J Food Bioact

Journal of Food Bioactives, ISSN 2637-8752 print, 2637-8779 online

Journal website www.isnff-jfb.com

Original Research

Volume 5, March 2019, pages 120-130

Phenolic content, antioxidant and anti-inflammatory activities of seeds and leaves of date palm (Phoenix dactylifera L.)

Figure 1. Inhibition percentage of supercoiled pBR 322 plasmid DNA scission in peroxyl radical-mediated systems with extracts from date seeds and palm leaf.

Figure 2. Effect of addition of palm leaf and date seed phenolic extracts in peroxyl radical treated DNA system. Lane 1: Control (DNA only); Lane 2: Blank (DNA and AAPH); Lane 3: soluble palm leaf extract ; Lane 4: bound palm leaf extract (Run A); and Lane 5: Soluble date seeds 1 extract; Lane 6: Bound date seeds 1 extract; Lane 7: Soluble date seeds 2 extract; Lane 8 (Run B): Bound date seeds 2 extract; S, supercoiled plasmid DNA strands; N, nicked DNA strands.

Figure 3. Inhibitory effect of date seed and palm leaf extracts on LPS stimulated COX-2 expression in J774A.1 mouse macrophage cells. Cells were pretreated with samples for 48 h prior to LPS induction, after 4 h of induction, RNA was isolated and COX-2 expression was examined. Negative control indicate COX-2 expression level without LPS stimulation and positive control was measured after 10 ng/mL LPS stimulation for 4 h.

**Table 1.** Total phenolic content of date seeds and date palm leaves¹
Sample	Crude yield of soluble phenolics (g/100g sample)	Total phenolics (mg GAE/g sample)
¹Data are expressed as means ± SD (n = 3). Means ± SD followed by the same letter within a column are not significantly different (p > 0.05).GAE, gallic acid equivalents.
Date seed 1	15.14	68.73 ± 0.95^a	2.43 ± 0.06^d
Date seed 2	13.81	82.62 ± 3.70^b	2.50 ± 0.12^d
Palm leaves	30.23	106.96 ± 1.76^c	0.49 ± 0.01^e

Table 1. Total phenolic content of date seeds and date palm leaves¹

Sample

Crude yield of soluble phenolics (g/100g sample)

Total phenolics (mg GAE/g sample)

Soluble phenolics

Bound phenolics

¹Data are expressed as means ± SD (n = 3). Means ± SD followed by the same letter within a column are not significantly different (p > 0.05).GAE, gallic acid equivalents.

Date seed 1

15.14

68.73 ± 0.95^a

2.43 ± 0.06^d

Date seed 2

13.81

82.62 ± 3.70^b

2.50 ± 0.12^d

Palm leaves

30.23

106.96 ± 1.76^c

0.49 ± 0.01^e

**Table 2.** Antioxidant activities of date seeds and date palm leaves¹
Sample	TEAC² (mmol TE/g sample)	DPPH radical scavenging activity (mmol TE/g sample)	Hydroxyl radical scavenging activity (mmol TE/g sample)	Reducing power (mmol TE/g sample)	ORAC³ (mmol TE/g sample)
¹Data are expressed as means ± SD (n = 3). Means ± SD followed by the same letter within a column are not significantly different (p > 0.05). ² TEAC, trolox equivalent antioxidant capacity, ³ORAC, oxygen radical absorbance capacity.
Date seed 1	39.26 ± 0.48^a	1.84 ± 0.02^a	12.94 ± 0.52^a	0.60 ± 0.08^a	0.076 ± 0.003^a	0.006 ± 0.0005^a	4.26 ± 0.04^a ^c	0.17 ± 0.003^a	22.47 ± 0.42^a	3.12 ± 0.05^a
Date seed 2	35.75 ± 1.53^a	1.76 ± 0.03^b	13.54 ± 0.69^a	0.64 ± 0.01^a	0.071 ± 0.005^a,b	0.005 ± 0.0005^a	6.01 ± 0.01^b	0.17 ± 0.003^a	22.18 ± 2.21^a	2.85 ± 0.20^a
Palm leaves	76.74 ± 3.81^b	0.50 ± 0.01^c	21.13 ± 0.13^b	0.07 ± 0.01^b	0.063 ± 0.001^b	0.0007 ± 0.0001^b	8.82 ± 0.48	0.024 ± 0.001^b	41.59 ± 0.66^b	5.48 ± 0.60^b

Table 2. Antioxidant activities of date seeds and date palm leaves¹

Sample

TEAC² (mmol TE/g sample)

DPPH radical scavenging activity (mmol TE/g sample)

Hydroxyl radical scavenging activity (mmol TE/g sample)

Reducing power (mmol TE/g sample)

ORAC³ (mmol TE/g sample)

Soluble phenolics

Bound phenolics

Soluble phenolics

Bound phenolics

Soluble phenolics

Bound phenolics

Soluble phenolics

Bound phenolics

Soluble phenolics

Bound phenolics

¹Data are expressed as means ± SD (n = 3). Means ± SD followed by the same letter within a column are not significantly different (p > 0.05). ² TEAC, trolox equivalent antioxidant capacity, ³ORAC, oxygen radical absorbance capacity.

