Page 313 - Read Online

Page 4 of 15 Hadadi et al. J Cancer Metastasis Treat 2018;4:25 I http://dx.doi.org/10.20517/2394-4722.2018.22

18

16
Water extract (mg/mL)
14 Methanol extract (mg/mL)
Gallic acid Eq (mg/g dry extract) 10 8 6
Ethanol extract (mg/mL)
12

2 4
0
Leaves Skin Pulp Seed

Figure 1. Total polyphenols analysis from various papaya fractions. The total phenolic content (TPC) of papaya extract was determined
by using Folin-Ciocalteu method. Results are mean ± SD for at least 3 experiments as gallic acid equivalents. The TPC in methanol and
ethanol extracts were compared to that in the water extracts. The significant differences, as marked “*”, are reported at P < 0.05

described . The TPC content of the papaya extract was calculated as gallic acid equivalents.
[37]

Determination of total flavonoid content
An aluminum-chloride based assay was used to determine the total flavonoid content (TFC) of the
[38]
extracts . Quercetin was used as standard and flavonoid content was determined as quercetin equivalent.

Anti-oxidation capacity assay
The anti-oxidation activity in papaya extracts was assayed by using 2, 2-Diphenyl-1-picrylhydrazyl (DPPH)
method . The data is reported as % inhibition of DPPH oxidation.
[39]
Cell culturing and anti-proliferation assay
MDA-MB-231, MCF7, MDA-MB-361, and AU565 cells were maintained in Dulbecco’s modified eagle
medium (DMEM; Invitrogen; Carlsbad, CA) supplemented with penicillin (100 units/mL), streptomycin
(100 μg/mL) and 10% FBS. SK-Br-3 cells were maintained in McCoy’s 5A medium (ATCC) supplemented
with penicillin (100 units/mL), streptomycin (100 μg/mL) and 10% FBS. All cell cultures were incubated in
a humidified incubator at 37 °C and 5% CO . Media was changed every 3 days and cells were subculture
2
when they became confluent. Effect of papaya leaves, skin, pulp and seeds extract on cell proliferation was
determined using a WST-1 assay as per manufacturer instructions. The results are expressed as % change
from control.

RESULTS
Characterization of papaya extract for anti-oxidation activity
The anti-oxidation potential of papaya extracts was determined by assessing their total polyphenol content,
total flavonoid content and by assaying their anti-oxidation capacity. The data showing the TPC is presented
in Figure 1. The highest amount of TPC was found in the seeds extract that ranged from 14-16 mg/g dry
weight of the extracts. There was no significant difference in TPC content between water, ethanol and
methanol extracts. The leaves were second highest in TPC content but had a considerably lower amount
of TPC than that of seeds. The leaves contained TPC in 1-4 mg/g of dry weights. Water extract contained
a lower amount of TPC (~1 mg/g dry weight) than that of ethanol or methanol extract. The amounts of
TPC between ethanol and methanol extracts from papaya leaves were not significantly different. The skin