ABSTRACT
The white croaker (Argyrosomus argentatus) derived Curvularia sp. IFB-Z10 produces curvulamine as a skeletally unprecedented alkaloid incorporating two undescribed extender units. Curvulamine is more selectively antibacterial than tinidazole and biosynthetically unique in the new extenders formed through a decarboxylative condensation between an oligoketide motif and alanine.
Subject(s)
Alkaloids/isolation & purification , Alkaloids/pharmacology , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Ascomycota/chemistry , Perciformes/microbiology , Actinomyces/drug effects , Alkaloids/chemistry , Animals , Anti-Bacterial Agents/chemistry , Bacteroides/drug effects , Indole Alkaloids , Marine Biology , Microbial Sensitivity Tests , Mitosporic Fungi , Molecular Structure , Peptostreptococcus/drug effects , Streptococcus/drug effects , Tinidazole/pharmacology , Veillonella/drug effectsABSTRACT
Chemical investigation of the insect-derived actinomycete Amycolatopsis sp. HCa1 with NMR-guided fractionation led to the isolation of eight new tetrasaccharide derivatives containing an unusual nonreducing glucotetraose skeleton, named actinotetraoses A-H (1-8), and one known compound, tigloside (9). The structures of these compounds were determined on the basis of analyses of their spectroscopic data. The in vitro immunosuppressive activity and cytotoxicity of these compounds were evaluated by T cell viability and MTT assays, respectively. Only actinotetraose E (5) displayed weak immunosuppressive activity.
Subject(s)
Actinobacteria/chemistry , Grasshoppers/microbiology , Immunosuppressive Agents/isolation & purification , Oligosaccharides/isolation & purification , T-Lymphocytes/drug effects , Actinobacteria/isolation & purification , Animals , Cell Survival/drug effects , Drug Screening Assays, Antitumor , Fermentation , HeLa Cells , Hep G2 Cells , Humans , Immunosuppressive Agents/chemistry , Immunosuppressive Agents/pharmacology , Magnetic Resonance Spectroscopy , Molecular Structure , Mycelium/chemistry , Oligosaccharides/chemistry , Oligosaccharides/pharmacology , Optical RotationABSTRACT
Two new polyketides, arthropsadiol C (1) and massarilactone H (2), together with six known derivatives (3-8) were isolated from the culture broth of the marine-derived fungus Phoma herbarum. Their structures were elucidated on the basis of spectroscopic methods, including 2D NMR techniques. Compounds 2, 4, 5, and 8 showed moderate neuraminidase inhibitory activity with IC(50) values ranging from 4.15 to 9.16 µM.
Subject(s)
Ascomycota/chemistry , Biological Products/pharmacology , Enzyme Inhibitors/pharmacology , Neuraminidase/antagonists & inhibitors , Polyketides/pharmacology , Biological Products/chemistry , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/isolation & purification , Molecular Structure , Polyketides/chemistry , Polyketides/isolation & purificationABSTRACT
With the current increased widespread interest in the development and applications of micro/nanosatellites, it was found that we needed to design a small high accuracy satellite attitude determination system, because the star trackers widely used in large satellites are large and heavy, and therefore not suitable for installation on micro/nanosatellites. A Sun sensor + magnetometer is proven to be a better alternative, but the conventional sun sensor has low accuracy, and cannot meet the requirements of the attitude determination systems of micro/nanosatellites, so the development of a small high accuracy sun sensor with high reliability is very significant. This paper presents a multi-aperture based sun sensor, which is composed of a micro-electro-mechanical system (MEMS) mask with 36 apertures and an active pixels sensor (APS) CMOS placed below the mask at a certain distance. A novel fast multi-point MEANSHIFT (FMMS) algorithm is proposed to improve the accuracy and reliability, the two key performance features, of an APS sun sensor. When the sunlight illuminates the sensor, a sun spot array image is formed on the APS detector. Then the sun angles can be derived by analyzing the aperture image location on the detector via the FMMS algorithm. With this system, the centroid accuracy of the sun image can reach 0.01 pixels, without increasing the weight and power consumption, even when some missing apertures and bad pixels appear on the detector due to aging of the devices and operation in a harsh space environment, while the pointing accuracy of the single-aperture sun sensor using the conventional correlation algorithm is only 0.05 pixels.
Subject(s)
Algorithms , Micro-Electrical-Mechanical Systems/instrumentation , Solar System , Calibration , Computer Simulation , Metals/chemistry , Oxides/chemistry , SemiconductorsABSTRACT
The chemical study of endophytic fungus of Cochliobolus led to the isolation of 10 terpenes (1-10), including one new compound named isocochlioquinone B (1). Their structures were elucidated on the basis of spectroscopic methods, including 2D NMR techniques. Compounds 5-7 showed significant neuraminidase inhibitory activity with IC(50) values of 0.79-1.75 µM.
