王 昊,梅文莉,杨德兰,钟惠民,戴好富*
1青岛科技大学化学与分子工程学院,青岛 266042;2 中国热带农业科学院热带生物技术研究所,农业部热带作物生物学与遗传资源利用重点实验室;3 海南省黎药资源天然产物研究与利用重点实验室,海口 571101
降香(Dalbergia odorifera)是豆科(Leguminosae)檀属(Dalbergia)植物降香檀(Dalbergia odorifera T.Chen)的树干和根的干燥心材,为传统中药,具有行气活血、止痛、止血的功效,用于脘腹疼痛、肝郁胁痛、胸痹刺痛、跌扑损伤、外伤出血[1]。降香檀原产海南,为海南特有植物,分布于白沙、东方、乐东和三亚等地。其心材降香主要含挥发油和黄酮类化合物。目前对降香挥发油及黄酮类成分的生理活性研究较多,其挥发油具有抗凝血、抗血栓、抗心肌缺血、抗菌等活性;其黄酮类化合物具有舒张血管、降血脂、抗菌、抗肿瘤、抗炎、抗氧化、抑制破骨细胞功能下降等活性[2-10]。本实验对降香进行化学成分的研究,从中分离得到10个酚性化合物,运用波谱学方法分别鉴定为dalbergin (1),7-O-methylvestitol (2),syringaresinol (3),2',4'-dimethoxy-3,7-dihydroxyisoflavanone (4),3'-hydroxy-8-methoxyvestitol (5),2',6-dihydroxy-4'-methoxy-2-arylbenzofuran (6),3'-O-methylviolanone (7),pinocembrin (8),prunetin(9)和mucronulatol (10)。本次研究仅对化合物1进行乙酰胆碱酯酶抑制的活性测试,化合物2~5 首次从该植物中分离得到。结果表明,化合物1 为降香提取物的主要成分(含量占总提物0.28%),具有乙酰胆碱酯酶抑制活性,研究结果为进一步开发和利用降香提供科学依据。
NMR 采用Brucker AV-500 型超导核磁仪(TMS内标,瑞士Bruker 公司);MS 采用Autospec-3000 质谱仪;薄层色谱硅胶板、柱色谱硅胶(200~300 目,60~80 目)均为青岛海洋化工厂产品;Sephadex LH-20 为Merck 公司产品;乙酰胆碱酯酶、碘化硫代乙酰胆碱、DTNB、他克林均购自Sigma;酶标仪为PE公司EnVision。
降香心材于2010 年10 月购自海南省海口市农贸市场,样品标本(No.20101009)经中国热带农业科学院热带生物技术研究所代正福副研究员鉴定为Dalbergia odorifera T.Chen,并存放于中国热带农业科学院热带生物技术研究所。
干燥并粉碎后的降香心材(8.4 kg)用体积分数为95%的乙醇室温浸提三次,每次7 d,过滤得提取液。提取液经减压浓缩回收乙醇得到乙醇浸膏。乙醇浸膏用水分散后依次用石油醚、乙酸乙酯、正丁醇萃取。乙酸乙酯部分477 g 先采用硅胶(200~300目)减压柱,以氯仿-甲醇(1∶0~0∶1)梯度洗脱,得18个流分(Fr.1-Fr.18)。Fr.3 以石油醚-丙酮(100∶1~1∶1)梯度洗脱共接收110个流分,流分54~105 结晶得化合物1(2.5 g);流分48~50 先过凝胶Sephadex-LH20(氯仿-甲醇1 ∶1)柱色谱,然后上硅胶柱(200~300 目),石油醚-氯仿(8∶2)洗脱得化合物2(3.0 mg)。Fr.6 采用硅胶H 减压柱,以石油醚-丙酮(50∶1~0∶1)梯度洗脱得128个流分。流分经TLC 检测合并后均先过过凝胶Sephadex-LH20(氯仿-甲醇1 ∶1)柱色谱。流分111~113 上硅胶柱(200~300 目),石油醚-乙酸乙酯(3∶2)洗脱,结晶得化合物3(40.2 mg)。流分100~104 上硅胶柱(200~300 目),氯仿-甲醇(60∶1)洗脱,结晶得化合物4(10.1 mg)。流分91-92 结晶得化合物5(20.3 mg)。流分82-86 结晶得化合物10(17.3 mg),母液上硅胶柱(200~300 目),氯仿-甲醇(100∶1)洗脱,结晶得化合物6(20.2 mg)。流分73~77 结晶得化合物7(10.1 mg)。流分43~46 上硅胶柱(200~300 目),氯仿-甲醇(100∶1)洗脱得化合物8(15.3 mg)。流分56~60 结晶得化合物9(12.2 mg)。
