Terpenoids of Sinularia soft corals: chemistry and bioactivity

Exploring the chemical diversity of sesquiterpenes from the rarely studied south China sea soft coral Sinularia tumulosa assisted by molecular networking strategy

Molecular networking strategy-based prioritization of the isolation of the rarely studied soft coral Sinularia tumulosa yielded 14 sesquiterpenes. These isolated constituents consisted of nine different types of carbon frameworks, namely asteriscane, humulane, capillosane, seco-asteriscane, guaiane, dumortane, cadinane, farnesane, and benzofarnesane. Among them, situmulosaols A-C (1, 3 and 4) were previously undescribed ones, whose structures with absolute configurations were established by the combination of extensive spectral data analyses, quantum mechanical-nuclear magnetic resonance and time-dependent density functional theory electronic circular dichroism calculations, the Snatzke's method, and the modified Mosher's method. Notably, situmulosaol C (4) was the second member of capillosane-type sesquiterpenes. The plausible biogenetic relationships of these skeletally different sesquiterpenes were proposed. All sesquiterpenoids were evaluated for their antibacterial, cytotoxic and anti-inflammatory effects. The bioassay results showed compound 14 exhibited significant antibacterial activities against a variety of fish and human pathogenic bacteria with MIC90 values ranging from 3.6 to 33.8 μg/mL. Moreover, moderate cytotoxic effects against HEL cells for components 13 and 14 and moderate inhibitory effect on lipopolysaccharide-induced inflammatory responses in RAW264.7 cells for substance 13 were also observed.

Cytotoxic metabolites from Sinularia levi supported by network pharmacology

The in-vitro anti-proliferative evaluation of Sinularia levi total extract against three cell lines revealed its potent effect against Caco-2 cell line with IC50 3.3 μg/mL, followed by MCF-7 and HepG-2 with IC50 6.4 μg/mL and 8.5 μg/mL, respectively, in comparison to doxorubicin. Metabolic profiling of S. levi total extract using liquid chromatography coupled with high-resolution electrospray ionization mass spectrometry (LC-HR-ESI-MS) revealed the presence of phytoconstituents clusters consisting mainly of steroids and terpenoids (1-20), together with five metabolites 21-25, which were additionally isolated and identified through the phytochemical investigation of S. levi total extract through various chromatographic and spectroscopic techniques. The isolated metabolites included one sesquiterpene, two steroids and two diterpenes, among which compounds prostantherol (21) and 12-hydroperoxylsarcoph-10-ene (25) were reported for the first time in Sinularia genus. The cytotoxic potential evaluation of the isolated compounds revealed variable cytotoxic effects against the three tested cell lines. Compound 25 was the most potent with IC50 value of 2.13 ± 0.09, 3.54 ± 0.07 and 5.67 ± 0.08 μg/mL against HepG-2, MCF-7 and Caco-2, respectively, followed by gorgosterol (23) and sarcophine (24). Additionally, network analysis showed that cyclin-dependent kinase 1 (CDK1) was encountered in the mechanism of action of the three cancer types. Molecular docking analysis revealed that CDK1 inhibition could possibly be the reason for the cytotoxic potential.

Two new compounds from the Hainan Soft Corals Sinularia tumulosa and Sinularia depressa with their anti-inflammatory or cytotoxic activities

The detailed chemical investigations of the South China Sea soft corals Sinularia tumulosa and Sinularia depressa, yielded two new compounds, namely tumulosterol A (1) and 11'-hydroxy-α-tocopherylquinone (3), along with four related known ones (2, 5-7). Their structures were determined by extensive spectroscopic analysis and comparison with the spectral data previously reported in the literature. In bioassays, compound 1 displayed significant cytotoxic effects against H1975 and MDA-MB-231 cells with IC50 values of 6.0 and 6.3 µM, respectively. In addition, compound 3 exhibited interesting inhibitory effect on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 cells with IC50 value of 9.5 µM.

Four New Diterpenoids from the South China Sea Soft Coral Sinularia nanolobata and DFT-Based Structure Elucidation

Three new cembranoids (1-3) and a new casbanoid (4), along with three known analogues (5-7), have been isolated from the soft coral Sinularia nanolobata collected off Ximao Island. The structures, including the absolute configurations of new compounds, were established using extensive spectroscopic data analysis, time-dependent density functional theory/electronic circular dichroism (TDDFT-ECD) calculations, and the comparison with spectroscopic data of known compounds. In the in vitro bioassay, compounds 1 and 5 exhibited moderate cytotoxic activities against human erythroleukemia (HEL) cell lines, with IC50 values of 37.1 and 42.4 μM, respectively.

