Immunosuppressive leucosesterterpane and penta-nor-leucosesterterpane sesterterpenoids from Leucosceptrum canum.

Five undescribed leucosesterterpane sesterterpenoids, leucosceptrines A-E, two undescribed penta-nor-leucosesterterpane (C20) sesterterpenoids, nor-leucosceptrines A and B, and three known analogues, were obtained from the aerial parts of Leucosceptrum canum of Chinese origin. Leucosceptrines A-C are the first examples of leucosesterterpane-type sesterterpenoids with unclosed dihydropyran rings and reverse configurations at chiral centers C-4 and/or C-12. Nor-leucosceptrines A and B possesses an unusual penta-nor-leucosesterterpane skeleton. Their structures were unambiguously elucidated through comprehensive spectroscopic analyses and single-crystal X-ray diffraction. A plausible biogenetic pathway for these sesterterpenoids was proposed. The immunosuppressive effects of these isolates on the secretion of the cytokine IFN-γ by T cells stimulated with anti-CD3/CD28 monoclonal antibodies were observed with different potencies.

Two new sesterterpenoids from Atractylodes japonica Koidz. ex Kitam.

Two new sesterterpenoids, atractylodes japonica terpenoid acid I (1) and atractylodes japonica terpenoid aldehyde I (2), were isolated from the rhizomes of Atractylodes japonica Koidz. ex Kitam together with ten known compounds (3-12). Their structures were elucidated on the basis of comprehensive spectroscopic analysis (1D/2D NMR, HRESIMS and IR). In addition, all of these isolated compounds were evaluated for their cytotoxic activities against human gastric cancer cell MGC-803 and human hepatocellular cancer cell HepG-2. Most of them exhibited moderate to weak inhibitory effects with IC50 values in the range of 25.15-88.85 µM except for 9-12.

Antibiofilm Activity of Phorbaketals from the Marine Sponge Phorbas sp. against Staphylococcus aureus.

Biofilm formation by Staphylococcus aureus plays a critical role in the persistence of chronic infections due to its tolerance against antimicrobial agents. Here, we investigated the antibiofilm efficacy of six phorbaketals: phorbaketal A (1), phorbaketal A acetate (2), phorbaketal B (3), phorbaketal B acetate (4), phorbaketal C (5), and phorbaketal C acetate (6), isolated from the Korean marine sponge Phorbas sp. Of these six compounds, 3 and 5 were found to be effective inhibitors of biofilm formation by two S. aureus strains, which included a methicillin-resistant S. aureus. In addition, 3 also inhibited the production of staphyloxanthin, which protects microbes from reactive oxygen species generated by neutrophils and macrophages. Transcriptional analyses showed that 3 and 5 inhibited the expression of the biofilm-related hemolysin gene hla and the nuclease gene nuc1.

Oshimalides A and B, Sesterterpenes of the Manoalide Class from a Luffariella sp. Deep-Sea Marine Sponge: Application of Asymmetric Dihydroxylation in Structure Elucidation.

Oshimalides A (1) and B (2) were isolated from a Luffariella sp. marine sponge. The absolute configurations of the stereogenic centers in the cyclohexenone ring were determined by the modified Mosher's analysis of the reduction product. The absolute configuration of the stereogenic center in the dihydropyran ring was assigned by analysis of the 1H NMR data of the vicinal diols which were prepared by AD-mix reagents stereoselectively.

Dysiscalarones A-E, scalarane sesterterpenoids with nitric oxide production inhibitory activity from marine sponge Dysidea granulosa.

Dysiscalarones A-E (1-5), five new scalarane-type bishomoscalarane sesterterpenoids, were isolated from marine sponge Dysidea granulosa collected from the South China Sea, together with two known ones, honulactone A (6) and phyllofolactone I (7). The new structures were determined by extensive spectroscopic analysis including HR-ESI-MS and 1D and 2D NMR data, and their absolute configurations were assigned by single crystal X-ray diffraction analyses. The inhibitory activity of all the seven isolates on the production of nitric oxide (NO) stimulated by lipopolysaccharide (LPS) in mouse RAW 264.7 macrophages was evaluated. Of these metabolites, dysiscalarones A-B (1-2), honulactone A (6), and phyllofolactone I (7) showed inhibitory activities with respective IC50 values of 16.4, 18.5, 2.6, and 3.7 µM, which suggested that the γ-methylated α,ß-unsaturated γ-lactone might be the functional group. In addition, all the seven metabolites showed no significant cytotoxicity against lung cancer PC9 cell line at the concentration of 20 µM.

