5595 John Emsley: New hope in the fight against fungi. New Scientist 28 August 1993, 15. Varacin is a recently synthesized natural compound which is very active against the fungus Candida albicans. The fungus causes thrush in humans and can also cause horrific infections of the throat and lungs in people with AIDS. Varacin is also active against tumour cells which form in the human colon, indicating that it damages the DNA of a fungus or tumour.