Marine pharmacology in 2005-6: Marine compounds with anthelmintic, antibacterial, anticoagulant, antifungal, anti-inflammatory, antimalarial, antiprotozoal, antituberculosis, and antiviral activities; affecting the cardiovascular, immune and nervous systems, and other miscellaneous mechanisms of action

Recent advances of edible marine algae-derived sulfated polysaccharides in antiviral treatments: challenges vs. opportunities

Marine polysaccharides, particularly those derived from red, brown, and green algae, have shown promising antiviral activity. Among them, sulfated polysaccharides are particularly notable due to their broad-spectrum antiviral properties. These include direct viral destruction, inhibition of virus adsorption, disruption of viral transcription and replication, and the stimulation of the host's antiviral immunity. With low toxicity, minimal drug resistance, and excellent biocompatibility, these polysaccharides represent promising candidates for the development of antiviral medications. For instance, carrageenan, a polysaccharide from red algae, and fucoidan, a polymer from brown algae, have both been proven to effectively inhibit viral infections. Sulfated polysaccharides from green algae, such as those found in Ulva species, also exhibit antiviral properties, including activity against the Japanese encephalitis virus. These polysaccharides function by blocking the attachment of viruses to host cells or interfering with various stages of the viral life cycle. Moreover, marine polysaccharides have been shown to enhance host immune responses, thereby aiding in viral clearance. Although these findings highlight the antiviral potential of marine polysaccharides, most studies have been conducted in vitro or in animal models. Further clinical trials are necessary to validate their effectiveness and safety for therapeutic use.

Investigation the effect of the aqueous extract of Chara vulgaris (L.) on visceral leishmaniasis

Background

Visceral leishmaniasis (VL) is a parasitic disease that affects public health. It is described by weight reduction, irregular fever bouts, anemia, and amplification of the spleen and liver.

Materials and Methods

Three concentrations (15.6, 31.2, and 62.5 μg/mL) were used to find the potency of an aqueous extract of Chara vulgaris algae in the treatment of VL. A cytotoxicity assay was performed to show the cytotoxic effect of this extract on human cells. High-performance liquid chromatography (HPLC) test was done to determine the active compounds in the extract. Histopathological sections for infected liver and spleen were performed, as were liver function tests (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase), which were assessed after 1 month of treatment.

Results

As cytotoxicity assay, results showed that there were no significant differences between the cells treated and those not treated with the extract. HPLC test demonstrated that phenolic and terpene compounds are the main active compounds in the extract. P-coumaric acid and ursolic acid present the highest percent among other phenolic and terpene compounds (21.84%, 17.82%), respectively. Histopathological sections showed that this extract had a significant effect in the treatment of infected tissues, and this effect was very clear after the end of the treatment period. As for the liver function tests, a significant increase (P < 0.01) in the studied liver enzymes was found in the infected group of mice compared to the healthy group, whereas in the infected and treated groups, a clear and gradual decrease in the level of enzymes was observed.

Marine Pharmacology in 2019-2021: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The current 2019-2021 marine pharmacology literature review provides a continuation of previous reviews covering the period 1998 to 2018. Preclinical marine pharmacology research during 2019-2021 was published by researchers in 42 countries and contributed novel mechanism-of-action pharmacology for 171 structurally characterized marine compounds. The peer-reviewed marine natural product pharmacology literature reported antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral mechanism-of-action studies for 49 compounds, 87 compounds with antidiabetic and anti-inflammatory activities that also affected the immune and nervous system, while another group of 51 compounds demonstrated novel miscellaneous mechanisms of action, which upon further investigation, may contribute to several pharmacological classes. Thus, in 2019-2021, a very active preclinical marine natural product pharmacology pipeline provided novel mechanisms of action as well as new lead chemistry for the clinical marine pharmaceutical pipeline targeting the therapy of several disease categories.

Synthesis, in vitro Anti-HIV-1RT evaluation, molecular modeling, DFT and acute oral toxicity studies of some benzotriazole derivatives

This study synthesized and evaluated a series of benzotriazole derivatives denoted 3(a-j) and 6(a-j) for their anti-HIV-1 RT activities compared to the standard drug efavirenz. Notably, compound 3 h, followed closely by 6 h, exhibited significant anti-HIV-1 RT efficacy relative to the standard drug. In vivo oral toxicity studies were conducted for the most active compound 3 h, confirming its nontoxic nature to ascertain the safety profile. By employing molecular docking techniques, we explored the potential interactions between the synthesized compounds (ligands) and a target biomolecule (protein)(PDB ID 1RT2) at the molecular level. We undertook the molecular dynamics study of 3 h, the most active compound, within the active binding pocket of the cocrystallized structure of HIV-1 RT (PDB ID 1RT2). We aimed to learn more about how biomolecular systems behave, interact, and change at the atomic or molecular level over time. Finally, the DFT-derived HOMO and LUMO orbitals, as well as analysis of the molecular electrostatic potential map, aid in discerning the reactivity characteristics of our molecule.

