Fermented and Unfermented Rooibos (Aspalathus linearis) Exhibit Selective Protection Against Hepatic Stress in Rats Exposed to Fumonisin B1

The exploration of natural redox-modulating agents to mitigate/reduce oxidative damage triggered by toxins is a major area of interest in nutritional and pharmacological fields. Aspalathus linearis (rooibos), traditionally consumed in South Africa for health benefits, was assessed for hepatoprotective effects against fumonisin B1 (FB1)-induced damage. This study involved 24 male rats (n = 6/group) that received FB1 (50 mg/kg diet equivalent, i.p. for 5 days) with or without oral exposure to unfermented (GR) or fermented (FR) rooibos extracts. Alongside somatic records, we assessed blood biochemicals, as well as liver histology, antioxidative stress markers (GSH, GPx, MDA, and carbonylation), regulatory proteins (Nrf2, Sirt3, PGC-α, TRX1, HSP70, and LONp1), inflammation (cytokines), and phospholipid fatty acid profile. Based on results, FB1 suppressed growth, compromised liver function, altered redox status, and elevated stress markers. Both rooibos extracts decreased oxidative damage (↓MDA, ↓carbonylation) and modulated stress regulators (↑Nrf2, ↓HSP70). FR uniquely increased GPx and TRX1 while decreasing IL-1β and PGC-α concentrations, whereas GR strongly increased Nrf2 and Sirt3, reflecting distinct bioactivities linked to their differing polyphenolic profiles. Neither extract compensated for FB1-induced alterations in the liver total phospholipid fatty acid profile or serum cholesterol. In conclusion, GR and FR improved redox potential and inflammatory/stress response; however, this effect was selective, as it did not translate into comprehensive hepatoprotection. These findings support the potential role of rooibos as a dietary modulator of endogenous antioxidant defenses, although clinical translational trials are needed.