Abstract:
The aim of the present study was to evaluate total phenolic, flavonoid
contents and in vitro antioxidant activity of four different solvents [acidified
70% aqueous acetone (AAD), 70% aqueous acetone (AD), acidified 80%
aqueous methanol (AMD) and 80% aqueous methanol (MD)] extracts
obtained from Canna (red) flowers. The crude extracts were prepared by
steeping method in the dark conditions from oven dried Canna (red)
flowers collected from Galle district in Sri Lanka. The freeze dried
powders of crude extracts were subjected to preliminary phytochemical
tests. The total phenolic and flavonoid contents and in vitro antioxidant
activity of the four different extracts were evaluated by Folin-Ciocalteu
assay, aluminium chloride colorimetric method and 2,2-diphenyl-1-
picrylhydrazyl (DPPH) assay respectively. The results of the preliminary
phytochemical screening exhibited the presence of phenolic compounds,
flavonoids, quinones, carbohydrates, reducing sugars and saponins and
absence of alkaloids in all four extracts. The results of the total phenolic
content of the four different extracts were 5389.067±681.343 (AAD),
4172.308±333.424 (AD), 4624.662±255.258 (AMD) and
4195.533±342.593 (MD) mg Gallic acid equivalent (GAE)/100 g dry
weight (DW) of flowers. Total flavonoid content of the four different
extracts were 6017.442±158.343 (AAD), 3023.633±450.899 (AD),
2973.658±233.448 (AMD) and 2205.822±379.418 (MD) mg Catechin
equivalents (CAE)/100 g DW of flowers. Antioxidant capacity of the four
different extracts were 17.430±2.673 (AAD), 15.401±2.452 (AD),
16.512±1.440 (AMD) and 14.752±3.154 (MD) mmol Trolox
equivalents/100 g DW of flowers. The results indicated that acidified 70%
aqueous acetone extract of Canna (red) contains significantly high total
phenolic and flavonoid contents as well as promising antioxidant activity.