RESUMEN
Twelve previously undescribed ophiobolin-type sesterterpenoids, undobolins A-L (1-12), were isolated from Aspergillus undulatus, and their structures were elucidated by spectroscopic analysis, ECD calculations, and single-crystal X-ray diffraction experiments. Compound 1 was the second example of 20-nor-ophiobolin reported, while compounds 2-6 were notable for oxygenation of C-2, and compound 6 showed significant inhibitory activity against ConA-induced T lymphocyte proliferation with an IC50 value of 2.3 µM, which suggests a promising new direction in the quest for immunosuppressive agents.
Asunto(s)
Aspergillus , Sesterterpenos , Sesterterpenos/farmacología , Sesterterpenos/química , Sesterterpenos/aislamiento & purificación , Aspergillus/química , Estructura Molecular , Animales , Linfocitos T/efectos de los fármacos , Cristalografía por Rayos X , Inmunosupresores/farmacología , Inmunosupresores/química , Inmunosupresores/aislamiento & purificación , Ratones , Proliferación Celular/efectos de los fármacosRESUMEN
Glioblastoma (GBM) is the most common form of malignant primary brain tumor and is one of the most lethal cancers. The difficulty in treating GBM stems from its highly developed mechanisms of drug resistance. Our research team has recently identified the fungal secondary metabolite ophiobolin A (OpA) as an agent with significant activity against drug-resistant GBM cells. However, the OpA's mode of action is likely based on covalent modification of its intracellular target(s) and thus possible off-target reactivity needs to be addressed. This work involves the investigation of an acid-sensitive OpA analogue approach that exploits the elevated acidity of the GBM microenvironment to enhance the selectivity for tumor targeting. This project identified analogues that showed selectivity at killing GBM cells grown in cultures at reduced pH compared to those maintained under normal neutral conditions. These studies are expected to facilitate the development of OpA as an anti-GBM agent by investigating its potential use in an acid-sensitive analogue form with enhanced selectivity for tumor targeting.
Asunto(s)
Antineoplásicos , Sesterterpenos , Humanos , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Sesterterpenos/química , Sesterterpenos/farmacología , Línea Celular Tumoral , Concentración de Iones de Hidrógeno , Glioblastoma/tratamiento farmacológico , Glioblastoma/patología , Ensayos de Selección de Medicamentos Antitumorales , Relación Estructura-Actividad , Estructura Molecular , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/patología , Proliferación Celular/efectos de los fármacos , Relación Dosis-Respuesta a DrogaRESUMEN
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.
Asunto(s)
Inmunosupresores , Sesterterpenos , Sesterterpenos/química , Sesterterpenos/farmacología , Sesterterpenos/aislamiento & purificación , Inmunosupresores/farmacología , Inmunosupresores/química , Inmunosupresores/aislamiento & purificación , Estructura Molecular , Humanos , Linfocitos T/efectos de los fármacos , Relación Estructura-Actividad , Conformación Molecular , Interferón gammaRESUMEN
Ophiobolin A (OPA) is a sesterterpenoid fungal natural product with broad anticancer activity. While OPA possesses multiple electrophilic moieties that can covalently react with nucleophilic amino acids on proteins, the proteome-wide targets and mechanism of OPA remain poorly understood in many contexts. In this study, we used covalent chemoproteomic platforms to map the proteome-wide reactivity of the OPA in a highly sensitive lung cancer cell line. Among several proteins that OPA engaged, we focused on two targets: lysine-72 of cytochrome c oxidase subunit 5A (COX5A) and cysteine-53 of mitochondrial hypoxia induced gene 1 domain family member 2A (HIGD2A). These two subunit proteins are part of complex IV (cytochrome C oxidase) within the electron transport chain and contributed significantly to the antiproliferative activity of OPA. OPA activated mitochondrial respiration in a COX5A- and HIGD2A-dependent manner, leading to an initial spike in mitochondrial ATP and heightened mitochondrial oxidative stress. OPA compromised mitochondrial membrane potential, ultimately leading to ATP depletion. We have used chemoproteomic strategies to discover a unique anticancer mechanism of OPA through activation of complex IV leading to compromised mitochondrial energetics and rapid cell death.
