Metabolism of 11'-α- and 11'-γ-Tocomonoenols in HepG2 Cells Favors the γ-Congener and Results Predominantly in Carboxymethylbutyl-Hydroxychromans.

SCOPE: Tocomonoenols (T1) are little-known vitamin E derivatives naturally occurring in foods. Limited knowledge exists regarding the cellular uptake and metabolism of α-tocomonoenol (αT1) and none about that of γ-tocomonoenol (γT1). METHODS AND RESULTS: The study investigates the cytotoxicity, uptake, and metabolism of αT1 and γT1 in HepG2 cells compared to the α- and γ-tocopherols (T) and -tocotrienols (T3). None of the studied tocochromanols are cytotoxic up to 100 µmol L-1. The uptake of the γ-congeners is significantly higher than that of the corresponding α-forms, whereas no significant differences are observed based on the degree of saturation of the sidechain. Carboxymethylbutyl-hydroxychromans (CMBHC) are the predominant short-chain metabolites of all tocochromanols and conversion is higher for γT1 than αT1 as well as for the γ-congeners of T and T3. The rate of metabolism increases with the number of double bonds in the sidechain. The rate of metabolic conversion of the T1 is more similar to tocopherols than to that of the tocotrienols. CONCLUSION: This is the first evidence that both αT1 and γT1 follow the same sidechain degradation pathway and exert similar rates of metabolism than tocopherols. Therefore, investigation into the biological activities of tocomonoenols is warranted.

Enzyme-treated red rice (Oryza sativa L.) bran extracts mitigate inflammatory markers in RAW 264.7 macrophage cells and exhibit anti-inflammatory efficacy greater/comparable to ferulic acid, catechin, γ-tocopherol, and γ-oryzanol.

ETHNOPHARMACOLOGICAL RELEVANCE: Rice (Oryza sativa L.), a staple food for a significant portion of the global population, has been recognized for its traditional medicinal properties for centuries. Rice bran, a by-product of rice milling, contains many bioactive compounds with potential pharmaceutical and therapeutic benefits. In recent years, research has highlighted the anti-inflammatory potential of rice bran, contributed by the bioactive components concentrated in their bran but, unfortunately, entrapped in the bran matrix, with limited bioavailability. Previous studies have reported that the enzymatic treatment of rice bran improves the bran's bioactive compound profile but did not investigate its impact on chronic conditions such as inflammation. AIM OF THE STUDY: This study investigates the anti-inflammatory effects of endo-1,4-ß-xylanase (ERB) and Viscozyme (VRB) treated red rice bran extracts against lipopolysaccharide-induced inflammation in RAW264.7 macrophages in comparison with non-enzyme-treated bran (CRB). Further established their efficacy with known anti-inflammatory compounds-ferulic acid (FA), catechin (CAT), γ-tocopherol (GTP), and γ-oryzanol (ORZ). MATERIALS AND METHODS: The RAW 264.7 macrophage cells were pre-treated with non-toxic concentrations (10-200 µg/mL) of FA, CAT, GTP, ORZ, CRB, ERB, and VRB, followed by inflammatory stimulation with LPS for 24 h. Further, the cell supernatant and pellets were harvested to study the anti-inflammatory effects by evaluating and measuring their efficacy in inhibiting pro-inflammatory cytokines (TNF-α, IL-6, IL-10, IL-1ß) and mediators (ROS, NO, PGE2, COX2, iNOS) through biochemical, ELISA, and mRNA expression studies. RESULTS: The findings showed that both ERB and VRB effectively inhibited the production of pro-inflammatory markers (TNF-α, IL-6) and mediators (ROS, NO, PGE2) by downregulating mRNA expressions of inflammatory genes (TNF-α, IL-1ß, IL-6, IL-10, COX2, iNOS) and demonstrated anti-inflammatory efficacy higher than CRB. On comparison, ERB demonstrated exceptional efficacy by causing a reduction of 48% in ROS, 20% in TNF-α, and 23% in PGE2 at 10 µg/mL, surpassing the anti-inflammatory capabilities of all the bioactive compounds, FA and ORZ, respectively. At the same time, VRB exhibited remarkable efficacy by reducing NO production by 52% at 200 µg/mL and IL-6 by 66% at 10 µg/mL, surpassing FA, CAT, ORZ, and GTP. Further, ERB downregulated the mRNA expression of IL-10 and iNOS, while VRB downregulated TNF-α, IL-1ß, and COX2 expression. Both extracts equally downregulated IL-6 expression at 10 µg/mL, demonstrating the efficacy more remarkable/on par with established anti-inflammatory compounds. CONCLUSIONS: Overall, enzyme-treated rice bran/extract, particularly ERB, possesses excellent anti-inflammatory properties, making them promising agents for alternatives to contemporary nutraceuticals/functional food against inflammatory diseases.