Se site targeted-two circles antioxidant in GPx4–like catalytic peroxide degradation by polyphenols (−)-epigallocatechin gallate and genistein using SERS

A Se site targeted-two circles antioxidant of polyphenols EGCG and genistein in glutathione peroxidase 4 (GPx4)–like catalytic peroxide H2O2 and cumene hydroperoxide degradation was demonstrated by surface-enhanced Raman scattering (SERS). Se atom's active center is presenting a ‘low-oxidation’ and a ‘high-oxidation’ catalytic cycle. The former is oxidized to selenenic acid (SeO−) with a Raman bond at 619/ 610 cm−1 assigned to the νO − Se by the hydroperoxide substrate at 544/ 551 cm−1 assigned to ωHSeC decreased. Under oxidative stress, the enzyme shifted to ‘high-oxidation’ catalytic cycle, in which GPx4 shuttles between R-SeO− and R-SeOO− with a Raman intensity of bond at 840/ 860 cm−1 assigned to νOSe. EGCG could act as a reducing agent both in H2O2 and Cu-OOH degradation, while, genistein can only reduce Cu-OOH, because it binds more readily to the selenium site in GPx4 than EGCG with a closer proximity, therefore may affect its simultaneous binding to coenzymes.