Herbal screening for malodor inhibition in vitro and in vivo

Introduction: Microbial putrefaction is a primary process in oral malodor generation. Anti-malodor agents are often tested for efficacy both in vitro and in vivo. Objective: This study assessed eight Asian natural herbs for ability to inhibit malodor both in vitro and in vivo. Methods: For in vitro testing, the salivary sediment mixed microbial system was used. Incubation mixtures were prepared with sediment at 16.7%(v/v), salivary supernatant at 33.3%(v/v), amino acids(cysteine or tryptophan) at 6mM and either herb extract at 1%(w/v) or water as control. Mixtures were incubated at 37oC and odor was monitored (i) organoleptically and (ii) for VSC with a sulfide monitor. This was done at intervals between 0 and 24h. At 24h, indole/skatole was determined by Kovac's colorimetric method. For in vivo testing, a test subject (following overnight fasting and oral hygiene avoidance) rinsed with 5 ml of 6mM cysteine for 30 seconds and VSC generation was followed with the sulfide monitor every 2 min for 20 min (i.e. baseline cysteine challenge determination). Each evaluation involved rinsing with 5 ml herbal solution for 30 sec and VSC measurements every 2 min for 20 min followed by cysteine challenges (i.e. 20 min) 6 times thereafter for up to 7 hours. Results: in vitro testing indicated that 3 of the herbs were inhibitory. These were Scutellaria baicalensis (SB), Angelica dahurica (AD) and Asarum sieboldii (AS). All three significantly reduced VSC, organoleptic odor and indole/skatole formation (p<0.05). The more stringent in vivo testing revealed anti-malodor activity only by SB. Initially, inhibition was 18%; thereafter, it was 36%. This mimicked earlier profiles seen with anti-microbial odor inhibitors. Magnolia officinalis (MO) known for its anti-microbial properties did not inhibit malodor. Conclusion: in vitro and in vivo testing identified SB as a potentially effective anti-malodor agent and suggests it is worthy of further exploration.