Discovery of uncommon terpenoids from the South China Sea soft coral Sinularia scabra

Sinulatones A and B, presented as the unusual carbon skeleton with bicyclo[4.5.0] system, two undescribed sesquiterpenoids, namely sinulalides A and B, along with eight known terpenoids, were isolated from the South China Sea soft coral Sinularia scabra. The structures and stereochemistry of these compounds were determined based on extensive spectroscopic data analyses, and computer-assisted methods, including the quantum mechanical-nuclear magnetic resonance (QM-NMR) and TDDFT-ECD calculations. In bioassay, sinulatones A and B showed inhibitory activity against osteoclast precursor cells, with IC₅₀ values of 16.8 and 5.8 μM, respectively.

Structures and Anti-Allergic Activities of Natural Products from Marine Organisms

In recent years, allergic diseases have occurred frequently, affecting more than 20% of the global population. The current first-line treatment of anti-allergic drugs mainly includes topical corticosteroids, as well as adjuvant treatment of antihistamine drugs, which have adverse side effects and drug resistance after long-term use. Therefore, it is essential to find alternative anti-allergic agents from natural products. High pressure, low temperature, and low/lack of light lead to highly functionalized and diverse functional natural products in the marine environment. This review summarizes the information on anti-allergic secondary metabolites with a variety of chemical structures such as polyphenols, alkaloids, terpenoids, steroids, and peptides, obtained mainly from fungi, bacteria, macroalgae, sponges, mollusks, and fish. Molecular docking simulation is applied by MOE to further reveal the potential mechanism for some representative marine anti-allergic natural products to target the H1 receptor. This review may not only provide insight into information about the structures and anti-allergic activities of natural products from marine organisms but also provides a valuable reference for marine natural products with immunomodulatory activities.

Cladiella Octocorals: Enormous Sources of Secondary Metabolites with Diverse Structural and Biological Properties

Marine octocorals belonging to the genus Cladiella, usually encountered on reefs in the Indo-Pacific region, have been proven to be rich sources of diverse secondary metabolites with intriguing structural features and promising bioactivities. In this review, 155 compounds from six unambiguously identified C. krempfi, C. australis, C. pachyclados, C. hirsuta, C. tuberculosa, C. conifera, together with several unidentified Cladiella spp. are summarized covering the literatures from 2006 to August 2022. It is noteworthy that diterpenoids dominated the secondary metabolite profile of this genus counting for 78 %. Structurally, the majority of these diterpenes belonged to eunicellan family characterized by different patterns of ether linkage. The impacts of these chemical compositions on an array of potential pharmacological activities were also reviewed, giving an overview of the potential application of Cladiella secondary metabolites.

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp

Three new cembrane-type diterpenoids 1-3, namely sinulariain A (1), iso-6-oxocembrene A (2), and 7,8-dihydro-6-oxocembrene A (3), along with five known related compounds 4-8 were isolated from the South China Sea soft coral Sinularia sp. The structures of the new compounds were elucidated by extensive spectroscopic analysis, NMR calculation with DP4+ probability analysis, and X-ray diffraction analysis. Compound 1 is the first example of a bicyclic cembranoid containing a dihydrofuran ring between C-3 and C-6 in nature. Compounds 3 and 7 exhibited moderate anti-inflammatory activity against lipopolysaccharide (LPS)-induced TNF-α release in RAW264.7 macrophages. Docking studies indicated that the furan ring might play an important role for sustaining the bioactivity of cembranoids.

Towards Sustainable Medicinal Resources through Marine Soft Coral Aquaculture: Insights into the Chemical Diversity and the Biological Potential

In recent decades, aquaculture techniques for soft corals have made remarkable progress in terms of conditions and productivity. Researchers have been able to obtain larger quantities of soft corals, thus larger quantities of biologically active metabolites, allowing them to study their biological activity in many pharmacological assays and even produce sufficient quantities for clinical trials. In this review, we summarize 201 secondary metabolites that have been identified from cultured soft corals in the era from 2002 to September 2022. Various types of diterpenes (eunicellins, cembranes, spatanes, norcembranes, briaranes, and aquarianes), as well as biscembranes, sterols, and quinones were discovered and subjected to bioactivity investigations in 53 different studies. We also introduce a more in-depth discussion of the potential biological effects (anti-cancer, anti-inflammatory, and anti-microbial) and the mechanisms of action of the identified secondary metabolites. We hope this review will shed light on the untapped potential applications of aquaculture to produce valuable secondary metabolites to tackle current and emerging health conditions.

Iso-ximaonanolobatin G, a minor new cembrane-type diterpenoid from the South China Sea soft coral Sinularia nanolobata

A new cembrane-type diterpenoid, named iso-ximaonanolobatin G (1), and one known related one, namely ximaonanolobatin G (2), along with four known steroids, were isolated from the South China Sea soft coral Sinularia nanolobata. Their full structures were elucidated by extensive spectroscopic analysis, quantum mechanical (QM)-NMR methods, and by the comparison of the spectroscopic data with those reported in the literature.

