β-氨基醇类香紫苏醇衍生物的合成及抑菌活性

2023-06-20 06:19麻妙锋周遵军仲崇民冯吉利
农药学学报 2023年3期
关键词:熔点紫苏苯基

麻妙锋, 白 雪, 周遵军, 刘 艺, 仲崇民*,, 冯吉利

(1.西北农林科技大学 化学与药学院,陕西 杨凌 712100;2.西北农林科技大学 生命科学学院,陕西 杨凌 712100)

β-氨基醇结构广泛存在于天然产物以及有机中间体中,含有β-氨基醇结构的分子一般具有消炎、抗肿瘤和抑菌等重要的生物活性[1-5]。三元环氧化合物由于分子内存在张力很大的三元环,化学性质活泼,其与胺亲核加成的氨解反应是合成β-氨基醇非常有效的方法,被广泛应用于合成具有生物活性的天然或非天然含β-氨基醇结构的药物,在生物医学、药学等领域起着十分重要的作用[6]。

香紫苏醇 (sclareol) 又名硬尾醇,是从唇形科植物南欧丹参Salvia sclareaL.中分离得到的一种半日花烷 (labdane) 二萜二叔醇类化合物,具有广谱的生物活性,在医药、农药、香料等领域中均有应用[7-11]。本研究以香紫苏醇为先导化合物,在保持二萜类骨架结构不变的情况下,对其进行结构修饰及抑菌活性构效关系的研究。前期研究发现,母体中的羟基是维持其良好活性的主要活性官能团,在骨架中非活性官能团双键部位引入活性药效基团进行结构优化,可以在一定程度上提高母体化合物的抑菌活性[12-13]。在此基础上,本研究对双键部位的结构优化进行了深入的研究,先对末端双键环氧化,再进行氨解反应,合成24 个新的β-氨基醇类香紫苏醇衍生物,并探究此类化合物对植物病原菌的抑菌活性。目标化合物的合成路线见图式1。

图式1 目标化合物的合成路线Scheme 1 Synthetic route of target compounds

1 材料与方法

1.1 仪器、试剂与药剂

Bruker Avance 型核磁共振谱仪 (TMS 为内标,1H NMR 为 500 MHz、13C NMR 为 125 MHz,美国 Bruker 公司);Waters Q-Tof 型高分辨质谱仪(美国 Waters 科技有限公司);Ry-1G 熔点仪 (天津光学仪器厂)。

薄层层析硅胶为 GF254型,柱层析硅胶粒度为 200~300 目 (筛孔径48~75μm),均为青岛海洋化工厂生产;无水二氯甲烷 (CH2Cl2) 在氮气保护下经氢化钙干燥后蒸馏除水使用;所用试剂邻、对、间-氟苯胺,邻、对、间-氯苯胺,邻、对、间-溴苯胺,邻、对、间-碘苯胺,邻、对、间-硝基苯胺,邻、对、间-甲基苯胺,邻、对、间-甲氧基苯胺,2-氨基噻唑,2-氨基苯并噻唑,间氯过氧苯甲酸 (m-CPBA),三氟甲烷磺酸锌 [Zn(OTf)2]等,均为分析纯 (AR) 国产试剂,购自上海阿拉丁生化科技股份有限公司,均未经进一步处理;原料香紫苏醇购自西安天一生物技术有限公司,光学纯度为 95%,天然香紫苏醇结构中 8-位和 13-位羟基均为R构型。98% 噻菌灵 (thiabendazole) 原药购自上海阿拉丁生化科技股份有限公司。

1.2 化合物的合成

1.2.1 香紫苏醇-1,2-环氧化合物 (1) 的合成 参考文献[14-15]方法进行。在干燥的 500 mL 双口烧瓶中,氮气保护下加入香紫苏醇 (6.16 g,20 mmol)及无水 CH2Cl2(200 mL),待上述反应体系冷却至 0 ℃ 后缓慢分批加入 75% 的m-CPBA (5.52 g,24 mmol),加完后室温继续搅拌反应1 h。待反应完成后,将 20 mL 饱和亚硫酸钠溶液倒入反应液中搅拌 0.5 h 后用二氯甲烷萃取。有机相依次用饱和碳酸氢钠、饱和食盐水洗涤,无水硫酸钠干燥,减压浓缩后经硅胶柱层析 [V(石油醚) :V(乙酸乙酯) = 2 : 1] 分离,得到白色固体化合物 1 (6.15 g),产率95%;熔点 131~132 ℃。1H NMR (CDCl3)δ2.95~2.90 (m, 1H), 2.85~2.79 (m, 1H), 2.73~2.68 (m,1H), 1.87~1.54 (m, 7H), 1.44~1.36 (m, 4H),1.28~1.09 (m, 9H), 0.97~0.90 (m, 2H), 0.87 (s, 3H),0.80~0.79 (m, 6H).13C NMR (CDCl3)δ74.6 (74.5),70.1 (69.7), 62.0 (61.8), 58.5 (58.4), 56.1 (56.1), 44.4(44.3), 44.1, 43.8 (43.6), 42.0 (42.0), 41.3, 39.8(39.7), 39.3 (39.2), 33.4 (33.3), 24.2 (24.0), 22.8,21.5, 20.5 (20.5), 18.5 (18.5), 18.2, 15.4 (15.4).

