Ashok D. Patil

Frondosins, five new sesquiterpene hydroquinone derivatives with novel skeletons from the sponge Dysidea frondosa: Inhibitors of interleukin-8 receptors

Abstract Bioassay-guided fractionation of the EtOAc extract of the sponge Dysidea frondosa collected in Pohnpei yielded five sesquiterpenes, frondosins A - E ( 1–5 ). The structures and relative stereochemistry of the frondosins were established by interpretation of spectral data. Frondosins A - E ( 1–5 ), which possess novel carbon skeletons, were found to be inhibitors of interleukin-8 receptors and protein kinase C in the low micromolar range.

Fasicularin, a novel tricyclic alkaloid from the ascidian Nephteis fasicularis with selective activity against a DNA repair-deficient organism

Abstract A novel tricyclic alkaloid, fasicularin (1), was isolated from the Micronesian ascidian Nephteis fasicularis. The structure of 1 was elucidated primarily by interpretation of spectral data. Fasicularin was found to be active in a DNA damaging assay.

The plakortones, novel bicyclic lactones from the sponge Plakortis halichondrioides: Activators of cardiac SR-Ca2+-pumping ATPase

Abstract Bioassay-guided fractionation of the EtOAc extract of sponge Plakortis halichondrioides yielded four novel bicyclic lactones, plakortones A, B, C, D and a novel acid, plakortide E ( 3, 4, 5, 6 and 7 ). The structures, including stereochemistry, of these compounds were established by interpretation of spectral data. Plakortones A-D ( 3–6 ) comprise a novel class of activators of cardiac SR-Ca 2+ -pumping ATPase which were found to be active at micromolar concentrations As part of an SAR study, the α and β diols 9 and 10 of plakortone D were prepared using Sharpless AD procedure.

PULCHERRIMINS A - D, NOVEL DITERPENE DIBENZOATES FROM CAESALPINIA PULCHERRIMA WITH SELECTIVE ACTIVITY AGAINST DNA REPAIR-DEFICIENT YEAST MUTANTS

Abstract Bioassay-guided fractionation of the MeOH/CH2Cl2 extract of the roots of Caesalpinia pulcherrima yielded four novel dibenzoate diterpenes, pulcherrimins A, B, C and D (1–4). The structures of these compounds including their absolute configuration were established by interpretation of spectral data and CD measurements. Pulcherrimins A and B (1 and 2) were found to be active in DNA repair-deficient yeast mutant. Bioassay-guided fractionation of the MeOH/CH2Cl2 extract of the roots of Caesalpinia pulcherrima yielded four novel dibenzoate tetracyclic diterpenes, pulcherrimins A, B, C and D (1–4_. The structures of these compounds including their absolute configuration were established by interpretation of spectral data and CD measurements. Pulcherrimins A and B (1 and 2)_ were found to be active in DNA repair-deficient yeast mutant.

Z-Axinohydantoin and Debromo-Z-Axinohydantoin from the Sponge Stylotella aurantium: Inhibitors of Protein Kinase C

Abstract During the large scale isolation of the hymenialdisine and debromohymenialdisine, potent inhibitors of PKC, from Stylotella aurantium, we also isolated several related minor metabolites, two of which proved to be novel. The structures of these new compounds, Z-axinohydantoin (1) and debromo-Z-axinohydantoin (2), were determined by interpretation of spectral data. Z-Axinohydantoin (1) and debromo-Z-axinohydantoin (2), were found to be inhibitors of PKC with IC50values of 9.0 and 22 μM respectively.

lissoclin Disulfoxide, A Novel Dimeric Alkaloid from the Ascidian lissoclinum Sp.: Inhibitor of Interleukin-8 Receptors

Abstract Bioassay-guided fractionation of the MeOH extract of the South African ascidian Lissoclinum sp. yielded three known compounds plus a novel alkaloid, lissoclin disulfoxide (1), whose structure was determined by interpretation of spectral data. Alkaloid 1 had IC50 values of 0.6 and 0.82 μM against the inhibition of IL-8 Rα and IL-8 Rβ receptors, respectively.

A novel sterol peroxide from the sea anenome Metridium senile

Nine 5 alpha, 8 alpha-epidioxy delta 6 and delta 6,9(11) sterols were identified including the hitherto unknown (22E)-5,8-epidioxy-5 alpha, 8 alpha-stigmasta-6,9(11),22-trien-3 beta-ol 9 from the sea anenome Metridium senile based on 200 MHz 1Hnmr and mass spectral data.

Preulithiacyclamide, a New Cyclic Peptide from the Ascidian Lissoclinum patella

Abstract Bioassay-guided fractionation of the ethyl acetate extract of the tunicate Lissoclinum patella, collected in the Republic of Palau, yielded six known compounds reported previously from L. patella plus a new cyclic peptide, preulithiacyclamide (2), whose structure was determined primarily by interpretation of spectral data. Of the seven compounds, ulithiacyclamide (1) was found to be the most potent inhibitor of the Macrophage Scavenger Receptor (MSR) with an IC50 of 98 nM.

A diterpene epoxide from the marine brown alga Dictyota sp.: possible vasopressin V1 receptor antagonist.

A novel epoxide, in addition to eight known diterpenes, has been isolated from a marine brown alga of the genus Dictyota. The structures of these compounds were established by the interpretation and comparison of spectral data with literature data. Most of the isolates demonstrated vasopressin receptor antagonist activity in vitro with the new epoxide being the most active of the diterpenes tested.

Antibacterial constituents of the red alga cystoclonium purpureum

Abstract The red alga Cystoclonium purpreum was found to contain α-carotene, plastoquinone-9, trans -phytol, ubiquinol-9, lutein and fucoxanthin. The composition of the antibacterial fatty acid fraction was determined by GC/MS.