19.8.12 Antioxidant Activity
Popović et al. (2013) investigated the antioxidant activity and functional properties
of cucurbitin extracted from pumpkin oil cake and enzymatically hydrolyzed by
pepsin, alcalase, and flavourzyme enzymes. The results of the study revealed that
cucurbitin hydrolysate obtained by alcalase and pepsin showed antioxidant potential
when compared with flavourzyme hydrolysates. The alcalase hydrolysate (at 25.6%
degree of hydrolysis) showed reducing power of 0.25 Æ 0.01 A700 nm and ABTS
(2,2
0 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) scavenging activity was
found to be 3.34 Æ 0.02 mmol/L Trolox equivalent antioxidant coefficients (TEAC).
In a study conducted to demonstrate the antioxidant and lipoxygenase inhibitory
activities of pumpkin seeds, extracts were prepared using solvents of decreased
polarity (water, methanol, acetone, and ethylacetate) from four varieties of pumpkin
seeds. The lipid fractions were extracted using the Folch method, polar and neutral
lipids were separated using a counter-current distribution extraction method. The
total extractable phenolic content was highest (85–92%) in water extracts with
54–64 μmol gallic acid equivalents followed by 7–15% of total extractable phenolics
and 5–11 μmol gallic acid in methanol extract. The highest 2, 2-diphenyl-1picrylhydrazyl (DPPH) radical scavenging activity was recorded in water
(4.63–6.71 mg/mL expressed as E50 values) and methanol extracts
(4.40–5.42 mg/mL expressed as E50 values) whereas ethylacetate extracts demonstrated lowest scavenging activity. The polar lipid fractions were found to have more
potent antioxidant activity compared to neutral lipid fractions. The inhibitions of
soybean lipoxygenase activity were stated as 34–60% and 50% for water and
methanol extracts, respectively. The lipid peroxidation inhibition was found to be
greater in acetone extracts (34.71–100%) (Xanthopoulou et al. 2009).
Saavedra et al. (2013) studied the effect of different drying methods and extraction solvents on antioxidant and total phenolic content of the seeds and shell of
squash pumpkin. The results revealed that among the drying methods, the ovendried samples were found to have higher antioxidant and phenolic content, whereas
among the shell and seeds, the shell samples reportedly had higher antioxidant
(1.47–70.96% inhibition of DPPH radicals) and phenol content values
(2.00–10.69 mg GAE/g DW).
Protein isolate from pumpkin oil cake (POCPI) obtained using food-grade
enzymes namely trypsin and alcalase was studied for antioxidative activities by
Nourmohammadi et al. (2017). The authors observed that alcalase-hydrolyzed
POCPI 1 exhibited better antioxidant activities in terms of total antioxidative potential, ferrous ion chelating activities, and DPPH radical scavenging activity. Also, the
amount of hydrophobic amino acids (33.49%) demonstrated a direct relationship
between alcalase-hydrolyzed POCPH 1 and the antioxidative activity.
In another study by Bardaa et al. (2016), β-carotene/linoleic acid bleaching test
was conducted to ascertain the inhibition of lipid peroxidation of pumpkin seed oil.
The results revealed that pumpkin seed oil showed higher lipid peroxidation inhibitory activity than BHT which could be attributed to its tocopherol content.
19 Pumpkin (Cucurbita pepo) Seed
493
Popović et al. (2013) investigated the antioxidant activity and functional properties
of cucurbitin extracted from pumpkin oil cake and enzymatically hydrolyzed by
pepsin, alcalase, and flavourzyme enzymes. The results of the study revealed that
cucurbitin hydrolysate obtained by alcalase and pepsin showed antioxidant potential
when compared with flavourzyme hydrolysates. The alcalase hydrolysate (at 25.6%
degree of hydrolysis) showed reducing power of 0.25 Æ 0.01 A700 nm and ABTS
(2,2
0 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) scavenging activity was
found to be 3.34 Æ 0.02 mmol/L Trolox equivalent antioxidant coefficients (TEAC).
In a study conducted to demonstrate the antioxidant and lipoxygenase inhibitory
activities of pumpkin seeds, extracts were prepared using solvents of decreased
polarity (water, methanol, acetone, and ethylacetate) from four varieties of pumpkin
seeds. The lipid fractions were extracted using the Folch method, polar and neutral
lipids were separated using a counter-current distribution extraction method. The
total extractable phenolic content was highest (85–92%) in water extracts with
54–64 μmol gallic acid equivalents followed by 7–15% of total extractable phenolics
and 5–11 μmol gallic acid in methanol extract. The highest 2, 2-diphenyl-1picrylhydrazyl (DPPH) radical scavenging activity was recorded in water
(4.63–6.71 mg/mL expressed as E50 values) and methanol extracts
(4.40–5.42 mg/mL expressed as E50 values) whereas ethylacetate extracts demonstrated lowest scavenging activity. The polar lipid fractions were found to have more
potent antioxidant activity compared to neutral lipid fractions. The inhibitions of
soybean lipoxygenase activity were stated as 34–60% and 50% for water and
methanol extracts, respectively. The lipid peroxidation inhibition was found to be
greater in acetone extracts (34.71–100%) (Xanthopoulou et al. 2009).
Saavedra et al. (2013) studied the effect of different drying methods and extraction solvents on antioxidant and total phenolic content of the seeds and shell of
squash pumpkin. The results revealed that among the drying methods, the ovendried samples were found to have higher antioxidant and phenolic content, whereas
among the shell and seeds, the shell samples reportedly had higher antioxidant
(1.47–70.96% inhibition of DPPH radicals) and phenol content values
(2.00–10.69 mg GAE/g DW).
Protein isolate from pumpkin oil cake (POCPI) obtained using food-grade
enzymes namely trypsin and alcalase was studied for antioxidative activities by
Nourmohammadi et al. (2017). The authors observed that alcalase-hydrolyzed
POCPI 1 exhibited better antioxidant activities in terms of total antioxidative potential, ferrous ion chelating activities, and DPPH radical scavenging activity. Also, the
amount of hydrophobic amino acids (33.49%) demonstrated a direct relationship
between alcalase-hydrolyzed POCPH 1 and the antioxidative activity.
In another study by Bardaa et al. (2016), β-carotene/linoleic acid bleaching test
was conducted to ascertain the inhibition of lipid peroxidation of pumpkin seed oil.
The results revealed that pumpkin seed oil showed higher lipid peroxidation inhibitory activity than BHT which could be attributed to its tocopherol content.
19 Pumpkin (Cucurbita pepo) Seed
493