Metabolite profiling, antioxidant activity, and glycosidase inhibition property of the mesocarp tissue extracts of sugar date palm [Phoenix sylvestris (L.) Roxb.] fruits

Figures & data

Table 1. GC-MS identified metabolites in P. sylvestris mesocarp tissue.

				Relative Response Ratios (g^−1 dry extract)
		FM			SI			SII
Compounds identified	IUPAC names of compounds	Average	±	sd.	Average	±	sd	Average	±	sd
ORGANIC ACIDS
Adipic acid	Hexanedioic acid		-		15.93^a	±	2.08	0.90^c	±	0.14
Citramalic acid	2-hydroxy-2-methylbutanedioic acid	3.59^a,b	±	0.42		-			-
Fumaric acid	(E)-Butenedioic acid	11.46^a,b	±	1.05	0.33	±	0.28	0.29	±	0.17
Gluconic acid	D-Gluconic acid	7.53^a.b	±	0.77		-			-
Glyceric acid	2,3-Dihydroxypropionic acid	3.47	±	1.29		-			-
Glycolic acid	2-Hydroxyethanoic acid	2.20^a,b	±	0.20	5.69	±	1.44	11.31^c	±	0.79
Lactic acid	2-Hydroxypropanoic acid	34.38^a,b	±	2.46	93.61	±	7.17	77.56^c	±	6.63
Maleic acid	Maleic acid	16.63^a,b	±	3.16		-			-
D-Malic acid	2-hydroxybutanedioic acid	81.70	±	48.71	0.87	±	0.30	4.77	±	0.93
Malonic acid	Propanedioic acid	0.63	±	0.60	0.85	±	0.19	1.12	±	0.94
Oxalic acid	Ethanedioic acid	29.61^a,b	±	6.67		-			-
Pimelic acid	Heptanedioic acid		-		2.48	±	2.48		-
Phosphoric acid	Trihydroxidooxidophosphorus phosphoric acid	41.07^a,b	±	12.38	0.86	±	0.74	0.22	±	0.02
Succinic acid	Butanedioic acid	17.07^a,b,	±	2.34	40.55	±	6.43	3.51^c	±	0.33
Trans-aconitic acid	(1E)-1-Propene-1,2,3-tricarboxylic acid	0.24^a,b	±	0.13		-			-
AMINO ACIDS
L-Alanine	Alanine	2.25	±	1.32	4.73	±	1.55	1.19^c	±	0.15
L-Glutamic acid	2-Aminopentanedioic acid	0.69^b	±	0.23		-		3.92^c	±	0.84
Glycine	Glycine	0.43^a,b	±	0.07		-			-
DL-Isoleucine	Isoleucine		-		18.87^a,b	±	0.89	2.32^c	±	0.21
L-Proline	Proline	6.57^a,b	±	1.18		-			-
L-Pyroglutamic acid	5-Oxoproline	0.12^a,b	±	0.01		-		0.64^c	±	0.04
L-Serine	Serine		-			-		0.23^b,c	±	0.13
L-Threonine	Threonine		-		18.21^a	±	2.69	1.35^c	±	0.47
SUGARS
Melezitose		5.13	±	8.66		-			-
Raffinose		20.85^a,b	±	3.71		-			-
Sucrose		93.52^a,b	±	10.51	12.17	±	0.87	45.63^c	±	2.51
Sophorose		22.70^a,b	±	3.71		-			-
D-(+) Trehalose		1.45^a,b	±	0.28		-			-
SUGAR ALCOHOLS
Glycerol	Propane-1,2,3-triol	33.07^b	±	6.68	24.14	±	2.88	9.84^c	±	0.50
1-Hexadecanol	Hexadecan-1-ol		-		0.54	±	0.06		-
D-Mannitol	(2R,3R,4R,5R)-hexane-1,2,3,4,5,6-hexol	233.03^a,b	±	30.53		-			-
Palatinitol		10.01^a,b	±	1.48		-			-
D-Sorbitol	(2S,3R,4R,5R)-Hexane-1,2,3,4,5,6-hexol	443.75^a,b	±	70.50		-			-
D-Threitol	(2R,3R)-1,2,3,4-Butanetetrol	0.71	±	0.45		-			-
Xylitol	(2R,3r,4S)-Pentane-1,2,3,4,5-pentol	4.66^a,b	±	0.57	110.92	±	18.29	96.18	±	5.34
FATTY ACIDS
Arachidic acid	Icosanoic acid		-		2.78^a,b	±	0.22	1.49^c	±	0.76
Behenic acid	Docosanoic acid		-		0.59^a,c	±	0.05		-
Capric acid	Decanoic acid		-		22.54^a,b	±	2.60	4.58^c	±	0.44
Caprylic acid	Octanoic acid		-		9.22^a	±	1.02	0.30^c	±	0.28
4-Guanidinobutyric acid	4- (Diaminomethylideneamino) butanoic acid	12.25^a,b	±	3.28		-			-
Heptadecanoic acid	Heptadecanoic acid		-		5.38^a	±	1.91	2.45	±	0.16
2-Hydroxy butyric acid	2-Hydroxybutanoic acid				1.44	±	1.32
Lauric acid	Dodecanoic acid	1.74^a,b	±	0.21	83.14	±	11.65	27.91^c	±	1.43
Linoleic acid	(9z,12z)-9,12-Octadecadienoic acid		-		21.70^a,c	±	3.27		-
Myristic acid	Tetradecanoic acid		-		45.70^a,b	±	6.63	28.73^c	±	1.74
Oleic acid	(9Z)-9-Octadecenoic acid		-		51.23^a,c	±	8.58		-
Palmitic acid	Hexadecanoic acid	1.25^a,b	±	1.07	1131.44	±	163.15	914.34	±	76.98
Stearic acid	Octadecanoic acid	0.43^a,b	±	0.33	529.27	±	62.48	447.79	±	30.85
PHENOLS
Alizarin	1,2-Dihydroxy-9,10-anthracenedione		-		0.83^a,b	±	0.16	0.81	±	0.10
2-Amino-3-methoxy benzoic acid	2-Amino-3-methoxybenzoic acid	185.98	±	22.33		-			-
Benzoic acid	Benzoic acid		-		0.30	±	0.11	0.12	±	0.10
Caffeic acid	(2E)-3-(3,4-Dihydroxyphenyl)acrylic acid		-		5.10^a,b	±	0.51	3.74	±	0.70
Catechin	(2R,3S)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-2H-chromene-3,5,7-triol	0.30^a,b	±	0.06		-		0.19^c	±	0.01
2,3-dihydroxy benzoic acid	2,3-Dihydroxybenzoic acid		-			-		0.28^b,c	±	0.02
3,4-Dihydroxybenzoic acid	3,4-Dihydroxybenzoic acid		-		285.40^a,b	±	36.58	378.30^c	±	27.80
3,4-Dihydroxyphenyl acetic acid	3,4-Dihydroxyphenyl acetic acid		-		0.11^b	±	0.01	12.40^c	±	1.20
DL-3,4-Dihydroxyphenyl glycol			-			-		0.65^b,c	±	0.07
Ferulic acid	3-Methoxy-4-hydroxycinnamic acid		-		93.73^a,b	±	11.95	159.77^c	±	10.80
4-Hydroxybenzoic acid	4-Hydroxybenzoic acid		-		414.01^a	±	61.16	22.30^c	±	5.38
4-Hydroxycinnamic acid	4-Hydroxycinnamic acid		-		80.05^a	±	11.10	4.45^c	±	1.84
4-Hydroxy-3-methoxybenzoic acid	4-Hydroxy-3-methoxybenzoic acid		-		2.86	±	1.80	1.83	±	0.17
1-Hydroxy-2-naphthoic acid	1-Hydroxy-2-naphthoic acid		-		3.49^a,c	±	0.92		-
DL-p-Hydroxyphenyl lactic acid			-		0.62^a,c	±	0.12		-
Hydroquinone	Benzene-1,4-diol		-		0.69^a,c	±	0.06
Piceatannol	Piceatannol		-			-		4.54^b,c	±	0.82
Quinic acid	(1S,3R,4S,5R)-1,3,4,5-		-		1.27^a,b	±	0.11	0.96	±	0.39
	Tetrahydroxycyclohexanecarboxylic acid
Shikimic acid	(3R,4S,5R)-3,4,5-Trihydroxy-1-cyclohexene-1-		-		0.90^a,b	±	0.07	0.98	±	0.07
	carboxylic acid
						-			-
Taxifolin	(2R,3R)-2-(3,4-Dihydroxyphenyl)-3,5,7-		-			-
	trihydroxy-2,3-dihydrochromen-4-one							0.98^b,c	±	0.14
OTHERS
Cholesterol	(3β)-cholest-5-en-3-ol		-		0.46^a,c	±	0.19		-
Porphine 1	Porphyrin		-		0.88	±	0.75	1.08	±	0.98
Serotonin 1	5-Hydroxytryptamine	0.25^a,b	±	0.04		-			-

