title: Cytotoxicity evaluation of Clinacanthus nutans through dimethylthiazol diphenyltetrazolium bromide and neutral red uptake assays.
abstract: OBJECTIVE
  The aim of this study was to compare the results of dimethylthiazol diphenyltetrazolium bromide (MTT) and neutral red uptake (NRU) assays of Clinacanthus nutans cytotoxicity.
  
  
  METHODS
  Mouse fibroblast (L929) cells were exposed to 0.01%, 0.1%, 0.25%, and 0.5% (W/V) C. nutans in a 96-cluster-well-culture plate for 24 h. The cell viability after exposure to C. nutans was determined by MTT and NRU assays in separate tissue culture plates. The two assays were compared through an intra-class correlation coefficient (ICC) analysis.
  
  
  RESULTS
  No significant differences in cytotoxicity were noted between the two assays (P > 0.05). The ICC values for agreement between two assays for the negative and positive control groups and C. nutans concentrations of 0.01%, 0.1%, 0.25%, and 0.5% were 0.84, 0.83, 0.77, 0.68, 0.74, and 0.71, respectively.
  
  
  CONCLUSIONS
  In general, the MTT and NRU assays performed similarly, exhibiting moderate to good correlation for the evaluation of the cytotoxicity of C. nutans.
authors.affiliation: Endodontics Section, Faculty of Dental Medicine, Rangsit University, Pathumthani, Thailand.
authors.forename: La-Ongthong
authors.initials: LO
authors.lastname: Vajrabhaya
authors.affiliation: Endodontics Section, Faculty of Dental Medicine, Rangsit University, Pathumthani, Thailand.
authors.forename: Suwanna
authors.initials: S
authors.lastname: Korsuwannawong
keywords: Clinacanthus nutans; dimethylthiazol diphenyltetrazolium bromide; intra-class correlation coefficient; neutral red uptake