Further polyoxygenated cembranoids from South China Sea soft coral Sarcophyton ehrenbergi

Antibacterial Methyl Ester Cembranoids from the Soft Coral Sarcophyton ehrenbergi and Their Structural Elucidation

Six previously undescribed methyl ester cembranoids, namely sarcoehrenolides L-Q (1-6), along with three known related ones (7-9), were isolated from the soft coral Sarcophyton ehrenbergi collected off Weizhou Island in the South China Sea. Their structures and absolute configurations were unambiguously established in the light of extensive spectroscopic data analysis, X-ray diffraction analysis, chemical conversion, and TDDFT-ECD calculations. All isolated compounds were evaluated via in vitro bioassays to investigate their antibacterial activity against eighteen human and fish pathogens. Compounds 2, 8, and 9 exhibited moderate antibacterial activity against Streptococcus parauberis with MIC values of 38.8, 37.4 and 31.6 μg/mL, respectively.

Cembranoid Diterpenes from South China Sea Soft Coral Sarcophyton crassocaule

Cembranoid diterpenes are characteristic compounds of soft corals with diverse structures and significant activities, making them an important source of drug lead compounds. In this paper, five new cembranoid diterpenes, meijicrassolins A-E (1-5), were isolated from the soft coral Sarcophyton crassocaule, along with five previously reported compounds (6-10). The structures and absolute configuration for new compounds 1-5 were assigned by extensive spectroscopic analysis, single-crystal X-ray crystallography, quantum mechanical nuclear magnetic resonance (QM-NMR), and time-dependent density functional theory/electronic circular dichroism (TDDFT/ECD) calculations. Compounds 3, 4, and 9 showed moderate inhibition of nitric oxide generation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Overall, our research results have enriched the library of secondary metabolites from soft corals, providing more molecular entities for subsequent research and development of related compounds.

The application and sustainable development of coral in traditional medicine and its chemical composition, pharmacology, toxicology, and clinical research

This review discusses the variety, chemical composition, pharmacological effects, toxicology, and clinical research of corals used in traditional medicine in the past two decades. At present, several types of medicinal coral resources are identified, which are used in 56 formulas such as traditional Chinese medicine, Tibetan medicine, Mongolian medicine, and Uyghur medicine. A total of 34 families and 99 genera of corals are involved in medical research, with the Alcyoniidae family and Sarcophyton genus being the main research objects. Based on the structural types of compounds and the families and genera of corals, this review summarizes the compounds primarily reported during the period, including terpenoids, steroids, nitrogen-containing compounds, and other terpenoids dominated by sesquiterpene and diterpenes. The biological activities of coral include cytotoxicity (antitumor and anticancer), anti-inflammatory, analgesic, antibacterial, antiviral, immunosuppressive, antioxidant, and neurological properties, and a detailed summary of the mechanisms underlying these activities or related targets is provided. Coral toxicity mostly occurs in the marine ornamental soft coral Zoanthidae family, with palytoxin as the main toxic compound. In addition, nonpeptide neurotoxins are extracted from aquatic corals. The compatibility of coral-related preparations did not show significant acute toxicity, but if used for a long time, it will still cause toxicity to the liver, kidneys, lungs, and other internal organs in a dose-dependent manner. In clinical applications, individual application of coral is often used as a substitute for orthopedic materials to treat diseases such as bone defects and bone hyperplasia. Second, coral is primarily available in the form of compound preparations, such as Ershiwuwei Shanhu pills and Shanhu Qishiwei pills, which are widely used in the treatment of neurological diseases such as migraine, primary headache, epilepsy, cerebral infarction, hypertension, and other cardiovascular and cerebrovascular diseases. It is undeniable that the effectiveness of coral research has exacerbated the endangered status of corals. Therefore, there should be no distinction between the advantages and disadvantages of listed endangered species, and it is imperative to completely prohibit their use and provide equal protection to help them recover to their normal numbers. This article can provide some reference for research on coral chemical composition, biological activity, chemical ecology, and the discovery of marine drug lead compounds. At the same time, it calls for people to protect endangered corals from the perspectives of prohibition, substitution, and synthesis.

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.

Guided Isolation of An Uncommon Cembranoid Orthoester, Sarcotortin A, and Three Skeletal Diverse Terpenoids from the Hainan Soft Coral Sarcophyton tortuosum Based on Molecular Networking Strategy

Applying the emerging molecular networking strategy, an uncommon cembranoid orthoester, sarcotortin A (1), featuring a 3/14/8/5-fused scaffold, an unusual eunicellane-type diterpenoid, sarcotorolide A (2), and two new biscembranoids, ximaolides M and N (7 and 8), along with nine known terpenoids 3-6 and 9-13 were isolated from the Hainan soft coral Sarcophyton tortuosum. The structure and absolute configuration of all new compounds were established by a combination of spectroscopic data, X-ray diffraction analysis, and/or quantum chemical computational approaches. The plausible biogenetic relationship among these skeletally different terpenoids was proposed and discussed. In in vitro bioassay, new compound 7 exhibited a remarkable inhibitory activity against protein tyrosine phosphatases 1B (PTP1B) with the IC₅₀ value of 8.06 μM. In addition, compounds 4 and 10 displayed significant inhibitory effects on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 macrophages cells with the IC₅₀ values of 19.13 and 16.45 μM, respectively. Compound 9 showed interesting cytotoxicity against H1975, MDA-MB231, A549, and H1299 cancer cell lines with IC₅₀ values of 31.59, 34.96, 43.87, and 27.93 μM, respectively.

