Isolation and Structure Identification of Bioactive Constituents of Sasa borealis

Abstract

Sasa borealis (Gramineae), a well known perennial plant, is widely distributed in Asia. This plant has been used for the treatment of burns, hemoptysis, and uremia in traditional medicines. Previous pharmacological reports about retard spontaneous mammary tumorigenesis and suppression of apoptosis induced by oxidative stress supported that S. borealis could be a good plant source targeting anti-cancer. Therefore, S. borealis was analyzed and investigated to assess pharmacological activities on their anti-cancer-related properties. As a result, fourteen known compounds, tricin (1), tricin 4′-O-(erythro-β-guaiacylglyceryl) ether (2), tricin 4′-O-(threo-β-guaiacylglyceryl) ether (3), tricin 4′-O-[erythro-β-guaiacyl-(9″-O-acetyl)-glyceryl] ether (4), tricin 4′-O-[threo-β-guaiacyl-(9″-O-acetyl)-glyceryl] ether (5), (-)-pinoresinol (6), (-)-syringaresinol (7), (+)-5,5'-dimethoxylariciresinol (8), p-hydroxybenzealdehyde (9), vanillin (10), (3S,5R,6S,7E)-5,6-epoxy-3-hydroxy-7-megastigmen-9-one (11), friedeline (12), 3-hydroxyglutinol (13), and squalene (14) were obtained from the n-hexane and EtOAc extracts of S. borealis. Compounds 2-14 were isolated from this plant for the first time. The structures of 1-14 were determined by analysis of physical and spectroscopic data (UV, IR, MS, 1H-, 13C-, HSQC, HMBC, NOESY and COSY NMR) as well as by comparison with published values. As a part of our research program to find novel chemosensitizers, compounds 1, 7, 9, 12 and 13 which their amounts were available, were tested for the P-glycoprotein inhibitory activity. Compounds 1 and 7 were evaluated to inhibit the P-gp because they significantly increased the cytotoxic potency of daunomycin (DNM) (IC50 of DNM 24.1 and 17.8 μM, respectively). Thus further research including accumulation and efflux studies were performed. As a conclusion, compounds 1 and 7 could be considered as the P-gp inhibitor candidates although they were not active as much as the positive control, verapamil.;조릿대 산죽 (Sasa borealis (Hack.) Makino)은 함경남도 이남에서 자생하는 벼과 (Gramineae)의 다년생 식물로서 약 550 속으로 나누어 10,000 여종이 알려져 있으며, 민간에서는 화상, 폐결핵성의 기침, 자궁염, 생리불순, 및 요독증 등의 질환에 효능을 나타낸다고 알려져 있다. Sasa의 여러 종으로부터 triterpenes, flavonoids, 및 flavonolignans 등이 분리 보고된 바 있으나 조릿대 산죽에 대한 연구 결과 보고는 많지 않다. 본 연구에서는 조릿대 산죽의 MeOH 추출물로부터 n-hexane, EtOAc, 및 n-BuOH 용매 분획 후 EtOAc 분획에서 알려진 1종의 flavone (1), 4종의 flavonolignans (2-5), 3종의 lignan (6-8), 2종의 aromatic compound (9-10), 및 1종의 ionone (11)을 분리하였고 n-hexane 분획에서 알려진 3종의 triterpene (12-14)을 분리하여 이화학적 성상 및 기기분석적 방법을 이용하여 구조를 확인 하였다. S. borealis의 n-hexane과 EtOAc 분획 추출물은 P-gp생성을 효과적으로 억제하여 multidrug resistence를 저해하는 활성을 보였다. 이러한 활성에 따른 분획을 실시하여, 총 14개의 물질을 분리하였다. 물질의 분리를 위해서 open column chromatography, Sephadex LH-20, reverse column (YMC GEL ODS-A) chromatography, TLC 등을 이용하였고, spectroscopic data (1H-, 13C-, HSQC, HMBC, NOESY and COSY NMR)와 문헌 조사를 통해 분리된 물질의 구조를 분석, 결정하였다. 그 결과, 2가지 주요 활성 물질, tricin (1) (IC50 = 24.1 μM)과 (-)-syringaresinol (7) (IC50 = 17.8 μM)을 분리하였다. 추가적으로 분리된, 12개의 물질, tricin 4′-O-(erythro-β-guaiacylglyceryl) ether (2), tricin 4′-O-(threo-β-guaiacylglyceryl) ether (3), tricin 4′-O-[erythro-β-guaiacyl-(9″-O-acetyl)-glyceryl] ether (4), tricin 4′-O-[threo-β-guaiacyl-(9″-O-acetyl)-glyceryl] ether (5), (-)-pinoresinol (6), (+)-5,5'-dimethoxylariciresinol (8), p-hydroxybenzealdehyde (9), vanillin (10), (3S,5R,6S,7E)-5,6-epoxy-3-hydroxy-7-megastigmen-9-one (11), friedeline (12), 3-hydroxyglutinol (13), 및 squalene (14)은 모두 이 식물에서 처음 보고되는 물질들이며 특히 화합물 8과 11은 벼과 식물에서는 처음 분리 보고하는 바이다.