化合物1 棕色晶体;ESI-MS m/z:267.0 [MH]-,分子式为C16H12O4。1H NMR (DMSO-d6,500 MHz)δ:9.45 (1H,s,-OH),7.57 (3H,m,H-2',4',6'),7.50 (2H,m,H-3',5'),7.11 (1H,s,H-8),6.82 (1H,s,H-5),6.19 (1H,s,H-3),3.89 (3H,s,7-OMe);13C NMR (DMSO-d6,125 MHz)δ:160.5(C-2),155.2 (C-4),152.0 (C-7),148.5 (C-9),143.7 (C-6),135.4(C-1'),129.6 (C-4'),128.9(C-3',5'),128.4 (C-2',6'),111.4 (C-3),111.0(C-10),110.5 (C-5),100.6 (C-8),56.3 (C-7-OMe)。以上波谱数据与文献[11]对照基本一致,故鉴定为dalbergin。
化合物2 黄色粉末;ESI-MS m/z:309.2[M +Na]+,分子式为C17H18O4。1H NMR (CDCl3,500 MHz)δ:7.02 (1H,d,J=8.3 Hz,H-6'),6.93(1H,d,J=8.2 Hz,H-5),6.48 (1H,d,J=2.4 Hz,H-3'),6.45 (1H,dd,J=8.3,2.4 Hz,H-5'),6.39 (1H,dd,J=8.2,2.5 Hz,H-6),6.35 (1H,d,J=2.5 Hz,H-8),4.29 (1H,ddd,J=10.3,3.4,2.0 Hz,H-2a),4.0 (1H,t,J=10.3 Hz,H-2b),3.80 (6H,s,7,4'-OMe)3.55 (1H,m,H-3),2.97(1H,dd,J=15.5,10.8 Hz,H-4a),2.85 (1H,ddd,J=15.7,5.2,1.7Hz,H-4b);13C NMR (CDCl3,125 MHz)δ:159.8 (C-2'),158.4 (C-4'),155.3 (C-7),155.0 (C-9),130.5 (C-5)127.7 (C-6'),122.0(C-1'),114.9 (C-10),108.0 (C-6),104.3 (C-5'),103.3 (C-8),98.8 (C-3'),70.3 (C-2),55.5 (C-4',7-OMe),31.7 (C-3),30.5 (C-4)。以上波谱数据与文献[12]对照基本一致,故鉴定为7-O-methylvestitol。
化合物3 无色晶体;ESI-MS m/z:441.2[M +Na]+,分子式为C22H26O8。1H NMR (DMSO-d6,500 MHz)δ:8.20 (2H,s,-OH),6.50 (4H,s,H-2,6,2',6'),4.51 (2H,d,J=4.0 Hz,H-7,7'),4.06 (2H,m,H-9a,9'a),3.67 (2H,m,H-9b,9'b),3.65 (12H,s,3,5,3',5'-OMe),2.95 (2H,m,H-8,8');13C NMR(DMSO-d6,125 MHz)δ:148.0 (C-3,5,3',5'),134.9 (C-4,4'),131.5 (C-1,1'),103.7 (C-2,6,2',6'),85.4 (C-7,7'),71.2 (C-9,9'),56.1 (C-3,5,3',5'),53.8(C-8,8')。以上波谱数据与文献[13]对照基本一致,故鉴定为syringaresinol。