多次合成累积化合物 1,以满足后续衍生物的制备。

1.2.2 目标化合物β-氨基醇类香紫苏醇衍生物(2a~2x) 的合成 参考文献[16]方法进行。将化合物 1 (1.94 g,6 mmol) 溶解于40 mL CH2Cl2中,加入胺 (7.2 mmol) 及三氟甲烷磺酸锌 (109 mg,0.3 mmol),室温下搅拌反应 24 h 或 30 h,待反应完成后,用饱和食盐水洗涤,无水硫酸钠干燥,减压浓缩后经硅胶柱层析 [V(石油醚) :V(乙酸乙酯) = 1 : 1] 分离,得到目标化合物 2a~2x。

14-羟基-15-(2-氟苯基氨基)-香紫苏醇(2a):白色固体,产率 48%;熔点 157~159 ℃。1H NMR (DMSO-d6)δ7.05~6.99 (m, 1H), 6.98~6.94 (m, 1H), 6.77 (t,J= 8.1 Hz,1H), 6.55~6.51 (m, 1H), 5.02~5.00 (m, 1H), 4.74~4.73 (m,1H), 4.15 (s, 1H), 3.90 (s, 1H), 3.48~3.45 (m, 1H), 3.38~3.35(m, 1H), 2.89~2.84 (m, 1H), 1.70~1.68 (m, 1H), 1.64~1.61 (m,1H), 1.56~1.46 (m, 5H), 1.37~1.31 (m, 3H), 1.24~1.19 (m,2H), 1.13~1.10 (m, 1H), 1.07 (s, 3H), 1.01 (s, 3H), 0.96~0.95(m, 1H), 0.90~0.85 (m, 2H), 0.83 (s, 3H), 0.75 (s, 3H), 0.74 (s,3H).13C NMR (125 MHz, DMSO-d6)δ151.5 (d,J= 234.9 Hz), 137.5 (d,J= 11.6 Hz), 125.3 (d,J= 3.4 Hz), 115.8 (d,J=6.5 Hz), 114.6 (d,J= 18.0 Hz), 112.6 (d,J= 3.9 Hz), 74.8,73.9, 72.9, 61.9, 56.3, 45.1, 44.5, 42.2, 41.5, 39.8, 39.2, 33.8,33.4, 24.4, 24.1, 21.9, 20.6, 18.9, 18.5, 15.8.HR-MS (ESI)m/z: 计算值 C26H43FNO3: 436.3221[M + H]+, 实测值436.3219.

14-羟基-15-(3-氟苯基氨基)-香紫苏醇 (2b):白色固体,产率52%;熔点 156~158 ℃。1H NMR (DMSO-d6)δ7.06~7.01 (m, 1H), 6.44~6.42 (m, 1H), 6.37~6.35 (m, 1H),6.26~6.22 (m, 1H), 5.74~5.71 (m, 1H), 4.59~4.58 (m, 1H),4.10 (s, 1H), 3.89 (s, 1H), 3.42~3.40 (m, 1H), 3.30~3.27(m,1H), 2.82~2.78 (m, 1H), 1.70~1.68 (m, 1H), 1.65~1.62 (m,1H), 1.55~1.50 (m, 5H), 1.38~1.31 (m, 3H), 1.24~1.19 (m,2H), 1.13~1.10 (m, 1H), 1.07 (s, 3H), 1.02 (s, 3H), 0.96~0.95(m, 1H), 0.91~0.86 (m, 2H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ164.0 (d,J= 237.4 Hz), 151.7 (d,J= 10.9 Hz), 130.5 (d,J= 10.1 Hz), 108.9 (d,J= 1.8 Hz),101.7 (d,J= 21.5 Hz), 98.7 (d,J= 24.9 Hz), 75.3, 73.8, 72.9,62.0, 56.3, 45.3, 44.5, 42.2, 41.5, 39.8, 39.2, 33.8, 33.4, 24.4,23.9, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H43FNO3: 436.3221 [M + H]+, 实测值436.3219.

14-羟基-15-(4-氟苯基氨基)-香紫苏醇 (2c):白色固体,产率 57%;熔点 146~148 ℃。1H NMR (DMSO-d6)δ6.90~6.87 (m, 2H), 6.61~6.57 (m, 2H), 5.30 (br s, 1H),4.58~4.54 (m, 1H), 4.07 (s, 1H), 3.91 (s, 1H), 3.44~3.42 (m,1H), 3.32~3.25 (m, 1H), 2.80~2.74 (m, 1H), 1.71~1.63 (m,3H), 1.57~1.53 (m, 4H), 1.38~1.31 (m, 3H), 1.24~1.19 (m,2H), 1.13~1.11 (m, 1H), 1.06 (s, 3H), 1.02 (s, 3H), 0.99~0.96(m, 2H), 0.89~0.86 (m, 1H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ154.6 (d,J= 230.5 Hz), 146.3,115.6 (d,J= 21.8 Hz), 113.4 (d,J= 7.2 Hz), 75.1, 73.8, 72.9,61.9, 56.3, 45.9, 44.5, 42.2, 41.6, 39.8, 39.2, 33.8, 33.4, 24.4,23.9, 21.8, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H43FNO3: 436.3221 [M + H]+, 实测值436.3220.