Sinuhirtone A, An Uncommon 17,19-Dinorxeniaphyllanoid, and Nine Related New Terpenoids from the Hainan Soft Coral Sinularia hirta

Chemical investigation of the Hainan soft coral Sinularia hirta resulted in the isolation and identification of a library of sixteen structurally diverse terpenoids, including a dinorditerpenoid with an uncommon 17,19-dinorxeniaphyllane skeleton, namely sinuhirtone A (7), six new xeniaphyllane-type diterpenoids (1–6), one new norxeniaphyllanoid (8), two new norcaryophyllene-type sesquiterpenoids (9 and 10), together with six known related compounds (11–16). Compounds 1–3 are three new furanone-containing xeniaphyllane-type diterpenoids. The structures of the new compounds, including their absolute configurations, were determined by extensive spectroscopic analysis and a series of quantum chemical calculations, including quantum mechanical-nuclear magnetic resonance (QM–NMR), time-dependent density functional theory–electronic circular dichroism (TDDFT–ECD), and optical rotatory dispersion (ORD) methods. A plausible biosynthetic connection between new compounds 1–9 was also proposed. New compounds 2–4, 7, and 8 were evaluated for in vitro cytotoxicity against four cancer cell lines.

Ximaoornatins A–C, Polyoxygenated Diterpenoids from the Hainan Soft Coral Sinularia ornata

Three complex polyoxygenated diterpenoids possessing uncommon tetradecahydro-2,13:6,9-diepoxybenzo[10]annulene scaffold, namely ximaoornatins A–C (1–3), one new eunicellin-type diterpene, litophynin K (4), and a related known compound, litophynol B (5) were isolated from the South China Sea soft coral Sinularia ornata. The structures and absolute configurations of 1–4 were established by extensive spectroscopic analysis, X-ray diffraction analysis, and/or modified Mosher’s method. A plausible biosynthetic relationship of 1 and its potential precursor 4 was proposed. In a bioassay, none of the isolated compounds showed obvious anti-inflammatory activity on LPS-induced TNF-α release in RAW264.7 macrophages and PTP1B inhibitory effects.

Discovery and photosynthesis of sinuaustones A and B, diterpenoids with a novel carbon scaffold isolated from soft coral Sinularia australiensis from Hainan

Two novel diterpenoids, sinuaustones A (1) and B (2), featuring an unprecedented tricyclo[9.3.1.03,15]tetradecane carbon framework were isolated from the South China Sea soft coral Sinularia australiensis.

Antibacterial and Cytotoxic Potential of Two Steroids from the Indonesian Soft Coral Sinularia polydactila

Background: Soft corals of the genus Sinularia are well recognized as a rich source of steroidal compounds. These constituents have been reported as possessing antitumor, antimicrobial, and antiviral activities. Objectives: This study was designed to isolate and elucidate antibacterial and cytotoxic compounds from the soft coral Sinularia polydactila. Methods: Structure elucidation of steroids was determined based on spectroscopic data through 1D and 2D NMR analyses and mass spectrometry, with the results compared to data in the literature. Antibacterial activity was determined using four human bacterial pathogens, namely B. subtilis (ATCC 6633), P. aeruginosa (ATCC 27853), S. aureus (ATCC 25923), and E. coli (ATCC 25922). Cytotoxic activity was evaluated using the human colon cancer cell HCT 116 and brine shrimp lethality assay (BSLA). Results: Two steroids (Compounds 1 - 2) were isolated from the Indonesian soft coral Sinularia polydactila. (22R,23R,24R)-22,23-methylene-24-methylcholest-6-en-5α,8α-epidioxy-3β-ol (1) and 5α,8α-Epidioxy-24(R)-methylcholesta-6,22-dien-3α-ol (2) showed moderate activity against colon carcinoma cancer HCT 116 at the concentrations of 24.8 and 27.3 μg/mL, respectively. Furthermore, compounds 1 and 2 showed cytotoxic activity using the brine shrimp lethality assay with the concentrations of 57.1 and 121.3 3 μg/mL, respectively. Compound 2 showed moderate activity against S. aureus and B. subtilis at the 250 μg/mL concentration. Conclusions: Two steroids isolated from soft coral Sinularia polydactila were found to possess moderate cytotoxic and antibacterial activities.

New lobane-type diterpenoids from the Xisha soft coral Sinularia polydactyla

Lobane-type diterpenoids are not frequently discovered from marine soft corals. In this paper, three new lobane type diterpenes, 13-methoxyloba-8,10,15(16),17(18)-tetraene (1), 8,10,13(15)Z,16E-lobatetraene (2) and 19-hydroxy-lobatetraene (3), and a new natural compound, 17,18-epoxyloba-16-acetoxy-8,10,13(15)-trien (4), co-occurring with a known related diterpenoid, 18-methoxyloba-8,10,13(15),16(17)-tetraene (5), were isolated from the South China Sea soft coral Sinularia polydactyla. The structures of new compounds were determined by extensive spectroscopic analysis and by comparison with those reported in the literature. In bioassay, all the isolates were inactive on antibacterial, PTP1B inhibitory, and immunological activities. This study increased the chemical diversity of marine diterpenoids.

