Marine Mollusk-Derived Agents with Antiproliferative Activity as Promising Anticancer Agents to Overcome Chemotherapy Resistance

Nutritional, Antibacterial and Thrombolytic Prospects of Freshwater Paludomas conica Protein Hydrolysate and Its Anti-Inflammatory Potential in LPS-Induced RAW 264.7 Macrophage Cells

Chronic inflammation and heme-iron overload can result from bacterial hemolysis. Along with the synthetic drugs, numerous traditional and functional food approaches are equally trialed to eradicate the problem. As a prospective new source of dietary protein hydrolysates, freshwater mollusks (Paludomas conica) have recently drawn huge interest from researchers. In this research, protein hydrolysate (PhPC) of Paludomas conica, prepared by the enzyme digestion method, was analyzed for proximate nutritional and minerals contents and deciphered its suppressive effects on inflammatory gene expression in LPS-stimulated RAW264.7 macrophage cells. The inhibitory action of protein denaturation is also unfolded with established in vitro and in vivo models. Anti-hemolytic, antibacterial, and thrombolytic effects of PhPC were respectively assessed by H2O2-induced hemolysis of RBCs, the disc diffusion method, and the clot lysis method. The proximate nutritional and mineral contents of PhPC revealed it to be an enriched source of nutrients, crude protein, carbohydrates, Calcium, and Magnesium. Heavy metals were found to be within the prescribed limit. The PhPC suppressed the expression of inflammatory genes, including COX-2, iNOS, IL-6, TNF-α, and IL-1, multifold in LPS-stimulated RAW264.7 macrophages. The inhibition concentrations (IC50) of PhPC in the bovine serum albumin denaturation inhibition test and membrane stabilization tests were 431.39 and 285.25 μg/mL, respectively. The PhPC was discerned to be active against Shigella flexneri, Pseudomonas aeruginosa, and Shigella dysenteriae; its maximum thrombolytic effect was displayed to be 23.72% ± 2.71%. The findings demonstrate that the nutritionally enriched PhPC could be affirmed as an exciting invertebrate anti-inflammatory agent Extending other biological functions needs to be further characterized with its pure protein or protein products.

Polymer-DNA assembled nanoflower for targeted delivery of dolastatin-derived microtubule inhibitors

Dolastatin derivatives possess excellent anticancer activity and have been translated into clinical trials for cancer therapy. Drug delivery systems enable dolastatin derivatives to break the limitation of instability during blood circulation and ineffective cell internalization in the application. Nevertheless, their potential has not been thoroughly established because of the limited loading efficacy and complicated chemical modification. Herein, we rationally propose a rolling circle amplification-based polymer-DNA assembled nanoflower for targeted and efficient delivery of dolastatin-derived drugs to achieve efficient anticancer therapy. The polymer-DNA assembled nanoflower with targeted aptamer conjugate is widely applicable for loading dolastatin-derived drugs with high encapsulation efficiency. The developed monomethyl auristatin E (MMAE) loaded PN@M exhibited increased cellular uptake and enhanced inhibitory effect, especially in multidrug-resistant tumor cells. The results of in vivo anticancer effects indicate that nanoflower as a dolastatin derivatives delivery system holds considerable potential for the treatment of malignant cancer.

Lead phytochemicals and marine compounds against ceruloplasmin in cancer targeting

In silico docking studies serve as a swift and efficient means to sift through a vast array of natural and synthetic small molecules, aiding in the identification of potential inhibitors for cancer biomarkers. One such biomarker, ceruloplasmin (CP), has been implicated in various tumor types due to its overexpression, earning it recognition as a marker of aggressive tumors. This study focused on pinpointing inhibitors for the CP -Myeloperoxidase (MPO) interaction site, a complex formation known to impede HOCl production, a crucial process for inducing apoptotic cell death in tumor cells. The initial phase of our investigation involved in silico docking studies, which screened a diverse library of phytochemicals and marine compounds. Through this process, we identified several promising drug candidates based on their binding affinities. Subsequently, these candidates underwent rigorous filtration based on Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) properties. Finally, we subjected the selected compounds to molecular dynamics (MDs) simulation to further assess their viability. Lycoperoside F, a steroidal alkaloid glycoside derived from tomatoes (Lycopersicon esculentum), stood out with notable interactions at the binding site. Another noteworthy compound was Xyloglucan (XG) oligosaccharides, predominantly found in the primary cell walls of higher plants. During the subsequent MDs simulations, these interactions were accompanied by highly stable root mean square deviation (RMSD) plots, signifying the consistency and robustness of the observed MDs behavior. XG oligosaccharides demonstrated the highest binding affinity with CP, reaffirming their potential as strong candidates. Additionally, Ardimerin digallate, known as a retroviral ribonuclease H inhibitor for HIV-1 and HIV-2, displayed favorable interactions at the MPO interaction site. Given that promising drug candidates must meet stringent criteria, including non-toxicity, effectiveness, specificity, stability and potency, these phytochemicals have the potential to progress to in vitro studies as CP inhibitors. Ultimately, this could contribute to the suppression of tumor growth, marking a significant step in cancer treatment research.Communicated by Ramaswamy H. Sarma.