Asunto(s)
Complejo IV de Transporte de Electrones , Mitocondrias , Sesterterpenos , Humanos , Sesterterpenos/farmacología , Sesterterpenos/química , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Complejo IV de Transporte de Electrones/metabolismo , Línea Celular Tumoral , Antineoplásicos/farmacología , Antineoplásicos/química , Estrés Oxidativo/efectos de los fármacos , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Adenosina Trifosfato/metabolismo , Proliferación Celular/efectos de los fármacosRESUMEN
Genome mining of Emericella sp. XL-029 achieved a new type E sesterterpene synthase, EmES, which affored a novel bipolyhydroindenol sesterterpene, emerindanol A. Heterologous coexpression with the upstream P450 oxidase revealed C-4 hydroxylated product, emerindanol B. Notably, emerindanols A and B represented the first sesterterpenes featuring a unique 5/6-6/5 coupled ring system. EmES was postulated to initiate through C1-IV-V pathway and convert the fused ring intermediate into the final coupled ring product through a spiro skeleton.
Asunto(s)
Sesterterpenos , Sesterterpenos/química , Estructura Molecular , Emericella/químicaRESUMEN
Little is known about the structures and catalytic mechanisms of sesterterpene synthases (StTSs), which greatly hinders the structure-based engineering of StTSs for structural diversity expansion of sesterterpenes. We here report on the crystal structures of the terpene cyclization (TC) domains of two fungal StTSs: sesterfisherol synthase (NfSS) and sesterbrasiliatriene synthase (PbSS). Both TC structures contain benzyltriethylammonium chloride (BTAC), pyrophosphate (PPi), and magnesium ions (Mg2+), clearly defining the catalytic active sites. A combination of theory and experiments including carbocationic intermediates modeling, site-directed mutagenesis, and isotope labeling provided detailed insights into the structural basis for their catalytic mechanisms. Structure-based engineering of NfSS and PbSS resulted in the formation of 20 sesterterpenes including 13 new compounds and four pairs of epimers with different configurations at C18. These results expand the structural diversity of sesterterpenes and provide important insights for future synthetic biology research.
Asunto(s)
Sesterterpenos , Sesterterpenos/química , Sesterterpenos/metabolismo , Ciclización , Terpenos/metabolismo , Terpenos/química , Transferasas Alquil y Aril/metabolismo , Transferasas Alquil y Aril/química , Transferasas Alquil y Aril/genética , Ingeniería de Proteínas , Dominio Catalítico , Modelos Moleculares , Cristalografía por Rayos XRESUMEN
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.
Asunto(s)
Atractylodes , Rizoma , Sesterterpenos , Atractylodes/química , Humanos , Estructura Molecular , Línea Celular Tumoral , Sesterterpenos/química , Sesterterpenos/farmacología , Sesterterpenos/aislamiento & purificación , Rizoma/química , Células Hep G2 , Antineoplásicos Fitogénicos/farmacología , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Espectroscopía de Resonancia Magnética , Extractos Vegetales/química , Extractos Vegetales/farmacologíaRESUMEN
An unusual pyridine-containing sesterterpenoid, leucosceptrodine (1), and five new nor-leucosceptrane sesterterpenoids, including bisnor- (C23, 2), tetranor- (C21, 3) and pentanor- (C20, 4-6) skeletons, were isolated from the leaves of Tibetan Leucosceptrum canum. Their structures including their absolute configurations were determined by extensive spectroscopic analyses and quantum chemical calculations. A single crystal of one epimer (5) was crystallized from a pair of inseparable epimers, and its structure including its absolute configuration was determined by X-ray crystallographic analysis. The immunosuppressive activities of compounds 1-4 with different potencies were evaluated by inhibiting the secretion of cytokines TNF-α and IL-6 in LPS-induced RAW264.7 macrophages.
Asunto(s)
Lamiaceae , Sesterterpenos , Sesterterpenos/química , Tibet , Lamiaceae/química , Cristalografía por Rayos X , Piridinas/farmacología , Estructura MolecularRESUMEN
Mining of two multiproduct sesterterpene synthases from Lentzea atacamensis resulted in the identification of the synthases for lentzeadiene (LaLDS) and atacamatriene (LaATS). The main product of LaLDS (lentzeadiene) is a new compound, while one of the side products (lentzeatetraene) is the enantiomer of brassitetraene B and the other side product (sestermobaraene F) is known from a surprisingly distantly related sesterterpene synthase. LaATS produces six new compounds, one of which is the enantiomer of the known sesterterpene Bm1. Notably, for both enzymes the products cannot all be explained from one and the same starting conformation of geranylfarnesyl diphosphate, demonstrating the requirement of conformational flexibility of the substrate in the enzymes' active sites. For lentzeadiene an intriguing thermal [1,5]-sigmatropic rearrangement was discovered, reminiscent of the biosynthesis of vitamin D3. All enzyme reactions and the [1,5]-sigmatropic rearrangement were investigated through isotopic labeling experiments and DFT calculations. The results also emphasize the importance of conformational changes during terpene cyclizations.
