Plum Polyphenol Composition In Relation To Total Antioxidant Capacity

Aidilla Mubarak School of Medicine and Pharmacology and School of Plant Biology Faculty of Medicine, Dentistry and Health Sciences Faculty of Natural and Agricultural Sciences Aidilla completed a Bachelor of Science degree with Honours in Molecular Bioscience, followed by a Masters in Nutrition in her home country of Malaysia. After working as an academic fellow and later a tutor in the Department of Agriculture and Food Science, at the Universiti Malaysia Terengganu, she was sponsored by the government of Malaysia to undertake full-time PhD at UWA. Upon completion of her PhD she will take up a lecturing position at her former university in Malaysia. Her current research investigates the links between plant polyphenol compounds and dietary health. Dietary polyphenols have been associated with reduced risk of cardiovascular disease. Fruit such as plums are a rich source of polyphenolic antioxidants. The objective of her study was to evaluate and quantify total phenolic content, selected individual polyphenols and total antioxidant capacity in 32 new Western Australia plum cultivars.

The UWA Institute of Agriculture Plum Polyphenol Composition In Relation To Total Antioxidant Capacity Aidilla Mubarak Supervisors: Assc. Prof Michael Considine, Prof Kevin Croft, Prof Jonathan Hodgson

Acknowledgement Supervisors Dr Ewald Swinny (ChemCentre) Dr Simon Ching (PathWest) Department of Agriculture and Food, Western Australia ARC (LP0882884) Malaysian Ministry of Higher Education

Polyphenols Secondary metabolites of plants Quercetin Chlorogenic Acid Catechin Widely dispersed in plants Diverse biological functions

Why is polyphenol important? Quality in fruits Visual appearance Taste

Why is polyphenol important? Interest from consumers and food manufacturers. Why? Prevention of diseases Acts an antioxidant Most abundant antioxidant from diet

Dietary sources

Distribution In Fruits Varies with different factors Different cultivar Storage condition

Concentration µg/g FW 700 Polyphenol distribution in apple skin of different cultivars Catechin 600 Epicatechin 500 400 300 200 100 0 Empire McIntosh Cortland Red Delicious Northern Spy Apple Cultivars Tsao et al, J. Agric. Food Chem., 2003, 51 (21), pp 6347 6353

Polyphenol distribution in apple skin and flesh Concentration µg/g FW 140 120 100 80 60 40 20 Skin Flesh Skin Flesh Chlorogenic acid Catechin 0 Cortland Cortland Red Delicious Red Delicious Apple cultivars Tsao et al, J. Agric. Food Chem., 2003, 51 (21), pp 6347 6353

Information on phenolic content few cultivars single group of compounds Polyphenol compositions among different cultivars of plums is important breeding program

Research Objective To quantify polyphenols and antioxidant capacity of 32 new Western Australia plum cultivars (DAFWA) To demonstrate a correlation between polyphenols composition and the antioxidant capacity

Methods Selected individual polyphenol identified & quantified: Reversed phase HPLC DAD 32 Western Australian Plum Total antioxidant capacity quantified: Antioxidant inhibition of oxygen radicals (AIOR) assay Total phenolic content measurement: Folin Ciocalteu s colorimetric reaction

Major polyphenol compound in plums Neo chlorogenic acid Mean: 29 ± 54 mg/kg Range: 0 221 mg/kg Quercetin Mean: 52 ± 41 mg/kg Range: 9 240 mg/kg

Variation of polyphenol amongst cultivars Conc. (mg/kg) 300 250 Neo chlorogenic acid Quercetin 200 150 100 50 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Plum cultivars

Total Phenolic Content in Plum TPC (mg/kg GAE) 2000 1800 1600 1400 1200 1000 800 600 400 200 0 Mean: 701 ± 322 mg/kg GAE Range: 222 1711 mg/kg GAE 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 Plum cultivar

Total Antioxidant Capacity in Plum TAC (mol/kg TE) 40000 35000 Mean: 13720 ± 6142 mol/kg TE Range: 4795 36187 mol/kg TE 30000 25000 20000 15000 10000 5000 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 Plum cultivar

Relationship of total antioxidant capacity with measured polyphenol content Measurements N Pearson Sig. (2 tailed) Correlation Total Phenolic 32 0.954 ** 0.000 Content Neo chlorogenic acid 32 0.242 0.182 content Quercetin content 32 0.180 0.324

Conclusion Total phenolic content positive relationship with the antioxidant capacity (P<0.001) Neochlorogenic acid & quercetin glycoside predominant polyphenols Do not individually account for the antioxidant capacity

Future analysis Ascorbic acid, glutathione and total thiols Controlled human intervention study: effect of chlorogenic acid on cardiovascular function