Synthetic and natural guanidine derivatives as antitumor and antimicrobial agents: A review

Guanidines are fascinating small nitrogen-rich organic compounds, which have been frequently associated with a wide range of biological activities. This is mainly due to their interesting chemical features. For these reasons, for the past decades, researchers have been synthesizing and evaluating guanidine derivatives. In fact, there are currently on the market several guanidine-bearing drugs. Given the broad panoply of pharmacological activities displayed by guanidine compounds, in this review, we chose to focus on antitumor, antibacterial, antiviral, antifungal, and antiprotozoal activities presented by several natural and synthetic guanidine derivatives, which are undergoing preclinical and clinical studies from January 2010 to January 2023. Moreover, we also present guanidine-containing drugs currently in the market for the treatment of cancer and several infectious diseases. In the preclinical and clinical setting, most of the synthesized and natural guanidine derivatives are being evaluated as antitumor and antibacterial agents. Even though DNA is the most known target of this type of compounds, their cytotoxicity also involves several other different mechanisms, such as interference with bacterial cell membranes, reactive oxygen species (ROS) formation, mitochondrial-mediated apoptosis, mediated-Rac1 inhibition, among others. As for the compounds already used as pharmacological drugs, their main application is in the treatment of different types of cancer, such as breast, lung, prostate, and leukemia. Guanidine-containing drugs are also being used for the treatment of bacterial, antiprotozoal, antiviral infections and, recently, have been proposed for the treatment of COVID-19. To conclude, the guanidine group is a privileged scaffold in drug design. Its remarkable cytotoxic activities, especially in the field of oncology, still make it suitable for a deeper investigation to afford more efficient and target-specific drugs.

Depsipeptides Targeting Tumor Cells: Milestones from In Vitro to Clinical Trials

Cancer is currently considered one of the most threatening diseases worldwide. Diet could be one of the factors that can be enhanced to comprehensively address a cancer patient's condition. Unfortunately, most molecules capable of targeting cancer cells are found in uncommon food sources. Among them, depsipeptides have emerged as one of the most reliable choices for cancer treatment. These cyclic amino acid oligomers, with one or more subunits replaced by a hydroxylated carboxylic acid resulting in one lactone bond in a core ring, have broadly proven their cancer-targeting efficacy, some even reaching clinical trials and being commercialized as "anticancer" drugs. This review aimed to describe these depsipeptides, their reported amino acid sequences, determined structure, and the specific mechanism by which they target tumor cells including apoptosis, oncosis, and elastase inhibition, among others. Furthermore, we have delved into state-of-the-art in vivo and clinical trials, current methods for purification and synthesis, and the recognized disadvantages of these molecules. The information collated in this review can help researchers decide whether these molecules should be incorporated into functional foods in the near future.

Thais savignyi tissue extract: bioactivity, chemical composition, and molecular docking

CONTEXT

Thais savignyi Deshayes (Muricidae) is widely distributed in the Red Sea. Its abundance and the history of Muricidae in traditional medicine make it a tempting target for investigation.

OBJECTIVE

To investigate the chemical profile and biological activities of T. savignyi tissue extracts.

MATERIALS AND METHODS

Methanol, ethanol, acetone, and ethyl acetate extracts from T. savignyi tissue were compared in their antioxidant by total antioxidant capacity, DPPH free radical scavenging, and total phenolic content. In addition, the antimicrobial, and antibiofilm properties (at 250 µg/mL) of the extracts were tested against Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella pneumoniae, Staphylococcus aureus, and Candida albicans. The antioxidant extract with greatest activity was assessed for cytotoxicity (range 0.4-100 µg/mL) against 3 human cancer cell lines (UO-31, A549 and A431), and its chemical composition was investigated using GC-MS. Moreover, docking simulation was performed to predict its constituents' binding modes/scores to the active sites of thymidylate kinase.

