1,720,999 research outputs found
Starfish Saponins, Part 51. Steroidal Oligoglycosides from the Starfish Distolasterias nipon
No full textA reinvestigation of the exts. from the starfish Distolasterias nipon, collected at Mutsu Bay, Japan, has led to the isolation of six glycosides of polyhydroxysteroids and six asterosaponins. Four steroidal glycosides have been identified as distolasterosides D1 and D2 (previously isolated from the same organism), and pycnopodioside C and pisasteroside A, previously found in the related species Pycnopodia helianthoides and Pisaster ochraceus (family Asteridae), resp. Two asterosaponins have been identified as the common versicoside A and thornasteroside A. The 2 remaining glycosides of polyhydroxysteroids, named distolasterosides D4 and D5, and 4 asterosaponins designated nipoglycosides A, B , C, and D are new compds., and their structures have been elucidated mainly by interpretation of spectral data and comparison with known compds
Starfish saponins, 45. Novel sulfated steroidal glycosides from the starfish Astropecten scoparius
No full textFive sulfated steroidal glycosides were isolated from the aq. exts. of the whole bodies of the starfish A. scoparius. One of them was identified as indicoside B, a sulfated steroidal xylofuranoside previously isolated from A. indicus, and the remaining 4 are new compds. Three of them, scopariosides A, B, and C (I, II, and III, resp.) have the same (24SS)-5a-cholestane-3β,6α,8,15β,24-pentaol aglycon as indicoside B but differ in the sugar moieties. The aglycon is also present in the aq. exts. as 24-O-sulfate deriv. The 4th new glycoside, scoparioside D (IV) was also identified. These glycosides are accompanied by 4 known polyhydroxysteroids and 1 known asterosaponin, the hexaglycoside marthasteroside A1
Starfish Saponins, 52. Chemical Constituents from the Starfish Echinaster brasiliensis
No full textThis paper reports an anal. of the chem. constituents from the Caribbean starfish E. brasiliensis collected at Grand Bahama Island. This species is completely devoid of cyclic steroidal glycosides, previously isolated from 2 species of Echinaster in place of the more common penta- and hexa-glycoside steroidal sulfates (asterosaponins). Two typical asterosaponins and 10 glycosides of polyhydroxysteroids were instead isolated in relatively large amts. from E. brasiliensis. The asterosaponins include the known marthasteroside A1 and the new brasiliensoside, while the glycosides of polyhydroxysteroids include 7 new compds. (6 monoglycosides and 1 diglycoside). The known echinasteroside A, previously found in E. sepositus and in the related Henricia laeviuscula (both belonging to the family Echinasteridae), and laeviusculosides C and I from H. laeviuscula were also isolated. Most of the glycosides from E. brasiliensis are 3-O-β-xylopyranosides of Δ4-3β,6β,8,15α,15β-pentahydroxysteroid aglycons, having different side chains and sometimes a sulfate group at C-15, structural features which are typical of steroidal glycosides from starfishes of the family Echinasteridae. Continuing the anal. of the constituents of E. brasiliensis, the authors have also isolated a series of anthraquinones, known animal pigments found only in echinoderms and particularly in Crinoidea and in the Echinasteridae family of Asteroidea
Starfish saponins, part 46. Steroidal glycosides and polyhydroxysteroids from the starfish Culcita novaeguineae
No full textA reinvestigation of the exts. from the starfish c. novaguineae has led to the isolation of 11 polyhydroxysteroidal glycosides and 5 polyhydroxysteroids. One of them has been identified with culcitoside C1, previously isolated from the same organism. Nine are known compds. previously found in starfishes, the majority having been isolated from the related species Halitle regularis. Six are new compds. and include 1 polyhydroxysteroid (I) and 5 steroid diglycosides, designated culcitosides C4, C5, C6, C7, and C8. All compds. have been obtained in very small amts., ranging from 9.2 to 2 mg from 3.8 kg of fresh organism. A 2nd group of compds. isolated from C. novaguineae consists of phosphorylglyceryl ethers
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Starfish saponins, part 41. Structure of two new steroidal glycoside sulfates (miniatosides A and B) and two new polyhydroxysteroids from the starfish Patiria miniata
No full textTwo new sulfated steroidal glycosides, miniatoside A (I) and miniatoside B were isolated from the H2O exts. of the whole bodies of the starfish P. miniata. They co-occur with known sulfated steroidal monoglycosides and seven polyhydroxysteroids, among which two are new
Two novel polyhydroxysteroids with a 24-ethyl-25-hydroxy-26-sulfoxy side chain from the deep water starfish Styracaster caroli
No full text- …
