梁煒薇,王大成,程 鴻,張明哲,張雅梅*,韋東勝,秦建春*
1吉林大學(xué)植物科學(xué)學(xué)院,長春 130062;2 漢堡大學(xué)生物學(xué)系木材科學(xué)中心,漢堡 21031
植物內(nèi)生菌近年來之所以受到人們的重視是因為人們逐漸認識到它們對寄主植物重要的生態(tài)學(xué)作用及其能夠產(chǎn)生結(jié)構(gòu)新穎多變,生物活性顯著的次生代謝產(chǎn)物的巨大潛力。現(xiàn)在,內(nèi)生菌被認為是一類開發(fā)潛力巨大的生物資源,尤其是從中可以發(fā)現(xiàn)各種生物活性的天然小分子化合物[1]。人參(Panax ginseng)為五加科名貴藥用植物,作為中草藥已經(jīng)被使用了幾千年,具有抗疲勞、減肥、抗腫瘤和抗氧化等多種保健功效[2]。雖然人參化學(xué)成分和藥理活性研究很多,但是關(guān)于人參內(nèi)生菌次生代謝產(chǎn)物的相關(guān)研究還很少,值得進一步研究開發(fā)其內(nèi)生菌天然產(chǎn)物。在長期從藥用植物內(nèi)共生菌次生代謝產(chǎn)物中尋找新穎活性化合物過程中[3-6],我們對東北地區(qū)長白山產(chǎn)的野生人參中分離的一株內(nèi)生真菌RSQMK-9 的化學(xué)成分進行了研究,從該菌的發(fā)酵產(chǎn)物中分離得到14個化合物。在此,我們報道這些化合物的分離純化和結(jié)構(gòu)鑒定以及對海蝦的細胞毒活性。
熔點儀為XRC-1 型顯微熔點儀,溫度計未校正。NMR 用BrukerAM-400 和Bruker DRX-500 型核磁共振儀測定(TMS 為內(nèi)標);EI-MS:70 eV,Varian MAT 731,Varian 311A,AMD-402;ESI-MS:Finnigan Mat-Incos 50,LCQ(Finnigan)。
柱色譜填料:硅膠(青島海洋化工廠);反相填料(Merck RP-18);凝膠填料Sephadex LH-20(Amersham Biosciences,Uppsala,Sweden);大孔樹脂填料Amberlite XAD-16(Rohm & Hass,Paris,F(xiàn)rance);制備TLC 板:Silica gel 60 GF254;TLC 在254 nm 和365 nm 紫外光顯色,并用10%硫酸-乙醇溶液加熱顯色。其余試劑均為分析純。
本實驗所用的內(nèi)生真菌(編號為RSQMK-9)是從人參(Panax ginseng)根部的新鮮組織分離得到,經(jīng)鑒定確定為球毛殼菌(Chaetomium globosum)。
菌株在PDA 培養(yǎng)基上28 ℃活化培養(yǎng)5 d,然后接種在液體培養(yǎng)基(氯化鈣0.2 g,磷酸二氫鉀0.1 g,氯化鉀0.05 g,硫酸鎂0.1 g,葡萄糖20.0 g,蛋白胨15.0g,1000 mL 水,pH7.0)。在1000 mL 的三角瓶中加入400 mL 液體培養(yǎng)基,在26 ℃的搖床上120 rpm 旋轉(zhuǎn)震蕩培養(yǎng)8 d,然后用于提取分離。
20 L 發(fā)酵產(chǎn)物經(jīng)過濾后分別獲得菌絲體和發(fā)酵液。菌絲在50 ℃下烘干粉碎,用丙酮做溶劑超聲提取3 次,合并蒸干溶解在甲醇中,用環(huán)己烷脫脂處理后濃縮得到粗提取物3.5 g,濾液經(jīng)過吸附柱(polymeric resin Amberlite XAD-16),水洗除去鹽和大分子水溶性物質(zhì),之后用甲醇洗脫得到非水溶性成分,濃縮后得到5.6 g 提取物,然后將其懸浮于少量水后用石油醚和乙酸乙酯分別萃取3 次,乙酸乙酯萃取相濃縮得2.2 g 萃取物。經(jīng)過TLC 對照,乙酸乙酯萃取物和菌絲部分脫脂后提取物成分基本相同,故將它們合并起來得到總提取物。提取物經(jīng)粗硅膠拌樣后進行硅膠層析,用二氯甲烷-甲醇系統(tǒng)梯度洗脫,檢測合并得到5個組分(Fr.1~Fr.5),F(xiàn)r.2~Fr.4 分別經(jīng)過反復(fù)的硅膠柱層析、RP-18、制備HPLC、Sephadex LH-20 進行分離純化得到化合物1~14。
海蝦致死活性采用微量滴定板法,采用豐年蝦(Artemiasalina)幼蟲作為測試生物[7]。在室溫下,直徑1.8 cm,深2 cm 的每個培養(yǎng)孔中裝入0.2 mL的人造海水,每個孔中放入人工孵化的游動的豐年蝦幼體30個。將化合物用DMSO 溶解,定量加入到每個培養(yǎng)孔中,稀釋到最終10 μg/mL 濃度。對照只加DMSO,每一處理重復(fù)三次。在室溫下黑暗培養(yǎng)24 h 后,在顯微鏡下計算每個槽中死亡的海蝦個數(shù),最后用以下公式計算致死率(M)。
其中:M=24 h 后的致死率;A=24 h 后的死亡總數(shù);B=24 h 后對照槽中的死亡總數(shù);N=在加入藥劑之前的死亡數(shù);G=挑選用于測試的小蝦總數(shù)。