RESULTS

The ethyl acetate extract (Ts-EtOAc) showed the highest total antioxidant capacity (551.33 mg AAE/g dry weight), total phenolics (254.46 mg GAE/g dry weight), and DPPH scavenging (IC₅₀= 24.0 µg/mL). Ts-EtOAc exhibited strong antibacterial (MIC: 3.9 µg/mL against K. pneumoniae), antibiofilm (MIC: 7.81 µg/mL against S. aureus), and antifungal (MIC: 3.9 µg/mL against C. albicans) activities and considerable cytotoxicity against cancer cells (UO-31: IC₅₀= 19.96 ± 0.93, A549: IC₅₀= 25.04 ± 1.15 μg/mL). GC-MS identified multiple bioactive metabolites in Ts-EtOAc extract belonging to miscellaneous chemical classes. Molecular docking studies revealed that the constituents of Ts-EtOAc have antibacterial potential.

DISCUSSION AND CONCLUSIONS

T. savignyi extract has considerable antimicrobial and cytotoxic activities. Further studies are needed to isolate the active constituents of this snail for comprehensive drug discovery tests.

Marine-Inspired Drugs and Biomaterials in the Perspective of Pancreatic Cancer Therapies

Despite its low prevalence, pancreatic cancer (PC) is one of the deadliest, typically characterised as silent in early stages and with a dramatically poor prognosis when in its advanced stages, commonly associated with a high degree of metastasis. Many efforts have been made in pursuing innovative therapeutical approaches, from the search for new cytotoxic drugs and other bioactive compounds, to the development of more targeted approaches, including improved drug delivery devices. Marine biotechnology has been contributing to this quest by providing new chemical leads and materials originating from different organisms. In this review, marine biodiscovery for PC is addressed, particularly regarding marine invertebrates (namely sponges, molluscs, and bryozoans), seaweeds, fungi, and bacteria. In addition, the development of biomaterials based on marine-originating compounds, particularly chitosan, fucoidan, and alginate, for the production of advanced cancer therapies, is also discussed. The key role that drug delivery can play in new cancer treatments is highlighted, as therapeutical outcomes need to be improved to give further hope to patients.

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.

Recent Discoveries on Marine Organism Immunomodulatory Activities

Marine organisms have been shown to be a valuable source for biologically active compounds for the prevention and treatment of cancer, inflammation, immune system diseases, and other pathologies. The advantage of studying organisms collected in the marine environment lies in their great biodiversity and in the variety of chemical structures of marine natural products. Various studies have focused on marine organism compounds with potential pharmaceutical applications, for instance, as immunomodulators, to treat cancer and immune-mediated diseases. Modulation of the immune system is defined as any change in the immune response that can result in the induction, expression, amplification, or inhibition of any phase of the immune response. Studies very often focus on the effects of marine-derived compounds on macrophages, as well as lymphocytes, by analyzing the release of mediators (cytokines) by using the immunological assay enzyme-linked immunosorbent assay (ELISA), Western blot, immunofluorescence, and real-time PCR. The main sources are fungi, bacteria, microalgae, macroalgae, sponges, mollusks, corals, and fishes. This review is focused on the marine-derived molecules discovered in the last three years as potential immunomodulatory drugs.

Physiological and Clinical Aspects of Bioactive Peptides from Marine Animals

Biological molecules in nutraceuticals and functional foods have proven physiological properties to treat human chronic diseases. These molecules contribute to applications in the food and pharmaceutical industries by preventing food spoilage and cellular injury. Technological advancement in the screening and characterization of bioactive peptides has enabled scientists to understand the associated molecules. Consistent collaboration among nutritionists, pharmacists, food scientists, and bioengineers to find new bioactive compounds with higher therapeutic potential against nutrition-related diseases highlights the potential of the bioactive peptides for food and pharmaceutic industries. Among the popular dietary supplements, marine animals have always been considered imperative due to their rich nutritional values and byproduct use in the food and pharmaceutical industries. The bioactive peptides isolated from marine animals are well-known for their higher bioactivities against human diseases. The physiological properties of fish-based hydrolyzed proteins and peptides have been claimed through in vitro, in vivo, and clinical trials. However, systematic study on the physiological and clinical significance of these bioactive peptides is scarce. In this review, we not only discuss the physiological and clinical significance of antioxidant and anticancer peptides derived from marine animals, but we also compare their biological activities through existing in vitro and in vivo studies.

Biomaterials and Bioactive Natural Products from Marine Invertebrates: From Basic Research to Innovative Applications

Aquatic invertebrates are a major source of biomaterials and bioactive natural products that can find applications as pharmaceutics, nutraceutics, cosmetics, antibiotics, antifouling products and biomaterials. Symbiotic microorganisms are often the real producers of many secondary metabolites initially isolated from marine invertebrates; however, a certain number of them are actually synthesized by the macro-organisms. In this review, we analysed the literature of the years 2010–2019 on natural products (bioactive molecules and biomaterials) from the main phyla of marine invertebrates explored so far, including sponges, cnidarians, molluscs, echinoderms and ascidians, and present relevant examples of natural products of interest to public and private stakeholders. We also describe omics tools that have been more relevant in identifying and understanding mechanisms and processes underlying the biosynthesis of secondary metabolites in marine invertebrates. Since there is increasing attention on finding new solutions for a sustainable large-scale supply of bioactive compounds, we propose that a possible improvement in the biodiscovery pipeline might also come from the study and utilization of aquatic invertebrate stem cells.