化合物4 白色粉末;ESI-MS m/z:339.1[M +Na]+,结合NMR 谱和ESI-MS 数据推断分子式为C17H16O6。1H NMR (CDCl3,500 MHz)δ:7.81 (1H,d,J=8.7 Hz,H-5),7.37 (1H,d,J=8.4 Hz,H-6'),6.51 (1H,dd,J=8.7,2.2 Hz,H-6),6.45(1H,dd,J=8.7,2.4 Hz,H-5'),6.44 (1H,d,J=2.3 Hz,H-3'),6.32 (1H,d,J=2.2 Hz,H-8),4.80(1H,d,J=11.8 Hz,H-2a),4.26 (1H,d,J=11.8 Hz,H-2b),3.74 (3H,s,H-2'-OMe),3.67 (3H,s,H-4'-OMe);13C NMR (CDCl3,125 MHz)δ:191.9 (C-4),163.4 (C-7),163.2 (C-9),161.4 (C-4'),158.2(C-2'),130.2 (C-5),128.6 (C-6'),119.1 (C-1'),113.6 (C-10),111.3 (C-6),104.8 (C-5'),103.4(C-8),99.8 (C-3'),74.3 (C-3),73.8 (C-2),55.7(C-2'-OMe),55.5 (C-4'-OMe)。根据HMBC 信号,δH7.81 (1H,d,J=8.7 Hz,H-5)与δC191.9 (C-4)相关,表明氢在C-5 上;从δH7.37 (1H,d,J=8.4 Hz,H-6')与δC74.3 (C-3)相关,且在ROESY 上与δH4.80 (1H,d,J=11.8 Hz,H-2a)有NOE 效应,表明氢在C-6'上。通过偶合常数可以判断芳环上的取代位置为C-7,2',4'。由HMBC 上δH3.74 (3H,s,H-2'-OMe)与δC158.2 (C-2')相关,δH3.67 (3H,s,H-4'-OMe)与δC161.4 (C-4')相关,而δH7.37 (1H,d,J=8.4 Hz,H-6')分别与δC158.2 (C-2')和δC161.4 (C-4')相关,在ROESY 上观察到δH3.67(3H,s,H-4'-OMe)和δH3.74 (3H,s,H-2'-OMe)与δH6.44 (1H,d,J=2.3 Hz,H-3')的NOE 效应,表明C-2',4'被甲氧基取代而C-7 被羟基取代。以上可以鉴定化合物结构为3,7-dihydroxy -2',4'-dimethoxyisoflavanone。
化合物5 白色粉末;ESI-MS m/z:341.1[M +Na]+,结合NMR 谱和ESI-MS 数据推断分子式为C17H18O6。1H NMR (DMSO-d6,500 MHz)δ:8.78(1H,s,7-OH),8.48 (1H,s,3'-OH),8.37 (1H,s,2'-OH),6.47 (1H,d,J=8.4 Hz,H-5),6.39 (1H,d,J=8.6 Hz,H-6'),6.28 (1H,d,J=8.6 Hz,H-5'),6.20 (1H,d,J=8.4 Hz,H-6),4.30 (1H,dd,J=15.2,4.3 Hz,H-4a),4.09 (1H,ddd,J=10.2,3.06,1.89 Hz,H-2a),3.77 (1H,dd,J=10.2,10.2 Hz,H-2b),3.59 (3H,s,H-4'-OMe),3.51 (3H,s,H-8-OMe),3.18 (1H,m,H-3),2.75 (1H,dd,J=15.6,11.0 Hz,H-4b);13C NMR (DMSO-d6,125 MHz)δ:148.8 (C-7),147.9 (C-9),147.3 (C-4'),144.0 (C-2'),135.7 (C-8),133.8 (C-3'),123.8(C-5),121.0 (C-1'),116.6 (C-6'),114.3 (C-10),108.3 (C-6),103.1 (C-5'),69.4 (C-2),60.0 (C-8-OMe),55.9 (C-4'-OMe),31.4 (C-3),30.1 (C-4)。根据HMBC 信号,δH6.47 (1H,d,J=8.4 Hz,H-5)与δC30.1 (C-4)相关,表明氢连接在C-5;δH6.39 (1H,d,J=8.6 Hz,H-6')与δC31.4 (C-3)相关,且δH3.18 (1H,m,H-3)与δC116.6 (C-6')相关表明氢连接在C-6'。