In order to search for bioactive natural products from marine algae, the chemical constituents of red alga Laurencia saitoi was separated by the combination of normal phase silica gel, Sephadex LH-20 column chromatography and recrystallization. Seven compounds: aplysistatin (1), 5-acetoxypalisadin B (2), palisadin B (3), palisadin A (4), pacifigorgiol (5), stigmast4-en-3alpha, 6beta-diol (6), 2, 3, 5, 6-Tetrabromoindole (7), were isolated and their structures were elucidated by spectroscopic methods including 1H-NMR, 13C-NMR and MS techniques. All compounds were isolated from L. saitoi for the first time. Cytotoxicities of purified compounds were evaluated by MTT method, however, all of them were found inactive (IC50 >10 mg x L(-1).
Cell Line, Tumor ; Humans ; Inhibitory Concentration 50 ; Laurencia ; chemistry ; Organic Chemicals ; chemistry ; isolation & purification ; pharmacology

OBJECTIVETo search for chemical constituents with structural diversity from Laurencia tristicha to supply for biological assay.

METHODCompounds were isolated by means of column chromatography over normal phase silica gel and Sephadex LH-20, recrystallization and HPLC. Structures were identified by spectroscopic methods including 1D NMR, IR and MS. Cytotoxicities of the purified compounds were evaluated by MTT method.

RESULTSeven compounds were isolated from L. tristicha. Their structures were elucidated as cholesterol (1), cholesta- 5-en-3beta, 7alpha-diol (2), beta-stigmasterol (3), phytol (4), zeaxanthin (5), 4 -hydroxybenzaldehyde (6), indolyl-3-carbaldehyde (7). In the cytotoxic assay compound 2 was active against human cancer cell lines HCT-8, Bel-7402, BGc-823, A549 and HELA with IC50 values of 1.90, 2.02, 1.99, 6.52 and 1.20 microg x mL(-1), respectively. Compound 4 showed cytotoxicity against HCT-8 and HELA with IC50 value of 3.51 and 2.04 microg x mL(-1), and other compounds were inactive ( IC50 > 10 microg x mL(-1)).

CONCLUSIONCompounds 1-7 were isolated from L. tristicha for the first time. In additon, compounds 2 and 4 were cytotoxic against several human cancer cell lines.

Antineoplastic Agents ; chemistry ; isolation & purification ; pharmacology ; Cell Line, Tumor ; drug effects ; Cholestenes ; chemistry ; isolation & purification ; pharmacology ; Cholesterol ; chemistry ; isolation & purification ; pharmacology ; Humans ; Inhibitory Concentration 50 ; Laurencia ; chemistry ; Phytol ; chemistry ; isolation & purification ; pharmacology