Methods: The PDL tissue was scraped from the roots of freshly extracted teeth to enzymatically digest using collagenase. The cells were sub-cultured. Flow-cytometric analysis for the MSC surface-markers CD105, CD73, CD166, CD90, CD34, CD45 and HLA-DR was performed. To confirm the phenotype, total RNA was extracted to synthesize cDNA and which was then subjected to RT-PCR. The gene-expression for Oct4A, Sox2, NANOG and GAPDH was determined by gel-electrophoresis. To assess their multilineage potential, cells were cultured with osteogenic, chondrogenic and adipogenic medium and then stained by Alizarin-red, Alcian-blue and Oil-Red-O respectively. MSCs from the bone-marrow were processed similarly to serve as controls.

Results: The cells isolated from extracted teeth expanded successfully. On flow-cytometric analysis, the cells were positive for CD73, CD90, CD105, CD166 and negative for CD34, CD45 and HLA-DR. The PDLSCs expressed Oct4A, Sox2, and NANOG mRNA with GAPDH expression. Cells cultured in the osteogenic, chondrogenic and adipogenic media stained positive for Alizarin-red, Alcian-blue and Oil- Red-O respectively. The surface marker expression and the trilineage differentiation characteristics were comparable to those of the BMMSCs.

MATERIALS AND METHODS: In silico Molecular Dynamics (MD) was used to determine the interactions of K21 inside the pocket of the targeted protein (crystal structure of fibroblast collagenase-1 complexed to a diphenyl-ether sulphone based hydroxamic acid; PDB ID: 966C; Crystal structure of MMP-2 active site mutant in complex with APP-derived decapeptide inhibitor. MD simulations were accomplished with the Desmond package in Schrödinger Drug Discovery Suite. Blood samples (~ 0.5 mL) collected into K2EDTA were immediately transferred for further processing using the Litron MicroFlow® PLUS micronucleus analysis kit for mouse blood according to the manufacturer's instructions. Bacterial Reverse Mutation Test of K21 Molecule was performed to evaluate K21 and any possible metabolites for their potential to induce point mutations in amino acid-requiring strains of Escherichia coli (E. coli) (WP2 uvrA (tryptophan-deficient)).

RESULTS: Molecular Simulation depicted that K21 has a specific pocket binding on various MMPs and SrtA surfaces producing a classical clouting effect. K21 did not induce micronuclei, which are the result of chromosomal damage or damage to the mitotic apparatus, in the peripheral blood reticulocytes of male and female CD-1 mice when administered by oral gavage up to the maximum recommended dose of 2000 mg/kg. The test item, K21, was not mutagenic to Salmonella typhimurium (S. typhimurium) strains TA98, TA100, TA1535 and TA1537 and E. coli strain WP2 uvrA in the absence and presence of metabolic activation when tested up to the limit of cytotoxicity or solubility under the conditions of the test.