Exploring the Antimicrobial Potential and Biofilm Inhibitory Properties of Hemocyanin from Hemifusus pugilinus (Born, 1778)

The seafood industry plays a huge role in the blue economy, exploiting the advantage of the enriched protein content of marine organisms such as shrimps and molluscs, which are cultured in aquafarms. Diseases greatly affect these aquatic organisms in culture and, hence, there is need to study, in detail, their innate immune mechanisms. Hemocyanin is a non-specific innate defense molecule present in the blood cells of several invertebrates, especially molluscs, arthropods, and annelids. It is concerned with oxygen transport, blood clotting, and immune enhancement. In the present study, this macromolecular metalloprotein was isolated from the hemolymph of the marine snail Hemifusus pugilinus (Born, 1778) using Sephadex G-100 gel filtration column chromatography. It occurred as a single band (MW 80 kDa) on SDS-PAGE. High-performance liquid chromatography (HPLC) of the purified hemocyanin showed a single peak with a retention time of 4.3 min. The secondary structure and stability of the protein were detected using circular dichroism (CD), and the spectra demonstrated negative ellipticity bands close to 208 nm and 225 nm, indicating β-sheets. Further exploration of the purified hemocyanin revealed remarkable antimicrobial and antibiofilm activities against Gram-positive (Enterococcus faecalis and Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa and Proteus vulgaris) at a concentration of 1-5 μg/mL. Spectrophotometric and in situ microscopic analyses (CLSM) unveiled the potential of the purified hemocyanin to inhibit biofilm formation in these bacteria with a minimal inhibitory concentration of 40 μg/mL. Furthermore, H. pugilinus hemocyanin (10 μg/mL concentration) displayed antifungal activity against Aspergillus niger. The purified hemocyanin was also assessed for cytotoxicity against human cancer cells using cell viability assays. Altogether, the present study shows that molluscan hemocyanin is a potential antimicrobial, antibiofilm, antifungal, anticancer, and immunomodulatory agent, with great scope for application in the enhancement of the immune system of molluscs, thereby facilitating their aquaculture.

Antiviral activity of red algae phycocolloids against herpes simplex virus type 2 in vitro

Herpes simplex virus type 2 (HSV-2) is a human infectious agent with significant impact on public health due to its high prevalence in the population and its ability to elicit a wide range of diseases, from mild to severe. Although several antiviral drugs, such as acyclovir, are currently available to treat HSV-2-related clinical manifestations, their effectiveness is poor. Therefore, the identification and development of new antiviral drugs against HSV-2 is necessary. Seaweeds are attractive candidates for such purposes because they are a vast source of natural products due to their highly diverse compounds, many with demonstrated biological activity. In this study, we evaluated the in vitro antiviral potential of red algae extracts obtained from Agarophyton chilense, Mazzaella laminarioides, Porphyridium cruentum, and Porphyridium purpureum against HSV-2. The phycocolloids agar and carrageenan obtained from the macroalgae dry biomass of A. chilense and M. laminarioides and the exopolysaccharides from P. cruentum and P. purpureum were evaluated. The cytotoxicity of these extracts and the surpluses obtained in the extraction process of the agar and carrageenans were evaluated in human epithelial cells (HeLa cells) in addition to their antiviral activity against HSV-2, which were used to calculate selectivity indexes (SIs). Several compounds displayed antiviral activity against HSV-2, but carrageenans were not considered as a potential antiviral therapeutic agent when compared to the other algae extracts with a SI of 23.3. Future assays in vivo models for HSV-2 infection should reveal the therapeutic potential of these algae compounds as new antivirals against this virus.

Advances in Natural Products from the Marine-Sponge-Associated Microorganisms with Antimicrobial Activity in the Last Decade

Microorganisms are the dominating source of food and nutrition for sponges and play an important role in sponge structure, chemical defense, excretion and evolution. In recent years, plentiful secondary metabolites with novel structures and specific activities have been identified from sponge-associated microorganisms. Additionally, as the phenomenon of the drug resistance of pathogenic bacteria is becoming more and more common, it is urgent to discover new antimicrobial agents. In this paper, we reviewed 270 secondary metabolites with potential antimicrobial activity against a variety of pathogenic strains reported in the literature from 2012 to 2022. Among them, 68.5% were derived from fungi, 23.3% originated from actinomycetes, 3.7% were obtained from other bacteria and 4.4% were discovered using the co-culture method. The structures of these compounds include terpenoids (13%), polyketides (51.9%), alkaloids (17.4%), peptides (11.5%), glucosides (3.3%), etc. Significantly, there are 124 new compounds and 146 known compounds, 55 of which have antifungal activity in addition to antipathogenic bacteria. This review will provide a theoretical basis for the further development of antimicrobial drugs.

Interaction of Scenedesmus quadricauda and native bacteria in marine biopharmaceutical wastewater for desirable lipid production and wastewater treatment

Improving knowledge of the alga-bacterium interaction can promote the wastewater treatment. The untreated marine biopharmaceutical wastewater (containing native bacteria) was used directly for culturing microalgae. Unlike previous studies on specific bacteria in algal-bacterial co-culture systems, the effect of native bacteria in wastewater on microalgae growth was investigated in this study. The results showed that the coexistence of native bacteria greatly promoted the microalgae growth, ultimately producing biomass of 0.64 g/L and biomass productivity of 56.18 mg/L·d. Moreover, the lipid accumulation in the algae + bacteria group was 1.31 and 1.13 times higher than those of BG11 and pure algae, respectively, mainly attributed to the fact that bacteria provided a good environment for microalgae growth by using extracellular substances released from microalgae for their own growth, and providing micromolecules of organic matter and other required elements to microalgae. This study would lay the theoretical foundation for improving biopharmaceutical wastewater treatment.

