Characterization of marine toxin(s) in Myripristis sp. by immunological, mouse toxicity, and guinea pig assays

Myripristis sp. (squirrelfish) has been assessed for toxicity by 1) the stick‐enzyme immunoassay (S‐EIA); 2) mouse toxicity bioassay; and 3) guinea pig atrial assay. Analysis of Myripristis flesh with MAb‐CTX and MAb‐OA showed that with every fish examined, the reaction with MAb‐OA was considerably higher. The mean S‐EIA value for MAB‐OA was 2.9 ± 0.8 while the mean for MAb‐CTX was 1.7 ± 0.5. The data strongly suggests that Myripristis sp. appear to contain okadaic acid‐like toxins and/or mixed with CTX. Five fractions of the flesh extracts were obtained by silica gel chromatography. These included 100% CHC13, 10% MeOH/CHC13, 50% MeOH‐CHC13, 100% MeOH, and 80% MeOH/H2O. The 100% CHC13 eluate proved to be the most toxic (mouse killed in 32 minutes) and the 10% MeOH‐CHC13 fraction killed in approximately 48 hours. The remaining fractions showed a significantly lower toxicity level in mice. In the guinea pig atria examinations, extracts of Myripristis flesh, gut, and crustacea (from the gut) were studied. Extracts of the gut and crustacea showed strong sodium channel blockage, while the flesh extracts showed a weak inotropic effect, characteristic of okadaic acid. The latter response was only blocked by verapamil, but not with tetrodotoxin (10−5M) or the adrenergic blockers (10−5M). The data from this study suggest toxic compound(s) not previously reported, in the non‐polar fraction of Myripristis flesh having a sodium channel blockage effect. © 1993 Wiley‐Liss, Inc.