14-羟基-15-(2-氯苯基氨基)-香紫苏醇 (2d):白色黏状固体,产率 51%;熔点 118~120 ℃。1H NMR (DMSO-d6)δ7.24 (dd,J= 7.9, 1.3 Hz, 1H), 7.15~7.11 (m, 1H), 6.76 (dd,J=8.2, 1.0 Hz, 1H), 6.59 (td,J= 7.8, 1.2 Hz, 1H), 5.17~5.15 (m,1H), 4.82~4.81 (m, 1H), 4.21 (s, 1H), 3.93 (s, 1H), 3.50~3.47(m, 1H), 3.41~3.37 (m, 1H), 2.93~2.89 (m, 1H), 1.71~1.47 (m,7H), 1.36~1.22 (m, 5H), 1.19~1.12 (m, 1H), 1.08 (s, 3H), 1.02(s, 3H), 0.97~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ144.8, 129.3, 128.5, 118.5, 116.8,111.9, 74.7, 74.0, 72.9, 61.9, 56.3, 45.1, 44.5, 42.2, 41.4, 39.8,39.2, 33.8, 33.4, 24.4, 24.0, 21.9, 20.6, 18.9, 18.5, 15.8.HRMS (ESI)m/z: 计算值C26H43ClNO3: 452.2926 [M + H]+, 实测值452.2924.

14-羟基-15-(3-氯苯基氨基)-香紫苏醇 (2e):白色固体,产率 60%;熔点 148~149 ℃。1H NMR (DMSO-d6)δ7.04 (t,J= 8.0 Hz, 1H), 6.60 (s, 1H), 6.57~6.48 (m, 2H),5.80~5.76 (m, 1H), 4.62~4.59 (m, 1H), 4.12 (s, 1H), 3.90 (s,1H), 3.40~3.39 (m, 1H), 3.30~3.26 (m, 1H), 2.82~2.80 (m,1H), 1.70~1.45 (m, 7H), 1.37~1.19 (m, 5H), 1.13~1.02 (m,7H), 0.95~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ151.1 134.1, 130.7, 115.1, 111.7,111.2, 75.3, 73.8, 72.9, 61.9, 56.3, 45.2, 44.5, 42.2, 41.4, 39.8,39.2, 33.8, 33.4, 24.4, 23.9, 21.9, 20.6, 19.0, 18.5, 15.8.HRMS (ESI)m/z: 计算值C26H43ClNO3: 452.2926 [M + H]+, 实测值452.2923.

14-羟基-15-(4-氯苯基氨基)-香紫苏醇 (2f):白色固体,产率 52%;熔点 172~174 ℃。1H NMR (DMSO-d6)δ7.06~7.05 (m, 2H), 6.62~6.60 (m, 2H), 5.61~5.57 (m, 1H),4.60~4.56 (m, 1H), 4.08 (s, 1H), 3.90 (s, 1H), 3.42~3.40 (m,1H), 3.29~3.25 (m, 1H), 2.80~2.78 (m, 1H), 1.68~1.47 (m,7H), 1.37~1.19 (m, 5H), 1.13~1.10 (m, 1H), 1.06 (s, 3H), 1.01(s, 3H), 0.95~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ148.5, 128.9, 119.0, 114.0, 75.1,73.8, 72.9, 61.9, 56.3, 45.4, 44.5, 42.2, 41.6, 39.8, 39.2, 33.8,33.4, 24.4, 24.0, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H43ClNO3: 452.2926 [M + H]+, 实测值452.2923.

14-羟基-15-(2-溴苯基氨基)-香紫苏醇 (2g):黄色黏状固体,产率42%;熔点 81~83 ℃。1H NMR (DMSO-d6)δ7.40 (dd,J= 7.9, 1.4 Hz, 1H), 7.19~7.15 (m, 1H), 6.74~6.72(m, 1H), 6.52 (td,J= 7.7, 1.3 Hz, 1H), 5.10~5.08 (m, 1H),4.83~4.82 (m, 1H), 4.23 (s, 1H), 3.93 (s, 1H), 3.48~3.47 (m,1H), 3.40~3.36 (m, 1H), 2.92~2.87 (m, 1H), 1.71~1.47 (m,7H), 1.37~1.22 (m, 5H), 1.12~1.10 (m, 1H), 1.08 (s, 3H), 1.02(s, 3H), 0.97~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ145.8, 132.6, 129.2, 117.5, 112.1,109.3, 74.7, 73.9, 72.9, 61.9, 56.3, 45.2, 44.5, 42.2, 41.4, 39.8,39.2, 33.8, 33.4, 24.4, 24.0, 21.9, 20.6, 18.9, 18.5, 15.8.HRMS (ESI)m/z: 计算值C26H43BrNO3: 496.2421 [M + H]+, 实测值496.2428.

