High-dose administration of purified cyanidin-3-glucose or a blackberry extract causes improved mitochondrial function but reduced content in 3T3-L1 adipocytes

Authors: SOLVERSON, PATRICK - Washington State University; Albaugh, George; Harrison, Dawn; Luthria, Devanand - Dave; Baer, David; Novotny, Janet

Submitted to: Food Frontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2022
Publication Date: 1/22/2022
Citation: Solverson, P., Albaugh, G.P., Harrison, D.J., Luthria, D.L., Baer, D.J., Novotny, J. 2022. High-dose administration of purified cyanidin-3-glucose or a blackberry extract causes improved mitochondrial function but reduced content in 3T3-L1 adipocytes. Frontiers in Nutrition. 1-9. https://doi.org/10.1002/fft2.139.
DOI: https://doi.org/10.1002/fft2.139

Interpretive Summary: Diets rich in berries have favorable effects on all-cause and cardiovascular disease related mortality as well as development of type-2 diabetes in epidemiological investigations. Some berries are a rich source of anthocyanins, a diverse class of compounds responsible for the dark blue and purple color of the fruits and vegetables. The anthocyanin cyanidin-3-glucoside has received attention in the area of obesity research due to effects first described in a diet-induced model of rodent obesity normalized weight gain, insulin sensitivity, and gene-expression of lipogenic enzymes in mice. The aim of this study was to characterize the effect of purified cyanidin-3-glucoside or a blackberry extract on cellular metabolism and mitochondrial number in 3T3-L1 adipocyte cells in order to explore potential mechanisms. Respiratory rate and number of mitochondria of the cells was measured after exposure of the cells to cyanidin-3-glucoside or a blackberry extract. Administration of purified cyanidin-3-glucoside or a blackberry extract caused decreased mitochondrial content, but increased function in cultured adipocytes at high doses. This is the first study to investigate the ability of anthocyanins from purified cyanidin-3-glucoside or a blackberry extract to affect cellular respiration in adipocytes. Positive findings include increased respiration on a fatty acid substrate as well as maximal respiratory capacity in adipocytes after treatment with high-doses of berry-derived anthocyanins that cannot be explained by increases in mitochondrial density, suggesting enhanced function. While these results may have limited applicability to dietary guidance for humans, they do provide insights into the mechanism by which these compounds can impact metabolism.

Technical Abstract: Berry consumption shows antiobesity and antidiabetic effects in animals and humans. Anthocyanin or berry extracts increase insulin sensitivity, reduce lipid droplet formation, and cause a white-to-brite phenotypic switch of adipocytes in vitro. The objective of this study was to investigate effects of cyanidin-3-glucoside (C3G) or blackberry extract (BBE) on cellular respiration of a fatty acid substrate in differentiated adipocytes. In separate experiments, 3T3-L1 adipocytes were treated with 0, 150 nM, or 50 µM purified C3G -or- 0, 150 nM, 25 µM, or 50 µM C3G-equivalents from a BBE. Baseline, state-4, state-3, and uncoupled respiration states were created experimentally and measured by high-resolution respirometry. Respiration rate within each state was corrected for mitochondrial content determined by PCR. Mitochondrial content was significantly reduced with high-dose C3G and the two high-dose BBE. The high-dose C3G caused a significant increase in respiration rate for baseline, state-4, state-3, and uncoupled states compared to control and physiologic dose C3G. The intermediate-high dose (25 µM) BBE also significantly increased respiration rate for the same states compared to control and other treatment levels of BBE; this effect was not observed at the high-dose (50 µM) BBE. Administration of high-dose purified C3G or BBE decreased mitochondrial content but enhanced cellular respiration on a fatty acid substrate in differentiated 3T3-L1 adipocytes across several mitochondrial states. We did not observe a phenotypic switch to brite adipocytes like others, but our empirical findings in cellular respiration on a fatty acid substrate support the antiobesity effects associated with anthocyanins and berries.