half of the compounds reported to be autophagy activators or inhibitors could not ultimately be assigned to either category. The experimental data reported for those substances could indicate both autophagy activation and inhibition, requiring further investigation. Thus, the reviewed molecules were divided into two groups: having validated and non-validated autophagy modulatory effects. This review gives an analysis of the recent updates in the field and raises an important problem of standardization in the experimental design and data interpretation.

Marine Cyanobacteria and Microalgae Metabolites-A Rich Source of Potential Anticancer Drugs

Cancer is at present one of the utmost deadly diseases worldwide. Past efforts in cancer research have focused on natural medicinal products. Over the past decades, a great deal of initiatives was invested towards isolating and identifying new marine metabolites via pharmaceutical companies, and research institutions in general. Secondary marine metabolites are looked at as a favorable source of potentially new pharmaceutically active compounds, having a vast structural diversity and diverse biological activities; therefore, this is an astonishing source of potentially new anticancer therapy. This review contains an extensive critical discussion on the potential of marine microbial compounds and marine microalgae metabolites as anticancer drugs, highlighting their chemical structure and exploring the underlying mechanisms of action. Current limitation, challenges, and future research pathways were also presented.

Piperine: A review of its biological effects

Medicinal plants have been used for years as a source of food, spices, and, in traditional medicine, as a remedy to numerous diseases. Piper nigrum, belonging to the family Piperaceae is one of the most widely used spices all over the world. It has a distinct sharp flavor attributed to the presence of the phytochemical, piperine. Apart from its use as a spice, P. nigrum is frequently used for medicinal, preservation, and perfumery purposes. Black pepper contains 2-7.4% of piperine, varying in content is associated with the pepper plant. Piperine displays numerous pharmacological effects such as antiproliferative, antitumor, antiangiogenesis, antioxidant, antidiabetic, anti-obesity, cardioprotective, antimicrobial, antiaging, and immunomodulatory effects in various in vitro and in vivo experimental trials. Furthermore, piperine has also been documented for its hepatoprotective, anti-allergic, anti-inflammatory, and neuroprotective properties. This review highlights and discusses the medicinal and health-promoting effects of piperine, along with possible mechanisms of its action in health promotion and disease prevention. In addition, the present review summarizes the recent literature related to piperine as a therapeutic agent against several diseases.

Chemistry of Renieramycins. Part 19: Semi-Syntheses of 22-O-Amino Ester and Hydroquinone 5-O-Amino Ester Derivatives of Renieramycin M and Their Cytotoxicity against Non-Small-Cell Lung Cancer Cell Lines

Two new series of synthetic renieramycins including 22-O-amino ester and hydroquinone 5-O-amino ester derivatives of renieramycin M were semi-synthesized and evaluated for their cytotoxicity against the metastatic non-small-cell lung cancer H292 and H460 cell lines. Interestingly, the series of 22-O-amino ester derivatives displayed a potent cytotoxic activity greater than the hydroquinone derivatives. The most cytotoxic derivative of the series was the 22-O-(N-Boc-l-glycine) ester of renieramycin M (5a: IC₅₀ 3.56 nM), which showed 7-fold higher potency than renieramycin M (IC₅₀ 24.56 nM) and 61-fold more than jorunnamycin A (IC₅₀ 217.43 nM) against H292 cells. In addition, 5a exhibited a significantly higher cytotoxic activity than doxorubicin (ca. 100 times). The new semi-synthetic renieramycin derivatives will be further studied and developed as potential cytotoxic agents for non-small-cell lung cancer treatment.

The role of natural products in revealing NRF2 function

Covering: up to 2020The transcription factor NRF2 is one of the body's major defense mechanisms, driving transcription of >300 antioxidant response element (ARE)-regulated genes that are involved in many critical cellular processes including redox regulation, proteostasis, xenobiotic detoxification, and primary metabolism. The transcription factor NRF2 and natural products have an intimately entwined history, as the discovery of NRF2 and much of its rich biology were revealed using natural products both intentionally and unintentionally. In addition, in the last decade a more sinister aspect of NRF2 biology has been revealed. NRF2 is normally present at very low cellular levels and only activated when needed, however, it has been recently revealed that chronic, high levels of NRF2 can lead to diseases such as diabetes and cancer, and may play a role in other diseases. Again, this "dark side" of NRF2 was revealed and studied largely using a natural product, the quassinoid, brusatol. In the present review, we provide an overview of NRF2 structure and function to orient the general reader, we will discuss the history of NRF2 and NRF2-activating compounds and the biology these have revealed, and we will delve into the dark side of NRF2 and contemporary issues related to the dark side biology and the role of natural products in dissecting this biology.

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.

Anti-Tumor Activity vs. Normal Cell Toxicity: Therapeutic Potential of the Bromotyrosines Aerothionin and Homoaerothionin In Vitro

Novel strategies to treat cancer effectively without adverse effects on the surrounding normal tissue are urgently needed. Marine sponges provide a natural and renewable source of promising anti-tumor agents. Here, we investigated the anti-tumor activity of Aerothionin and Homoaerothionin, two bromotyrosines isolated from the marine demosponge Aplysina cavernicola, on two mouse pheochromocytoma cells, MPC and MTT. To determine the therapeutic window of these metabolites, we furthermore explored their cytotoxicity on cells of the normal tissue. Both metabolites diminished the viability of the pheochromocytoma cell lines significantly from a concentration of 25 µM under normoxic and hypoxic conditions. Treatment of MPC cells leads moreover to a reduction in the number of proliferating cells. To confirm the anti-tumor activity of these bromotyrosines, 3D-pheochromocytoma cell spheroids were treated with 10 µM of either Aerothionin or Homoaerothionin, resulting in a significant reduction or even complete inhibition of the spheroid growth. Both metabolites reduced viability of normal endothelial cells to a comparable extent at higher micromolar concentration, while the viability of fibroblasts was increased. Our in vitro results show promise for the application of Aerothionin and Homoaerothionin as anti-tumor agents against pheochromocytomas and suggest acceptable toxicity on normal tissue cells.

Genome Mining as New Challenge in Natural Products Discovery

Drug discovery is based on bioactivity screening of natural sources, traditionally represented by bacteria fungi and plants. Bioactive natural products and their secondary metabolites have represented the main source for new therapeutic agents, used as drug leads for new antibiotics and anticancer agents. After the discovery of the first biosynthetic genes in the last decades, the researchers had in their hands the tool to understand the biosynthetic logic and genetic basis leading to the production of these compounds. Furthermore, in the genomic era, in which the number of available genomes is increasing, genome mining joined to synthetic biology are offering a significant help in drug discovery. In the present review we discuss the importance of genome mining and synthetic biology approaches to identify new natural products, also underlining considering the possible advantages and disadvantages of this technique. Moreover, we debate the associated techniques that can be applied following to genome mining for validation of data. Finally, we review on the literature describing all novel natural drugs isolated from bacteria, fungi, and other living organisms, not only from the marine environment, by a genome-mining approach, focusing on the literature available in the last ten years.