*Article Buchanania obovata***: Functionality and Phytochemical Profiling of the Australian Native Green Plum**

#### **Selina A. Fyfe 1,2, Gabriele Netzel 2, Michael E. Netzel 2 and Yasmina Sultanbawa 2,\***

1 School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072 Australia; selina.fyfe@uqconnect.edu.au

2 Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Health and Food Sciences Precinct, 39 Kessels Rd Coopers Plain;, PO Box 156, Archerfield, QLD4108,Australia;g.netzel@uq.edu.au(G.N.); m.netzel@uq.edu.au(M.E.N.)

**\*** Correspondence: y.sultanbawa@uq.edu.au; Tel.: +61-7-3443-2471

Received: 13 April 2018; Accepted: 26 April 2018; Published: 4 May 2018

**Abstract:** The green plum is the fruit of *Buchanania obovata* Engl. and is an Australian Indigenous bush food. Very little study has been done on the green plum, so this is an initial screening study of the functional properties and phytochemical profile found in the flesh and seed. The flesh was shown to have antimicrobial properties effective against gram negative (*Escherichia coli* 9001—NCTC) and gram positive (*Staphylococcus aureus* 6571—NCTC) bacteria. Scanning electron microscopy analysis shows that the antimicrobial activity causes cell wall disintegration and cytoplasmic leakage in both bacteria. Antioxidant 2,2-diphenyl-1-picrylhydrazyl (DPPH) testing shows the flesh has high radical scavenging activity (106.3 ± 28.6 μM Trolox equivalant/g Dry Weight in methanol). The flesh and seed contain a range of polyphenols including gallic acid, ellagic acid, p-coumaric acid, kaempferol, quercetin and trans-ferulic acid that may be responsible for this activity. The seed is eaten as a bush food and contains a delphinidin-based anthocyanin. The green plum has potential as a functional ingredient in food products for its antimicrobial and antioxidant activity, and further investigation into its bioactivity, chemical composition and potential applications in different food products is warranted.

**Keywords:** *Buchanania obovata*; green plum; fruit; polyphenols; antioxidants; Indigenous Australia