14-羟基-15-(3-溴苯基氨基)-香紫苏醇 (2h):白色固体,产率45%;熔点 138~139 ℃。1H NMR (DMSO-d6)δ6.98 (t,J= 8.0 Hz, 1H), 6.76~6.75 (m, 1H), 6.63~6.59 (m,2H), 5.79~5.75 (m, 1H), 4.62~4.59 (m, 1H), 4.12 (s, 1H), 3.90(br s, 1H), 3.40~3.35 (m, 1H), 3.29~3.26 (m, 1H), 2.82~2.79(m, 1H), 1.68~1.46 (m, 7H), 1.38~1.19 (m, 5H), 1.14~1.10 (m,1H), 1.06 (s, 3H), 1.02 (s, 3H), 0.95~0.86 (m, 3H), 0.84 (s,3H), 0.76 (s, 3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ151.3,131.1, 122.8, 117.9, 114.7, 111.5, 75.3, 73.8, 72.9, 62.0, 56.3,45.2, 44.5, 42.2, 41.4, 39.8, 39.2, 33.8, 33.4, 24.5, 24.0, 21.9,20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H43BrNO3: 496.2421 [M + H]+, 实测值496.2417.

14-羟基-15-(4-溴苯基氨基)-香紫苏醇 (2i):白色固体,产率 46%;熔点 182~184 ℃。1H NMR (DMSO-d6)δ7.17 (d,J= 7.4 Hz, 2H), 6.58~6.54 (m, 2H), 5.63 (br s, 1H),4.60~4.57 (m, 1H), 4.19 (s, 1H), 3.99 (s, 1H), 3.41~3.32 (m,1H), 3.30~3.25 (m, 1H), 2.83~2.79 (m, 1H), 1.67~1.45 (m,7H), 1.34~1.19 (m, 5H), 1.13~1.02 (m, 7H), 0.97~0.88 (m,3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s, 3H).13C NMR(DMSO-d6)δ148.9, 131.7, 114.4, 106.2, 74.7, 73.7, 73.0,61.9, 56.3, 45.3, 44.2, 43.1, 42.2, 39.8, 39.2, 33.8, 33.4, 24.6,23.9, 21.9, 20.5, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H43BrNO3: 496.2421 [M + H]+, 实测值496.2417.

14-羟基-15-(2-碘苯基氨基)-香紫苏醇 (2j):淡黄色液体,产率 55%。1H NMR (DMSO-d6)δ7.63~7.61 (m, 1H),7.20~7.17 (m, 1H), 6.65~6.59 (m, 1H), 6.39 (td,J= 7.6, 1.2 Hz, 1H), 4.90~4.89 (m, 1H), 4.85 (s, 1H), 4.21 (s, 1H), 3.93 (s,1H), 3.49~3.46 (m, 1H), 3.39~3.37 (m, 1H), 2.94~2.85 (m,1H), 1.69~1.47 (m, 7H), 1.38~1.23 (m, 5H), 1.19~1.09 (m,7H), 0.97~0.87 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.75 (s,3H).13C NMR (DMSO-d6)δ148.2, 139.1, 129.9, 118.5, 111.3,85.8, 74.8, 73.9, 72.9, 60.2, 56.3, 45.5, 44.5, 42.2, 41.4, 39.8,39.2, 33.8, 33.4, 24.4, 24.0, 21.9, 20.6, 18.9, 18.5, 15.8.HRMS (ESI)m/z: 计算值C26H43INO3: 544.2282 [M + H]+, 实测值544.2284.

14-羟基-15-(3-碘苯基氨基)-香紫苏醇 (2k):白色固体,产率 53%;熔点 139~140 ℃。1H NMR (DMSO-d6)δ6.94 (s, 1H), 6.83~6.81 (m, 2H), 6.63~6.59 (m, 1H), 5.68~5.64(m, 1H), 4.61~4.57 (m, 1H), 4.10 (s, 1H), 3.90 (s, 1H),3.40~3.38 (m, 1H), 3.31~3.24 (m, 1H), 2.82~2.76 (m, 1H),1.68~1.53 (m, 7H), 1.38~1.22 (m, 5H), 1.13~1.11 (m, 1H),1.06 (s, 3H), 1.02 (s, 3H), 0.95~0.86 (m, 3H), 0.84 (s, 3H),0.76 (s, 3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ151.2,131.3, 124.1, 120.8, 111.9, 96.0, 75.3, 73.8, 72.9, 62.0, 56.3,45.1, 44.5, 42.2, 41.4, 39.8, 39.2, 33.8, 33.4, 24.5, 24.0, 21.9,20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H43INO3:544.2282 [M + H]+, 实测值544.2282.

14-羟基-15-(4-碘苯基氨基)-香紫苏醇 (2l):白色固体,产率 60%;熔点 179~181 ℃。1H NMR (DMSO-d6)δ7.32~7.30 (m, 2H), 6.49~6.45 (m, 2H), 5.66~5.61 (m, 1H),4.60~4.56 (m, 1H), 4.08 (s, 1H), 3.90 (s, 1H), 3.41~3.39 (m,1H), 3.31~3.25 (m, 1H), 2.82~2.75 (m, 1H), 1.69~1.47 (m,7H), 1.37~1.22 (m, 5H), 1.13~1.09 (m, 1H), 1.06 (s, 3H), 1.02(s, 3H), 0.97~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ149.2, 137.5, 115.4, 115.2, 75.0,73.8, 72.9, 61.9, 56.3, 45.1, 44.5, 42.2, 41.6, 39.8, 39.2, 33.8,33.4, 24.4, 24.0, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H43INO3: 544.2282 [M + H]+, 实测值544.2278.