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.

Marine Natural Products from the Beibu Gulf: Sources, Chemistry, and Bioactivities

Marine natural products (MNPs) play an important role in the discovery and development of new drugs. The Beibu Gulf of South China Sea harbors four representative marine ecosystems, including coral reefs, mangroves, seaweed beds, and coastal wetlands, which are rich in underexplored marine biological resources that produce a plethora of diversified MNPs. In our ongoing efforts to discover novel and biologically active MNPs from the Beibu Gulf, we provide a systematic overview of the sources, chemical structures, and bioactive properties of a total of 477 new MNPs derived from the Beibu Gulf, citing 133 references and covering the literature from the first report in November 2003 up to September 2022. These reviewed MNPs were structurally classified into polyketides (43%), terpenoids (40%), nitrogen-containing compounds (12%), and glucosides (5%), which mainly originated from microorganisms (52%) and macroorganisms (48%). Notably, they were predominantly found with cytotoxic, antibacterial, and anti-inflammatory activities. This review will shed light on these untapped Beibu Gulf-derived MNPs as promising lead compounds for the development of new drugs.

Bistrochelides H-L: Biscembranoids from the south China sea soft coral Sarcophyton serenei

Five undescribed biscembranoids, bistrochelides H-L, along with four known biscembranoids, glaucumolides A-B and bistrochelides A-B, were isolated from the soft coral Sarcophyton serenei collected off the Xisha Island in the South China Sea. The structures of these compounds were elucidated by HRESIMS (high-resolution electrospray ionization mass spectroscopy) spectrometry, NMR (nuclear magnetic resonance) spectroscopy, X-ray diffraction analysis, electronic circular dichroism (ECD), and the comparison of their spectroscopic data with those reported in the literature. In bioassay, some compounds showed a strong inhibitory effect on osteoclast precursor cells at the concentration of 10 μM. Additionally, all compounds exhibited weakly antimicrobial activity against Vibrio harveyi.

Chemistry and bioactivity of secondary metabolites from South China Sea marine fauna and flora: recent research advances and perspective

Marine organisms often produce a variety of metabolites with unique structures and diverse biological activities that enable them to survive and struggle in the extremely challenging environment. During the last two decades, our group devoted great effort to the discovery of pharmaceutically interesting lead compounds from South China Sea marine plants and invertebrates. We discovered numerous marine secondary metabolites spanning a wide range of structural classes, various biosynthetic origins and various aspects of biological activities. In a series of reviews, we have summarized the bioactive natural products isolated from Chinese marine flora and fauna found during 2000-2012. The present review provides an updated summary covering our latest research progress and development in the last decade (2012-2022) highlighting the discovery of over 400 novel marine secondary metabolites with promising bioactivities from South China Sea marine organisms.

Marine natural products

Covering: 2020This review covers the literature published in 2020 for marine natural products (MNPs), with 757 citations (747 for the period January to December 2020) 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 (1407 in 420 papers for 2020), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. A meta analysis of bioactivity data relating to new MNPs reported over the last five years is also presented.

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.

Polyhydroxylated steroids from the Vietnamese soft coral Sarcophyton ehrenbergi

Fourteen polyhydroxylated steroids including six new compounds, ehrensteroids A - F (1-6), were isolated from the Vietnamese soft coral Sarcophyton ehrenbergi after applying various chromatographic separations. The structure elucidation was done by detailed analysis of 1D, 2D NMR and HR QTOF mass spectra. In addition, significant cytotoxicity (IC₅₀ values ranging from 8.45 ± 0.56 to 38.27 ± 2.39 μM) against all five tested cancer cell lines as LU-1 (lung cancer), HepG2 (hepatoma cancer), MCF-7 (breast cancer), HL-60 (acute leukemia), and SW480 (colon adenocarcinoma) was observed for compounds 1, 2, 6-10, and 12-14, whereas this activity on LU-1 (IC₅₀ = 21.91 ± 2.72 μM) and HepG2 (IC₅₀ = 20.32 ± 0.03 μM) cell lines was also observed for 4.

Cembranoids of Soft Corals: Recent Updates and Their Biological Activities

Soft corals are well-known as excellent sources of marine-derived natural products. Among them, members of the genera Sarcophyton, Sinularia, and Lobophytum are especially attractive targets for marine natural product research. In this review, we reported the marine-derived natural products called cembranoids isolated from soft corals, including the genera Sarcophyton, Sinularia, and Lobophytum. Here, we reviewed 72 reports published between 2016 and 2020, comprising 360 compounds, of which 260 are new compounds and 100 are previously known compounds with newly recognized activities. The novelty of the organic molecules and their relevant biological activities, delivered by the year of publication, are presented. Among the genera presented in this report, Sarcophyton spp. produce the most cembranoid diterpenes; thus, they are considered as the most important soft corals for marine natural product research. Cembranoids display diverse biological activities, including anti-cancer, anti-bacterial, and anti-inflammatory. As cembranoids have been credited with a broad range of biological activities, they present a huge potential for the development of various drugs with potential health and ecological benefits.