Berberine is the primary alkaloid found in barberry. Research appearing in Annals of Tropical Medicine and Parasitology (1991 Aug;85(4):417-25) examined the effects of berberine sulfate on various microorganisms. In vitro studies (performed in Petri dishes with nutrient media) showed that berberine inhibited growth and caused damaging cellular changes in Entamoeba histolytica, Giardia lamblia, and Trichomonas vaginalis. The researchers also observed morphological changes in the parasites. The authors concluded, “These observations demonstrate that, in vitro, this drug (berberine) was effective against E. histolytica, G. lamblia and T. vaginalis.”
Berberine has also demonstrated antibacterial activity against Streptococcus species. Research published in Antimicrobial Agents and Chemotherapy (1988;32:1370-1374) found that berberine sulfate was bacteriostatic for streptococci. In addition, low concentrations of berberine were shown to block the adherence of streptococci to host cells, a mechanism that may reduce bacterial colonization under laboratory conditions.