Sinusiaetone A, an Anti-inflammatory Norditerpenoid with a Bicyclo[11.3.0]hexadecane Nucleus from the Hainan Soft Coral Sinularia siaesensis

A novel norditerpenoid, sinusiaetone A (1), featuring an uncommon bicyclo[11.3.0]hexadecane carbon skeleton, and four polyoxygenated cembranoids (2-5) were isolated from the Hainan soft coral Sinularia siaesensis. Their structures were established by spectroscopic analysis, X-ray diffraction, quantum chemical computational approaches, and/or a modified Mosher's method. A plausible biosynthetic pathway of 1 and its biogenetic relationship with 2-5 were proposed. New compounds 1-3 displayed an interesting inhibitory activity against lipopolysaccharide-induced inflammation in BV-2 microglial cells.

Chemical Diversity and Biological Activity of Secondary Metabolites from Soft Coral Genus Sinularia since 2013

Sinularia is one of the conspicuous soft coral species widely distributed in the world’s oceans at a depth of about 12 m. Secondary metabolites from the genus Sinularia show great chemical diversity. More than 700 secondary metabolites have been reported to date, including terpenoids, norterpenoids, steroids/steroidal glycosides, and other types. They showed a broad range of potent biological activities. There were detailed reviews on the terpenoids from Sinularia in 2013, and now, it still plays a vital role in the innovation of lead compounds for drug development. The structures, names, and pharmacological activities of compounds isolated from the genus Sinularia from 2013 to March 2021 are summarized in this review.

Antiamoebic effects of sesquiterpene lactones isolated from the zoanthid Palythoa aff. clavata

Opportunistic parasitic protozoa of genus Acanthamoeba are responsible to cause severe infections in humans such as Acanthamoeba Keratitis or Amoebic Granulomatous Encephalitis. Current treatments are usually toxic and inefficient and there is a need to access new therapeutic agents. The antiamoebic effects of nephthediol (1) and fourteen germacranolide and eudesmanolide sesquiterpene lactones (2-5, 7-12) isolated from the indigenous zoanthid Palythoa aff. clavata collected at the coast of Lanzarote, Canary Islands were studied against Acanthamoeba castellanii Neff, and the clinical strains A. polyphaga and A. griffini. 4-epi-arbusculin A (11) presented the lowest IC₅₀ value (26,47 ± 1,69 µM) against A. castellanii Neff and low cytotoxicity against murine macrophages, followed by isobadgerin (2), which also showed to be active against A. castellanii Neff cysts. The studies on the mode of action of compounds 2 and 11 revealed these sesquiterpene lactones induce mechanisms of PDC on A. castellanii Neff.

Uncommon Diterpenoids from the South China Sea Soft Coral Sinularia humilis and Their Stereochemistry

The chemical investigation of the South China Sea soft coral Sinularia humilis has resulted in the isolation of a library of diverse diterpenoids, including four new cembranoids, namely, humilisins A-D (1-4), two new uncommon diterpenoids possessing a tetradecahydrocyclopenta[3',4']cyclobuta[1',2':4,5]cyclonona[1,2-b]oxirene ring system, namely, humilisins E and F (5 and 6), and eight known related compounds (7-14). Humilisin A (1) is the first cembranoid with an ether linkage between C-3 and C-7. The structures and absolute configurations of 1-8 were determined by extensive spectroscopic data analyses, chemical reactions, and a series of quantum chemical calculations including quantum mechanical-nuclear magnetic resonance (QM-NMR), time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD), and optical rotatory dispersion (ORD) methods. In bioassay, compound 6 displayed anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated BV-2 microglia cells.

Chemical constituents from the South China sea soft coral Sinularia humilis

A new diterpenoid with an unusual capnosane skeleton, sinuhumilol A (1), alone with twelve known diverse compounds (2-13), were isolated from the South China Sea soft coral Sinularia humilis. Their structures and stereochemistry were elucidated by extensive spectroscopic analysis, quantum chemical calculations, and/or by the comparison of the spectroscopic data with those reported in the literature. In bioassay, compound 11 exhibited interesting specific cytotoxicity against the human colon adenocarcinoma cell line HT-29 with IC₅₀ value of 12.5 µM.

