Phenolic Contents and Antioxidant Activities of Date Palm (Phoenix dactylifera L.) Leaves

Figures & data

Table 1 Total amount of phenolic, flavonoid, and condensed tannin contents of leaf extracts from different solvent extraction systems

Varieties	Solvents	Total phenolics (mg CAE/g plant extract)^a	Total flavonoids (mg QE/mg plant extract)^a	Condensed tannins (mg CE/mg plant extract)^a
Deglet Nour	Methanol	69.06 ± 0.41^a	176.76 ± 2.04^a	59.56 ± 2.93^a
	Ethyl acetate	10.69 ± 0.09^a	300.38 ± 24.32^a	9.52 ± 2.36^a
	Water	5.39 ± 1.33^a	22.84 ± 4.54^a	<1
	Hexane	2.78 ± 0.74^a	89.44 ± 17.35^a	<1
	Total	87.92 ± 2.57	589.42 ± 48.25	69.08 ± 5.29
Medjhoul	Methanol	79.71 ± 2.95^b	321.71 ± 25.34^b	117.82 ± 5.44^b
	Ethyl acetate	6.51 ± 1.70^a,b	302.75 ± 9.28^a	1.09 ± 0.78^b
	Water	10.59 ± 0.67^b	47.55 ± 0.31^b	<1
	Hexane	1.41 ± 0.28^a	69.93 ± 5.48^a,b	<1
	Total	98.22 ± 5.6	741.94 ± 40.41	118.91 ± 6.22
Barhee	Methanol	146.46 ± 2.61^c	149.45 ± 8.55^c	326.467 ± 24.25^c
	Ethyl acetate	4.03 ± 0.47^b	312.96 ± 26.59^a	33.46 ± 3.28^c
	Water	29.21 ± 5.41^c	24.62 ± 1.81^a,c	23.67 ± 9.08
	Hexane	2.28 ± 0.58^a	91.55 ± 1.99^a,c	<1
	Total	181.98 ± 9.07	578.58 ± 38.94	383.59 ± 36.91
Values are means ± SD (n = 3). Values with the same superscript letter (a–c) are not statistically significant at p < 0.05.

Figure 1 DPPH scavenging activity of leaf extracts from different solvent extraction systems: (a) Deglet Nour variety; (b) Medjhoul variety; (c) Barhee variety. Each value is expressed as mean ±SD (n = 3).

Table 2 Yield and free radical scavenging activity of leaf extract from different solvent extraction systems

	Yield and DPPH free radical scavenging activity (IC50) ^a
	Methanol leaf extract		Ethyl acetate leaf extract		Hexane leaf extract		Water leaf extract
Varieties	Yield (%)	IC50 (mg/ml)	Yield (%)	IC50 (mg/ml)	Yield (%)	IC50 (mg/ml)	Yield (%)	IC50 (mg/ml)
Deglet Nour	26.4	2.08 ± 0.00	10.6	2.15 ± 0.02	6.6	2.53 ± 0.01	21.2	3.30 ± 0.05
Medjhoul	21.2	2.11 ± 0.11	16.6	2.32 ± 0.03	10.6	5.09 ± 0.19	20.6	3.81 ± 0.18
Barhee	30	2.14 ± 0.00	11.7	2.34 ± 0.00	12.7	3.29 ± 0.01	25	3.80 ± 0.04
Values of EC50 are expressed as mean of triplicate determinations ±SD.
^aIC50, concentration in mg/ml required scavenging the DPPH radical (100 mg/ml) by 50%.

Figure 2 Reducing power of leaf extract from different solvent extraction systems: (a) Deglet Nour variety; (b) Medjhoul variety; (c) Barhee variety. Each value is expressed as mean ±SD (n = 3).

Table 3 Correlations between the antioxidant activity IC₅₀/EC₅₀/TAS values and the antioxidant components (total phenolics, flavonoids, and condensed tannins) of the methanol and ethyl acetate leaf extracts of three active Phoenix dactylifera varieties

	Equations
Value	Total phenols	Total flavonoids	Condensed tannins
MeOH leaf extracts
TAS	Y = 0.211x + 25.01	Y = 0.279x − 19.55	Y = 0.021x − 0.9
	r ^2 = 0.687, F = 25.23, p < 0.001	r ^2 = 0.773, F = 17.55, p < 0.001	r ^2 = 0.521, F = 11.12, p < 0.01
IC50 of DPPH	Y = −1.442x + 40.12	Y = −1.772x + 5.77	Y = −0.889x + 9.82
radical-scavenging activity	r ^2 = 0.667, F = 13.21, p < 0.003	r ^2 = 0.659, F = 21.41, p < 0.001	r ^2 = 0.421, F = 7.22, p < 0.01
EC50 of reducing power	Y = −0.522x + 87.22	Y = −0.933x + 33.62	Y = −0.121x + 101.29
	r ^2 = 0.631, F = 22.68, p < 0.01	r ^2 = 0.751, F = 19.22, p < 0.002	r ^2 = 0.485, F = 13.02, p < 0.005
Ethyl acetate leaf extracts
TAS	Y = 0.155x + 73.44	Y = 0.722x + 67.08	Y = 0.141x + 13.98
	r ^2 = 0.713, F = 18.25, p < 0.001	r ^2 = 0.712, F = 31.55, p < 0.001	r ^2 = 0.463, F = 25.23, p < 0.001
IC50 of DPPH	Y = −0.412x + 55.02	Y = −0.823x + 72.91	Y = −0.365x + 41.9
radical-scavenging activity	r ^2 = 0.633, F = 26.38, p < 0.001	r ^2 = 0.631, F = 17.68, p < 0.001	r ^2 = 0.521, F = 11.75, p < 0.001
EC50 of reducing power	Y = −0.130x + 38.65	Y = −0.326x + 36.74	Y = −0.278x + 58.33
	r ^2 = 0.599, F = 15.38, p < 0.003	r ^2 = 0.568, F = 14.68, p < 0.004	r ^2 = 0.723, F = 22.68, p < 0.001

Table 4 Reducing power (EC₅₀) and total antioxidant capacity of leaf extract from different solvent extraction systems

	Methanol leaf extract		Ethyl acetate leaf extract		Hexane leaf extract		Water leaf extract		Total
	EC50 (mg/ml)	TAS (mg Eq ascorbic acid/g extract)	EC50 (mg/ml)	TAS (mg Eq ascorbic acid/g extract)	EC50 (mg/ml)	TAS (mg Eq ascorbic acid/g extract)	EC50 (mg/ml)	TAS (mg Eq ascorbic acid/g extract)	TAS (mg Eq ascorbic acid/g extract)
Deglet Nour	1.62 ± 0.01	244.79 ± 6.37	3.85 ± 0.23	73.15 ± 0.51	20.23 ± 4.45	12.73 ± 2.39	13.58 ± 5.60	22.74 ± 2.08	353.41 ± 11.35
Medjhoul	1.22 ± 0.03	285.65 ± 13.75	6.90 ± 1.03	42.01 ± 3.47	21.16 ± 0.15	13.88 ± 2.05	7.18 ± 0.05	22.22 ± 0.87	363.76 ± 20.14
Barhee	1.16 ± 0.05	249.82 ± 34.46	22.35 ± 0.52	22.11 ± 2.46	31.81 ± 2.14	7.84 ± 0.63	9.43 ± 0.01	24.89 ± 0.51	304.66 ± 38.06