Antimicrobial Activity of Capsaicinoids

The chemicals in the pods of hot peppers responsible for pungency (perceived heat) are Capsaicinoids, of which there are over 12 similar compounds that are present in varying concentrations.  The two principle Capsaicinoids are capsaicin and dihydrocapsaicin.  These two compounds typically represent between 80-95% of the total Capsaicinoids.  Studies of these two compounds have shown antimicrobial (germ killing) properties against a variety of organisms.  While investigating Mayan medicinal practices researchers have “discovered” the use of Capsicum tissues as treatments for a variety of ailments of microbial (bacterial / fungal) origin.  These researchers tested various tissues of a variety of hot peppers for their antimicrobial properties and compared them to controls.  In their tests, they prepared pepper tissue extracts from the fruit or leaves either cooked or uncooked from cultivars of the 5 domesticated species, namely C. annuum, baccatum, chinense, frutescens, and pubescens and tested them against a number of commonly troublesome bacteria and one yeast (Bacillus, Clostridium, Streptococus, Escherichia,  and Candida).  In addition to the tissue extracts, the researchers tested the activity of pure capsaicin and dihydrocapsaicin and both showed no antimicrobial activity.  The tissue extracts showed a variety of activities ranging from complete inhibition (absence of microbial growth), partial inhibition (reduced microbial growth), to stimulation (increase microbial growth).  In particular, the yeast, Candida albicans, was stimulated by the extracts; Bacillus was partially inhibited by both cooked and uncooked leaf extract of C. annuum; Clostridium were completely or partially inhibited by the extracts; and Streptococcus was inhibited.  Although one cannot extrapolate the effects of the above results to those within the body (in vitro versus in vivo), these result clearly indicate that peppers have antimicrobial properties.

[1] Cichewicz, R. H., Thorpe, P. A., The antimicrobial properties of chile peppers (Capsicum species) and their uses in Mayan medicine, Journal of Ethnopharmacology 52 (1996) 61-70