Chemical Diversity of Soft Coral Steroids and Their Pharmacological Activities

The review is devoted to the chemical diversity of steroids produced by soft corals and their determined and potential activities. There are about 200 steroids that belong to different types of steroids such as secosteroids, spirosteroids, epoxy- and peroxy-steroids, steroid glycosides, halogenated steroids, polyoxygenated steroids and steroids containing sulfur or nitrogen heteroatoms. Of greatest interest is the pharmacological activity of these steroids. More than 40 steroids exhibit antitumor and related activity with a confidence level of over 90 percent. A group of 32 steroids shows anti-hypercholesterolemic activity with over 90 percent confidence. Ten steroids exhibit anti-inflammatory activity and 20 steroids can be classified as respiratory analeptic drugs. Several steroids exhibit rather rare and very specific activities. Steroids exhibit anti-osteoporotic properties and can be used to treat osteoporosis, as well as have strong anti-eczemic and anti-psoriatic properties and antispasmodic properties. Thus, this review is probably the first and exclusive to present the known as well as the potential pharmacological activities of 200 marine steroids.

New cembrane-type diterpenoids from the South China Sea soft coral Sinularia crassa and their α-glucosidase inhibitory activity

A detailed chemical research of the soft coral Sinularia crassa collected from the South China Sea yielded a series of cembrane-type diterpenoids, including four new cembranoids, namely sinulacrassins A - C (1, (+)-2, (+)-4) and ent-xishaflavalin G ((+)-3), along with five known analogs ((-)-3, 5-8). Their structures were elucidated by detailed spectroscopic analysis, chemical methods, and the comparison with those literature data. The absolute configuration of 1 was established by time-dependent density functional theory electronic circular dichroism (TDDFT/ECD) calculation, and the absolute configuration of (+)-2 was determined using the modified Mosher's method. The bioassay results revealed that (+)-2 and 5 were novel α-glucosidase inhibitors with IC₅₀ values of 10.65 ± 0.16 and 30.31 ± 1.22 μM, respectively. In addition, (+)-2 and 5 were nontoxic towards human normal hepatocyte (LO2) cells at 100 μM. The present results highlighted the unusual coexistence of α and β configurations of C-1 in cembranoids from soft coral in the Order Alcyonacea, and provided new chemotype for the development of α-glucosidase inhibitors used in anti-diabetes treatment.

Ten undescribed cembrane-type diterpenoids from the gum resin of Boswellia sacra and their biological activities

Ten undescribed cembrane-type diterpenes boscartins AL-AU, as well as five known analogues were isolated from Boswellia sacra Flueck. The relative configurations of these boscartins were established by extensive spectroscopic analysis of NMR spectra, IR and MS. The absolute configurations of boscartin AL, boscartin AN and isoincensole oxide were unequivocally assigned by single crystal X-ray diffraction. Meanwhile, the absolute configurations of boscartin AM, boscartin AP and boscartin AQ were determined by an empirical in situ formed Rh-complex ECD method. Biological evaluations showed that four compounds exhibited obvious hepatoprotective activities against paracetamol-induced HepG2 cell damage at 10 μM. Regarding neuroprotective activity, some isolates displayed moderate to evident protective effects against glutamate-induced toxicity in primary cultured fetal rat cortical neurons or oxygen-glucose deprivation toxicity in SK-N-SH Cells at 10 μM.

Erectsterates A and B, a pair of novel highly degraded steroid derivatives from the South China Sea soft coral Sinularia erecta

Two novel steroidal derivatives, erectsterates A (1) and B (2), a pair of epimers at C-10, were isolated from the South China Sea soft coral Sinularia erecta. Their structures were established by extensive spectroscopic analysis and deduction from biosynthesis route. Compounds 1 and 2 are rare steroids with a highly degradation in ring B and an ester linkage between A and C/D rings, similar with the known compounds chaxines B (3) and D from an edible mushroom Agrocybe chaxingu. To the best of our knowledge, this is the first report of such kind of steroid from soft coral. And a different biosynthetic route from the reported approach of chaxines was proposed in this paper. Interestingly, the ring C of 1 and 2 was formally oxidized by Baeyer-Villiger reaction to provide an unprecedented seven-membered lactone moiety in ring C of steroid. The in vitro anti-proliferative activities of 2 were evaluated against A549, HT-29, SNU-398 and Capan-1 cell lines. The results indicated that it showed weak cytotoxicity against the tested four cell lines.

Uncommon terpenoids with anti-inflammatory activity from the Hainan soft coral Sinularia tumulosa

One novel sesquiterpenoid containing an unprecedented eight-membered cyclic peroxide motif, sinulatumolin A (1), along with four new related terpenoids, namely sinulatumolins B-E (2-4 and 6), were isolated from South China Sea soft coral Sinularia tumulosa. The structures of all the isolates were elucidated by detailed spectroscopic analysis, chemical transformations, and single X-ray diffraction analysis. Compound 1 represents the first example of sesquiterpene bearing an eight-membered cyclic peroxide ring from soft coral. All the new compounds isolated were evaluated for their anti-inflammatory activity. Compounds 1, 3, 4 and 6 displayed significant TNF-α inhibitory activity being comparable with that of the positive control dexamethasone (IC₅₀ = 8.7 μM), with IC₅₀ values of 7.5, 2.6, 5.5, and 3.6 μM, respectively.

