Novel Diterpenoid Acetylcholinesterase Inhibitors from Salvia miltiorhiza

Abstract

Acetylcholinesterase (AChE, EC 3.1.1.7) inhibitors are the only registered drugs used to treat Alzheimer’s disease (AD). New AChE inhibitors may contribute to the design of new pharmaceuticals and supply information which will facilitate the understanding of the interaction between inhibitors and the enzyme. The dried root of Salvia miltiorhiza is called ‘Danshen’ in China, and has been used for the treatment of cerebrovascular disease and CNS deterioration in old age for over one thousand years. In this work, a modified Ellman method was used to guide the fractionation of the active AChE inhibitory compounds from an acetone extract. Four inhibitory compounds, dihydrotanshinone, cryptotanshinone, tanshinone I and tanshinone IIA were isolated, and the structures were identified by comparison of their spectral characteristics with previous reports. The inhibitory activities of dihydrotanshinone and cryptotanshinone were dose-dependent, their IC₅₀ values being 1.0 μM and 7.0 μM, respectively. These two compounds were the major inhibitory compounds in the extract as judged by HPLC analysis, forming 0.054 % w/w and 0.23 % w/w in the dried root, respectively, and in mixture they appear to be less active than as isolated compounds. The clogP values of dihydrotanshinone, cryptotanshinone, tanshinone I and tanshinone IIA were calculated as 2.4, 3.4, 4.8 and 5.8, respectively, which indicate that these compounds have potential to penetrate the blood-brain barrier. This is the first example of diterpenoids as inhibitors of AChE.

Acetylcholinesterase inhibitors - Salvia miltiorhiza - Lamiaceae - diterpenoids - dihydrotanshinone - cryptotanshinone

References

• 1 Massoulié J, Pezzementi L, Bon S. Molecular and cellular biology of cholinesterases.  Prog Neurobiol. 1993;  41 31-91
• 2 Bartus R T, Dean RL 3 rd, Beer B, Lippa A S. The cholinergic hypothesis of geriatric memory dysfunction.  Science. 1982;  217 408-14
• 3 Giacobini E. Pharmacotherapy of Alzheimer’s disease: New drugs and novel strategies.  Prog Brain Res. 1993;  98 447-54
• 4 Kuang P, Xiang J. Effect of Radix Salviae miltiorhizae on EAA and IAA during cerebral ischemia in gerbils: a microdialysis study.  J Trad Chin Med. 1994;  14 45-50
• 5 Massiah M A, Viragh C, Reddy P M, Kovach I M, Johnson J, Rosenberry T L. Short, strong hydrogen bonds at the active site of human acetylcholinesterase: proton NMR studies.  Biochemistry. 2001;  40 5682-90
• 6 Onitsuka M, Fujiu M, Shinma N, Maruyama H B. Novel diterpenoids from Salvia miltiorhiza .  Chem Pharm Bull. 1983;  31 1670-5
• 7 Ikeshiro Y, Hashimoto I, Iwamoto Y. Diterpenoids from Salvia miltiorhiza .  Phytochemistry. 1991;  30 2791-2
• 8 Ryu S Y, Oak M -H, Kim K -M. Inhibition of Mast cell degranulation by tanshinones from the roots of Salvia miltiorhiza .  Planta Med. 1999;  65 654-5
• 9 Perry N SL, Houghton P J, Theobald A E, Jenner P, Perry E K. In-vitro inhibition of human erythrocyte acetylcholine esterase by Salvia lavandulaefolia essential oil and constituent terpenes.  J Pharm Pharmacol. 2002;  52 895-902
• 10 Orhan I, Terzioglu S, Sener B. alpha-Onocerin: an acetylcholinesterase inhibitor from Lycopodium clavatum .  Planta Med. 2003;  69 265-7
• 11 Miyazawa M, Watanabe H, Umemoto K. Inhibition of acetylcholinesterase activity by monoterpenoids with a p-menthane skeleton.  J Agric Food Chem. 1997;  45 667-9
• 12 Chang H M, Cheng K P, Chong T F. Structure elucidation and total synthesis of new tanshinones isolated from Salvia miltiorhiza Bung.  J Org Chem. 1990;  55 3537-43
• 13 Pan X, Niu G, Liu H. Microwave-assisted extraction of tanshinones from Salvia miltiorhiza Bunge with analysis by HPLC.  J Chrom A. 2001;  922 371-5
• 14 Kang B Y, Chung S W, Kim S H, Ryu S Y, Kim T S. Inhibition of interleukin-12 and interferon-gamma production in immune cells by tanshinones from Salvia miltiorhiza .  Immunopharmacology. 2000;  49 355-61
• 15 Tezuka Y, Kasimu R, Basnet P. Aldose reductase inhibitory constituents of the root of Salvia miltiorhiza Bunge.  Chem Pharm Bull (Tokyo). 1997;  45 1306-11
• 16 Korpela M, Tahti H. The effect of selected organic solvents on intact human red cell membrane acetylcholinesterase in vitro .  Toxicol Appl Pharmacol. 1986;  85 257-62
• 17 Maatooq G T, Hoffmann J J. Microbial transformation of a mixture of argentatin A and incanilin.  Z Naturforsch [C]. 2002;  57 489-95