Scheme XXI.

Increase in antioxidative genes due to MnP-based treatment of rats which underwent kidney ischemia–reperfusion I/R. The GPM mixture treatment contained: bFGF, recombinant EPO, SDF-1 and BMP-7, and a mixture of mitochondria protective amino acids, including α-ketoglutarate and l-aspartic acid, and MnTnHex-2-PyP⁵⁺[67]. Note that major endogenous antioxidative defenses are up-regulated indicating that MnP under given conditions could not have acted as SOD mimic. During I/R the H₂O₂ is produced which MnP supposedly employs for oxidative modifications of protein thiols as indicated in other studies (Schemes XI, XIV and XX). We hypothesized that in this model MnP oxidizes Keap1 cysteine and in turn activates Nrf2 which then upregulates endogenous antioxidative defenses. Indeed the Keap1 oxidation and Nrf2 activation were implicated with another class of SOD mimic, M40403 [68], nitroxides, curcumin [73] and flavonoids [70,71]. The following groups, with 10 male Sprague–Dawley rats each, were studied: (a) sham-operated; (b) I/R with saline only; (c) I/R with growth factors only (G); (d) I/R with MnP only (P); (e) I/R a mixture of α-keto-glutarate and l-aspartic acid (M), and (f) GPM mixture. GPM was given 24 h before 40-min ischemia and 24 h post-reperfusion. The study was terminated at 48 h post-reperfusion. Periodic acid –Schiff (PAS) stains and tubular damage grading was assessed at 48 h post-I/R. All individual components of GPM mixture produced beneficial effects which were lower than those produced with whole GPM mixture. (A) Normal PAS staining of non-ischemic sham operated left kidney; (B) dramatically increased PAS positive necrosis in ischemic left kidney; (C) reversal of necrosis in ischemic+GPM treated left kidney; (D) significant decrease in the acute tubular necrosis grading in ischemic left kidney treated with the GPM mixture (p<0.0003). In next kidney I/R study, the authors introduce N-acetyl cysteine into the GPM mixture; all effects were enhanced; note that MnP cycles with thiols producing H₂O₂ (Scheme XI) [66,67]. Adapted from [67].