Allantoin, dipotassium glycyrrhizinate, and azulene sulfonate sodium hydrate inhibit gingival inflammation induced by advanced glycation end products via antiglycation effects <i>in vitro</i>

Advanced glycation end products (AGEs) influence periodontal disease onset and progression by denaturing proteins in the periodontal tissues and inducing inflammation. Therefore, inhibiting both AGE formation itself and the AGE-induced inflammation would be effective for preventing periodontal disease. This study aimed to find anti-inflammatory ingredients in oral-care products that also exhibit AGE formation inhibitory effect. We evaluated in vitro the AGE formation inhibitory effects of five ingredients with known anti-inflammatory effects in oral-care products: allantoin (ALA), 6-aminohexanoic acid, dipotassium glycyrrhizinate (GKII), lysozyme chloride, and azulene sulfonate sodium hydrate (AZU). Furthermore, in order to assess the implications of the antiglycation effect of these ingredients in periodontal disease, human gingival fibroblasts (HGFs) were treated with AGEs formed in the presence or absence of each ingredient, and the IL-6 expression level in the culture supernatant was analyzed by enzyme-linked immunosorbent assays. Our results showed that ALA, GKII, and AZU inhibited AGE formation in vitro. In addition, compared with bovine serum albumin (BSA) incubated with glyceraldehyde only (i.e. glyceraldehyde-derived AGE), BSA incubated with glyceraldehyde in the presence of each component inhibited IL-6 production from HGFs in vitro, suggesting that these components may prevent gingival inflammation by preventing the formation of AGE. Our in vitro results suggest the possibility that these oral-care product ingredients can help prevent periodontal disease by two distinctive functions-antiglycation and anti-inflammation.