Polyoxygenated cembrane diterpenoids from the soft coral Sarcophyton ehrenbergi

Cembrane diterpenoids: Chemistry and pharmacological activities

Cembrane diterpenoids (cembranoids), characterized by a 14-membered carbon ring and wide variety of functional groups, found in marine and terrestrial organisms. Many studies have shown that cembrane diterpenoids have cytotoxic and anti-inflammatory activities and are widely used in the development of new drugs. This review covered publications from 2011 to 2022 and classified the cembrane-type diterpenoids into isopropyl (ene) type, γ-lactone or unsaturated five-membered ring, δ-lactone or unsaturated six-membered ring, ε-lactone or unsaturated seven-membered ring, and other cembrane diterpenes. In addition, the biological activity and structure-activity relationship were summarized. This will provide guidance for new cembrane-type diterpenes as lead compounds to explore their potential application for treating cancer and inflammatory diseases.

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

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

Pitfalls in the structural elucidation of small molecules. A critical analysis of a decade of structural misassignments of marine natural products

Covering: July 2010 to August 2021This article summarizes more than 200 cases of misassigned marine natural products reported between July 2010 and August 2021, sorting out errors according to the structural elements. Based on a comparative analysis of the original and the revised structures, major pitfalls still plaguing the structural elucidation of small molecules were identified, emphasizing the role of total synthesis, crystallography, as well as chemical- and biosynthetic logic to complement spectroscopic data. Distinct "trends" in natural product misassignment are evident between compounds of marine and plant origin, with an overall much lower incidence of "impossible" structures within misassigned marine natural products.

Computationally Assisted Structural Elucidation of Cembranoids from the Soft Coral Sarcophyton tortuosum

A persistent study on soft coral Sarcophyton tortuosum resulted in the characterization of two new cembranolides, tortuolides A and B (1 and 2), and a new related diterpene, epi-sarcophytonolide Q. Their structures were determined not only by extensive spectroscopic analysis but also by DFT calculations of ECD and NMR data, the latter of which was combined with statistical analysis methods, e.g., DP4+ and J-DP4 approaches. Anti-inflammatory and cytotoxicity activities were evaluated in this study.

Cembranolides and Related Constituents from the Soft Coral Sarcophyton cinereum

In an attempt to explore the bioactive metabolites of the soft coral Sarcophyton cinereum, three new cembranolides, cinerenolides A–C (1–3), and 16 known compounds were isolated and identified from the EtOAc extract. The structures of the new cembranolides were elucidated on the basis of spectroscopic analysis, and the NOE analysis of cinerenolide A (1) was performed with the assistance of the calculated lowest-energy molecular model. The relative configuration of cinerenolide C (3) was determined by the quantum chemical NMR calculation, followed by applying DP4+ analysis. In addition, the cytotoxic assays disclosed that some compounds exhibited moderate to potent activities in the proliferation of P388, DLD-1, HuCCT-1, and CCD966SK cell lines.

Cembranoids from the Vietnamese soft coral Sarcophyton ehrenbergi

Using various chromatographic separations, two new cembranoids, ehrenbergols F and G (1 and 2), along with three known analogs ehrenbergol D (3), (+)-isosarcophine (4) and sinulariol Z₂ (5) were isolated from the soft coral Sarcophyton ehrenbergi. The structural elucidation was done by extensive analysis of the 1 D and 2 D NMR, HR-ESI-QTOF-MS as well as CD experiments. In addition, compounds 1 (IC₅₀ of 38.38 ± 2.89 µM), 3 (IC₅₀ of 37.14 ± 3.22 µM) and 4 (IC₅₀ of 45.01 ± 2.49 µM) revealed moderate inhibitory activity on LPS-induced NO production in RAW264.7 cells, whereas 2 (IC₅₀ of 73.32 ± 1.95 µM) and 5 (IC₅₀ of 64.48 ± 4.93 µM) exhibited weak effect.

New Hydroquinone Monoterpenoid and Cembranoid-Related Metabolites from the Soft Coral Sarcophyton tenuispiculatum

Chemical investigation of the marine soft coral Sarcophyton tenuispiculatum resulted in the isolation of a 1,4-dihydrobenzoquinone, sarcotenuhydroquinone (1), three new cembranoids, sarcotenusenes A‒C (2‒4), and ten previously reported metabolites 5–14. The chemical structures of all isolated metabolites were determined by detailed spectroscopic analyses. In biological assays, anti-inflammatory, cytotoxic, and peroxisome proliferator-activated receptor γ (PPAR-γ) transcription factor assays of all compounds were performed. None of the isolated compounds were found to exhibit activity in the PPAR-γ transcription factor assay. The anti-inflammatory assays showed that (+)-7α,8β-dihydroxydeepoxysarcophine (13) inhibited the production of IL-1β to 56 ± 1% at a concentration of 30 µM in lipopolysaccharide (LPS)-stimulated J774A.1 macrophage cells. In addition, 1 and 2 were found to exhibit cytotoxicity towards a panel of cancer cell lines.

Chemical Diversity in Species Belonging to Soft Coral Genus Sacrophyton and Its Impact on Biological Activity: A Review

One of the most widely distributed soft coral species, found especially in shallow waters of the Indo-Pacific region, Red Sea, Mediterranean Sea, and also the Arctic, is genus Sacrophyton. The total number of species belonging to it was estimated to be 40. Sarcophyton species are considered to be a reservoir of bioactive natural metabolites. Secondary metabolites isolated from members belonging to this genus show great chemical diversity. They are rich in terpenoids, in particular, cembranoids diterpenes, tetratepenoids, triterpenoids, and ceramide, in addition to steroids, sesquiterpenes, and fatty acids. They showed a broad range of potent biological activities, such as antitumor, neuroprotective, antimicrobial, antiviral, antidiabetic, antifouling, and anti-inflammatory activity. This review presents all isolated secondary metabolites from species of genera Sacrophyton, as well as their reported biological activities covering a period of about two decades (1998-2019). It deals with 481 metabolites, including 323 diterpenes, 39 biscembranoids, 11 sesquiterpenes, 53 polyoxygenated sterols, and 55 miscellaneous and their pharmacological activities.

Coral and Coral-Associated Microorganisms: A Prolific Source of Potential Bioactive Natural Products

Marine invertebrates and their associated microorganisms are rich sources of bioactive compounds. Among them, coral and its associated microorganisms are promising providers of marine bioactive compounds. The present review provides an overview of bioactive compounds that are produced by corals and coral-associated microorganisms, covering the literature from 2010 to March 2019. Accordingly, 245 natural products that possess a wide range of potent bioactivities, such as anti-inflammatory, cytotoxic, antimicrobial, antivirus, and antifouling activities, among others, are described in this review.

Coral and Coral-Associated Microorganisms: A Prolific Source of Potential Bioactive Natural Products

Marine invertebrates and their associated microorganisms are rich sources of bioactive compounds. Among them, coral and its associated microorganisms are promising providers of marine bioactive compounds. The present review provides an overview of bioactive compounds that are produced by corals and coral-associated microorganisms, covering the literature from 2010 to March 2019. Accordingly, 245 natural products that possess a wide range of potent bioactivities, such as anti-inflammatory, cytotoxic, antimicrobial, antivirus, and antifouling activities, among others, are described in this review.

Marine natural products

Covering: 2015. Previous review: Nat. Prod. Rep., 2016, 33, 382-431This review covers the literature published in 2015 for marine natural products (MNPs), with 1220 citations (792 for the period January to December 2015) 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 (1340 in 429 papers for 2015), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.