Regarding differences between both investigated species, C.
arabica cv. Yellow Bourbon extracts showed similar inhibitory
activity on the growth of S. mutans when compared to C. canephora
cv. Conillon. No significant difference was observed between the
numbers of CFU of both species (Table 4). In the biofilm formation
assays, however, while C. arabica cv. Yellow Bourbon extract did
not inhibit the biofilm formation at tested concentrations, C. canephora cv. Conillon showed an inhibition of 39.6% (compared to
91.7% of the positive control chlorhexidine) at 90 mg/mL, a concentration similar to that commonly used in Brazil and other countries for coffee preparation (100 mg/mL). As far as we know, this is the first study evaluating the inhibitory activity of coffee on biofilm formation, but it is possible that the anti-adhesive property reported for coffee (Daglia et al., 2002) is related to this activity. Considering that the contribution of caffeine for the anti-adhesive
property of coffee has previously been discarded (Daglia et al.,
2002), the possible involvement of chlorogenic acids and their lactones in such activity should be investigated, since the amount of both classes of compounds in the active C. canephora extract (6 min roasted) was about 27% and 73% higher than in C. arabica,
respectively.