14-羟基-15-(2-硝基苯基氨基)-香紫苏醇 (2m):橙色黏状液体,产率 49%。1H NMR (DMSO-d6)δ8.40~8.38 (m,1H), 8.07 (dd,J= 8.7, 1.5 Hz, 1H), 7.54~7.51 (m, 1H),7.09~7.06 (m, 1H), 6.67 (t,J= 7.7 Hz, 1H), 5.01~5.00 (m,1H), 4.28 (s, 1H), 3.95 (s, 1H), 3.60~3.57 (m, 1H), 3.54~3.50(m, 1H), 3.18~3.13 (m, 1H), 1.68~1.52 (m, 7H), 1.37~1.31 (m,5H), 1.24~1.21 (m, 1H), 1.10 (s, 3H), 1.02 (s, 3H), 1.00~0.86(m, 3H), 0.83 (s, 3H), 0.75 (s, 3H), 0.74 (s, 3H).13C NMR(DMSO-d6)δ146.0, 137.1, 131.4, 126.7, 115.4, 115.2, 74.8,73.8, 72.9, 61.9, 56.3, 44.7, 44.4, 42.2, 41.4, 39.8, 39.2, 33.8,33.4, 24.4, 24.0, 21.8, 20.6, 19.1, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H42N2NaO5: 485.2986 [M + Na]+, 实测值485.2984.

14-羟基-15-(3-硝基苯基氨基)-香紫苏醇 (2n):橙色黏状固体,产率 52%;熔点 91~92 ℃。1H NMR (DMSO-d6)δ7.39 (s, 1H), 7.31~7.30 (m, 2H), 7.05~7.03 (m, 1H), 6.30~6.25(m, 1H), 4.66~4.65 (m, 1H), 4.17 (s, 1H), 3.92 (s, 1H),3.44~3.41 (m, 1H), 3.40~3.37 (m, 1H), 2.93~2.90 (m, 1H),1.71~1.50 (m, 7H), 1.36~1.22 (m, 5H), 1.19~1.12 (m, 1H),1.09~1.02 (m, 6H), 0.99~0.89 (m, 3H), 0.84 (s, 3H), 0.76 (s,3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ150.7, 149.3, 130.3,118.7, 109.8, 105.8, 75.4, 73.8, 72.9, 61.9, 56.3, 45.2, 44.5,42.2, 41.3, 39.8, 39.2, 33.8, 33.4, 24.4, 24.0, 21.8, 20.6, 19.1,18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H42N2NaO5:485.2986 [M + Na]+, 实测值485.2992.

14-羟基-15-(4-硝基苯基氨基)-香紫苏醇 (2o):黄色固体,产率 58%;熔点 194~195 ℃。1H NMR (DMSO-d6)δ7.99~7.97 (m, 2H), 7.30~7.29 (m, 1H), 6.71~6.69 (m, 2H),4.76~4.75 (m, 1H), 4.19 (s, 1H), 3.94 (s, 1H), 3.44~3.43 (m,2H), 3.01~2.96 (m, 1H), 1.72~1.46 (m, 7H), 1.24~1.18 (m,5H), 1.13~1.11 (m, 1H), 1.08 (s, 3H), 1.03 (s, 3H), 0.96~0.86(m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.75 (s, 3H).13C NMR(DMSO-d6)δ155.4, 135.7, 126.7, 111.3, 75.2, 73.7, 72.9,61.9, 56.3, 45.0, 44.5, 42.2, 41.5, 39.8, 39.2, 33.8, 33.4, 24.4,24.0, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H42N2NaO5: 485.2986 [M + Na]+, 实测值485.2983.

14-羟基-15-(2-甲基苯基氨基)-香紫苏醇 (2p):淡黄色黏状液体,产率 58%。1H NMR (DMSO-d6)δ7.00 (t,J=7.6 Hz, 1H), 6.96 (d,J= 7.2 Hz, 1H), 6.58~6.53 (m, 1H), 6.49(t,J= 7.3 Hz, 1H), 4.75~4.74 (m, 1H), 4.71~4.70 (m, 1H),4.15 (s, 1H), 3.90 (s, 1H), 3.50~3.49 (m, 1H), 3.38~3.36 (m,1H), 2.91~2.87 (m, 1H), 2.07 (s, 3H), 1.70~1.47 (m, 7H),1.34~1.22 (m, 5H), 1.19~1.16 (m, 1H), 1.09~1.02 (m, 6H),0.98~0.89 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.75 (s, 3H).13C NMR (DMSO-d6)δ147.2, 130.1, 127.3, 122.1, 116.1,109.8, 74.7, 74.0, 72.9, 62.0, 56.3, 45.7, 44.5, 42.2, 41.5, 39.8,39.2, 33.8, 33.4, 24.4, 24.1, 21.9, 20.6, 19.1, 18.5, 17.9, 15.8.HR-MS (ESI)m/z: 计算值C27H46NO3: 432.3472 [M + H]+, 实测值432.3475.