-not detected, significant (p < 0.05) difference (a: FM vs SI; b: FM vs SII; c: SI vs SII)

FM: crude methanol extract; SI: ethyl acetate extract after alkaline hydrolysis step I; SII: ethyl acetate extract after alkaline hydrolysis step II.

Figure 1. Comparison of the glycosidase inhibition by three fractions isolated from mesocarp tissue of P. sylvestris fruits.

Table 2. Glycosidase inhibitory properties of metabolites detected in P. sylvestris mesocarp.

Metabolites	α-Glucosidase inhibitionIC50 value (µM ± sd)	α-Amylase inhibitionIC50 value (µM ±sd)
PHENOLS
Benzoic acid	ND	2.74 ± 0.001
Caffeic acid	1.8 ± 0.01	1.42 ± 0.01
3,4-Dihydroxy benzoic acid	2.58 ± 0.002	0.23 ± 0.00
4-Hydroxycinnamic acid	0.23 ± 0.001	ND
Ferulic acid	0.52 ± .002	ND
Quinic acid	4.95 ± 0.003	4.91 ± 0.002
Taxifolin	ND	0.31 ± 0.01
SUGARS
Raffinose	ND	0.36 ± 0.01
Sucrose	ND	0.51 ± 0.003
Trehalose	ND	0.85 ± 0.01

ND: activity not detected.

Table 3. Antioxidant properties of P. sylvestris mesocarp extracts and metabolites.

	Antioxidant activity
	DPPH radical	Superoxide radial
Extract /Metabolite	IC50 value (mg/ml) /[mM]		TAC (AAE)
FM	0.14 ± 0.001	0.55 ± 0.20	0.66
SI	0.27 ± 0.003	0.45 ± 0.02	0.08
SII	0.22 ± 0.001	0.44 ± 0.38	0.20
3,4-Dihydroxybenzoic acid	0.39 ± 0.003	0.09 ± 0.01	-
	[0.25 ± 0.00 mM]	[0.61 ± 0.00 mM]
4-Hydroxycinnamic acid	-	0.51 ± 0.05	-
		[3.10 ± 0.00 mM]
Caffeic acid	0.001 ± 0.00	2.93 ± 0.11	-
	[0.006 ± 0.00 mM]	[16.26 ± 0.0001 mM]
Ferulic acid	0.26 ± 0.003	0.14 ± 0.008	-
	[1.34 ± 0.00 mM]	[0.74 ± 0.00 mM]

Not done.