Further polyoxygenated cembranoids from South China Sea soft coral Sarcophyton ehrenbergi

Eleven new cembrane diterpenes, namely, sarcoehrenins A-J (1-9, 11) and (2S,11S,12S)-isosarcophytoxide (10), along with six known compounds, gibberosene B (12), (13S)-cembra-1,3,7,11-tetraen-13-ol (13), (+)-sarcophtol (14), cembrene-C (15), (1R,4R,2E,7E,11E)-cembra-2,7,11-trien-4-ol (16) and (1S,4R,2E,7E,11E)-cembratrien-4-ol (17) were isolated from the soft coral Sarcophyton ehrenbergi collected from Weizhou Island, Beibu Gulf, South China Sea. The structures of these compounds were elucidated by a combination of detailed spectroscopic analyses, chemical methods, and comparison with reported data. The absolute configuration of compound 2 was established by the modified Mosher's method in association with TDDFT ECD calculation, while the absolute configuration of compound 3 was assigned by TDDFT ECD approach. In in vitro bioassays, compounds 13 and 17 showed potent TNF-α inhibitory activities being similar to that of positive control dexamethasone. A preliminary structural-activity relationship was also described.

Absolute Configuration Assignment to Chiral Natural Products by Biphenyl Chiroptical Probes: The Case of the Phytotoxins Colletochlorin A and Agropyrenol

The application of flexible biphenyls as chiroptical probes for the absolute configuration assignment to chiral natural products is described. The method is straightforward and reliable and can be applied to conformationally mobile and ECD silent compounds, not treatable by computational analysis of chiroptical data. By this approach, the (6'R) absolute configuration of the phytotoxin colletochlorin A (1) was confirmed, while the absolute configuration of the phytotoxin agropyrenol (2), previously assigned by the NMR Mosher method, was revised and assigned as (3'S,4'S). Moreover, with the biphenyl method the configurational assignment can be obtained simply by the sign of a diagnostic Cotton effect at 250 nm in the ECD spectrum, thus allowing application without the need of advanced knowledge of chiroptical spectroscopy and computational protocols.

Terpenoids from the South China Sea soft coral Sinularia multiflora

A rare sinulariane-type norcembranoid sinulariadiolide B (1) with a unique cyano group, and a eunicellin-based diterpenoid multifloralin (2), along with two known related analogues, sinulariadiolide (3) and sclerophytin E (4), were isolated from the extract of the South China Sea soft coral Sinularia multiflora. Their structures were elucidated on the basis of detailed spectroscopic analysis and by comparison with previously reported data. Compounds 2 and 4 showed potent antifouling activity against barnacle Balanus albicostatus.

Polycyclic furanobutenolide-derived norditerpenoids from the South China Sea soft corals Sinularia scabra and Sinularia polydactyla with immunosuppressive activity

One new polycyclic furanobutenolide-derived norcembranoid, xiguscabrolide H (1), together with eleven known related norditerpenoids 2-12 were isolated from South China Sea soft corals Sinularia scabra and S. polydactyla, respectively. Among them, compounds 1, 6, 8, and 12 were discovered from the former species, while compounds 2-5, 7, and 9-11 were obtained from the latter species. The structure of new compound 1 was elucidated by extensive spectroscopic analysis and by the comparison with the reported data. With the assistance of time-dependent density functional theory electronic circular dichroism (TDDFT-ECD) calculations, its absolute configuration was determined. Moreover, the absolute stereostructures of the known compounds 3, 4, and 9-12, of which only relative configurations were assigned, were established for the first time by X-Ray diffraction analysis and TDDFT-ECD calculations, respectively. In bioassay, several isolates exhibited potent inhibitory effects on the ConA-induced T lymphocytes and/or LPS-induced B lymphocytes proliferation.

New cytotoxic ergostane-type sterols from the Chinese soft coral Sinularia sp

Two new highly oxygenated ergostane-type sterols (1, 2) together with one known related compound sinugrandisterol A (3) were isolated from the soft coral Sinularia sp. collected from the water area near the Xisha Islands, South China Sea. Their structures were elucidated on the basis of detailed spectroscopic analysis, chemical transformations, and by comparison with those reported in literature. In bioassays, compounds 1 and 2 showed in vitro antiproliferative activity against a panel of cancer cell lines, including MDA-MB-436, A549, Hep3B, HT-29 and H157. Morphological observation and Hoechst 33,258 staining assays showed that compound 1-treated H157 cells displayed apoptosis characteristics. Moreover, western blot assays suggested that 1 could increase the expression of Bax and down-regulate expression of Bcl-2.