Recent advances and limitations in the application of kahalalides for the control of cancer

Since the discovery of the kahalalide family of marine depsipeptides in 1993, considerable work has been done to develop these compounds as new and biologically distinct anti-cancer agents. Clinical trials and laboratory research have yielded a wealth of data that indicates tolerance of kahalalides in healthy cells and selective activity against diseased cells. Currently, two molecules have attracted the greates level of attention, kahalalide F (KF) and isokahalalide F (isoKF, Irvalec, PM 02734, elisidepsin). Both compounds were originally isolated from the sarcoglossan mollusk Elysia rufescens but due to distinct structural characteristics it has been hypothesized and recently shown that the ultimate origin of the molecules is microbial. The search for their true source has been a subject of considerable research in the anticipation of finding new analogs and a culturable expression system that can produce sufficient material through fermentation to be industrially relevant.

Design and synthesis of marine sesterterpene analogues as novel estrogen receptor α degraders for breast cancer treatment

Targeted protein degradation using small molecules is an intriguing strategy for drug development. The marine sesterterpene compound MHO7 had been reported to be a potential ERα degradation agent. In order to further improve its biological activity, two series of novel MHO7 derivatives with long side chains were designed and identified as novel selective estrogen receptor down-regulators (SERDs). The growth inhibition activity of the novel SERD compounds were significantly affected by the type and length of the side chain. Most of the derivatives were significantly more potent than MHO7 against both drug-sensitive and drug-resistant breast cancer cells. Among them, compound 16a, with IC₅₀ values of 0.41 μM against MCF-7 cell lines and 9.6-fold stronger than MHO7, was the most potential molecule. A whole-genome transcriptomic analysis of MCF-7 cells revealed that the mechanism of 16a against MCF-7 cell was similar with that of MHO7. The estrogen signaling pathway was the most affected among the disturbed genes, but the ERα degradation activity of 16a was observed higher than that of MHO7. Other effects of 16a were confirmed similar with MHO7, which means that the basic mechanisms of the derivatives are the same with the ophiobolin backbone, i.e. the degradation of ERα is mediated via proteasome-mediated process, the induction of apoptosis and the cell cycle arrest at the G1 phase. Meanwhile, a decrease of mitochondrial membrane potential and an increase of cellular ROS were also detected. Based on these results, as a novel modified ophiobolin derived compound, 16a may warrant further exploitation as a promising SERD candidate agent for the treatment of breast cancer.

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.

The Ethyl Acetate Extract of the Marine Edible Gastropod Haliotis tuberculata coccinea: a Potential Source of Bioactive Compounds

The phylum Mollusca represents one of the largest groups of marine invertebrates. Nowadays, molluscan shellfish belonging to the classes Bivalvia and Gastropoda are of commercial interest for fisheries and aquaculture. Although bioactive properties of bivalve molluscs have been widely investigated and several dietary supplements have been brought to the market, the bioactive potentialities of marine gastropods are poorly documented. The present study investigated the bioactive properties of tissue extracts derived from Haliotis tuberculata coccinea, or "European abalone," an edible abalone species distributed in the Mediterranean Sea and the northeast Atlantic Ocean. A bioactive organic compound-rich extract was obtained using ethyl acetate as extracting solvent. It showed antimicrobial activity towards the methicillin-resistant Staphylococcus epidermidis strain RP62A, the emerging multi-drug-resistant Stenotrophomonas maltophilia D71 and Staphylococcus aureus ATCC 6538P, being the most sensitive strain. It also showed anthelmintic activity, evaluated through the toxicity against the target model helminth Caenorhabditis elegans. In addition, the ethyl acetate extract demonstrated a selective cytotoxic activity on the cancer cell lines A375, MBA-MD 231, HeLa, and MCF7, at the concentration of 250 µg/mL. The fatty acid composition of the bioactive extract was also investigated through FAME analysis. The fatty acid profile showed 45% of saturated fatty acids (SAFA), 22% of monounsaturated fatty acids (MUFA), and 33% of polyunsaturated fatty acids (PUFA). The presence of some biologically important secondary metabolites in the extract was also analysed, revealing the presence of alkaloids, terpenes, and flavonoids.