14-羟基-15-(3-甲基苯基氨基)-香紫苏醇 (2q):白色固体,产率 56%;熔点 146~147 ℃。1H NMR (DMSO-d6)δ6.93 (t,J= 7.7 Hz, 1H), 6.41~6.40 (m, 2H), 6.33 (d,J= 7.2 Hz, 1H), 5.15 (br s, 1H), 4.53~4.52 (m, 1H), 4.06 (s, 1H), 3.88(s, 1H), 3.43~3.41 (m, 1H), 3.28~3.27 (m, 1H), 2.79~2.75 (m,1H), 2.17 (s, 3H), 1.70~1.48 (m, 7H), 1.37~1.20 (m, 5H),1.13~1.11 (m, 1H), 1.06 (s, 3H), 1.01 (s, 3H), 0.95~0.86 (m,3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s, 3H).13C NMR(DMSO-d6)δ149.6, 138.2, 129.2, 116.9, 113.4, 110.1, 75.3,73.9, 72.8, 62.0, 56.3, 45.4, 44.5, 42.2, 41.6, 39.8, 39.2, 33.8,33.4, 24.4, 24.0, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C27H46NO3: 432.3472 [M + H]+, 实测值432.3472.

14-羟基-15-(4-甲基苯基氨基)-香紫苏醇 (2r):白色固体,产率 62%;熔点 168~170 ℃。1H NMR (DMSO-d6)δ6.88~6.86 (m, 2H), 6.53~6.49 (m, 2H), 5.04~5.00 (m,1H),4.56~4.51 (m, 1H), 4.16 (s, 1H), 3.99 (s, 1H), 3.43~3.41 (m,1H), 3.32~3.25 (m, 1H), 2.81~2.75 (m, 1H), 2.14 (s, 3H),1.69~1.45 (m, 7H), 1.37~1.19 (m, 5H), 1.13~1.02 (m, 7H),0.98~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ147.4, 129.7, 124.3, 112.9, 74.7, 73.8,73.0, 61.9, 56.3, 45.6, 44.2, 42.2, 41.6, 39.8, 39.2, 33.8, 33.4,24.6, 23.9, 22.4, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C27H46NO3: 432.3472 [M + H]+, 实测值432.3468.

14-羟基-15-(2-甲氧基苯基氨基)-香紫苏醇 (2s):白色固体,产率 61%;熔点 103~105 ℃。1H NMR (DMSO-d6)δ6.80~6.75 (m, 2H), 6.58~6.52 (m, 2H), 4.74~4.69 (m, 1H),4.11 (s, 1H), 3.99 (s, 1H), 3.90 (s, 1H), 3.77 (s, 3H), 3.47~3.45(m, 1H), 3.33~3.31 (m, 1H), 2.85~2.76 (m, 1H), 1.68~1.48 (m,7H), 1.37~1.19 (m, 5H), 1.13~1.10 (m, 1H), 1.07~1.01 (m,6H), 0.98~0.87 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s,3H).13C NMR (DMSO-d6)δ147.0, 138.9, 131.1, 121.6, 116.0,110.0, 75.1, 73.9, 72.9, 61.9, 56.3, 55.7, 44.9, 44.5, 42.2, 41.6,39.8, 39.2, 33.8, 33.4, 24.4, 23.9, 21.9, 20.6, 18.9, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C27H46NO4: 448.3421 [M + H]+, 实测值448.3426.

14-羟基-15-(3-甲氧基苯基氨基)-香紫苏醇 (2t):白色固体,产率 60%;熔点 116~118 ℃。1H NMR (DMSO-d6)δ6.94 (t,J= 8.1 Hz, 1H), 6.21~6.17 (m, 1H), 6.16~6.15 (m,1H), 6.10 (dd,J= 8.0, 2.0 Hz, 1H), 5.35~5.31 (m,1H),4.58~4.54 (m, 1H), 4.08 (s, 1H), 3.89 (s, 1H), 3.66 (s, 3H),3.43~3.39 (m, 1H), 3.29~3.26 (m, 1H), 2.82~2.76 (m, 1H),1.70~1.45 (m, 7H), 1.37~1.19 (m, 5H), 1.13~1.08 (m, 1H),1.07~1.01 (m, 6H), 0.95~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s,3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ160.8, 150.9, 130.0,105.8, 101.6, 98.4, 75.4, 73.9, 72.9, 62.0, 56.3, 55.1, 45.4,44.5, 42.2, 41.5, 39.8, 39.2, 33.8, 33.4, 24.4, 23.9, 21.9, 20.6,19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C27H46NO4:448.3421 [M + H]+, 实测值448.3426.

14-羟基-15-(4-甲氧基苯基氨基)-香紫苏醇 (2u):白色固体,产率 65%;熔点 146~148 ℃。1H NMR (DMSO-d6)δ6.71~6.69 (m, 2H), 6.58~6.54 (m, 2H), 4.84 (br s, 1H),4.56~4.50 (m, 1H), 4.04 (s, 1H), 3.90 (s, 1H), 3.63 (s, 3H),3.43~3.40 (m, 1H), 3.26~3.23 (m, 1H), 2.79~2.71 (m, 1H),1.68~1.45 (m, 7H), 1.37~1.19 (m, 5H), 1.13~1.08 (m, 1H),1.05~1.02 (m, 6H), 0.97~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s,3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ151.1, 143.8, 115.0,114.0, 75.1, 73.8, 72.9, 61.9, 56.3, 55.8, 46.2, 44.5, 42.2, 41.7,39.8, 39.2, 33.8, 33.4, 24.4, 23.9, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C27H46NO4: 448.3421 [M + H]+, 实测值448.3418.