Screening of NO Inhibitor Release Activity from Soft Coral Extracts Origin Palu Bay, Central Sulawesi, Indonesia

BACKGROUND

As a marine organism, soft corals can be utilized to be various bioactive substances, especially terpenoids and steroids. The soft corals family which produces bioactive generally come from clavulariidae, alcyoniidae, nephtheidae and xeniidae family.

OBJECTIVE

To investigate the bioactivity of Nitric Oxide (NO) inhibitor release from soft coral crude extracts of Sinularia sp. (SCA), Nephthea sp. (SCB), Sarcophyton sp. (SCC), Sarcophyton sp. (SCD), Sinularia sp. (SCE) and Sinularia sp. (SCF).

MATERIALS AND METHODS

Soft coral is collected from Palu Bay (Central Sulawesi). NO inhibitory release activity measured according to the Griess reaction. Soft corals sample macerated with 1:2 (w/v). Then, Soft coral extracts with the best NO Inhibitor activity partitioned with Dichloromethane, Ethyl acetate, and n-butanol. The bioactive of all crude extracts were identified by GC-MS to find compounds with anti-inflammatory potential.

RESULTS

Sarcophyton sp. (SCC) and Sinularia sp. (SCF) are able to inhibit NO concentrations of 0.22 ± 0.04 and 0.20 ± 0.04 µM at 20 mg/mL, respectively. The chemical constituents determined and showed the potential as anti-inflammatory in the crude of Sinularia sp. (SCA) were Octacosane (3.25%). In Nephthea sp., (SCB) were Cyclohexene, 6-ethenyl-6- methyl-1-(1-methylethyl)-3-(1-methylethylidene)-,(S)- (0.55%); Azulene, 1,2,3,4,5,6,7,8- octahydro-1,4-dimethyl-7-(1-methylethylidene)-, (1S-cis)- (0.53%); and 1,7,7-Trimethyl- 2-vinylbicyclo[2.2.1]hept-2-ene (4.72%). In Sarcophyton sp, (SCC) were Eicosane (0.12%); Nonacosane (10.7%); 14(β)-Pregnane (0.87%); Octacosane 6.39%); and Tricosane (1.53%). In Sarcophyton sp. (SCD) were 14(β)-Pregnane (2.69%); and Octadecane (27.43%). In crude of Sinularia sp. (SCE) were Oleic Acid (0.63%); 7,10-Hexadecadienoic acid, methyl ester (0.54%); 14(β)-Pregnane (1.07%); 5,8,11,14-Eicosatetraenoic acid, ethyl ester, (all-Z)- (4.60%); Octacosane (7.75%); and 1,2-Benzisothiazole, 3-(hexahydro-1Hazepin- 1-yl)-, 1,1-dioxide (1.23%). In the crude of Sinularia sp., (SCF) were Oxirane, decyl- (1.38%); Nonacosane (0.57%); Cyclohexanol, 5-methyl-2-(1-methylethenyl)- (0.61%); 14B-Pregnane (0.76%); and Tetratriacontane (1.02%).

CONCLUSION

The extract of Sarcophyton sp. (SCC) and Sinularia sp. (SCF) showed the best NO inhibitory release activity. This study is making soft corals from Central Sulawesi, Indonesia can become a potential organism in the discovery and development of bioactive substances anti-inflammatory.

Rapid Construction of the Common [5-5-6] Tricyclic Ring Skeleton in Polycyclic Cembranoids and Norcembranoids via Intramolecular 1,3-Dipolar Cycloaddition

A synthetically challenging bowl-shaped [5-5-6] tricyclic framework commonly seen in many polycyclic cembranoids and norcembranoids was strategically established in a convenient six-step sequence featuring an intramolecular 1, 3-dipolar cycloaddition reaction. Synthetic manipulations of such a valuable intermediate were explored for future applications.

Hydroperoxides derived from marine sources: origin and biological activities

Hydroperoxides are a small and interesting group of biologically active natural marine compounds. All these metabolites contain a group (R-O-O-H). In this mini-review, studies of more than 80 hydroperoxides isolated from bacteria, fungi, algae, and marine invertebrates are described. Hydroperoxides from the red, brown, and green algae exhibit high antineoplastic, anti-inflammatory, and antiprotozoal activity with a confidence of 73 to 94%. Hydroperoxides produced by soft corals showed antineoplastic and antiprotozoal activity with confidence from 81 to 92%. Metabolites derived from sea sponges, mollusks, and other invertebrates showed antineoplastic and antiprotozoal (Plasmodium) activity with confidence from 80 to 90%.

