Comparison of Peroxynitrite-Scavenging Capacities of Several Citrus Fruit Peels

Figures & data

Table 1 Total phenolics, total flavonoids, DPPH-scavenging activity, and oxygen radical absorbance capacity (ORAC) of methanolic extract of different citrus fruit peels ^a

Scientific name	Local name	Total phenolics (mg GAE/100 g dried peel) ^b	Total flavonoids (mg CE/100 g dried peel) ^c	DPPH-scavenging (mg dried peel/mL) ^d	ORAC (mmole TE/100 g dried peel) ^e
Citrus limon (L.) Bur	Lemon	1024 ± 27^x	326 ± 4^y	8.6 ± 0.5^uv	18.8 ± 0.9^v
Citrus grandis Osbeck	Wendun	822 ± 36^u	136 ± 4^u	16.3 ± 0.8^x	19.3 ± 0.5^v
Citrus grandis Osbeck CV	Peiyou	874 ± 16^v	131 ± 5^u	9.7 ± 0.3^v	21.7 ± 0.8^w
Citrus paradis	Grapefruit	1009 ± 60^wx	208 ± 12^x	19.2 ± 0.4^y	30.9 ± 0.3^y
Citrus sinensis (L.) Osbeck	Liucheng	1102 ± 9^y	133 ± 3^u	14.2 ± 1.6^w	24.6 ± 1.1^x
Citrus reticulata × C. sinensis	Murcott	775 ± 14^u	139 ± 1^u	12.4 ± 1.5^w	15.4 ± 1.6^u
Citrus reticulate Blanco	Ponkan	969 ± 27^w	152 ± 2^v	13.3 ± 0.8^w	18.3 ± 1.8^v
Citrus tankan Hayata	Tonkan	1160 ± 4^z	184 ± 1^w	7.4 ± 0.3^u	22.5 ± 1.5^w
Fortunella margarita	Kumquat	450 ± 33^t	52 ± 1^t	38.5 ± 1.6^z	10.0 ± 2.1^t
^aThe values are expressed as means ± SD of triplicate tests. Means not sharing a common letter (t, u, v, w, x, y, z) in the same row were significantly different (p < 0.05) when analyzed by ANOVA and Duncan's multiple range test.
^bThe total phenolics content was expressed as milligrams of gallic-acid equivalents (GAE) per 100 g of dried peel.
^cThe total flavonoids content was expressed as milligrams of catechin equivalents (CE) per 100 g of dried peel.
^dThe DPPH radical scavenging capacity was expressed as the IC50, which denoted the concentration of dried peel that scavenged 50% of DPPH radicals.
^eThe ORAC was expressed as millimoles of trolox equivalent (TE) per 100 g of dried peel.

Table 2 Composition of flavanone glycoside and polymethoxy flavone in different citrus fruit peels ^a

	Flavanone glycosides (mg/100 g dried peel)				Polymethoxy flavones (mg/100 g dried peel)
Local name	Narirutin	Naringin	Hesperidin	Neohesperidin	Sinensetin	Nobiletin	Tangeretin
Lemon	ND^t	18 ± 5^t	1332 ± 17^u	ND^t	ND^t	ND^t	ND^t
Wendun	ND^t	1631 ± 16^v	ND^t	ND^t	ND^t	ND^t	ND^t
Peiyou	47 ± 1^u	1604 ± 29^u	ND^t	ND^t	ND^t	ND^t	ND^t
Grapefruit	403 ± 1^y	5054 ± 15^w	37 ± 10^t	ND^t	ND^t	ND^t	ND^t
Liucheng	241 ± 6^x	ND^t	2932 ± 60^w	ND^t	ND^t	30 ± 1^u	ND^t
Murcott	1063 ± 13^z	ND^t	39 ± 1^t	ND^t	ND^t	260 ± 6^w	81 ± 1^v
Ponkan	65 ± 2^v	ND^t	2091 ± 26^v	ND^t	ND^t	219 ± 1^v	283 ± 3^w
Tonkan	224 ± 19^w	ND^t	2041 ± 117^v	2.4 ± 2.4^u	5.0 ± 2.3^u	382 ± 35^x	67 ± 5^u
Kumquat	ND^t	7 ± 1^t	ND^t	ND^t	ND^t	ND^t	ND^t
^aThe values are expressed as means ± SD of triplicate tests. Means not sharing a common letter (t, u, v, w, x, y, z) in the same column were significantly different (p < 0.05) when analyzed by ANOVA and Duncan's multiple range test.

Figure 1 NO-scavenging capacity of methanolic extract of different citrus fruit peels. The values are expressed as means ± S.D. of triplicate tests. Means not sharing a common letter at the same tested concentration were significantly different (p < 0.05) when analyzed by ANOVA and Duncan's multiple range test. (Color figure available online.)

Figure 2 O₂ ⁻-scavenging capacity of methanolic extract of different citrus fruit peels. The values are expressed as means ± S.D. of triplicate tests. Means not sharing a common letter at the same tested concentration were significantly different (p < 0.05) when analyzed by ANOVA and Duncan's multiple range test. (Color figure available online.)

Figure 3 Peroxynitrite-scavenging capacity of methanolic extract of different citrus fruit peels. The peroxynitrite-scavenging capacity was evaluated based on the inhibitory activity of peroxynitrite-induced nitrotyrosine formation in BSA. The values are expressed as means ± S.D. of triplicate tests. Means not sharing a common letter at the same tested concentration were significantly different (p < 0.05) when analyzed by ANOVA and Duncan's multiple range test. (Color figure available online.)

Table 3 Correlation coefficients of total phenolics and flavonoids with antioxidant, radical scavenging, and peroxynitrite-scavenging capacities

	Coefficient (probability)
	Total phenolics	Total flavonoids
DPPH-scavenging	−0.80 ^a (0.005)	−0.56 (0.090)
ORAC	0.76 ^a (0.011)	0.39 (0.266)
NO-scavenging ^b	0.19 (0.623)	0.14 (0.726)
O2 ^−-scavenging ^c	0.82 ^a (0.040)	0.82 ^a (0.040)
Peroxynitrite-scavenging ^d	0.92 ^a (0.000)	0.65 ^a (0.041)
^aPresents significant correlation between two variants (p < 0.05).
^bThe NO-scavenging capacity of different citrus peel extract at a tested concentration of 3.1 mg/mL was used to perform the correlative analysis.
^cThe O2 ^−-scavenging capacity of different citrus peel extract at a tested concentration of 1.3 mg/mL was used to perform the correlative analysis.
^dThe peroxynitrite-scavenging capacity of different citrus peel extract at a tested concentration of 1 mg/mL was used to perform the correlative analysis.