Table 4. Antioxidant compound contents and antioxidant activities of natural extract mixtures

Treatments	Antioxidant compound contents		Antioxidant activities
Treatments	Total polyphenol (mg GAE/g)	Total flavonoid (mg CE/g)	DPPH radical scavenging activity (IC₅₀ mg/g)	ABTS radical scavenging activity (IC₅₀ mg/g)
Vit C	-	-	0.04±0.00^a	0.10±0.00^a
M1	254.45±4.85^d	159.52±2.61^e	0.17±0.00^c	0.15±0.01^ab
M2	386.70±1.57^f	212.49±10.80^g	0.07±0.00^b	0.11±0.00^a
M3	123.47±0.57^b	89.63±0.2^c	0.38±0.00^d	0.25±0.00^c
M4	334.14±7.20^e	196.0±4.58^f	0.08±0.00^b	0.14±0.00^ab
M5	116.02±6.02^b	69.72±1.61^b	0.18±0.01^c	0.32±0.00^d
M6	181.82±7.89^c	115.96±1.93^d	0.17±0.01^c	0.23±0.00^c
Grapefruit seed extracts	29.70±2.25^a	7.90±0.09^a	0.99±0.00^e	2.95±0.04^e

Means within a row with different letters are significantly different.
DPPH, 2,2-diphenyl-1-picrylhydrazyl; GAE, gallic acid equivalent;CE, catechin equivalent.