Halistanol sulfates I and J, new SIRT1–3 inhibitory steroid sulfates from a marine sponge of the genus Halichondria

A systematic review on understanding the mechanistic pathways and clinical aspects of natural CDK inhibitors on cancer progression.: Unlocking cellular and biochemical mechanisms

Cell division, differentiation, and controlled cell death are all regulated by phosphorylation, a key biological function. This mechanism is controlled by a variety of enzymes, with cyclin-dependent kinases (CDKs) being particularly important in phosphorylating proteins at serine and threonine sites. CDKs, which contain 20 unique components, serve an important role in regulating vital physiological functions such as cell cycle progression and gene transcription. Methodologically, an extensive literature search was performed using reputable databases such as PubMed, Google Scholar, Scopus, and Web of Science. Keywords encompassed "cyclin kinase," "cyclin dependent kinase inhibitors," "CDK inhibitors," "natural products," and "cancer therapy." The inclusion criteria, focused on relevance, publication date, and language, ensured a thorough representation of the most recent research in the field, encompassing articles published from January 2015 to September 2023. Categorization of CDKs into those regulating transcription and those orchestrating cell cycle phases provides a comprehensive understanding of their diverse functions. Ongoing clinical trials featuring CDK inhibitors, notably CDK7 and CDK4/6 inhibitors, illuminate their promising potential in various cancer treatments. This review undertakes a thorough investigation of CDK inhibitors derived from natural (marine, terrestrial, and peptide) sources. The aim of this study is to provide a comprehensive comprehension of the chemical classifications, origins, target CDKs, associated cancer types, and therapeutic applications.

Potent and Specific Activators for Mitochondrial Sirtuins Sirt3 and Sirt5

Sirtuins are NAD+-dependent protein deacylases involved in metabolic regulation and aging-related diseases. Specific activators for seven human Sirtuin isoforms would be important chemical tools and potential therapeutic drugs. Activators have been described for Sirt1 and act via a unique N-terminal domain of this isoform. For most other Sirtuin isoforms, including mitochondrial Sirt3-5, no potent and specific activators have yet been identified. We here describe the identification and characterization of 1,4-dihydropyridine-based compounds that either act as pan Sirtuin activators or specifically stimulate Sirt3 or Sirt5. The activators bind to the Sirtuin catalytic cores independent of NAD+ and acylated peptides and stimulate turnover of peptide and protein substrates. The compounds also activate Sirt3 or Sirt5 in cellular systems regulating, e.g., apoptosis and electron transport chain. Our results provide a scaffold for potent Sirtuin activation and derivatives specific for Sirt3 and Sirt5 as an excellent basis for further drug development.

Sulfated and Sulfur-Containing Steroids and Their Pharmacological Profile

The review focuses on sulfated steroids that have been isolated from seaweeds, marine sponges, soft corals, ascidians, starfish, and other marine invertebrates. Sulfur-containing steroids and triterpenoids are sourced from sedentary marine coelenterates, plants, marine sediments, crude oil, and other geological deposits. The review presents the pharmacological profile of sulfated steroids, sulfur-containing steroids, and triterpenoids, which is based on data obtained using the PASS program. In addition, several semi-synthetic and synthetic epithio steroids, which represent a rare group of bioactive lipids that have not yet been found in nature, but possess a high level of antitumor activity, were included in this review for the comparative pharmacological characterization of this class of compounds. About 140 steroids and triterpenoids are presented in this review, which demonstrate a wide range of biological activities. Therefore, out of 71 sulfated steroids, thirteen show strong antitumor activity with a confidence level of more than 90%, out of 50 sulfur-containing steroids, only four show strong antitumor activity with a confidence level of more than 93%, and out of eighteen epithio steroids, thirteen steroids show strong antitumor activity with a confidence level of 91% to 97.4%.

Marine natural products

This review covers the literature published between January and December in 2018 for marine natural products (MNPs), with 717 citations (706 for the period January to December 2018) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1554 in 469 papers for 2018), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. The proportion of MNPs assigned absolute configuration over the last decade is also surveyed.

Discovery and characterization of small molecule SIRT3-specific inhibitors as revealed by mass spectrometry

Sirtuins play a prominent role in several cellular processes and are implicated in various diseases. The understanding of biological roles of sirtuins is limited because of the non-availability of small molecule inhibitors, particularly the specific inhibitors directed against a particular SIRT. We performed a high-throughput screening of pharmacologically active compounds to discover novel, specific, and selective sirtuin inhibitor. Several unique in vitro sirtuin inhibitor pharmacophores were discovered. Here, we present the discovery of novel chemical scaffolds specific for SIRT3. We have demonstrated the in vitro activity of these compounds using label-free mass spectroscopy. We have further validated our results using biochemical, biophysical, and computational studies. Determination of kinetic parameters shows that the SIRT3 specific inhibitors have a moderately longer residence time, possibly implying high in vivo efficacy. The molecular docking results revealed the differential selectivity pattern of these inhibitors against sirtuins. The discovery of specific inhibitors will improve the understanding of ligand selectivity in sirtuins, and the binding mechanism as revealed by docking studies can be further exploited for discovering selective and potent ligands targeting sirtuins.

