Oleo gum resins are plant exudates commonly used in folk medicine for treating several disease
conditions. Anti-cariogenic properties of essential oil (E. oil) and crude extracts obtained from
Boswellia frereana (B. frereana), Boswellia carterii (B. carterii) and Commiphora myrrha
(C. myrrha) were investigated. Methanol and acetone extracts of the three plants inhibited
Streptococcus mutans (S. mutans) and Lactobacillus spp. growth. Hexane extracts showed
low anti-microbial activity. The average microbial inhibition was 14.6 mm for S. mutans and
13.8 mm for Lactobacillus spp. regardless of solvent type. B. frereana produced 8% E. oil
while B. carterii and C. myrrha gave 5% and 6%. B. frereana E. oil inhibited S. mutans and
Lactobacillus spp. more than B. carterii and C. myrrha E. oils.