Immunosuppressive and Adipogenesis Inhibitory Sesterterpenoids with a Macrocyclic Ether System from Eurysolen gracilis.

Eurysoloids A (1) and B (2), two novel diastereomeric sesterterpenoids possessing a pentacyclic 5/6/5/10/5 framework with an unusual macrocyclic ether system, were isolated from Eurysolen gracilis Prain. Their structures were unambiguously determined by spectroscopic, single-crystal X-ray diffraction and DP4+ analyses. A plausible biosynthetic pathway for compounds 1 and 2 was proposed. Both compounds exhibited immunosuppressive activity via inhibiting the production of cytokine IFN-γ of T cells, and compound 2 inhibited adipogenesis in 3T3-L1 adipocytes.

Cytotoxic Manoalide-Type Sesterterpenes from the Sponge Luffariella variabilis Collected in the South China Sea.

Thirteen new linear terpenes, including 11 rare acyclic manoalide derivatives (1-11), one polyprenylphenol derivative (12), and one polyprenylbenzaldehyde derivative (13), together with three known compounds (14-16) were isolated from the sponge Luffariella variabilis collected in the South China Sea. The planar structures were resolved by NMR and MS analyses, while the absolute configurations were fully elucidated by NOESY experiments, combined with experimental and calculated ECD spectra, acetal formation, empirical rules of 1H and 13C NMR shifts, DP4+ probability analyses, and Mosher's method. Compounds 1-7, 10, and 13 demonstrated cytotoxic activities against several human cancer cell lines with IC50 values ranging from 2 to 10 µM.

Sesquiterpene lactones from Lychnophora species: Antinociceptive, anti-inflammatory, and antioxidant pathways to treat acute gout.

ETHNOPHARMACOLOGICAL RELEVANCE: Lychnophora trichocarpha and Lychnophora passerina are species used in folk medicine to treat inflammation, pain, and rheumatism. Previous studies have demonstrated the anti-inflammatory effect of ethanol extracts of these species and identified that sesquiterpene lactones contribute to this activity. AIM OF THE STUDY: Gout is an acute inflammatory arthritis caused by the deposition of monosodium urate (MSU) crystals in joints. Inflammation in joints induces oxidative stress in defense cells, releasing pro-inflammatory mediators. This study has three objectives: (1) to demonstrate the effects of sesquiterpene lactones lychnopholide and eremantholide C isolated from L. trichocarpha and goyazensolide isolated from L. passerina on arthritis induced by MSU crystals in C57BL6 mice; (2) to determine whether or not these compounds can inhibit the migration of neutrophils and the release of TNF-α and IL-1ß cytokines in the inflammation region; and (3) to evaluate the effects of sesquiterpene lactones on the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the cartilage of C57BL/6 mice with gouty arthritis. MATERIALS AND METHODS: The anti-inflammatory, antinociceptive, and antioxidant activities of sesquiterpene lactones in C57BL/6 mice with MSU crystal-induced arthritis were evaluated. In our experimental model, the mice were injected with MSU crystals in the tibiofemoral joint to induce arthritis and then treated with indomethacin, vitamin C, and sesquiterpene lactones. Nociception was evaluated before and after inflammation induction and treatments, neutrophil migration, IL-1ß and TNF-α concentrations, and SOD and CAT activities. RESULTS: Sesquiterpene lactones exerted an anti-inflammatory effect by inhibiting neutrophil migration and TNF-α production. These compounds also demonstrated antinociceptive and antioxidant activities. CONCLUSION: Lychnopholide, eremantholide C, and goyazensolide improved the inflammation induced by MSU crystals by inhibiting the migration of neutrophils to the inflamed area and by blocking the release of the pro-inflammatory cytokine TNF-α. In addition, sesquiterpene lactones reduced oxidative stress by activating SOD and CAT. These results suggest that sesquiterpene lactones have anti-gout activity through the inflammation, pain, and oxidative stress pathways.

Ophiobolin Sesterterpenoids and Farnesylated Phthalide Derivatives from the Deep Sea Cold-Seep-Derived Fungus Aspergillus insuetus SD-512.