通过偶合常数可以确定δH6.28 (1H,d,J=8.6 Hz,H-5')连接在C-5',δH6.20(1H,d,J=8.4 Hz,H-6)连接在C-6。在ROESY上观察到δH6.28 (1H,d,J=8.6 Hz,H-5')与δH3.59 (3H,s,H-4'-OMe)的NOE 效应表明C-4'连接甲氧基;δH6.20 (1H,d,J=8.4 Hz,H-6)与δH8.78(1H,s,7-OH)有NOE 效应,而δH8.78 (1H,s,7-OH)与δH3.51 (3H,s,H-8-OMe)有NOE 效应,表明C-8 连接甲氧基。以上可以鉴定化合物结构为3'-hydroxy-8-methoxyvestitol。
化合物6 白色粉末;1H NMR (DMSO-d6,500 MHz)δ:10.4 (1H,s,-OH),9.50 (1H,s,-OH),7.69 (1H,d,J=8.6 Hz,H-4),7.36 (1H,d,J=8.3,H-6'),7.11 (1H,s,H-3),6.92 (1H,br.s,H-3'),6.70 (1H,dd,J=8.3,2.0 Hz,H-5'),6.55(1H,d,J=2.4 Hz,H-7),6.53 (1H,dd,J=8.6,2.4 Hz,H-5),3.74 (3H,s,4'-OMe);13C NMR (DMSO-d6,125 MHz)δ:159.9 (C-2),155.5 (C-7a),155.2 (C-6),154.2 (C-4'),151.2 (C-2'),126.7(C-4),121.6 (C-1'),120.8 (C-6'),112.0 (C-5'),110.7 (C-3a),105.3 (C-5),103.5 (C-3),101.8
(C-7),97.4 (C-3'),55.2 (C-4'-OMe)。以上波谱数据与文献[14]对照基本一致,故鉴定为2',6-dihydroxy-4'-methoxy-2-arylbenzofuran。
化合物7 无色晶体;1H NMR (DMSO-d6,500 MHz)δ:7.68 (1H,d,J=8.6 Hz,H-5),6.84 (1H,d,J=8.5 Hz,H-6'),6.74 (1H,d,J=8.5 Hz,H-5'),6.53 (1H,dd,J=8.5,2.2Hz,H-6),6.35(1H,d,J=2.2 Hz,H-8),4.50 (1H,dd,J=11.2,11.2 Hz,H-2a),4.44 (1H,dd,J=11.2,5.5 Hz,H-2b),4.14 (1H,dd,J=11.6,5.5 Hz,H-3),3.77 (3H,s,3'-OMe),3.73 (3H,s,2'-OMe)3.70(3H,s,4'-OMe);13C NMR (DMSO-d6,125 MHz)δ:190.6 (C-4),164.5 (C-7),163.4 (C-9),153.1 (C-4'),151.6 (C-2'),141.8 (C-3'),129.1 (C-5),124.6 (C-1'),121.8 (C-6'),114.0 (C-10),110.8(C-6),107.8 (C-5'),102.5 (C-8),70.7 (C-2),60.6 (C-2'-OMe),60.3 (C-4'-OMe),55.9 (C-3'-OMe),47.4 (C-3)。以上波谱数据与文献[11]对照基本一致,故鉴定为3'-O-methylviolanone。
化合物8 白色晶体;1H NMR (DMSO-d6,500 MHz)δ:12.1 (1H,s,-OH),10.8 (1H,s,-OH),7.53 (2H,d,J=6.0 Hz,H-2',6'),7.44 (2H,t,J=6.0 Hz,H-3',5'),7.39 (1H,t,J=6.0 Hz,H-4'),5.94 (1H,d,J=2.2 Hz,H-8),5.91 (1H,d,J=2.2 Hz,H-6),5.58 (1H,dd,J=12.6,3.0,H-2),3.26 (1H,dd,J=17.1,12.6 Hz,H-2a),2.80(1H,dd,J=17.1,3.0 Hz,H-3b);13C NMR (DMSO-d6,125 MHz)δ:196.0 (C-4),166.8 (C-7),163.6 (C-5),162.8 (C-9),138.8 (C-1'),128.6(C-3',4',5'),126.1 (C-2',6'),101.9 (C-10),96.0(C-6),95.1 (C-8),78.5 (C-2),42.2 (C-3)。以上波谱数据与文献[11]对照基本一致,故鉴定为pinocembrin。
