Evaluation of the cytotoxicity, genotoxicity, and antifungal activities of race-index compounds from the red alga Laurencia nipponica

The multivariate analytical approach based on LC/MS chemical constituent data differentiated the three chemical races of Laurencia nipponica, i.e., laurencin (1)-, laurallene (2)-, and prepacifenol-producing races, according to the first report of chemical races in the 1990s. The race-index compounds (1 and 2), prepacifenol structural isomer pacifenol (3), and another brominated compound laureatin (4), were isolated from each corresponding race. The compounds (1–4) were subjected to cytotoxicity and genotoxicity assays using the human lymphoblastoid TK6 cell line, as well as antifungal activity assays against Aspergillus niger and Penicillium citrinum. Among them, only 2 showed cytotoxicity against TK6 cells at concentrations of 5.0 and 10.0 μg mL⁻¹. In genotoxicity assays, DNA migration and chromosome aberrations were observed in 2 at cytotoxic concentrations, suggesting that the compound’s cytotoxicity was induced by genotoxic factors such as DNA and chromosome damage. In acridine orange (AO)/ethidium bromide (EB) staining, TK6 cells treated with 2 were stained with EB but not AO, implying that the compound’s genotoxic effects caused necrotic cytotoxicity. None of the four compounds (1–4) showed fungicidal activity against A. niger and P. citrinum. Thus, the multivariate approach facilitates detection of races. Moreover, this study reveals new biological activity information about race-index compounds whose ecological roles have not yet been characterized.