Polyphenol oxidase activity and antioxidant properties of Yomra apple (Malus communis L.) from Turkey

Figures & data

Table 1. The standard chromatogram values of 17 individual phenolic substances and an internal standard.

No	RTMean*	Compound	m†	c‡	r2	%RSD (RT)	%RSD (AREA)	LOD¶,§	LOQ¶
1	2.97	Gallic acid	0.23	0.16	0.9998	0.320	2.377	0.042	0.126
2	5.77	Protocatechuic acid	0.11	0.076	0.9998	0.183	3.842	0.048	0.144
3	10.35	p-Hydroxy benzoic acid	0.15	0.10	0.9998	0.119	4.966	0.038	0.114
4	12.06	Catechin	0.05	0.03	0.9998	0.115	2.124	0.028	0.085
5	12.97	Chlorogenic acid	133.32	−74.34	0.9998	0.107	8.732	0.039	0.119
6	14.13	Vanillic acid	0.13	0.09	0.9998	0.094	2.692	0.029	0.088
7	14.62	Caffeic acid	239.10	−49.54	0.9997	0.094	1.928	0.037	0.112
8	16.08	Syringic acid	0.24	0.16	0.9998	0.085	2.474	0.046	0.138
9	17.02	Epicatechin	0.05	0.03	0.9998	0.073	5.222	0.036	0.108
10	18.61	p-Coumaric acid	350.6	−95.40	0.9995	0.054	0.517	0.104	0.312
11	19.42	Rutin	44.76	−10.64	0.9990	0.077	3.709	0.032	0.097
12	19.83	Ferulic acid	287.69	72.03	0.9999	0.745	0.897	0.054	0.162
13	21.63	Benzoic acid	0.03	0.02	0.9995	0.075	1.854	0.033	0.101
14	22.29	o-Coumaric acid	0.48	0.34	0.9998	0.076	1.687	0.036	0.109
15	26.45	cis.trans-Abscisic acid	0.38	0.26	0.9998	0.089	2.138	0.024	0.072
16	28.41	Quercetin	51.96	−6.73	0.9999	0.131	3.956	0.027	0.083
17	29.53	trans-Cinnamic acid	0.73	0.49	0.9998	0.114	4.554	0.036	0.109
18	36.91	Propylparaben (IS)				0.026	3.193	0.293	0.880

*Time is expressed as minute.

†Slope.

‡Intercept.

¶Values are expressed as mg/L.

§The number of significant digits of values of LOD and LOQ is given three-digit after comma.

Table 2. Antioxidant activity measured by TPC, FRAP and DPPH assays in the peel and flesh of Yomra apple.

Tissue	Total phenolics* (mg GAE/ 100 g FW)	FRAP* (µmol FeSO4ċ7H2O/ 100 g FW)	DPPH SC50* (mg/mL)
Peels	182.5 ± 37.25†	123.60 ± 45.62†	0.93 ± 0.01†
Flesh	70.2 ± 1.30‡	51.50 ± 3.03‡	2.59 ± 0.17‡
Total	252.70 ± 38.55	175.20 ± 97.12	3.83 ± 0.18

*Values are means of triplicate determinations.

†,‡Values with differences symbols in a column are significantly different to each other (Mann–Whitney test p < 0.05).

Table 3. Phenolic constituents of Yomra apple of determined by RP-HPLC-UV.

Phenolic compounds	Peels (mg/100 g FW)	Flesh (mg/100 g FW)
Gallic acid	–	–
Protocatechuic acid	–	–
p-Hydroxybenzoic acid	–	0.12
Catechin	19.20	4.00
Chlorogenic acid	12.15	7.86
Vanillic acid	–	–
Caffeic acid	0.23	0.12
Syringic acid	–	–
Epicatechin	–	–
p-Coumaric acid	–	0.02
Rutin	–	–
Ferulic acid	0.73	0.07
Benzoic acid	–	–
o-Coumaric acid	–	–
Abscisic acid	–	–
Quercetin	0.04	0.08
t-Cinnamic acid	–	–
Proplyparaben	IS*	IS*

–, not detected; *, Internal Standard.

Table 4. Optimization and kinetic characterization of Yomra apple PPO-catalyzed oxidation reactions againts monophenolic and diphenolic substrates.

Substrate	pH* optimum	Temperature optimum* (°C)	Vmax* (μM/min)	Km* (mM)	Vmax/Km (min^−1)
Monophenols
l-Tyrosine	5.0	20	7.60	9.30	0.82.10^−3
HPPA	7.0	30	1.02	0.70	1.46.10^−3
Diphenols
Catechol	5.0	40	21.50	7.90	2.72.10^−3
4-MCT	7.0	40	24.80	10.10	2.46.10^−3
L-DOPA	7.0	40	1.60	2.50	0.64.10^−3

*Values are means of triplicate determinations.

Table 5. Sensitivity of Yomra apple PPO catalyzed oxidation of 4-MCT to some common PPO inhibitors.

Inhibitor	Ki (mM)	I50 (mM)
Sodium metabisulphite	0.05 ± 0.01*	0.07 ± 0.02*
Ascorbic acid	0.05 ± 0.01*	0.05 ± 0.01*
Sodium azid	14.90 ± 1.10†	30.04 ± 2.55†
Benzoic acid	7.80 ± 0.85‡	9.80 ± 1.76†

*,†,‡Values with different symbols in a column are significantly different to each other (Mann–Whitney test. p < 0.05).

Randhir R, Lin YT, Shetty K. Phenolics, their antioxidant and antimicrobial activity in dark germinated fenugreek sprouts in response to peptide and phytochemical elicitors. Asia Pac J Clin Nut 2004;13:295–307

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