Distribution of polyphenolic and sugar compounds in different buckwheat plant parts

Milica Nešović; Uroš Gašić; Tomislav Tosti; Nikola Horvacki; Nebojša Nedić; Milica Sredojević; Stevan Blagojević; Ljubiša Ignjatović; Živoslav Tešić

doi:10.1039/d1ra04250e

Distribution of polyphenolic and sugar compounds in different buckwheat plant parts

RSC Adv. 2021 Jul 28;11(42):25816-25829. doi: 10.1039/d1ra04250e. eCollection 2021 Jul 27.

Authors

Milica Nešović¹, Uroš Gašić², Tomislav Tosti³, Nikola Horvacki⁴, Nebojša Nedić⁵, Milica Sredojević³, Stevan Blagojević¹, Ljubiša Ignjatović⁶, Živoslav Tešić³

Affiliations

¹ Institute of General and Physical Chemistry Studentski trg 12-16 11158 Belgrade Serbia.
² Department of Plant Physiology, Institute for Biological Research "Siniša Stanković", National Institute of Republic of Serbia, University of Belgrade Bulevar Despota Stefana 142 11060 Belgrade Serbia uros.gasic.@ibiss.bg.ac.rs.
³ University of Belgrade - Faculty of Chemistry Studentski trg 12-16 11158 Belgrade Serbia ztesic@chem.bg.ac.rs.
⁴ Innovation Center, University of Belgrade - Faculty of Chemistry Studentski trg 12-16 11158 Belgrade Serbia.
⁵ Faculty of Agriculture, Institute for Zootehnics, University of Belgrade Nemanjina 6 11080 Belgrade - Zemun Serbia.
⁶ University of Belgrade - Faculty of Physical Chemistry Studentski trg 12-16 11158 Belgrade Serbia.

Abstract

The aim of this study was to provide information on the phenolic and sugar profiles of different parts of the buckwheat plant, which can define that buckwheat is a functional food, with a high nutritional value and very useful for human health. Therefore, the extracts of buckwheat leaf, stem, and flower, as well as buckwheat grain were analysed for the content of polyphenol and antioxidant tests. The identification of a notable number of phenolic compounds and quantification of sugars in different parts of buckwheat indicates that buckwheat is a highly valuable plant. A total of 60 phenolic compounds were identified (18 cinnamic acid derivatives, 14 flavonols, 13 flavan-3-ols (including proanthocyanidins), 10 hydroxybenzoic acid derivatives, and 5 flavones) using ultra-high-performance liquid chromatography (UHPLC), coupled with a hybrid mass spectrometer which combines the Linear Trap Quadrupole (LTQ) and OrbiTrap mass analyzer. The highest number of phenolic compounds was found in the analysed buckwheat flower sample, and then in the leaf, followed by the grain and the stem. In addition, the sugar profile of buckwheat leaf, stem, flower and grain, as well as the buckwheat pollen and the nectar was analysed. Hence, 16 sugars and 5 sugar alcohols were detected by the high-performance anion exchange chromatography (HPAEC) with a pulsed amperometric detector (PAD). Sucrose was found in a significant amount with the highest content in buckwheat leaf. Trisaccharides had similar accumulation in the sample extracts, while disaccharides dominated in buckwheat leaf, followed by nectar and pollen. The sugar alcohols showed the highest content in buckwheat grain, where erythritol was predominant. The obtained results show that buckwheat is very rich in phenolic compounds and sugars. In addition to grain, the other parts of the buckwheat plant can be used as a very good source of different classes of phenolic compounds. This study provides useful information on the distribution of phytochemicals in different parts of the buckwheat plant, which contribute to the maintaining of the status of buckwheat as a functional food.