Date seed 1

39.26 ± 0.48^a

1.84 ± 0.02^a

12.94 ± 0.52^a

0.60 ± 0.08^a

0.076 ± 0.003^a

0.006 ± 0.0005^a

4.26 ± 0.04^a
^c

0.17 ± 0.003^a

22.47 ± 0.42^a

3.12 ± 0.05^a

Date seed 2

35.75 ± 1.53^a

1.76 ± 0.03^b

13.54 ± 0.69^a

0.64 ± 0.01^a

0.071 ± 0.005^a,b

0.005 ± 0.0005^a

6.01 ± 0.01^b

0.17 ± 0.003^a

22.18 ± 2.21^a

2.85 ± 0.20^a

Palm leaves

76.74 ± 3.81^b

0.50 ± 0.01^c

21.13 ± 0.13^b

0.07 ± 0.01^b

0.063 ± 0.001^b

0.0007 ± 0.0001^b

8.82 ± 0.48

0.024 ± 0.001^b

41.59 ± 0.66^b

5.48 ± 0.60^b

**Table 3.** Effect of different antioxidants (soluble extracts at 200 ppm GAE) on the formation of TBARS in a cooked lean meat model system¹
Soluble extracts added to pork	Concentration.(g/kg pork)	TBARS (mg of MDA equiv/kg pork)
¹Data are expressed as means ± SD (n = 3). Abbreviations : MDA, malondialdehyde; and BHA, butylated hydroxyanisole.
Control	–	3.14 ± 0.14	4.75 ± 0.18	4.89 ± 0.12	4.46 ± 0.10	4.85 ± 0.27	5.71 ± 0.11
BHA	0.20	1.07 ± 0.14	0.95 ± 0.05	0.65 ± 0.05	0.48 ± 0.04	0.68 ± 0.04	0.75 ± 0.02
Palm leaves, dechlorophillized	0.50	0.74 ± 0.01	2.14 ± 0.02	2.40 ± 0.09	2.13 ± 0.03	3.01 ± 0.03	3.50 ± 0.11
Palm leaves, as such	0.50	1.20 ± 0.10	2.58 ± 0.13	2.59 ± 0.06	2.88 ± 0.06	3.67 ± 0.15	4.15 ± 0.22
Date seeds 1	0.46	0.86 ± 0.09	3.13 ± 0.02	3.79 ± 0.17	3.78 ± 0.09	3.37 ± 0.05	4.63 ± 0.10
Date seeds 2	0.30	1.05 ± 0.49	1.78 ± 0.09	2.64 ± 0.07	2.68 ± 0.05	3.52 ± 0.17	3.35 ± 0.16

Table 3. Effect of different antioxidants (soluble extracts at 200 ppm GAE) on the formation of TBARS in a cooked lean meat model system¹

Soluble extracts added to pork

Concentration.(g/kg pork)

TBARS (mg of MDA equiv/kg pork)

Day 0

Day 2

Day 5

Day 7

Day 10

Day 14

¹Data are expressed as means ± SD (n = 3). Abbreviations : MDA, malondialdehyde; and BHA, butylated hydroxyanisole.