SIRT1 and SIRT2 Activity Control in Neurodegenerative Diseases

Sirtuins are NAD+ dependent histone deacetylases (HDAC) that play a pivotal role in neuroprotection and cellular senescence. SIRT1-7 are different homologs from sirtuins. They play a prominent role in many aspects of physiology and regulate crucial proteins. Modulation of sirtuins can thus be utilized as a therapeutic target for metabolic disorders. Neurological diseases have distinct clinical manifestations but are mainly age-associated and due to loss of protein homeostasis. Sirtuins mediate several life extension pathways and brain functions that may allow therapeutic intervention for age-related diseases. There is compelling evidence to support the fact that SIRT1 and SIRT2 are shuttled between the nucleus and cytoplasm and perform context-dependent functions in neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). In this review, we highlight the regulation of SIRT1 and SIRT2 in various neurological diseases. This study explores the various modulators that regulate the activity of SIRT1 and SIRT2, which may further assist in the treatment of neurodegenerative disease. Moreover, we analyze the structure and function of various small molecules that have potential significance in modulating sirtuins, as well as the technologies that advance the targeted therapy of neurodegenerative disease.

Four new polyhydroxylated steroids from the South Sea sponge Plakortis sp

Four new polyhydroxylated steroids plaksterols A-D (1-4), together with two known related steroids ergost-7,9(11),22-trien-3β,5α,6α-triol (5) and ergosta-6β-methoxy-7,22-diene-3β,5α-diol (6), were isolated from methanol extract of the South China Sea marine sponge Plakortis sp. Their structures were identified by spectroscopic analysis, including NMR, MS, and IR. The cytotoxicity of the polyhydroxylated steroids were evaluated, and compound 6 showed moderate inhibitory activities against K562, HL-60 and BEL-7402 cells.

Histone Deacetylase Inhibitors from Marine Invertebrates

Histone deacetylases (HDACs) are key components of the epigenetic machinery controlling gene expression. They are involved in chromatin remodeling events via post-translational histone modifications but may also act on nonhistone proteins, influencing many fundamental cellular processes. Due to the key involvement of HDACs in serious human pathologies, including cancer, HDAC inhibitors (HDACis) have received increased attention in recent years. It is known that marine invertebrates produce significant amounts of secondary metabolites showing active pharmacological properties and an extensive spectrum of biomedical applications. The aim of this review is to gather selected studies that report the extraction and identification of marine invertebrate-derived compounds that possess HDACi properties, grouping the producing species according to their taxonomic hierarchy. The molecular, biochemical, and/or physiological aspects, where available, and modes of action of these naturally occurring HDACis will be recapitulated, taking into consideration their possible utilization for the future design of analogs with increased bioavailability and efficacy, less toxicity, and, also, higher isoform selectivity.

Sulfated steroids of Halichondriidae family sponges - Natural inhibitors of polysaccharide-degrading enzymes of bacterium Formosa algae, inhabiting brown alga Fucus evanescens

Inhibiting effects of sulfated steroids from marine sponges of Halichondriidae family: halistanol sulfate, topsentiasterol sulfate D and chlorotopsentiasterol sulfate D were investigated on three different types of enzymes degrading polysaccharides of brown algae: endo-1,3-β-d-glucanase GFA, fucoidan hydrolase FFA2 and bifunctional alginate lyase ALFA3 from marine bacterium Formosa algae KMM 3553T, inhabiting thalli of brown alga Fucus evanescens. This is the first research, devoted to influence of a marine natural compound on three functionally related enzymes that make up the complex of enzymes, necessary to degrade unique carbohydrate components of brown algae. Alginic acid, 1,3-β-D-glucan (laminaran) and fucoidan jointly constitute practically all carbohydrate biomass of brown algae, so enzymes, able to degrade such polysaccharides, are crucial for digesting brown algae biomass as well as for organisms surviving and proliferating on brown algae thalli. Halistanol sulfate irreversibly inhibited native endo-1,3-β-D-glucanases of marine mollusks, but reversibly competitively inhibited recombinant endo-1,3-β-d-glucanase GFA. This fact indicates that there are significant structural differences between the enzymes of practically the same specificity. For alginate lyase and fucoidan hydrolase halistanol sulfate was irreversible inhibitor. Topsentiasterol sulfate D was less active inhibitor whereas chlorotopsentiasterol sulfate D was the strongest inhibitor of enzymes under the study. Chlorotopsentiasterol sulfate D caused 98% irreversible inhibition of GFA. Chlorotopsentiasterol sulfate D also caused reversible and 100% inhibition of ALFA3, which is unusual for reversible inhibitors. Inhibition of FFA2 was complete and irreversible in all cases.

