Maktoob Alam

Dinoflagellate sterols I: Sterol composition of the dinoflagellates of ? species

The sterol composition of five species of dinoflagellates of the family Gonyaulacaeae (Div. Pyrrhophyta) were examined. All the five species (Gonyaulax acatenella, G. tamarensis, G. catennela, G. washing-tonesis, and G. polyedra) were found to contain 4 alpha-23,24(R)-trimethyl-5 alpha-cholest-22-en-3 -ol (dinosterol) and cholesterol as major sterols.

The structure of PB-1, an unusual toxin isolated from the red tide dinoflagellate nttychodiscus brevis

The structure of PB-1, 1, an ichthyotoxin isolated from Ptychodiscus brevis was determined to be O,O-dĩnthenyl-N-cyclooctyl nthosnthoramidate.

Dinoflagellate sterols IV: Isolation and structure of 4α,23ξ,24ξ-trimethylcholestanol from the dinoflagellate Glenodinium hallii

Abstract The dinoflagellate Glenodinium hallii was investigated for its sterol composition. Five of the six sterols were isolated and identified as cholest-5-en-3β-ol, (24ξ)-24-methylcholest-5-en-3β-ol, stigmasta-5,22-dien-3β-ol, (22E,24R)-4α,23,24-trimethyl-5α-cholest-22-en-3β-ol, and 4α,23ξ,24ξ-trimethyl-5α-cholestan-3β-ol.

STEROL DISTRIBUTION IN THE GENUS HETEROCAPSA (PYRRHOPHYTA)1

The sterol composition of seven strains of marine peridinioid dinoflagellates comprising the four known species of Heterocapsa Stein was examined by gas chromatography‐mass spectrometry to determine the utility of these compounds in systematics. Cholest‐5‐en‐3β‐ol (cholesterol), 24‐methyl‐cholest‐5‐en‐3β‐ol (24‐methylcholesterol), 4α,24(S)‐dimethyl‐5α‐cholestan‐3β‐ol (4,24‐dimethylcholestanol), 4α,23,24(R)‐trimethyl‐5α‐cholest‐22‐en‐3β‐ol (dinosterol), 4α,23ξ,24ξ‐trimethyl‐5α‐cholestan‐3β‐ol (dihydrodinosterol), and an unknown sterol were detected. Sterol composition does not vary significantly from species to species within the genus Heterocapsa and thus cannot be used for species differentiation. Sterols may, however, have value in defining the properties of dinoflagellate taxa above the family level. Over the course of the growth curve for Heterocapsa niei (Loeblich) Morrill & Loeblich 4,24‐dimethylcholestanol and dinosterol covaried, suggesting that 4,24‐dimethylcholestanol is converted into dinosterol by a previously proposed bioalkylation scheme.

About gonyautoxins-I, -II, -III, and -IV

Abstract The identity of recently reported neurotoxins from Gonyaulax excavata and Bay of Fundy scallops with previously described gonyautoxins is suggested.

Crooksidine, an indole alkaloid from Haplophyton crooksii

Abstract Crooksiine, a new bisindole alkaloid with antiacetylcholinesterase activity was isolated from Haplophyton crooksii . Its structure was established utilizing spectrometric methods.

Isolation and structure of a cytotoxic epoxy sterol from the marine mollusc Planaxis sulcatus

A novel epoxy sterol isolated from the marine mollusc Planaxis sulcatus has been identified as 9 alpha,11 alpha-epoxycholest-7-ene-3 beta,5 alpha,6 beta-triol by spectrometric methods.

Applications of cosy and homonuclear relay 2D-NMR in the determination of the structure of new cembrane isolated from the mollusc planaxis sulcatus

Abstract Proton-proton homonuclear chemical shift correlation (COSY) and homonuclear relayed coherence transfer (RELAY) have been used to establish the structure of 3,11-diacetoxy-15,16-dehydrocembran-6-one.

Isolation and crystal structure of 5-hydroxy-2,8-dimethyl-6,7-dimethoxybenzopyran-4-one from Couepia paraensis

Abstract A highly substituted chromone constituent of Couepia paraensis was isolated and identified as 5-hydroxy-2,8-dimethyl-6,7-dimethoxychromone by spect

Chemical Studies on Toxins from the Blue-Green Alga Aphanizomenon Flos-Aquae

Natural blooms of the blue-green alga Aphanizomenon flos-aquae occur periodically in the lakes of the northern United States and in certain provinces of Canada. These blooms have been reported to cause poisoning in fish and cattle. Investigation of the toxins of A. flos-aquae indicates that this alga contains three toxins in addition to saxitoxin. The aphantoxins appear to have a chemical structure similar to saxitoxin.