Asunto(s)
Sesterterpenos , Terpenos , Terpenos/metabolismo , Terpenos/química , Sesterterpenos/química , Sesterterpenos/metabolismo , Conformación Molecular , Transferasas Alquil y Aril/metabolismo , Transferasas Alquil y Aril/química , EstereoisomerismoRESUMEN
Bipoladiens A-E (1-5), five new ophiobolin-derived sesterterpenoids, and a known compound 6 (bipolaricin R) were isolated from the cultures of the phytopathogenic fungus Bipolaris maydis. Their structures and absolute configurations were elucidated based on comprehensive spectroscopic analyses, HRESIMS, electronic circular dichroism (ECD) calculations, and single-crystal X-ray diffraction analyses. Notably, compound 1 has an undescribed tetracyclic 5/8/5/7 fused carbon skeleton, and compound 2 possesses a rare multicyclic caged ring system. The biosynthetic pathway of 1 was proposed starting from 6 via a series of oxidation and cyclization reactions. Compound 6 showed excellent antiproliferation and apoptosis induction effects against A549 cell line. Additionally, compounds 5 and 6 exhibited noticeable antimicrobial ability against Bacillus cereus, Staphylococcus aureus, and Staphylococcus epidermidis. These findings not only developed the chemical and bioactivities diversities of ophiobolin-sesterterpenoid but also provided an idea to boost the application of natural products in the control of food pathogens.
Asunto(s)
Antiinfecciosos , Sesterterpenos , Sesterterpenos/farmacología , Sesterterpenos/química , Bipolaris , Estructura MolecularRESUMEN
Four new sesterterpenes, arthproliferins A-D (1-4), together with four known derivatives, were isolated and characterized from the mangrove-sediment-derived fungus Arthrinium sp. SCSIO41221. Their structures were determined using detailed nuclear magnetic resonance (NMR) and mass spectroscopic (MS) analyses. Some of the isolated compounds were evaluated for their cytotoxicity in vitro. The results revealed that terpestacin (6) exhibited significant activity with an IC50 value of 20.3 µM, and compounds 2 and 5 were found to show weak inhibitory effects against U87MG-derived GSCs.
Asunto(s)
Sesterterpenos , Xylariales , Sesterterpenos/química , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Estructura MolecularRESUMEN
Eight new scalarane sesterterpenes, phyllofenones F-M (1-8), together with two known analogues, carteriofenones B and A (9-10), were isolated from the marine sponge Phyllospongia foliascens collected from the South China Sea. The structures of these compounds were determined based on extensive spectroscopic and quantum chemical calculation analysis. The antibacterial and cytotoxic activity of these compounds was evaluated. Among them, only compounds 4 and 6 displayed weak inhibitory activity against Staphylococcus aureus and Escherichia coli, with MIC values of 16 µg/mL and 8 µg/mL, respectively. Compounds 1-10 exhibited cytotoxic activity against the HeLa, HCT-116, H460, and SW1990 cancer cell lines, with IC50 values ranging from 3.4 to 19.8 µM.
Asunto(s)
Antineoplásicos , Poríferos , Animales , Humanos , Sesterterpenos/química , Poríferos/química , Espectroscopía de Resonancia Magnética , Antineoplásicos/química , Células HeLa , Escherichia coli , Estructura MolecularRESUMEN
Mining of a terpene synthase from Streptomyces subrutilus resulted in the identification of the hexacyclic sesterterpene subrutilane, besides eight pentacyclic side products. Subrutilane represents the first case of a saturated sesterterpene hydrocarbon. Its structure, including the absolute configuration, was unambiguously determined through X-ray crystallographic analysis and stereoselective deuteration. The cyclisation mechanism to subrutilane and its side products was investigated in all detail by isotopic labelling experiments and DFT calculations. The subrutilane synthase (SrS) also converted (2Z)-GFPP into one major product. Additional compounds were obtained from the substrate analogues (7R)-6,7-dihydro-GFPP and (2Z,7R)-6,7-dihydro-GFPP with blocked reactivity at the C6-C7 bond. Interestingly, the early steps of the cyclisation cascade with (2Z)-GFPP and the saturated substrate analogues were analogous to those of GFPP, but then deviations from the natural cyclisation mode occur.
