Rooibos Flavonoids, Aspalathin, Isoorientin, and Orientin Ameliorate Antimycin A-Induced Mitochondrial Dysfunction by Improving Mitochondrial Bioenergetics in Cultured Skeletal Muscle Cells

Abstract

The current study investigated the physiological effects of flavonoids found in daily consumed rooibos tea, aspalathin, isoorientin, and orientin on improving processes involved in mitochondrial function in C2C12 myotubes. To achieve this, C2C12 myotubes were exposed to a mitochondrial channel blocker, antimycin A (6.25 µM), for 12 h to induce mitochondrial dysfunction. Thereafter, cells were treated with aspalathin, isoorientin, and orientin (10 µM) for 4 h, while metformin (1 µM) and insulin (1 µM) were used as comparators. Relevant bioassays and real-time PCR were conducted to assess the impact of treatment compounds on some markers of mitochondrial function. Our results showed that antimycin A induced alterations in the mitochondrial respiration process and mRNA levels of genes involved in energy production. In fact, aspalathin, isoorientin, and orientin reversed such effects leading to the reduced production of intracellular reactive oxygen species. These flavonoids further enhanced the expression of genes involved in mitochondrial function, such as Ucp 2, Complex 1/3, Sirt 1, Nrf 1, and Tfam. Overall, the current study showed that dietary flavonoids, aspalathin, isoorientin, and orientin, have the potential to be as effective as established pharmacological drugs such as metformin and insulin in protecting against mitochondrial dysfunction in a preclinical setting; however, such information should be confirmed in well-established in vivo disease models.

Identification of Novel Cannabinoid CB2 Receptor Agonists from Botanical Compounds and Preliminary Evaluation of Their Anti-Osteoporotic Effects

“…Mangiferin is a xanthone present in significant levels in higher plants and possesses a variety of pharmacological actions, including anticancer, antidiabetic, antioxidative, immunomodulatory, hepatoprotective, analgesic, and neuroprotective effects [ 69 , 70 ]. Orientin is a water-soluble flavonoid C-glycoside with antioxidant, antiaging, antiviral, antibacterial, anti-inflammation, vasodilatation and cardioprotective, antiadipogenesis, antinociceptive, radiation-protective, neuroprotective, and antidepressant-like effects [ 71 , 72 , 73 , 74 ]. CB2R was also reported to be involved in the regulation of inflammation, anti-cancer, anti-fibrotic, and nerve system disease [ 10 , 13 ].…”

Potential regulatory role of PGC-1α within the skeletal muscle during metabolic adaptations in response to high-fat diet feeding in animal models

“…Here, injection with the isoflavone puerarin, at 100 mg/kg for 4 weeks, could downregulate the expression of a range of genes involved in mitochondrial biogenesis and oxidative phosphorylation, such as PGC-1α, NRF1/2, and transcription factor A (TFAM) in HFD-fed Wistar rats [ 13 ], whereas treatment with HFD containing the phenylpropanoid chicoric acid, at 0.03%, w/w for 6 weeks, was associated with improved glucose and insulin metabolism, while also reversing mitochondrial biogenesis and oxidative phosphorylation within the skeletal muscle in C57BL/6 mice fed HFD for 10 weeks [ 34 ]. Collaboratively, our group has increasingly reported on the potential therapeutic effects of bioactive compounds with abundant antioxidant effects, including polyphenols which are highly present in fruits and vegetables, in improving skeletal muscle function by ameliorating insulin resistance and targeting improving mitochondrial function [ 58 , 59 ].…”

Translation of preclinical ethnomedicine data in LMICs: the example of rooibos

“…Secondly, rooibos constituents quercetin, aspalathin and catechin inhibit lipid peroxidation ( Snijman et al, 2009 ), a mechanism likely responsible for its reported membrane-protective effects of rooibos ( Ulicna et al, 2019 ; Pretorius and Smith, 2022 ). A multitude of studies in cell-free systems and in cell culture have also demonstrated improved antioxidant enzyme activities (particularly for catalase and superoxide dismutase (SOD)) ( Waisundara and Hoon, 2015 ) and mitochondrial bioenergetics ( Mthembu et al, 2021 ).…”