Versatile Applications of Cyanobacteria in Biotechnology

Cyanobacteria are blue-green Gram-negative and photosynthetic bacteria which are seen as one of the most morphologically numerous groups of prokaryotes. Because of their ability to fix gaseous nitrogen and carbon dioxide to organic materials, they are known to play important roles in the universal nutrient cycle. Cyanobacteria has emerged as one of the promising resources to combat the issues of global warming, disease outbreaks, nutrition insecurity, energy crises as well as persistent daily human population increases. Cyanobacteria possess significant levels of macro and micronutrient substances which facilitate the versatile popularity to be utilized as human food and protein supplements in many countries such as Asia. Cyanobacteria has been employed as a complementary dietary constituent of feed for poultry and as vitamin and protein supplement in aquatic lives. They are effectively used to deal with numerous tasks in various fields of biotechnology, such as agricultural (including aquaculture), industrial (food and dairy products), environmental (pollution control), biofuel (bioenergy) and pharmaceutical biotechnology (such as antimicrobial, anti-inflammatory, immunosuppressant, anticoagulant and antitumor); recently, the growing interest of applying them as biocatalysts has been observed as well. Cyanobacteria are known to generate a numerous variety of bioactive compounds. However, the versatile potential applications of cyanobacteria in biotechnology could be their significant growth rate and survival in severe environmental conditions due to their distinct and unique metabolic pathways as well as active defensive mechanisms. In this review, we elaborated on the versatile cyanobacteria applications in different areas of biotechnology. We also emphasized the factors that could impede the implementation to cyanobacteria applications in biotechnology and the execution of strategies to enhance their effective applications.

Marine Natural Products from the Russian Pacific as Sources of Drugs for Neurodegenerative Diseases

Neurodegenerative diseases are growing to become one of humanity's biggest health problems, given the number of individuals affected by them. They cause enough mortalities and severe economic impact to rival cancers and infections. With the current diversity of pathophysiological mechanisms involved in neurodegenerative diseases, on the one hand, and scarcity of efficient prevention and treatment strategies, on the other, all possible sources for novel drug discovery must be employed. Marine pharmacology represents a relatively uncharted territory to seek promising compounds, despite the enormous chemodiversity it offers. The current work discusses one vast marine region-the Northwestern or Russian Pacific-as the treasure chest for marine-based drug discovery targeting neurodegenerative diseases. We overview the natural products of neurological properties already discovered from its waters and survey the existing molecular and cellular targets for pharmacological modulation of the disease. We further provide a general assessment of the drug discovery potential of the Russian Pacific in case of its systematic development to tackle neurodegenerative diseases.

Marine Biological Macromolecules and Chemically Modified Macromolecules; Potential Anticoagulants

Coagulation is a potential defense mechanism that involves activating a series of zymogens to convert soluble fibrinogen to insoluble fibrin clots to prevent bleeding and hemorrhagic complications. To prevent the extra formation and diffusion of clots, the counterbalance inhibitory mechanism is activated at levels of the coagulation pathway. Contrariwise, this system can evade normal control due to either inherited or acquired defects or aging which leads to unusual clots formation. The abnormal formations and deposition of excess fibrin trigger serious arterial and cardiovascular diseases. Although heparin and heparin-based anticoagulants are a widely prescribed class of anticoagulants, the clinical use of heparin has limitations due to the unpredictable anticoagulation, risk of bleeding, and other complications. Hence, significant interest has been established over the years to investigate alternative therapeutic anticoagulants from natural sources, especially from marine sources with good safety and potency due to their unique chemical structure and biological activity. This review summarizes the coagulation cascade and potential macromolecular anticoagulants derived from marine flora and fauna.

Structure and Antimicrobial Activity of Rare Lactone Lipids from the Sooty Mold (Scorias spongiosa)

Two new lactone lipids, scoriosin (1) and its methyl ester (2), with a rare furylidene ring joined to a tetrahydrofurandione ring, were isolated from Scorias spongiosa, commonly referred to as sooty mold. The planar structure of these compounds was assigned by 1D and 2D NMR. The conformational analysis of these molecules was undertaken to evaluate the relative and absolute configuration through GIAO NMR chemical shift analysis and ECD calculation. In addition to the potent antimicrobial activities, compound 2 strongly potentiated the activity of amphotericin B against Cryptococcus neoformans, suggesting the potential utility of this compound in combination therapies for treating cryptococcal infections.

Cyanobacteria: Model Microorganisms and Beyond

In this review, the general background is provided on cyanobacteria, including morphology, cell membrane structure, and their photosynthesis pathway. The presence of cyanobacteria in nature, and their industrial applications are discussed, and their production of secondary metabolites are explained. Biofilm formation, as a common feature of microorganisms, is detailed and the role of cell diffusion in bacterial colonization is described. Then, the discussion is narrowed down to cyanobacterium Synechocystis, as a lab model microorganism. In this relation, the morphology of Synechocystis is discussed and its different elements are detailed. Type IV pili, the complex multi-protein apparatus for motility and cell-cell adhesion in Synechocystis is described and the underlying function of its different elements is detailed. The phototaxis behavior of the cells, in response to homogenous or directional illumination, is reported and its relation to the run and tumble statistics of the cells is emphasized. In Synechocystis suspensions, there may exist a reciprocal interaction between the cell and the carrying fluid. The effects of shear flow on the growth, doubling per day, biomass production, pigments, and lipid production of Synechocystis are reported. Reciprocally, the effects of Synechocystis presence and its motility on the rheological properties of cell suspensions are addressed. This review only takes up the general grounds of cyanobacteria and does not get into the detailed biological aspects per se. Thus, it is substantially more comprehensive in that sense than other reviews that have been published in the last two decades. It is also written not only for the researchers in the field, but for those in physics and engineering, who may find it interesting, useful, and related to their own research.

