Polyphenolic Compounds from Protect Neuronal Cells from Oxidative Stress.

Pterocarpans and related polyphenolics are known as promising neuroprotective agents. We used models of rotenone-, paraquat-, and 6-hydroxydopamine-induced neurotoxicity to study the neuroprotective activity of polyphenolic compounds from and their effects on mitochondrial membrane potential. We isolated 11 polyphenolic compounds: a novel coumestan lespebicoumestan A () and a novel stilbenoid 5'-isoprenylbicoloketon () as well as three previously known pterocarpans, two pterocarpens, one coumestan, one stilbenoid, and a dimeric flavonoid. Pterocarpans and , stilbenoid , and dimeric flavonoid significantly increased the percentage of living cells after treatment with paraquat (PQ), but only pterocarpan slightly decreased the ROS level in PQ-treated cells. Pterocarpan and stilbenoid were shown to effectively increase mitochondrial membrane potential in PQ-treated cells. We showed that pterocarpans and , containing a 3'-methyl-3'-isohexenylpyran ring; pterocarpens and , with a double bond between C-6a and C-11a; and coumestan significantly increased the percentage of living cells by decreasing ROS levels in 6-OHDA-treated cells, which is in accordance with their rather high activity in DPPH and FRAP tests. Compounds and effectively increased the percentage of living cells after treatment with rotenone but did not significantly decrease ROS levels.