Studies on puupehenone-metabolites of a Dysidea sp.: structure and biological activity

Antifungal Potential of Marine Organisms of the Yucatan Peninsula (Mexico) against Medically Important Candida spp

Invasive fungal infections represent a global health threat. They are associated with high mortality and morbidity rates, partly due to the ineffectiveness of the available antifungal agents. The rampant increase in infections recalcitrant to the current antifungals has worsened this scenario and made the discovery of new and more effective antifungals a pressing health issue. In this study, 65 extracts from marine organisms of the Yucatan Peninsula, Mexico, were screened for antifungal activity against Candida albicans and Candida glabrata, two of the most prevalent fungal species that cause nosocomial invasive fungal infections worldwide. A total of 51 sponges, 13 ascidians and 1 gorgonian were collected from the coral reef and mangrove forest in the Yucatan Peninsula (Mexico) and extracted with organic solvents. Nine crude extracts showed potent antifungal activity, of which four extracts from the sponge species Aiolochroia crassa, Amphimedon compressa, Monanchora arbuscula and Agelas citrina had promising activity against Candida spp. Bioassay-guided fractionation of the M. arbuscula extract revealed the remarkable fungicidal activity of some fractions. Analysis of the chemical composition of one of the most active fractions by UHPLC-HRMS and NMR indicated the presence of mirabilin B and penaresidin B, and their contribution to the observed antifungal activity is discussed. Overall, this work highlights marine organisms of the Yucatan Peninsula as important reservoirs of natural products with promising fungicidal activity, which may greatly advance the treatment of invasive fungal infections, especially those afflicting immunosuppressed patients.

Assessment on facile Diels-Alder approach of α-pyrone and terpenoquinone for the expedient synthesis of various natural scaffolds

The development of highly facile synthetic procedures for the expedient synthesis of complex natural molecules is always in demand. As this aspect, the Diels-Alder reaction (DAR) has a versatile approach to the synthesis of complex natural compounds and highly regio-/stereoselcetive heterocyclic scaffolds. Additionally, α-pyrone and terpenoquinone are two versatile key intermediates that are prevalent in various bioactive natural compounds for instance, (±)-crinine, (±)-joubertinamine, (±)-pancratistatin, (-)-cyclozonarone, and 8-ephipuupehedione, etc. Hence, the current review summarizes the Diels-Alder reaction application of α-pyrone and terpenoquinone to the constructive synthesis of various natural products over the past two decades (2001-2021). Equally, it serves as a stencil for the invention and development of new synthetic strategies for high-complex molecular structured natural and heterocyclic molecules.

Total syntheses of (−)-15-oxopuupehenol and (+)-puupehenone and formal syntheses of (−)-puupehenol and (+)-puupehedione

A concise collective synthesis of (−)-15-oxopuupehenol, (+)-puupehenone, (−)-puupehenol and (+)-puupehedione has been accomplished.

Cinerols, Nitrogenous Meroterpenoids from the Marine Sponge Dysidea cinerea

Eleven new nitrogenous meroterpenoids, cinerols A-K (1-11), were isolated from the marine sponge Dysidea cinerea collected in the South China Sea, and their structures were determined by detailed spectroscopic analysis. Cinerols A (1) and B (2) feature a rare 5H-pyrrolo[1,2a]benzimidazole moiety, while cinerols C-G (3-7) are examples of rare meroterpene benzoxazoles. The cinerols are noncytotoxic to human melanoma A375 cells at the concentration of 32 μM; however, selected cinerols exhibit moderate inhibitory activity against one or more of protein-tyrosine phosphatase 1B, ATP-citrate lyase, and SH2 domain-containing phosphatase-1 with IC₅₀ values of 2.8-27 μM.

Marine Natural Products and Drug Resistance in Latent Tuberculosis

Pyrazinamide (PZA) is the only drug for the elimination of latent Mycobacterium tuberculosis (MTB) isolates. However, due to the increased number of PZA-resistance, the chances of the success of global TB elimination seems to be more prolonged. Recently, marine natural products (MNPs) as an anti-TB agent have received much attention, where some compounds extracted from marine sponge, Haliclona sp. exhibited strong activity under aerobic and hypoxic conditions. In this study, we screened articles from 1994 to 2019 related to marine natural products (MNPs) active against latent MTB isolates. The literature was also mined for the major regulators to map them in the form of a pathway under the dormant stage. Five compounds were found to be more suitable that may be applied as an alternative to PZA for the better management of resistance under latent stage. However, the mechanism of actions behind these compounds is largely unknown. Here, we also applied synthetic biology to analyze the major regulatory pathway under latent TB that might be used for the screening of selective inhibitors among marine natural products (MNPs). We identified key regulators of MTB under latent TB through extensive literature mining and mapped them in the form of regulatory pathway, where SigH is negatively regulated by RshA. PknB, RshA, SigH, and RNA polymerase (RNA-pol) are the major regulators involved in MTB survival under latent stage. Further studies are needed to screen MNPs active against the main regulators of dormant MTB isolates. To reduce the PZA resistance burden, understanding the regulatory pathways may help in selective targets of MNPs from marine natural sources.

