Rhizoma acori graminei and its active principles protect PC-12 cells from the toxic effect of amyloid-β peptide

The effects of water extracts of six medicinal herbs (Radix polygalae tenuifoliae, Radix salviae miltiorrhizae, Rhizoma acori graminei, Rhizoma pinelliae ternatae, Tuber curcumae and Scletrotium poriae cocos) on the cytotoxic action of Abeta(1-40) were tested with PC-12 cells. Only the extract of R. acori graminei (RAG) significantly decreased Abeta(1-40)-induced cell death. Further, eugenol and beta-asarone were isolated and identified as the major active principles. Both purified eugenol and beta-asarone protected PC-12 cells from the toxic effect of Abeta(1-40). Eugenol was active between 1 and 100 muM, and 10 muM eugenol gave approximately a 50% response. beta-Asarone was less potent and exhibited little, if any, activity at this concentration. Both eugenol and beta-asarone inhibited Ca2+ intake by PC-12 cells: beta-asarone mainly inhibited basal Ca2+ intake, whereas eugenol inhibited Abeta-induced Ca2+ intake preferentially. These results suggest that eugenol may act by blocking Abeta-induced-Ca2+ intake and provide a strong case for further pursuit of the therapeutic and prophylactic potentials of RAG and its active principles for the management of Alzheimer's disease. (C) 2002 Elsevier Science B.V. All rights reserved.