Organic acids in Kakadu plum ( Terminalia ferdinandiana ): The good (ellagic), the bad (oxalic) and the uncertain (ascorbic)

Abstract

The phenolic ellagic acid (EA) is receiving increasing attention for its nutritional and pharmacological potential as an antioxidant and antimicrobial agent. The Australian native Kakadu plum (Terminalia ferdinandiana) fruit is an abundant source of this phytochemical. The fruit also contains large amounts of vitamin C (mainly as ascorbic acid, AA) and possibly the undesirable oxalic acid (OA). Regular consumption of high oxalate foods poses a variety of health risks in humans including interference with calcium absorption and kidney stone formation. Oxalate is also the end-product of AA metabolism so that consumption of fruit with heightened AA content has the potential to elevate urinary oxalate levels. The aims of this study were to investigate the distribution of EA and the presence of other bioactives in other Kakadu plum tissues. Chemical analysis of Kakadu plum fruit and leaves for EA (free and total), OA (water-soluble and total), calcium (Ca) and AA indicated that EA and AA concentrations were high in the fruit while the leaves had significantly higher EA levels but little or no detectable AA. OA content in fruit and leaves was substantial with the fruit being placed in the high-Oxalate category. These findings suggest that there is potential to elevate oxalate levels in the urine of susceptible people and intake of fruit-derived products should be closely monitored. By measuring tissues collected from specific trees, high EA-producing or low OA-containing individuals were identified.

Extraction and characterization of a novel Terminalia pectin

“…Although T. ferdinandiana pectins were found to be LM in nature, from our observations T. ferdinandiana puree and powder can form gel without adding any external Ca 2? source which is a necessity for LM pectins [16]. This can be explained by the fact that T. ferdinandiana has a high level of calcium (273-287 mg/100 g DW) [17]. Presence of both calcium and pectin in the T. ferdinandiana tissue indicate that pectin from this source may exist in the 'eggbox' formation where the Ca 2?…”

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

“…Ellagic acid has antioxidant functions and has an inhibitory effect on the growth of micro-organisms [ 38 ]. There is an abundance of ellagic acid in the Kakadu plum that contributes to its use as a natural food preservative [ 7 ], and it was found in both the flesh and seed of the green plum.…”

“…Other native Australian foods have good nutritional and functional properties. The Kakadu plum ( Terminalia ferdinandiana ) has very high levels of ascorbic acid, high antioxidant capacity [ 7 , 8 ], and strong antimicrobial activity, enabling it to be used as a natural preservative for the commercial dipping of prawns in Queensland, Australia [ 9 ]. It is increasingly being used for its functional properties and is currently used in food and beauty products [ 10 ].…”

Natural Compounds with Potential to Modulate Cancer Therapies and Self-Reactive Immune Cells

“…Some phytochemicals may be toxic at high doses but beneficial at low doses, with antioxidant, anti-inflammatory and anti-tumour effects [208]. For example, whole extracts of Kakadu plum contain beneficial phenols, such as ellagic acid, though there are also detrimental levels of specific compounds at high doses, such as oxalic acid which can bind calcium, preventing absorption, and can aid in the production of kidney stones [209]. Methods to increase bioavailability, such as using carrier systems, will also allow for decreased amounts of the polyphenols required to be used that still display a therapeutic effect.…”