Three new ophiobolin sesterterpenoids, (6R)-16,17,21,21-O-tetrahydroophiobolin G (1), (6R)-16,17-dihydroophiobolin H (2), and (5S,6S)-16,17-dihydroophiobolin H (3), and three new farnesylated phthalide derivatives farnesylemefuranones D-F (9-11), along with five known ophiobolin analogues (4-8), were isolated and identified from the culture extract of Aspergillus insuetus SD-512, a deep-sea-derived fungus obtained from cold seep sediments collected at a depth of 1331 m. Among them, compounds 9-11 are rare examples of phthalide derivatives linked with farnesyl moieties via ether bonds. Their structures were established on the basis of detailed interpretation of the NMR spectroscopic and mass spectrometric data. X-ray crystallographic analysis, ECD calculations, and DP4+ probability analysis were performed to confirm the structures and establish the relative and absolute configurations of compounds 1-4. Compounds 3 and 9-11 showed broad-spectrum antibacterial activities, and differences in potencies could be assigned to structural modifications. This is the first report of secondary metabolites obtained from a deep sea cold-seep-derived fungus.

New Ophiobolins from the Deep-Sea Derived Fungus Aspergillus sp. WHU0154 and Their Anti-Inflammatory Effects.

Deep-sea fungi have become a new arsenal for the discovery of leading compounds. Here five new ophiobolins 1-5, together with six known analogues 6-11, obtained from a deep-sea derived fungus WHU0154. Their structures were determined by analyses of IR, HR-ESI-MS, and NMR spectra, along with experimental and calculated electronic circular dichroism (ECD) analysis. Pharmacological studies showed that compounds 4 and 6 exhibited obvious inhibitory effects on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in murine macrophage RAW264.7 cells. Mechanical study revealed that compound 6 could inhibit the inducible nitric oxide synthase (iNOS) level in LPS-stimulated RAW264.7 cells. In addition, compounds 6, 9, and 10 could significantly inhibit the expression of cyclooxygenase 2 (COX 2) in LPS-induced RAW264.7 cells. Preliminary structure-activity relationship (SAR) analyses revealed that the aldehyde group at C-21 and the α, ß-unsaturated ketone functionality at A ring in ophiobolins were vital for their anti-inflammatory effects. Together, the results demonstrated that ophiobolins, especially for compound 6, exhibited strong anti-inflammatory effects and shed light on the discovery of ophiobolins as new anti-inflammatory agents.

Drophiobiolins A and B, Bioactive Ophiobolan Sestertepenoids Produced by Dreschslera gigantea.

Two new bioactive ophiobolan sestertepenoids, named drophiobiolins A and B (1 and 2) were isolated from Drechslera gigantea, a fungus proposed as a mycoherbicide for biocontrol of Digitaria sanguinalis. They were isolated together with ophiobolin A, the main metabolite, 6-epi-ophiobolin A, 3-anhydro-6-epi-ophiobolin A, and ophiobolin I. Drophiobolins A and B were characterized by NMR, HRESIMS, and chemical methods as 7-hydroxy-7-(6-hydroxy-6-methylheptan-2-yl)-1,9a-dimethyl-3-oxo-3,3a,6,6a,7,8,9,9a,10,10a-decahydrodicyclopenta [a,d][8]annulene-4-carbaldehyde and 6-(hydroxymethyl)-3',9,10a-trimethyl-5'-(2-methylprop-1-en-1-yl)-3a,4,4',5',10,10a-hexahydro-1H,3'H-spiro[dicyclopenta[a,d] [8]annulene-3,2'-furan]-5,7(2H,9aH)-dione. The relative configuration of drophiobolins A and B, which did not afford crystals suitable for X-ray analysis, was determined by NOESY experiments, while the absolute configuration was assigned by comparison of their experimental and TDDFT calculated electronic circular dichroism (ECD) spectra. The phytotoxic activity of drophiobolins A and B was tested by leaf-puncture assay on cultivated (Lycopersicon esculentum L.), as well as on host (Digitaria sanguinalis L.) and nonhost (Chenopodium album L.) weed plants, compared to that of ophiobolin A. Both of the newly identified ophiobolins showed significant phytotoxicity. Drophiobolins A and B exhibited cytotoxicity against Hela B cells with an IC50 value of 10 µM. However, they had a lesser or no effect against Hacat, H1299, and A431 cells when compared to that of ophiobolin A.

Biosynthetic Gene Cluster for Asperterpenols A and B and the Cyclization Mechanism of Asperterpenol A Synthase.

