Inhibition of photosynthetic O2 evolution of Anabaena sp. PCC 7120 by addition of different fractions of the solid phase extraction (SPE) of M. spicatum extract (1, water; 2, 25% [v/v] MeOH; 3, 50% [v/v] MeOH; 4, 75% [v/v] MeOH; and 5, 100% [v/v] MeOH). The amount of extract used in the experiments was equivalent to 190 μg TAE mL−1. Error bars indicate se; n = 3 to 7 measurements per treatment. Significant differences between treatment and control are shown by an asterisk (Mann Whitney U-test, P < 0.05, experimentwise Bonferroni adjusted).