14-羟基-15-苯基氨基-香紫苏醇 (2v):白色固体,产率52%;熔点 170~171 ℃。1H NMR (DMSO-d6)δ7.05 (t,J=7.6 Hz, 2H), 6.61~6.57 (m, 2H), 6.50 (t,J= 7.2 Hz, 1H), 5.30(br s, 1H), 4.59~4.54 (m, 1H), 4.07 (s,1H), 3.90 (s, 1H),3.44~3.43 (m, 1H), 3.32~3.29 (m, 1H), 2.84~2.76 (m, 1H),1.68~1.45 (m, 7H), 1.37~1.19 (m, 5H), 1.13~1.02 (m, 7H),0.97~0.86 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ149.6, 129.3, 115.9, 112.8, 75.1, 73.8,73.0, 61.9, 56.3, 45.3, 44.5, 42.2, 41.6, 39.8, 39.2, 33.8, 33.4,24.4, 23.9, 21.9, 20.6, 19.0, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C26H44NO3: 418.3316 [M + H]+, 实测值418.3314.

14-羟基-15-(2-苯并噻唑氨基)-香紫苏醇 (2w):淡黄色固体,产率 42%;熔点 138~140 ℃。1H NMR (DMSO-d6)δ8.13 (br s, 1H), 7.38 (t,J= 7.6 Hz, 1H), 7.19 (t,J= 7.7 Hz,1H), 7.11~7.08 (m, 1H), 6.96 (t,J= 7.5 Hz, 1H), 5.06~4.89(m, 1H), 4.22 (br s, 1H), 4.17~4.07 (m, 1H), 4.04~3.77(m,2H), 3.75~3.63 (m, 1H), 1.69~1.47 (m, 7H), 1.37~1.20 (m,5H), 1.13~1.06 (m, 7H), 1.01~0.87 (m, 3H), 0.83 (s, 3H), 0.75(s, 3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ161.0, 141.8,126.3, 122.7, 121.8, 121.4, 111.0, 74.7, 73.7, 73.0, 62.2, 56.3,45.9, 44.1, 43.1, 42.2, 39.8, 39.1, 33.8, 33.4, 24.5, 23.9, 21.9,20.5, 18.9, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C27H43N2O3S:475.2989 [M + H]+, 实测值475.2995.

14-羟基-15-(2-噻唑氨基)-香紫苏醇 (2x):淡黄色固体,产率 38%;熔点 168~170 ℃。1H NMR (DMSO-d6)δ7.26~7.20 (m, 1H), 6.82~6.74 (m, 1H), 4.22~4.10 (m, 1H),4.00~3.82 (m, 2H), 3.66~3.64 (m, 1H), 3.42 (br s, 2H),1.69~1.52 (m, 7H), 1.34~1.22 (m, 5H), 1.12~1.02 (m, 7H),0.97~0.87 (m, 3H), 0.84 (s, 3H), 0.76 (s, 3H), 0.74 (s, 3H).13C NMR (DMSO-d6)δ167.6, 131.3, 105.4, 74.5, 73.7, 73.0, 62.0,56.3, 50.2, 44.2, 42.2, 41.9, 39.8, 39.1, 33.8, 33.4, 24.4, 24.1,21.8, 20.6, 18.9, 18.5, 15.8.HR-MS (ESI)m/z: 计算值C23H41N2O3S: 425.2832 [M + H]+, 实测值425.2831.

1.3 供试病原菌与培养基

番茄灰霉病菌Botrytis cinerea、马铃薯干腐病菌Fusarium coeruleum、小麦赤霉病菌Fusarium graminearum、玉米弯孢病菌Curvularia lunata和白菜黑斑病菌Alternaria brassicae,由西北农林科技大学生命科学学院提供。选用马铃薯葡萄糖琼脂 (PDA) 培养基[16]。

1.4 抑菌活性测定

采用菌丝生长速率法[17]测定目标化合物 2a~2x对 5 种供试植物病原菌的抑菌活性。以质量浓度100 μg/mL 带药培养基为例:预先将 10 mg 目标化合物溶解于 1 mL 二甲基亚砜 (DMSO) 中,配制成10 mg/mL 药液待用。将 10 mg/mL 待测药液加入到低于 55 ℃ 的 100 mL PDA 培养基中,混合均匀,配制成 100 μg/mL 带药培养基,然后倒入高温灭菌后的 5 个培养皿中。待培养基凝固后,每个培养基平面放入 3 个直径5mm 的供试菌饼,每处理 3 个重复。以香紫苏醇为阳性对照,以 DMSO为阴性对照(1 mL DMSO 加入到 100 mL 液体培养基中,摇匀平均倒入 5 个培养皿中)。25 ℃培养 3 d,用十字交叉法测量菌落扩展直径,按 (1) 式计算抑制率。

式中:I为菌丝生长抑制率,%;D0为阴性对照组菌落增长直径,cm;Dt为处理组菌落增长直径,cm。

对抑菌活性较好的化合物进一步测定其有效中浓度(EC50),设置化合物的质量浓度梯度为100、50、25、12.5、6.25 μg/mL。利用 SPSS 19.0 软件分析数据求得EC50值。试验以香紫苏醇和噻菌灵为阳性对照,DMSO 为阴性对照。

