The toxic properties of a number of simple hydroxy and methoxy flavanones and chalkones have been studied using fresh-water fish. The flavanones resemble the flavones in a general way. However the methyl ethers of the flavanones appear to be less toxic than the corresponding flavone derivatives, whereas with the hydroxy compounds the reverse seems to be the case.

With the chalkones the toxic symptoms set in more slowly but they are more persistent. The methoxy chalkones are less toxic than the isomeric flavanones whereas when a number of hydroxyl groups are present the reverse is the case. As soon as all the hydroxyl groups in chalkones are methylated the toxicity increases considerably.