化合物1 無色針狀晶體(氯仿)。1H NMR(500 MHz,CDCl3)δ:3.64 (1H,m,H-3),5.56 (1H,d,J=4.2 Hz,H-6),5.38 (1H,d,J=6.0 Hz,H-7),0.62 (3H,s,H-18),0.96 (3H,s,H-19),1.03 (3H,d,J=6.4 Hz,H-21),5.19 (1H,dd,J=15.5,8.0 Hz,H-22),5.25 (1H,dd,J=15.8 Hz,H-23),0.93(3H,s,H-25),0.85 (3H,d,J=6.0 Hz,H-27),0.84(3H,d,J=6.0 Hz,H-28)。以上數(shù)據(jù)和常見的真菌代謝產(chǎn)物ergosterol[8]數(shù)據(jù)一致,進一步通過與麥角甾醇標準品比較確定其結(jié)構(gòu)。
化合物2 黃色粉末(氯仿)。1H NMR (CDCl3,500MHz)δ:5.72 (1H,s,H-4),6.01 (1H,d,J=9.4 Hz,H-6),6.60 (1H,d,J=9.4 Hz,H-7),0.95 (3H,s,H-18),0.98 (3H,s,H-19),1.05 (3H,d,J=6.6 Hz,H-21),5.21 (1H,m,H-22),5.22 (1H,m,H-23),0.82 (3H,d,J=7.0 Hz,H-26),0.84 (3H,d,J=6.8 Hz,H-27),0.92 (3H,d,J=6.8 Hz,H-28);13C NMR (CDCl3,125 MHz)δ:34.1 (C-1),34.3(C-2),199.2 (C-3),123.1 (C-4),164.2 (C-5),124.5 (C-6),133.9 (C-7),124.6 (C-8),44.5 (C-9),36.8 (C-10),19.0 (C-11),35.6 (C-12),44.0(C-13),155.9 (C-14),25.3 (C-15),27.7 (C-16),55.8 (C-17),19.0 (C-18),16.8 (C-19),39.2 (C-20),21.2 (C-21),135.0 (C-22),132.5 (C-23),43.0 (C-24),33.2 (C-25),20.0 (C-26),19.8 (C-27),17.7 (C-28)。以上數(shù)據(jù)和文獻報道一致[9],所以化合物被鑒定為ergosta-4,6,8(14),22-tetraen-3-one。
化合物3 無色針狀晶體(氯仿)。1H NMR(CDCl3,500 MHz)δ:4.07 (1H,m,H-3),3.62(1H,d,J=4.8 Hz,H-6),5.35 (1H,dd,J=4.8,2.4 Hz,H-7),0.59 (3H,s,H-18),1.09 (3H,s,H-19),1.03 (3H,d,J=6.7 Hz,H-21),5.16 (1H,dd,J=15.4,8.0 Hz,H-22),5.23 (1H,dd,J=15.4,8.0 Hz,H-23),0.82 (3H,d,J=6.2 Hz,H-26),0.84(3H,d,J=6.9 Hz,H-27),0.92 (3H,d,J=6.6 Hz,H-28);13C NMR (CDCl3,125 MHz)δ:32.8 (C-1),30.4 (C-2),67.2 (C-3),39.3 (C-4),75.9 (C-5),73.1 (C-6),117.3 (C-7),143.2 (C-8),43.2 (C-9),37.0 (C-10),22.0 (C-11),38.9 (C-12),43.6(C-13),54.7 (C-14),22.9 (C-15),28.0 (C-16),55.9 (C-17),12.3 (C-18),18.4 (C-19),40.4 (C-20),19.6 (C-21),131.9 (C-22),135.3 (C-23),42.8 (C-24),33.1 (C-25),19.9 (C-26),21.1 (C-27),17.6 (C-28)。通過與文獻中NMR 數(shù)據(jù)比較[9],確定化合物為cerevisterol。
化合物4 白色晶體(氯仿)。EI-MS(m/z):426[M]+,394,376,299,251,69;1H NMR (600 MHz,CDCl3)δ:3.98 (1H,m,H-3),6.35 (1H,d,J=8.4 Hz,H-6),6.54 (1H,d,J=8.4 Hz,H-7),5.48(1H,m,H-11),0.78 (3H,s,H-18),1.19 (3H,s,H-19),1.05 (3H,d,J=6.8 Hz,H-21),5.21 (1H,dd,J=15.4,8.0 Hz,H-22),5.30 (1H,dd,J=15.3,7.4 Hz,H-23),0.84 (3H,d,J=6.5 Hz,H-26),0.81(3H,d,J=6.2 Hz,H-27),0.98 (3H,d,J=6.8 Hz,H-28)。以上數(shù)據(jù)與文獻報道的9(11)-dehyoergosterol peroxide 一致[8],通過進一步和標準品比較Rf值(0.49,氯仿∶丙酮=8∶1)確定化合物結(jié)構(gòu)。