化合物9 浅黄色粉末;1H NMR (DMSO-d6,500 MHz)δ:12.9 (1H,s,-OH),8.35 (1H,s,H-2),7.49 (2H,d,J=8.4 Hz,H-2',6'),6.99 (1H,d,J=8.4 Hz,H-3',5'),6.39 (1H,d,J=1.5 Hz,H-8),6.23 (1H,d,J=1.5 Hz,H-6),3.79 (3H,s,7-OMe);13C NMR (DMSO-d6,125 MHz)δ:180.2 (C-4),164.4 (C-7),162.1 (C-5),159.2 (C-4'),157.7(C-9),154.3 (C-2),130.3 (C-2',6'),123.0 (C-3),122.1 (C-1'),113.8 (C-3',5'),104.6 (C-10),99.1 (C-6),93.8 (C-8),55.2 (C-7-OMe)。以上波谱数据与文献[11]对照基本一致,故鉴定为prunetin。
化合物10 白色粉末;1H NMR (DMSO-d6,500 MHz)δ:9.22 (1H,s,-OH),8.66 (1H,s,-OH),6.86 (1H,d,J=8.2 Hz,H-5),6.68 (1H,d,J=8.6 Hz,H-5'),6.59 (1H,d,J=8.6 Hz,H-6'),6.29 (1H,dd,J=8.2,2.3 Hz,H-6),6.20 (1H,d,J=2.3 Hz,H-8),4.10 (1H,dt,J=10.2,2.1 Hz,H-2a),3.89 (1H,t,J=10.2 Hz,H-2b),3.75(3H,s,4'-OMe)3.72 (3H,s,2'-OMe),3.31 (1H,m,H-3),2.81 (1H,dd,J=15.5,11.2 Hz,H-4a),2.73 (1H,dd,J=15.6,3.7 Hz,H-4b);13C NMR(DMSO-d6,125 MHz)δ:156.6 (C-7),154.6 (C-9),147.8 (C-2'),146.1 (C-4'),139.4 (C-3'),130.2 (C-5),127.0 (C-1'),116.3 (C-6'),112.8(C-10),108.1 (C-6),107.6 (C-5'),102.6 (C-8),69.8 (C-2),60.4 (C-2'-OMe),56.0 (C-4'-OMe),31.4 (C-3),31.0 (C-4)。以上波谱数据与文献[15]对照基本一致,故鉴定为mucronulatol。
采用Ellman 方法[16]测定样品的乙酰胆碱酯酶抑制活性。在96 孔酶标板中依次加入110 μL PBS(0.1M pH=8.0),10 μL 样品溶液(1.0 mg/mL,DMSO),40 μL AChE (0.10 U/mL,pH=8.0 PBS溶解稀释)。4 ℃孵育20 min 后,加40 μL DTNB(6.25 Mm)和碘化硫代乙酰胆碱(6.25 mM)的等体积混合液。30 ℃孵育20 min 后,用酶标仪在405 nm 下测定其吸光度值。
抑制率的计算公式:抑制率={[A对照-(A样品-A空白)]/A对照}×100%,其中,对照组用10 μL DMSO 代替10 μL 样品溶液;空白组用10 μL DMSO代替10 μL 样品溶液,再用40 μL PBS 代替40 μL AChE。实验以他克林为阳性对照,所有实验重复3 次。
化合物1(50 μg/mL)对乙酰胆碱酯酶抑制率为30.36%,阳性对照他克林(0.08 (g/mL)对乙酰胆碱酯酶的抑制率为72.40%。实验表明化合物1具有一定的乙酰胆碱酯酶抑制活性。
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