Ethyl palmitate, an anti-chikungunya virus principle from Sauropus androgynus, a medicinal plant used to alleviate fever in ethnomedicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Sauropus androgynus is a medicinal shrub used for the treatment of fever in ethnomedical traditions in various Southeast Asian countries. AIM OF THE STUDY: This study was aimed to identify antiviral principles from S. androgynus against Chikungunya virus (CHIKV), a major mosquito-borne pathogen that re-emerged in the last decade, and to unravel their mechanism of action. MATERIALS AND METHODS: Hydroalcoholic extract of S. androgynus leaves was screened for anti-CHIKV activity using cytopathic effect (CPE) reduction assay. The extract was subjected to activity guided isolation and the resultant pure molecule was characterized by GC-MS, Co-GC and Co-HPTLC. The isolated molecule was further evaluated for its effect by plaque reduction assay, Western blot and immunofluorescence assays. In silico docking with CHIKV envelope proteins and molecular dynamics simulation (MD) analyses were used to elucidate its possible mechanism of action. RESULTS: S. androgynus hydroalcoholic extract showed promising anti-CHIKV activity and its active component, obtained by activity guided isolation, was identified as ethyl palmitate (EP), a fatty acid ester. At 1 µg/mL, EP led to 100% inhibition of CPE and a significant 3 log10 reduction in CHIKV replication in Vero cells at 48 h post-infection. EP was highly potent with an EC50 of 0.0019 µg/mL (0.0068 µM) and a very high selectivity index. EP treatment significantly reduced viral protein expression, and time of addition studies revealed that it acts at the stage of viral entry. A strong binding to the viral envelope protein E1 homotrimer during entry, thus preventing viral fusion, was identified as a possible mechanism by which EP imparts its antiviral effect. CONCLUSIONS: S. androgynus contains EP as a potent antiviral principle against CHIKV. This justifies the use of the plant against febrile infections, possibly caused by viruses, in various ethnomedical systems. Our results also prompt more studies on fatty acids and their derivatives against viral diseases.

Novel ultra-small Pd NPs on SOS spheres: a new catalyst for domino intramolecular Heck and intermolecular Sonogashira couplings.

We report a novel catalyst Pd/SOS that catalyzes the dual C-C bond forming coupling of an iodoarene moiety with an internal alkene and an external alkyne via an intramolecular Heck reaction, followed by an intermolecular Sonogashira reaction, respectively. The catalyst was characterized using XRD, IR, XPS, SEM and TEM analyses. Notably, for the first time, cheap and readily available new silica [nanosilica on microsilica (SOS)] material-supported ultra-small Pd nanoparticles (2.20 nm) are employed for the efficient synthesis of dihydrobenzofuran and oxindole derivatives in a domino one-pot reaction. Significantly, a sub-molar quantity of Pd (0.3 mol%) was found to be sufficient to furnish the products in very good to near quantitative yields. Gratifyingly, the catalyst could be recycled up to five cycles with a marginal loss (∼no loss) of the product.

Identification of forced degradation products of tamsulosin using liquid chromatography/electrospray ionization tandem mass spectrometry.

A rapid and gradient high-performance liquid chromatography combined with quadrupole time-of-flight electrospray ionization tandem mass spectrometry (LC/Q-TOF-ESI-MS/MS) method has been developed for the identification and structural characterization of stressed degradation products of tamsulosin. Tamsulosin, a selective α1-adrenoceptor antagonist, was subjected to forced degradation studies under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress conditions as per ICH guidelines Q1A (R2). The drug degraded significantly under hydrolytic (base and neutral), thermal, oxidative and photolytic conditions, while it was stable to acid hydrolytic stress conditions. A total of twelve degradation products were formed and the chromatographic separation of the drug and its degradation products were achieved on a GRACE C-18 column (250mm×4.6mm, 5µm). All the degradants have been identified and characterized by LC/ESI-MS/MS and accurate mass measurements. To elucidate the structures of degradation products, fragmentation of the [M+H](+) ions of tamsulosin and its degradation products was studied by using LC-MS/MS experiments combined with accurate mass measurements. The product ions of all the protonated degradation products were compared with the product ions of protonated tamsulosin to assign most probable structures for the observed degradation products.

Bioactive potential of seagrass bacteria against human bacterial pathogens.

Study of marine organisms for their bioactive potential, being an important part of marine ecosystem, has picked up the rhythm in recent years with the growing recognition of their importance in human life. Investigation was carried out to isolate 32 strains of endo and epiphytic bacteria in 2 seagrass species viz., Syringodium isoetifolium and Cymodocea serrulata. Morphologically different bacterial strains were tested against 5 antibiotic resistant human bacterial pathogens, of which 10 associated bacteria shown inhibitory activity against one or more bacterial pathogens. Minimum inhibitory concentration (MIC) and Minimum bacterial concentration (MBC) determination with extracellular bioactive compounds from the associated bacteria reveals that, the strain ENC 5 showed inhibitory activity against all the bacterial pathogens with the maximum sensitivity against Pseudomonas aeruginosa at the MIC value of 500 microg ml(-1).