2 结果与讨论

2.1 化合物的合成

β-氨基醇类香紫苏醇衍生物的合成方法较为简单:首先,天然先导化合物香紫苏醇在弱氧化剂m-CPBA 的作用下得到链端环氧化产物 1,产率高达 95%;然后,使用路易斯酸作为催化剂,化合物 1 与芳香胺进行氨解反应制得目标化合物 2a~2x,产率在 38%~65% 之间。与文献报道的环氧化物氨解反应常用催化剂 Al(OTf)3、Sc(OTf)3、Sm(OTf)3及 Ti(OiPr)4等相比较[16,18],本研究中使用的 Zn(OTf)2为催化剂,除了对 2-氨基噻唑 (产率 38%) 和 2-氨基苯并噻唑 (产率 42%) 表现出较低的催化活性外,对其他芳胺类化合物的催化活性均在中等偏上。使用1H NMR,13C NMR 和 HRMS 对化合物 1 及目标产物 2a~2x 的结构进行表征,表明本研究成功合成了邻、间、对不同位置取代吸电子基团 (-F、-Cl、-Br、-I 及 -NO2)、给电子基团 (-CH3和 -OCH3) 和噻唑类的β-氨基醇类香紫苏醇衍生物,这些结构特征为后续探究目标产物与抑菌活性的构效关系提供了可靠支撑。

2.2 目标化合物的抑菌活性分析

菌丝生长速率法测定结果 (表1) 表明,在质量浓度为 100 μg/mL 时,目标化合物 2a~2x 对供试 5 种病原菌均具有抑菌活性。说明对天然先导化合物香紫苏醇骨架中末端双键进行结构修饰,引入β-氨基醇结构单元后可以在一定程度上影响衍生物的抑菌活性。

表1 目标化合物对 5 种供试病原菌的抑制率 (100 μg/mL)Table 1 Inhibition rate values of compounds against five phytopathogens at 100 μg/mL

对目标化合物的结构与抑菌活性相关性研究表明,与苯环上无取代基的化合物 2v 比较,苯环上含有氟吸电性原子和甲基、甲氧基斥电性基团的衍生物对 5 种病原菌的抑菌活性有所提高,但引入溴和碘原子却不甚理想,均导致衍生物的抑菌活性降低,说明衍生物的抑菌活性会受到苯环上连接基团性质的影响。进一步对邻、间、对异构体的抑菌活性数据分析可知,间位氟原子取代衍生物 2b 的抑菌活性与邻、对位衍生物 2a 及 2c相似或略好,而其他间位取代衍生物的抑菌活性普遍要优于对应的邻位和对位衍生物,说明此类衍生物的抑菌活性也会受到取代基位置的影响,且取代基位于间位时的贡献大部分高于其他位置。本研究中还合成了含有苯并噻唑和噻唑的两个杂环衍生物,抑菌活性测定结果表明,苯并噻唑衍生物 2w 对 5 种病原菌的抑菌活性均高于噻唑衍生物 2x。

鉴于 2a~2c、2e、2n、2p~2q、2s~2u 和 2w共 11 个目标化合物在100 μg/mL 下对 5 种供试病原菌具有较高的抑制率,分别以先导化合物香紫苏醇和药剂噻菌灵为阳性对照,溶剂 DMSO 为阴性对照,对其抑菌活性进行了进一步研究,结果见表2。

表2 11 个目标化合物抑制5 种病原菌的EC50 值Table 2 EC50 values of 11 target compounds against five phytopathogens

由表2 可知,11 个目标化合物对马铃薯干腐病菌和小麦赤霉病菌表现出良好的抑菌活性,EC50值分别在 5.48~18.65 μg/mL 和 3.35~11.83 μg/mL之间,活性均高于先导化合物香紫苏醇,但低于噻菌灵。除个别化合物外,11 个目标化合物中绝大部分对其余 3 种病菌的抑菌活性高于或和香紫苏醇相当,且全部对玉米弯孢病菌 (EC50值在5.35~16.37 μg/mL 之间) 和白菜黑斑病菌 (EC50值在 14.32~34.81 μg/mL 之间) 的抑菌活性高于药剂噻菌灵,对番茄灰霉病菌的抑菌活性低于噻菌灵。与其他化合物相比较,2a~2c对供试 5 种病原菌均具有很好的抑菌活性,特别是对小麦赤霉病菌的抑菌活性最好,EC50值分别为 3.79、3.35 和4.66 μg/mL。

3 结论

本研究以天然先导化合物香紫苏醇为母体,通过对末端双键的环氧化、氨解反应于骨架中引入β-氨基醇结构单元,合成 24 个香紫苏醇衍生物,并利用1H NMR、13C NMR 和 HR-MS 对其结构进行表征。采用菌丝生长速率法,以常见的 5 种植物病原菌为靶标,对目标化合物进行了抑菌活性及构效关系研究。结果表明,目标化合物的抑菌活性会受到苯环上连接基团性质及位置的影响,氟原子对化合物抑菌活性的贡献优于其他取代基,且大部分间位取代衍生物的抑菌活性普遍高于对应的邻位和对位取代衍生物,并且其中活性较好的 11 个衍生物对 5 种供试病原菌的抑菌活性大部分高于母体香紫苏醇,对玉米弯孢病菌和白菜黑斑病菌的抑菌活性均高于噻菌灵。此次体外抑菌活性的研究结果为后期的盆栽和小区试验奠定了一定基础,具有进一步研究的价值。

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