Future Directions for the Discovery of Natural Product-Derived Immunomodulating Drugs

Drug discovery from natural sources is going through a renaissance, having spent many decades in the shadow of synthetic molecule drug discovery, despite the fact that natural product-derived compounds occupy a much greater chemical space than those created through synthetic chemistry methods. With this new era comes new possibilities, not least the novel targets that have emerged in recent times and the development of state-of-the-art technologies that can be applied to drug discovery from natural sources. Although progress has been made with some immunomodulating drugs, there remains a pressing need for new agents that can be used to treat the wide variety of conditions that arise from disruption, or over-activation, of the immune system; natural products may therefore be key in filling this gap. Recognising that, at present, there is no authoritative article that details the current state-of-the-art of the immunomodulatory activity of natural products, this in-depth review has arisen from a joint effort between the International Union of Basic and Clinical Pharmacology (IUPHAR) Natural Products and Immunopharmacology, with contributions from a Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation number of world-leading researchers in the field of natural product drug discovery, to provide a "position statement" on what natural products has to offer in the search for new immunomodulatory argents. To this end, we provide a historical look at previous discoveries of naturally occurring immunomodulators, present a picture of the current status of the field and provide insight into the future opportunities and challenges for the discovery of new drugs to treat immune-related diseases.

Fascaplysin derivatives binding to DNA via unique cationic five-ring coplanar backbone showed potent antimicrobial/antibiofilm activity against MRSA in vitro and in vivo

Methicillin-resistant Staphylococcus aureus (MRSA) is considered as one of the most dangerous clinical pathogens. Biofilms forming ability of MRSA is also a major cause of drug resistance. Hence, it is in urgent need to develop novel antibacterial/antibiofilm drugs. Fascaplysin with a unique cationic five-ring coplanar backbone is emerging as a potential antibacterial compound. In this study, aiming at developing novel and more effective agents, a series of fascaplysin derivatives and their corresponding β-carboline precursors have been synthesized. Then their antibacterial/antibiofilm activity and mechanisms against MRSA were investigated for the first time. The results showed that most fascaplysins rather than β-carboline precursors exhibit superior antimicrobial activity against MRSA ATCC43300, demonstrating the important role of cationic five-ring coplanar backbone playing in antibacterial activity. Among them, 14 and 18 are the most potent compounds with MIC value of 0.098 μg/ml (10-fold lower than vancomycin), and 18 featuring the lowest toxicity. Subsequent mechanisms exploration indicates that 18 has relatively stronger ability to destroy bacterial cell wall and membrane, higher binding affinity to bacterial genomic DNA. Molecular docking study revealed that besides the key role of cationic five-ring coplanar backbone, introduction of N-aryl amide at 9-position of fascaplysin promoted the combination of compound 18 and DNA via additional π-π stacking and hydrogen bonding of the naphthyl group. Moreover, fascaplysins could inhibit MRSA biofilm formation in vitro and bacterial infection in vivo. All these results illustrate that fascaplysin derivative 18 is a strong and safe multi-target antibacterial agent, which makes it an attractive candidate for the treatment of MRSA and its biofilm infections.

Cnidarians as a potential source of antiparasitic drugs

New antiparasitic drugs are urgently required for treating parasitic infections. The marine environment has proven to be a valuable source of compounds with therapeutic properties against many diseases, including parasitic diseases. Cnidarian venoms are known for their toxicological properties and are candidates for developing medications. In this review, the antiparasitic properties of cnidarian toxins, discovered over the last two decades, were examined. A total of 61 cnidarian compounds from 18 different genera of cnidaria were studied for their antiparasitic activities. The assessed genera belonged mainly to three geographical areas: South America, North America, and Southeast Asia. The in vitro activities of crude extracts and compounds against a range of parasites including Plasmodium falciparum, Trypanosoma brucei gambiense, T. cruzi, T. congolense, Leishmania donovani, L. chagasi, L. braziliensis, and Giardia duodenalis are reviewed. The challenges involved in developing these compounds into effective drugs are discussed.

Cytotoxic Polyketide Metabolites from a Marine Mesophotic Zone Chalinidae Sponge-Associated Fungus Pleosporales sp. NBUF144

Two new polyketide natural products, globosuxanthone F (1), and 2'-hydroxy bisdechlorogeodin (2), were isolated from the fungus Pleosporales sp. NBUF144, which was derived from a 62 m deep Chalinidae family sponge together with four known metabolites, 3,4-dihydroglobosuxanthone A (3), 8-hydroxy-3-methylxanthone-1-carboxylate (4), crosphaeropsone C (5), and 4-megastigmen-3,9-dione (6). The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis, including 1D and 2D NMR and high-resolution electrospray ionization mass spectra (HRESIMS) data. The absolute configuration of 1 was further established by single-crystal X-ray diffraction studies. Compounds 1-5 were evaluated for cytotoxicity towards CCRF-CEM human acute lymphatic leukemia cells, and it was found that 1 had an IC50 value of 0.46 µM.

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

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

The methanol extract of red algae, Dichotomaria obtusata, from Persian Gulf promotes in vitro osteogenic differentiation of bone marrow mesenchymal stem cells; a biological and phytochemical study

OBJECTIVES

Osteoporosis is a major public health problem that is appeared with increasing age. This study evaluated the effect of the algae Dichotomaria obtusata methanol extract on osteogenic differentiation of the cultured bone marrow mesenchymal stem cells (BMMSCs) in vitro and analyzed the algae methanol extract to find out the potent beneficial components.