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.

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.

Molluscan Compounds Provide Drug Leads for the Treatment and Prevention of Respiratory Disease

Respiratory diseases place an immense burden on global health and there is a compelling need for the discovery of new compounds for therapeutic development. Here, we identify research priorities by critically reviewing pre-clinical and clinical studies using extracts and compounds derived from molluscs, as well as traditional molluscan medicines, used in the treatment of respiratory diseases. We reviewed 97 biomedical articles demonstrating the anti-inflammatory, antimicrobial, anticancer, and immunomodulatory properties of >320 molluscan extracts/compounds with direct relevance to respiratory disease, in addition to others with promising bioactivities yet to be tested in the respiratory context. Of pertinent interest are compounds demonstrating biofilm inhibition/disruption and antiviral activity, as well as synergism with approved antimicrobial and chemotherapeutic agents. At least 100 traditional medicines, incorporating over 300 different mollusc species, have been used to treat respiratory-related illness in cultures worldwide for thousands of years. These medicines provide useful clues for the discovery of bioactive components that likely underpin their continued use. There is particular incentive for investigations into anti-inflammatory compounds, given the extensive application of molluscan traditional medicines for symptoms of inflammation, and shells, which are the principal molluscan product used in these preparations. Overall, there is a need to target research toward specific respiratory disease-related hypotheses, purify bioactive compounds and elucidate their chemical structures, and develop an evidence base for the integration of quality-controlled traditional medicines.

Pharmacokinetics of Marine-Derived Drugs

Marine organisms represent an excellent source of innovative compounds that have the potential for the development of new drugs. The pharmacokinetics of marine drugs has attracted increasing interest in recent decades due to its effective and potential contribution to the selection of rational dosage recommendations and the optimal use of the therapeutic arsenal. In general, pharmacokinetics studies how drugs change after administration via the processes of absorption, distribution, metabolism, and excretion (ADME). This review provides a summary of the pharmacokinetics studies of marine-derived active compounds, with a particular focus on their ADME. The pharmacokinetics of compounds derived from algae, crustaceans, sea cucumber, fungus, sea urchins, sponges, mollusks, tunicate, and bryozoan is discussed, and the pharmacokinetics data in human experiments are analyzed. In-depth characterization using pharmacokinetics is useful for obtaining information for understanding the molecular basis of pharmacological activity, for correct doses and treatment schemes selection, and for more effective drug application. Thus, an increase in pharmacokinetic research on marine-derived compounds is expected in the near future.

High-value compounds from the molluscs of marine and estuarine ecosystems as prospective functional food ingredients: An overview

Extensive biodiversity and availability of marine and estuarine molluscs, along with their their wide-range of utilities as food and nutraceutical resources developed keen attention of the food technologists and dieticians, particularly during the recent years. The current review comprehensively summarized the nutritional qualities, functional food attributes, and bioactive properties of these organisms. Among the phylum mollusca, Cephalopoda, Bivalvia, and Gastropoda were mostly reported for their nutraceutical applications and bioactive properties. The online search tools, like Scifinder/Science Direct/PubMed/Google Scholar/MarinLit database and marine natural product reports (1984-2019) were used to comprehend the information about the molluscs. More than 1334 secondary metabolites were reported from marine molluscs between the periods from 1984 to 2019. Among various classes of specialized metabolites, terpenes were occupied by 55% in gastropods, whereas sterols occupied 41% in bivalves. The marketed nutraceuticals, such as CadalminTM green mussel extract (Perna viridis) and Lyprinol® (Perna canaliculus) were endowed with potential anti-inflammatory activities, and were used against arthritis. Molluscan-derived therapeutics, for example, ziconotide was used as an analgesic, and elisidepsin was used in the treatment of cancer. Greater numbers of granted patents (30%) during 2016-2019 recognized the increasing importance of bioactive compounds from molluscs. Consumption of molluscs as daily diets could be helpful in the enhancement of immunity, and reduce the risk of several ailments. The present review comprehended the high value compounds and functional food ingredients from marine and estuarine molluscs.

Bioactive compounds from marine invertebrates as potent anticancer drugs: the possible pharmacophores modulating cell death pathways

Marine invertebrates are extremely diverse, largely productive, untapped oceanic resources with chemically unique bioactive lead compound contributing a wide range of screening for the discovery of anticancer compounds. The lead compounds have unfurled an extensive array of pharmacological properties owing to the presence of polyphenols, alkaloids, terpenoids and other secondary metabolites. The antioxidant, immunomodulatory and anti-tumor activities exhibited, are possibly regulated by the apoptosis induction, scavenging of ROS and modulation of cellular signaling pathways to defy the cellular deafness during carcinogenesis. Despite the enriched bioactive compounds, the marine invertebrates are largely unexplored as identification, screening, pre-clinical and clinical assessment of lead compounds and their synthetic analogs remain a major task to be solved. In the current review, we focus on the principle strategy and underlying mechanisms deployed by the bioactive anticancer compounds derived from marine invertebrates to combat cancer with special insight into the cell death mechanism.