The biosynthetic gene cluster for the sesterterpenoids asperterpenols A and B from Aspergillus calidoustus CBS121601 is described. The cluster contains two genes, acldAS for a chimeric sesterterpene synthase and acldA-P450 for a cytochrome P450 monooxygenase. The cyclization mechanism of the asperterpenol A synthase, catalyzing the formation of a unique sesterterpene with a 6/6/8/5 tetracyclic ring system, was studied using isotopically labeled terpene precursors.

Dactylospenes A-E, Sesterterpenes from the Marine Sponge Dactylospongia elegans.

Chemical investigation on a marine sponge, Dactylospongia elegans, yielded five new γ-oxygenated butenolide sesterterpene derivatives, dactylospenes A-E (1-5), as well as two known biosynthetically related compounds, luffariellolide (6) and furospinosulin B (7). The structures of these compounds were elucidated on the basis of their spectroscopic data, experimental and calculated electronic circular dichroism (ECD) analysis, as well as comparison of the NMR data with those of known analogs. These metabolites are the first γ-oxygenated butenolide sesterterpenes to be reported from this genus. These compounds were evaluated in antimicrobial, anti-inflammatory, and cytotoxic assays. Only compounds 1, 3, and 6 exhibited moderate cytotoxicity against DU145, SW1990, Huh7, and PANC-1 cancer cell lines with IC50 values in the range of 2.11-13.35 µM. Furthermore, compound 2, without cytotoxicity, exhibited significant inhibitory effects (inhibitory rate 77.5%) on nitric oxide production induced by lipopolysaccharide at 10 µM.

Guanahanolide A, a Meroterpenoid with a Sesterterpene Skeleton from Coral-Derived Streptomyces sp.

A meroterpenoid, guanahanolide A (1), was purified from a fermentation extract of Streptomyces sp. RKBH-B7. The planar structure of guanahanolide A (1) was elucidated by NMR spectroscopy, revealing a meroterpenoid comprised of an unprecedented sesterterpene skeleton. Upon determination of the relative configuration of 1 through X-ray crystallography, its absolute configuration was unambiguously assigned using Mosher ester analysis. Guanahanolide A (1) showed moderate cytotoxicity against human cancer cell lines MCF-7, HTB-26, and HCT-116.

Sponge-Derived 24-Homoscalaranes as Potent Anti-Inflammatory Agents.

Scalarane-type sesterterpenoids are known for their therapeutic potential in cancer treatments. However, the anti-inflammatory properties of this class of metabolites remain elusive. Our current work aimed to investigate the anti-inflammatory scalaranes from marine sponge Lendenfeldia sp., resulting in the isolation of six new 24-homoscalaranes, lendenfeldaranes E-J (1-6). The structures of the new metabolites were determined by extensive spectroscopic analyses, and the absolute configuration of 1 was established by electronic circular dichroism (ECD) calculations. Compounds 2 and 3 were discovered to individually reduce the generation of superoxide anions, and compound 1 displayed an inhibitor effect on the release of elastase. These three compounds were proven to be the first anti-neutrophilic scalaranes.

12-Deacetyl-12-epi-Scalaradial, a Scalarane Sesterterpenoid from a Marine Sponge Hippospongia sp., Induces HeLa Cells Apoptosis via MAPK/ERK Pathway and Modulates Nuclear Receptor Nur77.

12-Deacetyl-12-epi-scalaradial, a scalarane sesterterpenoid from a marine sponge Hippospongia sp, has been reported to possess cytotoxic activity on HepG2, MCF-7, and HCT-116 cells. However, there is no research to indicate that 12-deacetyl-12-epi-scalaradial exhibited anticancer effect on cervical cancer HeLa cells. The aim of this study was to investigate the anticancer activity of 12-deacetyl-12-epi-scalaradial against HeLa cells and to explore the mechanism. The results from a methylthiazolyldiphenyl-tetrazolium (MTT) assay suggested that 12-deacetyl-12-epi-scalaradial suppressed the proliferation of HeLa cells and flow cytometry analysis showed 12-deacetyl-12-epi-scalaradial could induce the apoptosis of HeLa cells in dose- and time-dependent manner. Western blotting analysis demonstrated that 12-deacetyl-12-epi-scalaradial triggered apoptosis via mediating the extrinsic pathway and was found to suppress MAPK/ERK pathway which was associate with cancer cell death. Nur77, a critical number of orphan nuclear receptors, plays diverse roles in tumor development as a transcription factor and has been considered as a promising anticancer drug target. The dual-luciferase reporter assays suggested that 12-deacetyl-12-epi-scalaradial could selectively enhance the trans-activation activity of Nur77. Furthermore, Western blotting analysis and fluorescence quenching showed that 12-deacetyl-12-epi-scalaradial could induce the phosphorylation of Nur77 and interact with the ligand-binding domain (LBD) of Nur77. Our research confirmed 12-deacetyl-12-epi-scalaradial as a potential agent for cervical cancer therapy and provided a view that 12-deacetyl-12-epi-scalaradial may be a modulator of Nur77.