Asunto(s)
Transferasas Alquil y Aril , Streptomyces , Humanos , Sesterterpenos/química , Terpenos/químicaRESUMEN
An integrated purification procedure through the LC-MS/MS-based molecular networking strategy combined with bioactive evaluation was first ushered for discovering bioactive ophiobolins from Bipolaris eleusines. Ophiobolins were mainly dispersed in five clusters, which were classified based on different ring systems and functional groups. Nine undescribed ophiobolins (1-6 and 9-11) and an undescribed natural product (8) along with two known analogs (7 and 12) were isolated in target. The undescribed structures were characterized by HR-ESI-MS, NMR spectra, and X-ray diffraction experiments. Compounds 3-12 exhibited strong phytotoxic effects on green foxtails by producing visible lesions, and compounds 1-10 and 12 displayed different levels of cytotoxic activities against cancer cell lines B16, Hep G2, and MCF-7, from which the possible structure-activity relationships were then suggested. The results have supported that bioactivity-guided molecular networking is an efficient strategy to expedite the discovery of undescribed bioactive natural products.
Asunto(s)
Sesterterpenos , Espectrometría de Masas en Tándem , Cromatografía Liquida , Sesterterpenos/farmacología , Sesterterpenos/química , Estructura MolecularRESUMEN
In reviewing a selection of recent case studies from our laboratory, we revealed some lessons learned and benefits accrued from the application of mass spectrometry (MS/MS) molecular networking in the field of marine sponge natural products. Molecular networking proved pivotal to our discovery of many new natural products and even new classes of natural product, some of which were opaque to alternate dereplication and prioritization strategies. Case studies included the discovery of: (i) trachycladindoles, an exceptionally rare class of bioactive indole alkaloid previously only known from a single southern Australia sample of Trachycladus laevispirulifer; (ii) dysidealactams, an unprecedented class of sesquiterpene glycinyl-lactam and glycinyl-imide from a Dysidea sp., a sponge genera often discounted as having been exhaustively studied; (iii) cacolides, an unprecedented family of sesterterpene α-methyl-γ-hydroxybutenolides from a Cacospongia sp., all too easily mischaracterized and deprioritized during dereplication as a well-known class of sponge sesterterpene tetronic acids; and (iv) thorectandrins, a new class of indole alkaloid which revealed unexpected insights into the chemical and biological properties of the aplysinopsins, one of the earliest and more extensively reported class of sponge natural products.
Asunto(s)
Productos Biológicos , Poríferos , Animales , Espectrometría de Masas en Tándem , Sesterterpenos/química , Poríferos/química , Productos Biológicos/química , Alcaloides Indólicos/farmacologíaRESUMEN
A gene coding for a terpene synthase homolog from Kitasatospora viridis was cloned and expressed in Escherichia coli. The purified recombinant protein possessed sesterterpene synthase activity and efficiently converted geranylfarnesyl diphosphate (GFPP) with 19 % yield into the sesterterpene hydrocarbon sestervirideneâ A. Large scale enzymatic conversions also allowed for the isolation of two side products that are generated with very low yields of ca. 0.1 %. Several derivatives of sestervirideneâ A were obtained by chemical transformations, securing the NMR-based structural assignments. The absolute configuration of sestervirideneâ A was determined by chemical correlation using stereoselectively deuterated precursors and by anomalous dispersion X-ray crystallography. The cyclisation mechanism from GFPP to sestervirideneâ A was extensively studied through isotopic labelling experiments and DFT calculations.
Asunto(s)
Transferasas Alquil y Aril , Streptomycetaceae , Sesterterpenos/química , Streptomycetaceae/metabolismo , Proteínas RecombinantesRESUMEN
Phyllospongianes A-E (1-5), five new scalarane derivatives featuring an unprecedented 6/6/6/5 tetracyclic dinorscalarane scaffold, along with the known probable biogenetic precursor, 12-deacetylscalaradial (6), were isolated from the marine sponge Phyllospongia foliascens. The structures of the isolated compounds were determined by analysis of spectroscopic data and electronic circular dichroism experiments. Compounds 1-5 are the first 6/6/6/5 tetracyclic scalarane derivatives to be reported within the scalarane family. Compounds 1, 2, and 4 exhibited antibacterial activity against Vibrio vulnificus, Vibrio parahemolyticus, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and Pseudomonas aeruginosa with MIC values ranging from 1 to 8 µg/mL. Furthermore, compound 3 exhibited significant cytotoxic activity on MDA-MB-231, HepG2, C4-2-ENZ, MCF-7, H460, and HT-29 cancer cell lines with IC50 values in the range between 0.7 and 13.2 µM.