Marine Natural Products with High Anticancer Activities

This review covers recent literature from 2012-2019 concerning 170 marine natural products and their semisynthetic analogues with strong anticancer biological activities. Reports that shed light on cellular and molecular mechanisms and biological functions of these compounds, thus advancing the understanding in cancer biology are also included. Biosynthetic studies and total syntheses, which have provided access to derivatives and have contributed to the proper structure or stereochemistry elucidation or revision are mentioned. The natural compounds isolated from marine organisms are divided into nine groups, namely: alkaloids, sterols and steroids, glycosides, terpenes and terpenoids, macrolides, polypeptides, quinones, phenols and polyphenols, and miscellaneous products. An emphasis is placed on several drugs originating from marine natural products that have already been marketed or are currently in clinical trials.

From Seabed to Bedside: A Review on Promising Marine Anticancer Compounds

The marine environment represents an outstanding source of antitumoral compounds and, at the same time, remains highly unexplored. Organisms living in the sea synthesize a wide variety of chemicals used as defense mechanisms. Interestingly, a large number of these compounds exert excellent antitumoral properties and have been developed as promising anticancer drugs that have later been approved or are currently under validation in clinical trials. However, due to the high need for these compounds, new methodologies ensuring its sustainable supply are required. Also, optimization of marine bioactives is an important step for their success in the clinical setting. Such optimization involves chemical modifications to improve their half-life in circulation, potency and tumor selectivity. In this review, we outline the most promising marine bioactives that have been investigated in cancer models and/or tested in patients as anticancer agents. Moreover, we describe the current state of development of anticancer marine compounds and discuss their therapeutic limitations as well as different strategies used to overcome these limitations. The search for new marine antitumoral agents together with novel identification and chemical engineering approaches open the door for novel, more specific and efficient therapeutic agents for cancer treatment.

Exploring Antimicrobials from the Flora and Fauna of Marine: Opportunities and Limitations

About 95% of earth living space lies deep below the ocean's surface and it harbors extraordinary diversity of marine organisms. Marine biodiversity is an exceptional reservoir of natural products, bioactive compounds, nutraceuticals and other potential compounds of commercial value. Timeline for the development of the drug from a plant, synthetic and other alternative sources is too lengthy. Exploration of the marine environment for potential bioactive compounds has gained focus and huge opportunity lies ahead for the exploration of such vast resources in the ocean. Further, the evolution of superbugs with increasing resistance to the currently available drugs is alarming and it needs coordinated efforts to resolve them. World Health Organization recommends the need and necessity to develop effective bioactive compounds to combat problems associated with antimicrobial resistance. Based on these factors, it is imperative to shift the focus towards the marine environment for potential bioactive compounds that could be utilized to tackle antimicrobial resistance. Current research trends also indicate the huge strides in research involving marine environment for drug discovery. The objective of this review article is to provide an overview of marine resources, recently reported research from marine resources, challenges, future research prospects in the marine environment.

Loading Auristatin PE onto boron nitride nanotubes and their effects on the apoptosis of Hep G2 cells

Auristatin PE (PE) as an anti-microtubule agent possesses good anticancer activity. However, the poor target effect and strong side effect limit the clinical application of PE. Boron nitride nanotubes (BNNTs) represent an outstanding carrier candidate providing a wise choice for liver-targeted drug delivery. A drug delivery system based on BNNTs and PE (BNNTs-PE) against liver cancer cells was designed and constructed in this study. Firstly, BNNTs were prepared and hydroxylated, subsequently, PE was loaded onto BNNTs by noncovalent conjugation and was stable at neutral pH but released at pH 4.49. It was found that BNNTs-PE demonstrates an enhanced anticancer activity against Hep G2 cells in comparison with free PE. BNNTs-PE kills cancer cells in a manner of mitochondria-mediated apoptosis pathway through reducing the mitochondrial membrane potential, activating caspase cascade. This BNNTs-PE system may be very promising for the treatment of liver cancer in the future.