METHODS

Dichotomaria obtusata were collected from the coastal area of Bushehr City in the Persian Gulf, Iran. The expression of osteogenesis-related genes was examined using real-time PCR. The formation of calcium deposits in differentiated MSCs was examined by Alizarin R staining. Analyses of algae extract ingredients were performed by gas chromatography-mass spectrometry (GC-MS).

KEY FINDINGS

Methanol extract of the algae caused the up-regulation of osteogenic genes that were significant for Osteopontin and Osteocalcin (P < 0.05) and also led to an increase in calcium deposits and matrix mineralization in BMMSCs. The GC-MS analyses of the algae extracts resulted in the identification of steroids and essential fatty acids.

CONCLUSION

The results of the study indicated that the methanol extract of D. obtusata may possess significant potentials for the prevention of osteoporosis in vitro.

Advances in the discovery and development of anthelmintics by harnessing natural product scaffolds

Widespread resistance to currently-used anthelmintics represents a major obstacle to controlling parasitic nematodes of livestock animals. Given the reliance on anthelmintics in many control regimens, there is a need for the continued discovery and development of new nematocides. Enabling such a focus are: (i) the major chemical diversity of natural products; (ii) the availability of curated, drug-like extract-, fraction- and/or compound-libraries from natural sources; (iii) the utility and practicality of well-established whole-worm bioassays for Haemonchus contortus-an important parasitic nematodes of livestock-to screen natural product libraries; and (iv) the availability of advanced chromatographic (HPLC), spectroscopic (NMR) and spectrometric (MS) techniques for bioassay-guided fractionation and structural elucidation. This context provides a sound basis for the identification and characterisation of anthelmintic candidates from natural sources. This chapter provides a background on the importance and impact of helminth infections/diseases, parasite control and aspects of drug discovery, and reviews recent work focused on (i) screening well-defined compound libraries to establish the methods needed for large-scale screening of natural extract libraries; (ii) discovering plant and marine extracts with nematocidal or nematostatic activity, and purifying bioactive compounds and assessing their potential for further development; and (iii) synthesising analogues of selected purified natural compounds for the identification of possible 'lead' candidates. The chapter describes some lessons learned from this work and proposes future areas of focus for drug discovery. Collectively, the findings from this recent work show potential for selected natural product scaffolds as candidates for future development. Developing such candidates via future chemical optimisation, efficacy and safety evaluations, broad spectrum activity assessments, and target identification represents an exciting prospect and, if successful, could pave the way to subsequent pre-clinical and clinical evaluations.

Where are all the anthelmintics? Challenges and opportunities on the path to new anthelmintics

Control of helminth parasites is a key challenge for human and veterinary medicine. In the absence of effective vaccines and adequate sanitation, prophylaxis and treatment commonly rely upon anthelmintics. There are concerns about the development of drug resistance, side-effects, lack of efficacy and cost-effectiveness that drive the need for new classes of anthelmintics. Despite this need, only three new drug classes have reached the animal market since 2000 and no new classes of anthelmintic have been approved for human use. So where are all the anthelmintics? What are the barriers to anthelmintic discovery, and what emerging opportunities can be used to address this? This was a discussion group focus at the 2019 8th Consortium for Anthelmintic Resistance and Susceptibility (CARS) in Wisconsin, USA. Here we report the findings of the group in the broader context of the human and veterinary anthelmintic discovery pipeline, highlighting challenges unique to antiparasitic drug discovery. We comment on why the development of novel anthelmintics has been so rare. Further, we discuss potential opportunities for drug development moving into the 21st Century.

Seaweeds' neuroprotective potential set in vitro on a human cellular stress model

Neurodegenerative diseases, such as Parkinson's disease, represent a biggest challenge for medicine, imposing high social and economic impacts. As a result, it is of utmost importance to develop new therapeutic strategies. The present work evaluated the neuroprotective potential of seaweeds extracts on an in vitro dopamine (DA)-induced neurotoxicity cellular model. The neuroprotective effects on SH-SY5Y cells' viability were estimated by the MTT assay. Changes in mitochondrial membrane potential (MMP), caspase-3 activity, and hydrogen peroxide (H2O2) production were determined. DA (30-3000 µM; 24 h) treatment decreased SH-SY5Y cells' viability in concentration and time-dependent manner, increasing the H2O2 production, MMP depolarization, and caspase-3 activity. On the other hand, DA (1000 µM; 24 h) toxicity was reduced (10-15%) with Sargassum muticum and Codium tomentosum extracts (1000 µg/mL; 24 h). The highest neuroprotective activity was exhibited by a methanolic extract obtained from Saccorhiza polyschides, which completely blunted DA effects. Results show that the marine seaweed S. polyschides contain substances with high neuroprotective potential against the toxicity induced by DA, exhibiting anti-apoptotic effects associated with both mitochondrial protection and caspase-3 inhibition. S. polyschides reveals, therefore, to be an excellent source of bioactive molecules, for new drugs development aiming PD therapeutics.

Ilimaquinone Induces Apoptosis and Autophagy in Human Oral Squamous Cell Carcinoma Cells

In this study, the anti-tumor activity of ilimaquinone (IQ), a sesquiterpene quinone isolated from marine sponge Halichondria sp., in oral squamous cell carcinoma (OSCC) cells, was investigated. IQ suppressed the viability of the OSCC cell lines SCC4 and SCC2095 with IC₅₀ values of 7.5 and 8.5 μM, respectively. Flow cytometric analysis demonstrated that IQ induced caspase-dependent apoptosis in SCC4 cells and modulated the expression of several cell growth-related gene products, including Akt, p38, Mcl-1, and p53. Notably, p53 knockdown caused higher resistance to IQ’s anti-tumor activity. In addition, IQ increased reactive oxygen species generation, which was partially reversed by the addition of antioxidants. Furthermore, it triggered autophagy, as evidenced by acidic organelle formation and LC3B-II and Atg5 expression in SCC4 cells. Pretreatment with the autophagy inhibitor 3-methyladenine or chloroquine partially decreased IQ-induced apoptosis, suggesting that IQ induced protective autophagy. In summary, IQ has potential to be used in OSCC therapy.