New Trisulfated Steroids from the Vietnamese Marine Sponge Halichondria vansoesti and Their PSA Expression and Glucose Uptake Inhibitory Activities

Seven new unusual polysulfated steroids—topsentiasterol sulfate G (1), topsentiasterol sulfate I (2), topsentiasterol sulfate H (3), bromotopsentiasterol sulfate D (4), dichlorotopsentiasterol sulfate D (8), bromochlorotopsentiasterol sulfate D (9), and 4β-hydroxyhalistanol sulfate C (10), as well as three previously described—topsentiasterol sulfate D (7), chlorotopsentiasterol sulfate D (5) and iodotopsentiasterol sulfate D (6) have been isolated from the marine sponge Halichondria vansoesti. Structures of these compounds were determined by detailed analysis of 1D- and 2D-NMR and HRESIMS data, as well as chemical transformations. The effects of the compounds on human prostate cancer cells PC-3 and 22Rv1 were investigated.

Antitumor Anthraquinones from an Easter Island Sea Anemone: Animal or Bacterial Origin?

The presence of two known anthraquinones, Lupinacidin A and Galvaquinone B, which have antitumor activity, has been identified in the sea anemone (Gyractis sesere) from Easter Island. So far, these anthraquinones have been characterized from terrestrial and marine Actinobacteria only. In order to identify the anthraquinones producer, we isolated Actinobacteria associated with the sea anemone and obtained representatives of seven actinobacterial genera. Studies of cultures of these bacteria by HPLC, NMR, and HRLCMS analyses showed that the producer of Lupinacidin A and Galvaquinone B indeed was one of the isolated Actinobacteria. The producer strain, SN26_14.1, was identified as a representative of the genus Verrucosispora. Genome analysis supported the biosynthetic potential to the production of these compounds by this strain. This study adds Verrucosispora as a new genus to the anthraquinone producers, in addition to well-known species of Streptomyces and Micromonospora. By a cultivation-based approach, the responsibility of symbionts of a marine invertebrate for the production of complex natural products found within the animal’s extracts could be demonstrated. This finding re-opens the debate about the producers of secondary metabolites in sea animals. Finally, it provides valuable information about the chemistry of bacteria harbored in the geographically-isolated and almost unstudied, Easter Island.

Two new 4-methylidene containing steroids, craterol A and B, from the New Zealand two sponge association between Stelletta crater and Desmacella dendyi

NMR-directed investigation of the two sponge association between Stelletta crater and Desmacella dendyi has resulted in the isolation of two new members of the rare 4-methylidene class of sterols. Craterol A (1) and B (2) represent the first examples of natural products reported from the species S. crater. The isolation of these compounds challenges the role of 4-methylidene sterols as chemotaxonomic markers for the sponge genus Theonella.

Microbial Sterolomics as a Chemical Biology Tool

Metabolomics has become a powerful tool in chemical biology. Profiling the human sterolome has resulted in the discovery of noncanonical sterols, including oxysterols and meiosis-activating sterols. They are important to immune responses and development, and have been reviewed extensively. The triterpenoid metabolite fusidic acid has developed clinical relevance, and many steroidal metabolites from microbial sources possess varying bioactivities. Beyond the prospect of pharmacognostical agents, the profiling of minor metabolites can provide insight into an organism's biosynthesis and phylogeny, as well as inform drug discovery about infectious diseases. This review aims to highlight recent discoveries from detailed sterolomic profiling in microorganisms and their phylogenic and pharmacological implications.

SULFATION PATHWAYS: Sources and biological activities of marine sulfated steroids

Marine environment is rich in structurally unique molecules and can be an inspiring source of novel drugs. Currently, six marine-derived drugs are in the market with FDA approval and several more are in the clinical pipeline. Structurally diverse and complex secondary metabolites have been isolated from the marine world and these include sulfated steroids. Biological activities of nearly 150 marine sulfated steroids reported from 1978 to 2017 are compiled and described, namely antimicrobial, antitumor, cardiovascular and antifouling activities. Structure-activity relationship for each activity is discussed.

Sterol Sulfates and Sulfotransferases in Marine Diatoms

Sterol sulfates are widely occurring molecules in marine organisms. Their importance has been so far underestimated although many of these compounds are crucial mediators of physiological and ecological functions in other organisms. Biosynthesis of sterol sulfates is controlled by cytosolic sulfotransferases (SULTs), a varied family of enzymes that catalyze the transfer of a sulfo residue (-SO₃H) from the universal donor 3'-phosphoadenosine-5'-phosphosulfate to the hydroxyl function at C-3 of the steroid skeleton. The absence of molecular tools has been the main impediment to the development of a biosynthetic study of this class of compounds in marine organisms. In fact, there is very limited information about these enzymes in marine environments. SULT activity has, however, been reported in several marine species, and, recently, the production of sterol sulfates has been linked to the control of growth in marine diatoms. In this chapter, we describe methods for the study of sterol sulfates in this lineage of marine microalgae. The main aim is to provide the tools useful to deal with the biosynthesis and regulation of these compounds and to circumvent the bottleneck of the lack of molecular information. The protocols have been designed for marine diatoms, but most of the procedures can be used for other marine organisms.