To compare the cytotoxicity of six medicinal plants (
) using 3-(4, 5-
dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red uptake (NRU) assays.
Hexane, chloroform, ethyl acetate, ethanol, methanol and water extracts were obtained for
each plant by sequential solvent extraction. Cytotoxicity was evaluated in triplicate, from 640 to 5 μg/mL,
two-fold, serially on monkey kidney epithelial (Vero) cells.
The hexane, chloroform and ethyl acetate extracts of the six plants were more toxic to the
Vero cells compared to the ethanol, methanol and water extracts. Thirty one percent (11/36) and 75 %
(27/36) of the extracts showed significant cytotoxicity (p < 0.05) in MTT and NRU assays, respectively.
The 78, 52 and 7 % cytotoxicity levels detected in 27 extracts using the MTT assay were significantly (p
< 0.05) underestimated at 640, 320 and 160 μg/mL, respectively, using NRU assay. Nine extracts from
five plants exhibited significantly lower (p < 0.05) 50 % cytotoxic concentration (CC50
) when NRU assay
was employed compared to MTT assay. At 640 μg/mL, 10 of the 21 extracts were also found to react
chemically with MTT, causing a 2.0 – 29.1-fold increase in the absorbance value (550 nm) compared to
The plant extracts of A. ciliata
, A. tricolor
, C. sativum
, G. coronaria
, K. brevifolia
show concentration- and extraction method-dependent cytotoxicity using MTT and NRU assays.
NRU assay appears to be more sensitive and reliable than MTT assay for cell viability evaluation of the