Assessment of the antioxidant and anticancer potential of different isolated strains of cyanobacteria and microalgae from soil and agriculture drain water

The potential usage of cyanobacteria and microalgae as a promising and alternative source for new and safe therapeutic compounds is recently caught the attention, due to its versatile properties as antitumor, antioxidant, antifungal, and antiviral agents. Primarily, the cyanobacteria and microalgae from fresh and marine water are previously studied, however those isolated from soil and agriculture drain water were poorly investigated. Therefore, this study aimed to screen and characterize the antioxidant profile, as well as the potential anticancer assessment of 12 species of cyanobacteria and two species of microalgae strains isolated from soil and agriculture drain water. The data showed that total phenol contents were highest in Anabaena oryzae and Aphanizomenon gracile (27.39 and 26.83 mg GAE/g, respectively), followed by Leptolyngbya fragilis (22.96 mg GAE/g). Out of the 14 species identified, the cyanobacterium Dolichospermum flos-aquae HSSASE2 exhibited the most elevated antioxidant activity in terms of NO scavenging activity and anti-lipid peroxidation potential (IC₅₀ = 28.7 ± 0.1 and 11.9 ± 0.2 μg/ml, respectively) and the lowest DPPH radical scavenging activity (467.7 μg/ml). Screening of the anticancer potential of all studied strains against four different human cancer cell lines (Caco-2, MCF-7, PC3, and HepG-2) demonstrated that Dolichospermum crassum HSSASE20 has the highest anticancer effect among all tested species against colon and prostate cancer cell lines (IC₅₀ = 57.9 ± 0.4 and 44.1 ± 0.2 μg/ml, respectively), while Oscillatoria sancta HSSASE19 recorded the most anticancer effect against MCF-7 (breast cancer) cell line (IC₅₀ = 15.1 ± 0.7 μg/ml). Dolichospermum spiroides HSSASE18 obtained the highest anticancer effect HepG-2 (hepatic cancer) cell line (IC₅₀ = 48.8 ± 0.7 μg/ml). Additionally, cytotoxicity against healthy peripheral blood mononuclear cells was studied and revealed that Oscillatoria sancta was the safest one among all studied strains. Data obtained from the sensitivity index demonstrated that Dolichospermum crassum was the most sensitive strain against the four cancerous cell lines. Cyanobacteria and microalgae from the soil and drain water sources are efficient free radical scavengers, containing apoptogens capable of stimulating apoptotic cascades and overcoming chemo-resistance in cancer therapy. Thus, these novel secondary metabolites are an excellent alternative, safe, and low-cost antioxidant and anticancer therapeutic compounds.

Cyanobacteria: Review of Current Potentials and Applications

Continual increases in the human population and growing concerns related to the energy crisis, food security, disease outbreaks, global warming, and other environmental issues require a sustainable solution from nature. One of the promising resources is cyanobacteria, also known as blue-green algae. They require simple ingredients to grow and possess a relatively simple genome. Cyanobacteria are known to produce a wide variety of bioactive compounds. In addition, cyanobacteria’s remarkable growth rate enables its potential use in a wide range of applications in the fields of bioenergy, biotechnology, natural products, medicine, agriculture, and the environment. In this review, we have summarized the potential applications of cyanobacteria in different areas of science and development, especially related to their use in producing biofuels and other valuable co-products. We have also discussed the challenges that hinder such development at an industrial level and ways to overcome such obstacles.

Marine Pharmacology in 2014-2015: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis, Antiviral, and Anthelmintic Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The systematic review of the marine pharmacology literature from 2014 to 2015 was completed in a manner consistent with the 1998-2013 reviews of this series. Research in marine pharmacology during 2014-2015, which was reported by investigators in 43 countries, described novel findings on the preclinical pharmacology of 301 marine compounds. These observations included antibacterial, antifungal, antiprotozoal, antituberculosis, antiviral, and anthelmintic pharmacological activities for 133 marine natural products, 85 marine compounds with antidiabetic, and anti-inflammatory activities, as well as those that affected the immune and nervous system, and 83 marine compounds that displayed miscellaneous mechanisms of action, and may probably contribute to novel pharmacological classes upon further research. Thus, in 2014-2015, the preclinical marine natural product pharmacology pipeline provided novel pharmacology as well as new lead compounds for the clinical marine pharmaceutical pipeline, and thus continued to contribute to ongoing global research for alternative therapeutic approaches to many disease categories.

Oceans as a Source of Immunotherapy

Marine flora is taxonomically diverse, biologically active, and chemically unique. It is an excellent resource, which offers great opportunities for the discovery of new biopharmaceuticals such as immunomodulators and drugs targeting cancerous, inflammatory, microbial, and fungal diseases. The ability of some marine molecules to mediate specific inhibitory activities has been demonstrated in a range of cellular processes, including apoptosis, angiogenesis, and cell migration and adhesion. Immunomodulators have been shown to have significant therapeutic effects on immune-mediated diseases, but the search for safe and effective immunotherapies for other diseases such as sinusitis, atopic dermatitis, rheumatoid arthritis, asthma and allergies is ongoing. This review focuses on the marine-originated bioactive molecules with immunomodulatory potential, with a particular focus on the molecular mechanisms of specific agents with respect to their targets. It also addresses the commercial utilization of these compounds for possible drug improvement using metabolic engineering and genomics.