Pleiotropic Role of Puupehenones in Biomedical Research

Marine sponges represent a vast source of metabolites with very interesting potential biomedical applications. Puupehenones are sesquiterpene quinones isolated from sponges of the orders Verongida and Dictyoceratida. This family of chemical compounds is composed of a high number of metabolites, including puupehenone, the most characteristic compound of the family. Chemical synthesis of puupehenone has been reached by different routes, and the special chemical reactivity of this molecule has allowed the synthesis of many puupehenone-derived compounds. The biological activities of puupehenones are very diverse, including antiangiogenic, antitumoral, antioxidant, antimicrobial, immunomodulatory and antiatherosclerotic effects. Despite the very important roles described for puupehenones concerning different pathologies, the exact mechanism of action of these compounds and the putative therapeutic effects in vivo remain to be elucidated. This review offers an updated and global view about the biology of puupehenones and their therapeutic possibilities in human diseases such as cancer.

Selective Killing of Dormant Mycobacterium tuberculosis by Marine Natural Products

The dormant phenotype acquired by Mycobacterium tuberculosis during infection poses a major challenge in disease treatment, since these bacilli show tolerance to front-line drugs. Therefore, it is imperative to find novel compounds that effectively kill dormant bacteria. By screening 4,400 marine natural product samples against dual-fluorescent M. tuberculosis under both replicating and nonreplicating conditions, we have identified compounds that are selectively active against dormant M. tuberculosis This validates our strategy of screening all compounds in both assays as opposed to using the dormancy model as a secondary screen. Bioassay-guided deconvolution enabled the identification of unique pharmacophores active in each screening model. To confirm the activity of samples against dormant M. tuberculosis, we used a luciferase reporter assay and enumerated CFU. The structures of five purified active compounds were defined by nuclear magnetic resonance (NMR) and mass spectrometry. We identified two lipid compounds with potent activity toward dormant and actively growing M. tuberculosis strains. One of these was commercially obtained and showed similar activity against M. tuberculosis in both screening models. Furthermore, puupehenone-like molecules were purified with potent and selective activity against dormant M. tuberculosis In conclusion, we have identified and characterized antimycobacterial compounds from marine organisms with novel activity profiles which appear to target M. tuberculosis pathways that are conditionally essential for dormancy survival.

Antibacterial Meroterpenoids from the South China Sea Sponge Dysidea sp

Chemical investigation of the sponge Dysidea sp. afforded three new sesquiterpene phenols (1-3) and one new sesquiterpene aminoquinone (4), together with four known sesquiterpene derivatives (5-8). The structures of all compounds were unambiguously elucidated by extensive spectroscopic analysis, as well as by comparison with the literature. The absolute configurations of compounds 1-4 were determined by electron capture detector (ECD) calculations and circular dichroism (CD) spectrum analysis. Their antibacterial activity against Escherichia coli (25922), Bacillus subtilis (6633), and Staphylococcus aureus (25923) were evaluated. Compounds 1 and 3 showed weak antibacterial activity against the above three strains, whereas compounds 4-8 showed potent antibacterial activities with minimum inhibitory concentration (MIC) values in the range of 3.125 to 12.5 µg/mL.

Bioactive sesquiterpene quinols and quinones from the marine sponge Dysidea avara

Reports the isolation, structure determination, and cytotoxic and NF-κB inhibitory activities of eight sesquiterpene quinols and quinones from Dysidea avara.

Dysidinoid A, an unusual meroterpenoid with anti-MRSA activity from the South China Sea sponge Dysidea sp

An unusual meroterpenoid, dysidinoid A (1), was isolated from the South China Sea sponge Dysidea sp. Its structure was elucidated by extensive spectroscopic methods including HRESIMS and 2D NMR, and its absolute configuration was determined by single-crystal X-ray diffraction analysis. Dysidinoid A (1) is the first meroterpenoid from Nature bearing a 9,4-friedodrime skeleton and a 2,5-dionepyrrole unit. Dysidinoid A (1) showed potent antibacterial activity against two strains of pathogenic bacteria methicillin-resistant Staphylococcus aureus (MRSA) with MIC90 values of 8.0 μg/mL against both.

Dysideanones A-C, unusual sesquiterpene quinones from the South China Sea sponge Dysidea avara

Dysideanones A-C (1-3), three unusual sesquiterpene quinones with unprecedented carbon skeletons, were isolated from the South China Sea sponge Dysidea avara. Their structures including absolute configurations were determined by a combination of spectroscopic analyses and calculated ECD spectra. Within the sesquiterpene quinone structures, dysideanones A (1) and B (2) share an unprecedented 6/6/6/6-fused tetracyclic carbon skeleton, while dysideanone C (3) possesses an unusual 6/6/5/6-fused tetracyclic core. Dysideanone B (2) showed cytotoxicity against two human cancer cell lines, HeLa and HepG2, with IC50 values of 7.1 and 9.4 μM, respectively.