Marine Macrolides with Antibacterial and/or Antifungal Activity

Currently, the increasing resistance of microorganisms to antibiotics is a serious problem. Marine organisms are the source of thousands of substances, which also have antibacterial and antifungal effects. Among them, marine macrolides are significant. In this review, the antibacterial and/or antifungal activities of 34 groups of marine macrolides are presented. Exemplary groups are chalcomycins, curvulides, halichondramides, lobophorins, macrolactins, modiolides, scytophycins, spongistatins, or zearalanones. In the paper, 74 antibiotics or their analog sets, among which 29 with antifungal activity, 25 that are antibacterial, and 20 that are both antifungal and antibacterial are summarized. Also, 36 macrolides or their sets are produced by bacteria, 18 by fungi, ten by sponges, seven by algae, two by porifera, and one by nudibranch. Moreover, the chemical structures of representatives from each of the 34 groups of these antibiotics are presented. To summarize, marine organisms are rich in natural macrolides. Some of these may be used in the future in the treatment of bacterial and fungal infections. Marine macrolides can also be potential drugs applicable against pathogens resistant to currently known antibiotics.

Induction of Apoptosis by Extract of Persian Gulf Marine Mollusk, Turbo Coronatus through the ROS-Mediated Mitochondrial Targeting on Human Epithelial Ovarian Cancer Cells

Despite recent improvements in treatment, ovarian cancer is still the leading cause of death from gynaecological malignancies. Today, marine mollusks are considered as natural source of new biologically and pharmacologically active compounds by scientists and the pharmaceutical industries. The aim of this study is to investigate the selective apoptotic effects of Turbo coronatus crude extract fractions on human epithelial ovarian cancer (EOC) cells and mitochondria. The cells and mitochondria were isolated from cancerous and non-cancerous ovarian tissues and exposed to IC₅₀ concentration of F1 fraction for evaluation of mitochondrial and cellular parameters. Our results showed that F1 fraction of T. coronatus crude extract significantly induced toxic effects only in the cancerous ovarian mitochondria, including increased reactive oxygen species (ROS) formation, mitochondrial membrane depolarization, mitochondrial swelling, and cytochrome c release.Flow-cytometry analysis demonstrated that F1 fraction of T. coronatus progressively induced apoptosis and necrosis only on EOC but not non-cancerous cells. We eventuallyconcluded that F1 fraction of T. coronatus crude extract selectively induces apoptosis in EOC through a ROS- mediated pathway.

Doxorubicin-loaded protease-activated near-infrared fluorescent polymeric nanoparticles for imaging and therapy of cancer

INTRODUCTION

Despite significant progress in the field of oncology, cancer remains one of the leading causes of death. Chemotherapy is one of the most common treatment options for cancer patients but is well known to result in off-target toxicity. Theranostic nanomedicines that integrate diagnostic and therapeutic functions within an all-in-one platform can increase tumor selectivity for more effective chemotherapy and aid in diagnosis and monitoring of therapeutic responses.

MATERIAL AND METHODS

In this work, theranostic nanoparticles were synthesized with commonly used biocompatible and biodegradable polymers and used as cancer contrast and therapeutic agents for optical imaging and treatment of breast cancer. These core-shell nanoparticles were prepared by nanoprecipitation of blends of the biodegradable and biocompatible amphiphilic copolymers poly(lactic-co-glycolic acid)-b-poly-l-lysine and poly(lactic acid)-b-poly(ethylene glycol). Poly-l-lysine in the first copolymer was covalently decorated with near-infrared fluorescent Alexa Fluor 750 molecules.

RESULTS

The spherical nanoparticles had an average size of 60-80 nm. The chemotherapeutic drug doxorubicin was encapsulated in the core of nanoparticles at a loading of 3% (w:w) and controllably released over a period of 30 days. A 33-fold increase in near-infrared fluorescence, mediated by protease-mediated cleavage of the Alexa Fluor 750-labeled poly-l-lysine on the surface of the nanoparticles, was observed upon interaction with the model protease trypsin. The cytocompatibility of drug-free nanoparticles and growth inhibition of drug-loaded nanoparticles on MDA-MB-231 breast cancer cells were investigated with a luminescence cell-viability assay. Drug-free nanoparticles were found to cause minimal toxicity, even at high concentrations (0.2-2,000 µg/mL), while doxorubicin-loaded nanoparticles significantly reduced cell viability at drug concentrations >10 µM. Finally, the interaction of the nanoparticles with breast cancer cells was studied utilizing fluorescence microscopy, demonstrating the potential of the nanoparticles to act as near-infrared fluorescence optical imaging agents and drug-delivery carriers.

CONCLUSION

Doxorubicin-loaded, enzymatically activatable nanoparticles of less than 100 nm were prepared successfully by nanoprecipitation of copolymer blends. These nanoparticles were found to be suitable as controlled drug delivery systems and contrast agents for imaging of cancer cells.

