Folate vitamers in the Australian green plum: Through growth and ripening and across locations

Selina Fyfe; Hung Hong; Horst Joachim Schirra; Heather E Smyth; Yasmina Sultanbawa; Michael Rychlik

doi:10.3389/fnut.2022.1006393

Folate vitamers in the Australian green plum: Through growth and ripening and across locations

Front Nutr. 2022 Oct 14:9:1006393. doi: 10.3389/fnut.2022.1006393. eCollection 2022.

Authors

Selina Fyfe^{1

2}, Hung Hong^{1

3}, Horst Joachim Schirra^{2

4

5}, Heather E Smyth¹, Yasmina Sultanbawa¹, Michael Rychlik^{1

6}

Affiliations

¹ Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, Australia.
² Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD, Australia.
³ School of Agriculture and Food Science, The University of Queensland, Brisbane, QLD, Australia.
⁴ School of Environment and Science, Griffith University, Brisbane, QLD, Australia.
⁵ Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia.
⁶ Chair of Analytical Food Chemistry, Technical University of Munich, Freising, Germany.

Abstract

The green plum is a native fruit of Australia that grows on the tree Buchanania obovata. This study aimed to confirm the high level of folate in green plums by analyzing a large number of ripe samples from multiple locations and to understand how folate vitamers change as the fruit grows through maturity stages. This study analyzed green plums for five vitamers of folate, H₄folate, 5-CH₃-H₄folate, 5-CHO-H₄folate, 10-CHO-PteGlu, and PteGlu (folic acid) using a stable isotope dilution assay on a liquid chromatograph mass spectrometer (LC-MS). Green plums were tested from four locations, two harvests and five maturity stages. Another 11 ripe samples, each from different tree clumps from one location, were also tested as were ripe red-colored green plums. The results show the 5-CH₃-H₄folate in green plum increases and accumulates in the fruit through development, ripening and senescence. The ripe green plums contain between 82.4 ± 5.5 and 149.4 ± 10.7 μg/100 g Fresh Weight (FW). The red-colored green plums are even higher in folate, with total folate measured as 192.5 ± 7.0 and 293.7 ± 27.4 μg/100 g FW, and further analysis of them is suggested. There is some variation in amounts of folate between fruit from different locations and sets of trees, but all ripe green plums tested are considered good dietary sources of folate.

Keywords: 5-CH3-H4folate; 5-methyl-tetrahydrofolate; Anacardiaceae; Buchanania obovata; folate; green plum; micronutrients; vitamers.