170
A. Sultana and U. Ghosh
where
A = weight of empty crucible (gm),
B = weight of crucible and sample (gm), and
C = weight of crucible and ash (gm).
3.4 Determination of FRAP Activity
The FRAP assay was determined according to the method of Li et al. (2012). In this
process, ferric (Fe3 +) ion was reduced to ferrous (Fe2 +) ion and the intensive blue
color was observed because of the formation of ferrous-tripyridyl-s-triazine (TPTZ)
at maximum absorbance of 593 nm. Absorbance was measured after 8 min and was
proportional to the combined ferric reducing/antioxidant power of the antioxidants in
the extracts. The percentage of inhibition of DPPH by the leaf extract was calculated
according to the following equation:
% of Inhibition =
1 − A test sample /A blank
× 100
where
A blank = absorbance of the methanolic blank and
A test sample = absorbance of the leaf extracts.
3.5 Determination of Total Phenol Content
Total phenol content was determined by using Folin–Ciocalteu reagent as described
by Li et al. (2012) and Pieroni et al. (2011). The absorbance of the reaction mixture
was read at 765 nm using a (U-1800, HITACHI, Tokyo, Japan) spectrophotometer.
The results were expressed as mg gallic acid equivalent/g dry weight (mg GAE/g
DW). Results were expressed of three independent extractions.
3.6 Determination of Total Anthocyanin Content
The total anthocyanin pigment content was estimated by the pH differential method
(Lee et al. 2005). 1 g of the defatted sample was extracted with 1 ml of acetonitrile
containing 4% acetic acid. The absorbance was measured at 510 nm and 700 nm
in buffers at different pH levels (pH 1.0 and 4.5). The total monomeric anthocyanin
was calculated by using the following equation:
A = [(A 510 − A 700 ) × pH1.0 − (A 510 − A 700 ) × pH4.5]
A. Sultana and U. Ghosh
where
A = weight of empty crucible (gm),
B = weight of crucible and sample (gm), and
C = weight of crucible and ash (gm).
3.4 Determination of FRAP Activity
The FRAP assay was determined according to the method of Li et al. (2012). In this
process, ferric (Fe3 +) ion was reduced to ferrous (Fe2 +) ion and the intensive blue
color was observed because of the formation of ferrous-tripyridyl-s-triazine (TPTZ)
at maximum absorbance of 593 nm. Absorbance was measured after 8 min and was
proportional to the combined ferric reducing/antioxidant power of the antioxidants in
the extracts. The percentage of inhibition of DPPH by the leaf extract was calculated
according to the following equation:
% of Inhibition =
1 − A test sample /A blank
× 100
where
A blank = absorbance of the methanolic blank and
A test sample = absorbance of the leaf extracts.
3.5 Determination of Total Phenol Content
Total phenol content was determined by using Folin–Ciocalteu reagent as described
by Li et al. (2012) and Pieroni et al. (2011). The absorbance of the reaction mixture
was read at 765 nm using a (U-1800, HITACHI, Tokyo, Japan) spectrophotometer.
The results were expressed as mg gallic acid equivalent/g dry weight (mg GAE/g
DW). Results were expressed of three independent extractions.
3.6 Determination of Total Anthocyanin Content
The total anthocyanin pigment content was estimated by the pH differential method
(Lee et al. 2005). 1 g of the defatted sample was extracted with 1 ml of acetonitrile
containing 4% acetic acid. The absorbance was measured at 510 nm and 700 nm
in buffers at different pH levels (pH 1.0 and 4.5). The total monomeric anthocyanin
was calculated by using the following equation:
A = [(A 510 − A 700 ) × pH1.0 − (A 510 − A 700 ) × pH4.5]