Dysidaminones A–M, cytotoxic and NF-κB inhibitory sesquiterpene aminoquinones from the South China Sea sponge Dysidea fragilis

Structural determination, absolute configuration assignments, and biological activities of new sesquiterpene aminoquinones from Dysidea fragilis.

Meroterpenes from marine invertebrates: structures, occurrence, and ecological implications

Meroterpenes are widely distributed among marine organisms; they are particularly abundant within brown algae, but other important sources include microorganisms and invertebrates. In the present review the structures and bioactivities of meroterpenes from marine invertebrates, mainly sponges and tunicates, are summarized. More than 300 molecules, often complex and with unique skeletons originating from intra- and inter-molecular cyclizations, and/or rearrangements, are illustrated. The reported syntheses are mentioned. The issue of a potential microbial link to their biosynthesis is also shortly outlined.

Synthetic strategies to terpene quinones/hydroquinones

The cytotoxic and antiproliferative properties of many natural sesquiterpene-quinones and -hydroquinones from sponges offer promising opportunities for the development of new drugs. A review dealing with different strategies for obtaining bioactive terpenyl quinones/hydroquinones is presented. The different synthetic approches for the preparation of the most relevant quinones/hydroquinones are described.

Marine pharmacology in 2007-8: Marine compounds with antibacterial, anticoagulant, antifungal, anti-inflammatory, antimalarial, antiprotozoal, antituberculosis, and antiviral activities; affecting the immune and nervous system, and other miscellaneous mechanisms of action

The peer-reviewed marine pharmacology literature in 2007-8 is covered in this review, which follows a similar format to the previous 1998-2006 reviews of this series. The preclinical pharmacology of structurally characterized marine compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, anticoagulant, antifungal, antimalarial, antiprotozoal, antituberculosis and antiviral activities were reported for 74 marine natural products. Additionally, 59 marine compounds were reported to affect the cardiovascular, immune and nervous systems as well as to possess anti-inflammatory effects. Finally, 65 marine metabolites were shown to bind to a variety of receptors and miscellaneous molecular targets, and thus upon further completion of mechanism of action studies, will contribute to several pharmacological classes. Marine pharmacology research during 2007-8 remained a global enterprise, with researchers from 26 countries, and the United States, contributing to the preclinical pharmacology of 197 marine compounds which are part of the preclinical marine pharmaceuticals pipeline. Sustained preclinical research with marine natural products demonstrating novel pharmacological activities, will probably result in the expansion of the current marine pharmaceutical clinical pipeline, which currently consists of 13 marine natural products, analogs or derivatives targeting a limited number of disease categories.

Antiproliferative effects of curcuphenol, a sesquiterpene phenol

Curcuphenol is a sesquiterpene isolated from sponges and plants having several significant biological activities. The present study explored its effect on cell proliferation and apoptosis in Caco-2 human colon cancer cells. It was demonstrated that curcuphenol in concentrations in the range of 29-116 µg/ml inhibited cell proliferation and DNA replication and induced cell death in a dose-dependent manner. The induction of apoptosis was associated with a stimulation of the activity of caspase-3. The findings presented here suggest that curcuphenol has antiproliferative and pro-apoptotic properties.

Puupehanol, a sesquiterpene-dihydroquinone derivative from the marine sponge Hyrtios sp

Puupehanol (1), a new sesquiterpene-dihydroquinone derivative, was isolated from the marine sponge Hyrtios sp., along with the known compounds puupehenone (2) and chloropuupehenone (3) that are responsible for the antifungal activity observed in the extract. The structure of 1 was established as (20R,21R)-21-hydroxy-20,21-dihydropuupehenone by extensive spectroscopic and computational methods. Compound 2 exhibited potent activity against Cryptococcus neoformans and Candida krusei with MFCs of 1.25 and 2.50 microg/mL, respectively.

Marine natural products

This review covers the literature published in 2007 for marine natural products, with 948 citations(627 for the period January to December 2007) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, cnidarians,bryozoans, molluscs, tunicates, echinoderms and true mangrove plants. The emphasis is on new compounds (961 for 2007), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.1 Introduction, 2 Reviews, 3 Marine microorganisms and phytoplankton, 4 Green algae, 5 Brown algae, 6 Red algae, 7 Sponges, 8 Cnidarians, 9 Bryozoans, 10 Molluscs, 11 Tunicates (ascidians),12 Echinoderms, 13 Miscellaneous, 14 Conclusion, 15 References.

Natural sesquiterpenoids

This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. 423 references are cited.

Bispuupehenone from the South Chinese Sea sponge Dysidea sp

Bispuupehenone, C₄₂H₅₄O₆, formally results from dimerization of puupehenone, which is constructed of sesquiterpene and benzene units. Bispuupehenone was isolated from the South China Sea sponge Dysidea sp. and the single-crystal X-ray diffraction analysis confirmed the previously reported structure. The mol­ecule is located on a twofold axis and the dimerization forms two fused dibenzopyran systems related by symmetry. In the asymmetric unit, the two cyclohexane rings adopt chair conformations, while the two pyran rings adopt half-chair conformations. The relative stereochemistry and configurations for the ring junctions are in agreement with the structure reported previously.