Asunto(s)
Antineoplásicos , Poríferos , Animales , Sesterterpenos/química , Poríferos/química , Antineoplásicos/química , Antibacterianos/farmacología , Bacillus subtilis , Escherichia coli , Estructura MolecularRESUMEN
Respiratory syncytial virus (RSV) is a highly contagious human pathogen that poses a significant threat to children under the age of two, and there is a current need for new small molecule treatments. The Antarctic sponge Suberites sp. is a known source of sesterterpenes, and following an NMR-guided fractionation procedure, it was found to produce several previously unreported metabolites. Neosuberitenone (1), with a new carbon scaffold herein termed the 'neosuberitane' backbone, six suberitenone derivatives (2-7), an ansellane-type terpenoid (8), and a highly degraded sesterterpene (9), as well as previously reported suberitenones A (10) and B (11), were characterized. The structures of all of the isolated metabolites including absolute configurations are proposed on the basis of NMR, HRESIMS, optical rotation, and XRD data. The biological activities of the metabolites were evaluated in a range of infectious disease assays. Suberitenones A, B, and F (3) were found to be active against RSV, though, along with other Suberites sp. metabolites, they were inactive in bacterial and fungal screens. None of the metabolites were cytotoxic for J774 macrophages or A549 adenocarcinoma cells. The selectivity of suberitenones A, B, and F for RSV among other infectious agents is noteworthy.
Asunto(s)
Poríferos , Suberites , Animales , Niño , Humanos , Virus Sincitiales Respiratorios , Regiones Antárticas , Terpenos/química , Sesterterpenos/químicaRESUMEN
Sarcotragusolides A-D (1-4), four new butenolide sesterterpenes featuring a rare methyl-transferred 6/6/6-tricyclic fused ring system with a butyrolactone moiety, and echinohalimane B (8), an unprecedented monocyclic diterpenoid featuring a 2,7-ring-opened halimane-type skeleton, were isolated from the sponge Sarcotragus sp. A γ-hydroxybutenolide sesterterpene derivative (5), a new scalarane sesterterpene (7), a new subersin-type diterpenoid (10), and two known terpenoids were also isolated and identified. The discovery of sarcotragusolides C and D (3 and 4) with an unprecedented inversion of configuration implied a distinct biosynthetic pathway. The structures of these compounds were elucidated based on their spectroscopic data, single-crystal X-ray diffraction, chemical derivatization, and quantum chemical calculations. Compounds 1a, 1b, and 2 presented modest cytotoxic activities against several human cancer cell lines.
Asunto(s)
Antineoplásicos , Diterpenos , Poríferos , Humanos , Animales , Terpenos , Sesterterpenos/química , Antineoplásicos/química , Lactonas , Estructura MolecularRESUMEN
The synthetic biology approach enables efficient and directional mining of target compounds during drug discovery. Ten new asperterpenoids (6-15) and five known analogues (1-5), possessing a rare 5/7/3/6/5 skeleton, were obtained from two Aspergillus oryzae transformants with heterologous expression of a terpene cyclase gene AstC with one or two P450 genes AstB/A under the guidance of molecular networking. Their planar structures were determined by 1D and 2D NMR and HR-ESI-MS. The absolute configurations of compounds 6 and 9-13 were determined by single crystal X-ray diffraction, and those of compounds 7-8 and 14-15 were compared with the ECD of known compounds. Seven of all the compounds are the first asperterpenoid oxidation products at C-17 or at C-25. In bioassay, compounds 1-2, 4-5, and 6-8 displayed moderate to strong eliminating activities against chloroquine-sensitive strain (P.f.3D7) with EC50 values ranging from 2.1 to 19.3 µM. The structure-activity relationship (SAR) was discussed, which showed that substituents at C-3, C-11, C-17, C-18, and C-23 of asperterpenoids significantly affected anti-plasma parasite activity.