Complex sentence: Cyanobacteria produce the potent toxins which are the subject of the rest of this article, but they also produce useful bioactive compounds which are non-toxic, including substances with antitumour, antiviral, anti-cancer, antibiotic and antifungal activity, UV protectants and specific inhibitors of enzymes.
Split into simpler sentences: Cyanobacteria produce the potent toxins which are the subject of the rest of this article. But they also produce useful bioactive compounds which are non-toxic, including substances with antitumour, antiviral, anti-cancer, antibiotic and antifungal activity, UV protectants and specific inhibitors of enzymes.