HOP PROANTHOCYANIDINS PROTECT AGAINST SIN-1-INDUCED CYTOTOXICITY IN PC12 CELLS

C.L. Miranda, D.R. Buhler, X. Liang, M.L. Deinzer, A.W. Taylor, J.F. Stevens, V. Bomben, J.S. Beckman
The present work was conducted to determine if proanthocyanidins (PCys) from hops protect PC12, a rat pheochromocytoma derived cell line, from the toxic effects of SIN-1 (3-morpholinosydnonimime). Undifferentiated PC12 cells were pre-incubated with hop PCys for 3 h and then exposed to SIN-1 for 24 h at 37ºC. At 5 µg/ml, pooled PCy fractions of monomers, dimers, trimers and tetramers partially protected PC12 cells from the toxic effects of 1.0 mM SIN-1. Pentamers or higher oligomeric PCys were not cytoprotective. When the SIN-1 concentration was lowered to 0.75 mM, the PCy mixtures of monomers to tetramers were completely protective. Furthermore, the individual monomer, (-)-epicatechin, and the individual trimer, epicatechin-(4β→8)-catechin-(4α→8)-catechin, at 1 or 5 µg/ml, were effective in preventing the toxic effects of SIN-1 in PC12 cells. The protective effect of the PCys against SIN-1-induced cytotoxicity was confirmed by the LDH assay. In contrast, the major polyphenol in tea, epigallocatechin gallate (EGCG), at 1 or 5 µg/ml, enhanced the toxic effects of SIN-1 in PC12 cells. EGCG significantly increased the levels of H2O2 in the culture medium used in growing the cells. SIN-1, at 0.5 or 0.75 mM, also increased the levels of H2O2 in the culture medium. However, none of the pooled hop PCy fractions increased H2O2 levels in the PC12 culture medium; instead, the PCys prevented the SIN-1-induced increase in H2O2 levels. At 25 µg/ml, the hop PCy fractions, from monomers to tetramers, induced cell proliferation in PC12 cells in the presence and absence of SIN-1. It is proposed that SIN-1 impairs mitochondrial function and that hop oligomeric PCys protect PC12 cells against SIN-1-induced mitochondrial damage, possibly, by reducing H2O2 formation and by reacting with oxidizing/nitrating intermediate species arising from SIN-1.
Miranda, C.L., Buhler, D.R., Liang, X., Deinzer, M.L., Taylor, A.W., Stevens, J.F., Bomben, V. and Beckman, J.S. (2005). HOP PROANTHOCYANIDINS PROTECT AGAINST SIN-1-INDUCED CYTOTOXICITY IN PC12 CELLS. Acta Hortic. 668, 207-212
DOI: 10.17660/ActaHortic.2005.668.26
https://doi.org/10.17660/ActaHortic.2005.668.26
epicatechin, epigallocatechin gallate, MTT, hydrogen peroxide, antioxidant
English

Acta Horticulturae