Observatory Marijuana may be something of a wonder drug — though perhaps not in the way you might think. Researchers in Italy and Britain have found that the main active ingredient in marijuana — tetrahydrocannabinol, or THC — and related compounds show promise as antibacterial agents, particularly against microbial strains that are already resistant to several classes of drugs. It has been known for decades that Cannabis sativa has antibacterial properties. Experiments in the 1950s tested various marijuana preparations against skin and other infections, but researchers at the time had little understanding of marijuana’s chemical makeup.