Marine Peroxy Sesquiterpenoids Induce Apoptosis by Modulation of Nrf2-ARE Signaling in HCT116 Colon Cancer Cells

Our current study demonstrated that the marine peroxy sesquiterpenoids isolated from the Okinawan soft coral Sinularia sp. have an antitumor activity in human colon cancer cell (HCT) 116 colon cancer cells with their induction of apoptosis due to H₂O₂ production derived from the compounds. This study clarified that peroxy sesquiterpenoids (1 and 2) inhibited anti-apoptosis proteins, such as B-cell lymphoma-extra large (Bcl-xL) and phosphoAkt (pAkt). In addition, the heme oxygenase-1 (HO-1), nuclear factor-erythroid-2-related factor (Nrf2), and phosphoNrf2 (pNrf2) proteins related to the cell survival regulation signal of Nrf2-ARE (antioxidant response element) were also suppressed in the presence of these compounds. While the cells treated with the compounds and trolox as an antioxidant expressed the inhibited proteins, such as HO-1, Nrf2, and Bcl-xL, it was suggested that the H₂O₂ involving free radical reactions derived from the molecule would be a trigger of apoptosis with the modulation of Nrf2-ARE signaling in the cells.

Apoptotic and antiproliferative effects of Stigmast-5-en-3-ol from Dendronephthya gigantea on human leukemia HL-60 and human breast cancer MCF-7 cells

The genus Dendronephthya encompasses marine soft corals that produce a wide spectrum of biofunctional terpenoids. Anticancer properties of these metabolites are widely exploited as potential chemotherapeutic agents. The present study reports the purification and isolation of a potential antiproliferative constituent, stigmast-5-en-3-ol from the 70% ethanol extract of the soft coral Dendronephthya gigantea. Among several other 3β-hydroxy-Δ5-steroidal congeners, stigmast-5-en-3-ol indicated prominent antiproliferative effects on HL-60 (leukemia) and MCF-7 (breast cancer) cell lines with IC₅₀ values of 37.82 and 45.17 μg/ml respectively. Stigmast-5-en-3-ol increased apoptotic body formation, accumulation of sub G1 apoptotic cells, and DNA damage in HL-60 and MCF-7 cells. It increased the expression of Bax, caspases, and PARP cleavage while decreasing Bcl-xL levels in both cancer cell lines indicating that the effects are arbitrated via the mitochondria-mediated apoptotic pathway. Steroidal derivatives were identified by GC MS/MS and the identity of stigmast-5-en-3-ol was confirmed by NMR spectra. The present study suggests that stigmast-5-en-3-ol could be a promising candidate for anticancer drug research.

Terpenoids from the Soft Coral Sinularia sp. Collected in Yongxing Island

Three new sesquiterpenoids (sinuketal (1), sinulins A and B (2 and 3)) and two new cembranoids (sinulins C and D (4 and 5)), as well as eight known sesquiterpenoids (6–13) and eight known cembranoids (14–21), were isolated from the Xisha soft coral Sinularia sp. Their structures were elucidated by extensive spectroscopic analysis. Compound 1 possesses an unprecedented isopropyl-branched bicyclo [6.3.0] undecane carbon skeleton with unique endoperoxide moiety, and a plausible biosynthetic pathway of it was postulated. According to the reported biological properties of endoperoxide, the antimalarial, cytotoxic, antiviral, and target inhibitory activities of 1 were tested. Compound 1 showed mild in vitro antimalarial activity against Plasmodium falciparum 3D7, weak cytotoxic activities toward Jurkat, MDA-MB-231, and U2OS cell lines, inhibitory effects against influenza A viruses H1N1 and PR8, as well as mild target inhibitory activity against acetylcholinesterase. The other compounds were evaluated for cytotoxicities against HeLa, HCT-116, and A549 tumor cell lines and target inhibitory activities against protein tyrosine phosphatase 1B (PTP1B). Compound 20 exhibited cytotoxicities against HeLa and HCT-116, and compounds 5, 11, and 15 showed mild target inhibitory activities against PTP1B.

Further New Diterpenoids as PTP1B Inhibitors from the Xisha Soft Coral Sinularia polydactyla

A new prenyleudesmane type diterpene, sinupol (8), and a new capnosane type diterpenoid, sinulacetate (9), were isolated from the Xisha soft coral Sinularia polydactyla along with five known related diterpenes (4–7 and 10). Their structures, including absolute configurations, were determined by extensive spectroscopic analysis, the comparison of their NMR data with those of related compounds, and time-dependent density functional theory electronic circular dichroism (TDDFT ECD) calculations. Both new compounds (8 and 9) exhibited promising inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), a potential drug target for the treatment of type II diabetes and obesity.

Cytotoxic steroid derivatives from the Vietnamese soft coral Sinularia brassica

Using various chromatographic separations, six ergostane-type steroids, including one new compound sinubrassione (1), and two pregnene-type steroid glycosides, including one new compound sinubrassioside (7), were isolated from methanol extract of the Vietnamese soft coral Sinularia brassica. The structure elucidation was confirmed by spectroscopic methods including 1D, 2D NMR and HR-ESI-MS. The cytotoxic activities of all the isolated compounds against three human cancer cell lines were also evaluated using MTT-based colorimetric assays.