Use of an isolated guinea-pig ileum assay to detect bioactive compounds in microalgal cultures

An isolated guinea-pig ileum preparation was used to screen for bioactive compounds from algae. 212 culture supernatants and methanolic extracts of randomly chosen marine and freshwater algae were tested for their effect on electrically evoked muscle contractions (recorded as a change in tension) and on the resting muscle tone. 15 out of 42 (35%) of the marine algae tested and 5 out of 64 (8%) of freshwater algae gave positive results. Of the 20 algae giving positive results, 6 had previously been shown to produce bioactive compounds (mainly toxins) but we can find no reports in the literature of bioactive compounds from the remaining 14. Of these 14 cultures, 9 were axenic and therefore production of the biological activity can be assigned unambiguously to the alga. These results confirm the usefulness of the guinea-pig ileum preparation as a screen for bioactive compounds from microbial cultures.