Ultrasound-assisted extraction of antimicrobial compounds from Thymus daenensis and Silybum marianum: Antimicrobial activity with and without the presence of natural silver nanoparticles

The present study is devoted to prepare a new antibacterial and antifungal agent based on in situ-synthesized silver nanoparticles at room temperature using Rosmarinus officinalis (R. officinalis) leaf extract. The Ag-NPs characterization by UV-visible, SEM, TEM and XRD revealed that the particles sizes were in the range of 10-33 nm. In this study, hydroalcoholic extracts were used with ultrasonic method. Ultrasonication has recently received attention as a novel bioprocessing tool for process intensification in many areas of downstream processing. The antimicrobial activities of T. daenensis and S. marianum extracts with and without the presence of Ag-NPs were investigated at concentrations from 12.5 to 50 mg/mL against Staphylococcus aureus (S. aureus, Gram-positive organism) and Escherichia coli (E. coli, Gram-negative organism), and fungal strains were Aspergillus oryzae (A. oryzae) and Candida albicans (C. albicans). Antimicrobial activity determined using agar disc diffusion method revealed that the activities of Ag-NPs/T. daenensis were superior to Ag-NPs/S. marianum and extracts (T. daenensis and S. marianum). The medicinal plant extract can be used to synthesize the Ag-NPs as an eco-friendly and inexpensive method in large scale. The results showed that the prepared Ag-NPs/extracts as good antibacterial and antifungal agents can be potentially applied against rapidly increasing of antibiotic resistance.

Two new pyrrolo-2-aminoimidazoles from a Myanmarese marine sponge, Clathria prolifera

Marine organisms such as marine sponges and soft corals are valuable sources of pharmacologically active secondary metabolites. In our ongoing research on the discovery of new secondary metabolites from marine organisms, two new pyrrolo-2-aminoimidazoles, clathriroles A (1) and B (2), were isolated from the water-soluble portion prepared from the methanol and acetone (2:1) extract of the marine sponge, Clathria prolifera, collected in Myanmar. The chemical structures of the isolated compounds were determined using extensive spectroscopic techniques, including NMR, HRESIMS, IR, and optical rotation, and comparisons with the reported literature. The spectroscopic analyses of 1 and 2 suggested that 1 is an enantiomer of antifungal N-methylmanzacidin C isolated from the marine sponge Axinella brevistyla, whereas 2 is a diastereomer of manzacidin D at C-11 isolated from the marine sponge Astrosclera willeyana. To the best of our knowledge, this is the first report of the isolation of the pyrrolo-2-aminoimidazole compounds from C. prolifera. Furthermore, in contrast to the potency of N-methylmanzacidin C against Saccharomyces cerevisiae, the antifungal assay revealed that 1 and 2 lack any activity against this strain. Thus, these observations may suggest that the absolute configurations at both C-9 and C-11 play an important role in controlling the antifungal activity of this type of compound.

The Rigidins: Isolation, Bioactivity, and Total Synthesis-Novel Pyrrolo[2,3-d]Pyrimidine Analogues Using Multicomponent Reactions

Rigidins (2-6) are pyrrolopyrimidine alkaloids isolated from marine tunicates. Since their isolation, refinement of their total syntheses, and biochemical evaluation, interest toward this pyrrolo[2,3-d]pyrimidine scaffold as a medicinal candidate has been triggered. The derivatization of these natural products has led to the discovery of a novel range of 7-deazahypoxanthines, which exhibit extremely potent anticancer activity in human cancer cell lines. A major breakthrough toward the synthesis of rigidin and various rigidin analogues has been the application of multicomponent reactions (MCRs). The rapid assembly of molecular diversity and flexibility displayed by MCRs makes it an attractive strategy for the preparation of rigidin-inspired small molecules. Furthermore, a number of rigidin-like 7-deazaxanthine compounds have been reported in the literature and the popularity of implementing MCRs to construct these 7-deazaxanthines is highlighted here. It is our hope that the synthetic methods described in this chapter will result in the further generation of rigidin-inspired compounds that will move on from being "hits" into "leads" in the medicinal chemistry drug discovery pipeline and potentially into anticancer therapeutics.

Marine Pharmacology in 2012-2013: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis, and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The peer-reviewed marine pharmacology literature from 2012 to 2013 was systematically reviewed, consistent with the 1998–2011 reviews of this series. Marine pharmacology research from 2012 to 2013, conducted by scientists from 42 countries in addition to the United States, reported findings on the preclinical pharmacology of 257 marine compounds. The preclinical pharmacology of compounds isolated from marine organisms revealed antibacterial, antifungal, antiprotozoal, antituberculosis, antiviral and anthelmitic pharmacological activities for 113 marine natural products. In addition, 75 marine compounds were reported to have antidiabetic and anti-inflammatory activities and affect the immune and nervous system. Finally, 69 marine compounds were shown to display miscellaneous mechanisms of action which could contribute to novel pharmacological classes. Thus, in 2012–2013, the preclinical marine natural product pharmacology pipeline provided novel pharmacology and lead compounds to the clinical marine pharmaceutical pipeline, and contributed significantly to potentially novel therapeutic approaches to several global disease categories.