Marine Natural Peptides: Determination of Absolute Configuration Using Liquid Chromatography Methods and Evaluation of Bioactivities

Over the last decades, many naturally occurring peptides have attracted the attention of medicinal chemists due to their promising applicability as pharmaceuticals or as models for drugs used in therapeutics. Marine peptides are chiral molecules comprising different amino acid residues. Therefore, it is essential to establish the configuration of the stereogenic carbon of their amino acid constituents for a total characterization and further synthesis to obtain higher amount of the bioactive marine peptides or as a basis for structural modifications for more potent derivatives. Moreover, it is also a crucial issue taking into account the mechanisms of molecular recognition and the influence of molecular three-dimensionality in this process. In this review, a literature survey covering the report on the determination of absolute configuration of the amino acid residues of diverse marine peptides by chromatographic methodologies is presented. A brief summary of their biological activities was also included emphasizing to the most promising marine peptides. A case study describing an experience of our group was also included.

Toward aplyronine payloads for antibody–drug conjugates: total synthesis of aplyronines A and D

We report an expedient total synthesis of aplyronines A and D, together with a linker-modified analogue for bioconjugation studies.

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.

The Potential of Indonesian Heterobranchs Found around Bunaken Island for the Production of Bioactive Compounds

The species diversity of marine heterobranch sea slugs found on field trips around Bunaken Island (North Sulawesi, Indonesia) and adjacent islands of the Bunaken National Marine Park forms the basis of this review. In a survey performed in 2015, 80 species from 23 families were collected, including 17 new species. Only three of these have been investigated previously in studies from Indonesia. Combining species diversity with a former study from 2003 reveals in total 140 species from this locality. The diversity of bioactive compounds known and yet to be discovered from these organisms is summarized and related to the producer if known or suspected (might it be down the food chain, de novo synthesised from the slug or an associated bacterium). Additionally, the collection of microorganisms for the discovery of natural products of pharmacological interest from this hotspot of biodiversity that is presented here contains more than 50 species that have never been investigated before in regard to bioactive secondary metabolites. This highlights the great potential of the sea slugs and the associated microorganisms for the discovery of natural products of pharmacological interest from this hotspot of biodiversity.

Marine Terpenoid Diacylguanidines: Structure, Synthesis, and Biological Evaluation of Naturally Occurring Actinofide and Synthetic Analogues

A new diacylguanidine, actinofide (1), has been isolated from the marine mollusk Actinocyclus papillatus. The structure, exhibiting a guanidine moiety acylated by two terpenoid acid units, has been established by spectroscopic methods and secured by synthesis. Following this, a series of structural analogues have been synthesized using the same procedure. All of the compounds have been evaluated in vitro for the growth inhibitory activity against a variety of cancer cell lines.

Anti-Inflammatory Activity and Structure-Activity Relationships of Brominated Indoles from a Marine Mollusc

Marine molluscs are rich in biologically active natural products that provide new potential sources of anti-inflammatory agents. Here we used bioassay guided fractionation of extracts from the muricid Dicathais orbita to identify brominated indoles with anti-inflammatory activity, based on the inhibition of nitric oxide (NO) and tumour necrosis factor α (TNFα) in lipopolysaccharide (LPS) stimulated RAW264.7 macrophages and prostaglandin E2 (PGE2) in calcium ionophore-stimulated 3T3 ccl-92 fibroblasts. Muricid brominated indoles were then compared to a range of synthetic indoles to determine structure-activity relationships. Both hypobranchial gland and egg extracts inhibited the production of NO significantly with IC₅₀ of 30.8 and 40 μg/mL, respectively. The hypobranchial gland extract also inhibited the production of TNFα and PGE2 with IC₅₀ of 43.03 µg/mL and 34.24 µg/mL, respectively. The purified mono-brominated indole and isatin compounds showed significant inhibitory activity against NO, TNFα, and PGE2, and were more active than dimer indoles and non-brominated isatin. The position of the bromine atom on the isatin benzene ring significantly affected the activity, with 5Br > 6Br > 7Br. The mode of action for the active hypobranchial gland extract, 6-bromoindole, and 6-bromoisatin was further tested by the assessment of the translocation of nuclear factor kappa B (NFκB) in LPS-stimulated RAW264.7 mouse macrophage. The extract (40 µg/mL) significantly inhibited the translocation of NFκB in the LPS-stimulated RAW264.7 macrophages by 48.2%, whereas 40 µg/mL of 6-bromoindole and 6-bromoistain caused a 60.7% and 63.7% reduction in NFκB, respectively. These results identify simple brominated indoles as useful anti-inflammatory drug leads and support the development of extracts from the Australian muricid D. orbita, as a new potential natural remedy for the treatment of inflammation.