Preparation method and stability of ellagic acid-rich pomegranate fruit peel extract

Figures & data

Figure 1.  HPLC-chromatograms of the solution of ellagic acid-rich pomegranate extract (pH 8) at the initial time (A) and after keeping for 10 weeks (B).

Table 1.  Extraction yield, ellagic acid content and antioxidant activity of the ellagic acid-rich pomegranate fruit peel extract.

Extracts/compounds	Extraction yield (% w/w*)	Ellagic acid content (%w/w**)	Antioxidant activity^† ED50 (μg/mL)
Crude extract	32.51 ± 2.14	7.06 ± 0.025	38.21 ± 0.138
Ellagic acid-rich extract	16.56 ± 1.132	13.63 ± 0.891^#	14.91 ± 0.239^#
Standard quercetin	-	-	3.57 ± 0.637
Standard ellagic acid	-	-	3.12 ± 0.349

*Compared to the weight of dried powder.

**Compared to the weight of the extract.

^†Evaluated by DPPH radical scavenging assay.

#Significant difference (P < 0.05) when compared with the crude extract.

Table 2.  Ellagic acid content and antioxidant activity of the ethyl acetate fractions obtained from liquid-liquid extractions.

Solvents for liquid–liquid extraction	Ellagic acid content (%w/w, mean ± SD)	Antioxidant activity^†, ED50 (μg/mL, mean ± SD)
Ethyl acetate and water	9.24 ± 0.511	16.31 ± 0.722
Ethyl acetate and 2% aq. acetic acid	13.63 ± 0.891*	14.91 ± 0.239*

^†Evaluated by DPPH radical scavenging assay.

*Significant difference (P < 0.05).

Figure 2.  Hydrolysis of ellagic acid to hexahydroxydiphenic acid.

Table 3.  Ellagic acid content of the ellagic acid-rich pomegranate fruit peel extract in the solution at pH 5.5, 7 and 8.

Weeks	Ellagic acid content (% w/w, mean ± SD)
	pH 5.5	% Remaining	pH 7	% Remaining	pH 8	% Remaining
0	12.81 ± 0.669	100	12.81 ± 0.673	100	12.81 ± 0.671	100
1	12.82 ± 0.408	100.08	12.68 ± 0.533	98.99	12.59 ± 0.809	98.28
2	12.71 ± 0.189	99.22	12.76 ± 0.614	99.61	12.68 ± 0.513	98.98
3	12.59 ± 0.808	98.28	12.62 ± 0.523	98.52	12.76 ± 0.582	99.61
4	11.02 ± 0.321*	86.03	12.02 ± 0.838*	93.83	11.92 ± 0.367*	93.05
6	11.89 ± 0.512*	92.82	11.15 ± 0.789*	87.04	10.03 ± 0.177*	78.3
8	10.41 ± 0.484*	81.26	9.77 ± 0.4111*	76.27	9.31 ± 0.432*	72.68
10	7.01 ± 0.314*	54.72	8.21 ± 0.573*	64.09	7.29 ± 0.514*	56.91
12	4.21 ± 0.332*	32.86	7.66 ± 0.728*	59.8	3.93 ± 0.831*	30.68
14	4.09 ± 0.708*	31.93	7.65 ± 0.424*	59.72	3.17 ± 0.518*	24.75
17	2.69 ± 0.361*	21	3.29 ± 0.253*	25.68	2.57 ± 0.447*	20.06

* Significance at P < 0.05 when compared with the content at the initial time.