Investigation of in vitro digestibility of dietary microalga Chlorella vulgaris and cyanobacterium Spirulina platensis as a nutritional supplement

Microalgal proteins are promising sources for functional nutrition and a sustainable candidate for nutraceutical formulations. They also gain importance due to emerging focus on a healthy nutrition and increase in the number of chronic diseases. In this study, dried dietary species of microalga, Chlorella vulgaris, and cyanobacterium Spirulina platensis were hydrolyzed with pancreatin enzyme to obtain protein hydrolysates. The hydrolysis yield of biomass was 55.1 ± 0.1 and 64.8 ± 3.6% for C. vulgaris and S. platensis; respectively. Digestibility, as an indicator for dietary utilization, was also investigated. In vitro protein digestibility (IVPD) values depicted that cell wall structure due to the taxonomical differences affected both hydrolysis and digestibility yield of the crude biomass (p < 0.05). Epithelial cells (Vero) maintained their viability around 70%, even in relatively higher concentrations of hydrolysates in the culture. The protein hydrolysates showed no any antimicrobial activities. This study clearly shows that the conventional protein sources in nutraceutical formulations such as soy, whey, and fish proteins can be replaced by enzymatic hydrolysates of microalgae, which shows elevated digestibility values as a sustainable and reliable source.

Antibacterial Activity of 2-(3’,5'-Dibromo-2'-methoxyphenoxy)-3,5-dibromophenol Isolated from Phyllospongia papyracea

A principal active antimicrobial compound, 2-(3’,5'-dibromo-2'-methoxyphenoxy)-3,5-dibromophenol, was isolated from the methanol extract of Phyllospongia papyracea via bioassay-guided fractionation and isolation. The crude extract and the purified compound were assayed to determine the minimal inhibitory concentration and minimal bactericidal concentration (MBC) using the broth microdilution method. The purified compound was found to be highly active against Bacillus subtilis and Staphylococcus aureus at MIC=1 μg/mL, Campylobacter jejuni at MIC=2 μg/mL, Pseudomonas aeruginosa at MIC=4 μg/mL, and Streptococcus pneumoniae and Listeria monocytogenes at MIC = 8 μg/mL. The activity of this compound was found to be comparable with antibiotics commonly used to control these species of bacteria. The results establish 2-(3’,5'-dibromo-2'-methoxyphenoxy)-3,5-dibromophenol as a potential lead molecule for the development of antibacterial agents.

Antibacterial Activity of 2-(3',5'-Dibromo-2'-methoxyphenoxy)-3,5- dibromophenol Isolated from Phyllospongia papyracea

A principal active antimicrobial compound, 2-(3',5'-dibromo-2'-methoxyphenoxy)-3,5-dibromophenol, was isolated from the methanol extract of Phyllospongiapapyracea via bioassay-guided fractionation and isolation. The crude extract and the purified compound were assayed to determine the minimal - inhibitory concentration and minimal bactericidal concentration (MBC) using the broth. microdilution method. The purified compound was found to be highly active against Bacillus subtilis and Staphylococcus aureus at MIC=1 μg/mL, Campylobacter jejuni at MIC=2 gg/mL, Pseudomonas aeruginosa at MIC=4 μg/mL; and Streptococcus pneumoniae and Listeria monocytogenes at MIC = 8 μg/mL. The activity of this compound was found to be comparable with antibiotics commonly used to control these species of bacteria. The results establish 2-(3',5'-dibromo-2'-methoxyphenoxy)-3,5-dibromopheno as a potential lead molecule for the development of antibacterial agents.

Marine pharmacology: therapeutic targeting of matrix metalloproteinases in neuroinflammation

Alterations in matrix metalloproteinase (MMP) expression and activity are recognized as key pathogenetic events in several neurological disorders. This evidence makes MMPs possible therapeutic targets. The search for substances that can inhibit MMPs is moving progressively toward the screening of natural products. In particular, marine bioprospecting could be promising for the discovery of marine natural products with anti-MMP activities. Despite recent advances in this field, the possibility of using marine MMP inhibitors (MMPIs) for the treatment of neuroinflammation is still under-investigated. Here, we review the latest findings in this promising research field and the potential that marine MMPIs can have in the management and treatment of various neurological diseases.

High cytotoxicity and anti-proliferative activity of algae extracts on an in vitro model of human hepatocellular carcinoma

Background

Cancer represents a serious threat for human health with high social and economic impacts worldwide. Therefore, the development of new anticancer drugs is of most importance. The aim of the present study was to evaluate the antitumor potential of twelve algae from Portugal coast on an in vitro model of human hepatocellular carcinoma (HepG-2 cells).

Results

Both extracts of Asparagopsis armata (1000 µg/ml; 24 h) presented high cytotoxicity with 11.22 ± 2.98 and 1.51 ± 0.38 % of HepG-2 live cells, respectively. Sphaerococcus coronopifolius methanolic and dichloromethane extracts (1000 µg/ml) also generated high reduction on HepG-2 viability (14.04 ± 2.62 and 12.84 ± 3.82 % of HepG-2 live cells, respectively). The most potent anti-proliferative activity was induced by dichloromethane extract (1000 µg/ml; 24 h) of Sphaerococcus coronopifolius, Asparagopsis armata and Plocamium cartilagineum with 99.61 ± 0.27, 98.56 ± 0.81 and 85.13 ± 1.04 % of cell’s proliferation reduction, respectively. Sphaerococcus coronopifolius dichloromethane extract exhibited the highest potency both on cytotoxicity and anti-proliferation assays with an IC₅₀ of 14.1 and 32.3 μg/ml, respectively.

Conclusions

Sphaerococcus coronopifolius is a promising source of new molecules with possible application on cancer therapeutics.