Sesterterpenes and macrolide derivatives from the endophytic fungus Aplosporella javeedii.

Five sesterterpenes (1-5) including two new compounds (1 and 2), as well as a new (6) and a known macrolide (7) were isolated from the endophytic fungus Aplosporella javeedii. The structures of the new compounds were elucidated by analysis of their 1D and 2D NMR and HRMS data as well as by comparison with the literature. Compound 4 and its acetyl derivatives 4a, 4b, 4c which were prepared by acetylation of 4 exhibited moderate cytotoxicity against the mouse lymphoma cell line L5178Y with IC50 values ranging from 6.2 to 12.8 µM, respectively. Moreover, 4a and 4c exhibited also cytotoxicity against human leukemia (Jurkat J16) and lymphoma (Ramos) cell lines. Compound 7 showed strong cytotoxicity against the L5178Y cell line, as well as against human Jurkat J16 and Ramos cells with IC50 values of 0.4, 5.8, and 4.4 µM, respectively. Mechanistic studies indicated that 7 induces apoptotic cell death. In addition, compounds 3, 4 and 7 showed low antibacterial activities against Mycobacterium tuberculosis H37Rv and compound 6 against Staphylococcus aureus, respectively, with MICs of 100 µM. Preliminary structure-activity relationships are discussed.

Bishomoscalarane Sesterterpenoids from the Sponge Dysidea granulosa Collected in the South China Sea.

Granulosane A (1), a new C27 bishomoscalarane sesterterpenoid with a rare 6/6/6/8 tetracyclic skeleton, together with eight additional new C27 bishomoscalarane sesterterpenes (2, 8-14) and five new C26 20,24-bishomo-25-norscalarane sesterterpenes (3-7), were isolated from the marine sponge Dysidea granulosa collected in the South China Sea. Their structures were elucidated by extensive spectroscopic analysis and quantum chemical calculation methods. Compound 4 showed antiproliferative activities against two cancer cell lines.

Probing Anti-Proliferative 24-Homoscalaranes from a Sponge Lendenfeldiasp.

In the current study, an NMR spectroscopic pattern-based procedure for probing scalarane derivatives was performed and four new 24-homoscalaranes, lendenfeldaranes A-D (1- 4), along with three known compounds, 12α-acetoxy-22-hydroxy-24-methyl-24-oxoscalar-16-en- 25-al (5), felixin F (6), and 24-methyl-12,24,25-trioxoscalar-16-en-22-oic acid (7) were isolated from the sponge Lendenfeldia sp. The structures of scalaranes 1-7 were elucidated on the basis of spectroscopic analysis. Scalaranes 1-7 were further evaluated for their cytotoxicity toward a series of human cancer cell lines and the results suggested that 5 and 7 dominated in the anti- proliferative activity of the extract. The 18-aldehyde functionality was found to play a key role in their activity.

Perisomalien A, a new cytotoxic scalarane sesterterpene from the fruits of Periploca somaliensis.

The CHCl3 fraction of MeOH extract of Periploca somaliensis (family Asclepiadaceae) fruits afforded a new scalarane sesterterpene, namely perisomalien A (1), along with lupeol acetate (2), ß-amyrin (3), cycloart-23Z-ene-3ß,25-diol (4), and ß-sitosterol-3-O-ß-D-glucopyranoside (5). Their chemical structures were established by various spectroscopic analyses, in addition to comparison with the formerly reported data. Moreover, the cytotoxic activity of these metabolites was assessed towards MCF-7, HepG2, and HCT-116 tumour cell lines using sulforhodamine B (SRB) assay. Compound 4 showed the most potent cytotoxic profile with IC50 9.0 µM towards MCF-7, compared to doxorubicin (IC50 0.18 µM). Also, 1 and 4 possessed the most potent effect towards HepG2 with IC50s 26.7 and 25.9 µM, respectively. In addition, all tested compounds showed cytotoxic effects with IC50 values ranging from 19.9 to 39.3 µM against HCT-116.