Control

–

3.14 ± 0.14

4.75 ± 0.18

4.89 ± 0.12

4.46 ± 0.10

4.85 ± 0.27

5.71 ± 0.11

BHA

0.20

1.07 ± 0.14

0.95 ± 0.05

0.65 ± 0.05

0.48 ± 0.04

0.68 ± 0.04

0.75 ± 0.02

Palm leaves, dechlorophillized

0.50

0.74 ± 0.01

2.14 ± 0.02

2.40 ± 0.09

2.13 ± 0.03

3.01 ± 0.03

3.50 ± 0.11

Palm leaves, as such

0.50

1.20 ± 0.10

2.58 ± 0.13

2.59 ± 0.06

2.88 ± 0.06

3.67 ± 0.15

4.15 ± 0.22

Date seeds 1

0.46

0.86 ± 0.09

3.13 ± 0.02

3.79 ± 0.17

3.78 ± 0.09

3.37 ± 0.05

4.63 ± 0.10

Date seeds 2

0.30

1.05 ± 0.49

1.78 ± 0.09

2.64 ± 0.07

2.68 ± 0.05

3.52 ± 0.17

3.35 ± 0.16

**Table 4.** Inhibition of LDL cholesterol oxidation in the presence of date palm leaves and date seed soluble phenolic extracts¹
Sample soluble phenolic extract	Inhibition (%)
¹Data are expressed as the mean ± SD (n = 3). Values with different letters in the same column are significantly different (p < 0.05).
Palm leaves	87.82 ± 3.50^a
Date seed 1	58.84 ± 1.11^b
Date seed 2	74.22 ± 5.02^c

Table 4. Inhibition of LDL cholesterol oxidation in the presence of date palm leaves and date seed soluble phenolic extracts¹

Sample soluble phenolic extract

Inhibition (%)

¹Data are expressed as the mean ± SD (n = 3). Values with different letters in the same column are significantly different (p < 0.05).

Palm leaves

87.82 ± 3.50^a

Date seed 1

58.84 ± 1.11^b

Date seed 2

74.22 ± 5.02^c

**Table 5.** Major phenolic compounds in date palm seeds and leaves identified using HPLC/ESI-MS/MS
No.	Phenolic compound	Retention time (min)	[M-H]⁻	Fragments	Extracts in which detected¹
¹S, soluble phenolic extracts and B, bound phenolic extract.
1	Caffeoyl hexoside	4.0	342	179	Date seed^S
2	Methyl gallate	4.1	183	169	Date palm leaf^S
3	Protocatechuic acid	7.1	153	109	Date palm leaf^B
4	Catechin	8.4	289	245, 125	Date seed^B
5	p-Hydroxybenzoic acid	9.6	137	93	Date palm leaf^B
6	Proanthocyanidin dimer isomers	8.7, 9.1, 11.4	577	425, 405, 289	Date palm leaf^S, date seed^S
7	Epicatechin	11.9	289	245, 125	Date palm leaf^S, date seed^S
8	5-O-caffeoylshikimic acid isomers	12.1, 13.0	335	–	Date seed^S
9	p-Coumaric acid	14.4	163	119	Date seed^B, Date palm leaf^B
10	Apigenin di-C-hexoside	13.2	593	325, 427	Date palm leaf^S
11	Ferulic acid	15.3	193	178, 150	Date palm leaf^B
12	Quercetin-3-heteroside	18.0	463	301	Date palm leaf^S
13	Rutin	18.6	609	301	Date palm leaf^S,B
14	Isorhamnetin hexoside	20.9	477	462, 315	Date palm leaf^S,B
15	Isorhamnetin-3-rhamnoglucoside	21.2	623	315, 300	Date palm leaf^S
16	Hydrocaffeic acid	27.2	181	–	Date seed^S
17	Isorhamnetin	31.5	315	271, 254, 151	Date seed^S,B

Table 5. Major phenolic compounds in date palm seeds and leaves identified using HPLC/ESI-MS/MS

No.

Phenolic compound

Retention time (min)

[M-H]⁻

Fragments

Extracts in which detected¹

¹S, soluble phenolic extracts and B, bound phenolic extract.

Caffeoyl hexoside

4.0

342

179

Date seed^S

Methyl gallate

4.1

183

169

Date palm leaf^S

Protocatechuic acid

7.1

153

109

Date palm leaf^B

Catechin

8.4

289

245, 125

Date seed^B

p-Hydroxybenzoic acid

9.6

137

Date palm leaf^B

Proanthocyanidin dimer isomers

8.7, 9.1, 11.4

577

425, 405, 289

Date palm leaf^S, date seed^S

Epicatechin

11.9

289

245, 125

Date palm leaf^S, date seed^S

5-O-caffeoylshikimic acid isomers

12.1, 13.0

335

–

Date seed^S

p-Coumaric acid

14.4

163

119

Date seed^B, Date palm leaf^B

Apigenin di-C-hexoside

13.2

593

325, 427

Date palm leaf^S

Ferulic acid

15.3

193

178, 150

Date palm leaf^B

Quercetin-3-heteroside

18.0

463

301

Date palm leaf^S

Rutin

18.6

609

301

Date palm leaf^S,B

Isorhamnetin hexoside

20.9

477

462, 315

Date palm leaf^S,B

Isorhamnetin-3-rhamnoglucoside

21.2

623

315, 300

Date palm leaf^S

Hydrocaffeic acid

27.2

181

–

Date seed^S

Isorhamnetin

31.5

315

271, 254, 151

Date seed^S,B