化合物5 白色晶體(甲醇)。EI-MS m/z 258[M]+;HR-ESI-MS m/z:259.0607 [M+H]+,calcd.for C14H11O5259.0602);1H NMR (600 MHz,DMSO-d6)δ:2.63 (3H,s,H-Me),6.37 (1H,d,J=1.70 Hz,H-4),6.71 (1H,d,J=2.20 Hz,H-3'),6.62 (1H,d,J=2.20 Hz,H-5'),7.24 (1H,d,J=1.80 Hz,H-6),11.72 (OH),10.43(2OH);13C NMR(125 MHz,DMSO-d6)δ:138.0 (C-1),108.9 (C-1'),97.2 (C-2),152.5 (C-2'),164.6 (C-3),101.5(C-3'),100.8 (C-4),158.3 (C-4'),165.4 (C-5),117.4 (C-5'),104.3(C-6),138.2 (C-6'),164.0(C-7),25.1 (C-8)。以上數(shù)據(jù)與文獻報道一致[10],故鑒定化合物為alternariol。
化合物6 橘紅色晶體(氯仿)。ESI-MS m/z 283[M-H]-;1H NMR (600 MHz,CDCl3)δ:12.30(1H,s,1-OH),7.61 (1H,s,H-4),7.36(1H,d,J=2.4 Hz,H-5),7.05 (1H,d,J=1.2 Hz,H-2),6.67(1H,d,J=2.4 Hz,H-7),3.97 (3H,s,6-OMe),2.43(3H,s,3-Me);13C NMR (125 MHz,CDCl3)δ:190.8(C-9),182.0(C-10),166.5(C-6),165.2 (C-8),162.5 (C-1),148.4(C-3),135.3 (C-4a),133.2(C-10a),124.5(C-2),121.3(C-4),113.7(C-9a),110.3 (C-8a),108.2 (C-5),106.8(C-7),56.1(6-OMe),22.2(2-Me)。以上數(shù)據(jù)與文獻報道數(shù)據(jù)一致[11]。故鑒定化合物為physcion。
化合物7 黃色晶體(甲醇)。1H NMR (CD3OD,400 MHz)δ:10.96 (1H,br s,NH),7.92 (1H,s,H-2),8.06 (1H,dd,J=2.1,6.0 Hz,H-4),7.18(2H,m,H-5,6),7.42 (1H,dd,J=2.1,6.4 Hz,H-7);13C NMR (CD3OD,125 MHz) δ:169.2(COOH),133.2 (C-2),108.8 (C-3),121.9 (C-4),123.3 (C-5),122.3 (C-6),112.8 (C-7),127.5(C-8),138.3 (C-9)。經(jīng)過和數(shù)據(jù)庫antibase 以及文獻中Indole-3-carboxylic acid 數(shù)據(jù)比較確定化合物為Indole-3-carboxylic acid[12]。
化合物8 白色結(jié)晶(甲醇)。1H NMR (C5D5N,500MHz)δ:4.42 (1H,m,H-2),3.02 (1H,m,H-3),6.96 (1H,s,H-6),1.29 (3H,d,J=6.4 Hz,2-CH3),1.23 (3H,d,J=6.6 Hz,3-CH3),2.39 (3H,s,4-CH3);13C NMR(C5D5N,125 MHz)δ:86.5 (C-2),44.8 (C-3),111.8 (C-4),151.0 (C-5),104.4(C-6),140.8 (C-7),139.8 (C-8),132.6 (C-9),21.1 (2-CH3),19.6 (3-CH3),12.2 (4-CH3)。以上數(shù)據(jù)與文獻報道一致[13],故鑒定化合物為2,3,4-trimethyl-5,7-dihydroxy-2,3-dihydrobenzofuran。
化合物9 白色結(jié)晶(甲醇)。EI-MS m/z 136[M]+;ESI-MS m/z:137 [M+H]+;1H NMR (600 MHz,CD3OD)δ:6.74 (1H,d,J=6.8 Hz,H-3),7.19 (1H,t,J=16.0 Hz,H-4),6.58 (1H,t,J=16.0 Hz,H-5),7.51 (1H,d,J=7.0 Hz,H-6)。經(jīng)過和數(shù)據(jù)庫antibase 以及文獻中anthranilamide 數(shù)據(jù)比較確定化合物為anthranilamide[14]。
化合物10 白色晶體(甲醇)。1H NMR (CDCl3,500 MHz)δ:6.68 (1H,d,J=7.8 Hz,H-3),7.33(1H,td,J=7.8,1.8 Hz,H-4),6.69 (1H,t,J=7.8 Hz,H-5),7.19 (1H,dd,J=7.8,1.8 Hz,H-6);13C NMR (CDCl3,125 MHz)δ:109.6 (C-1),151.1 (C-2),116.5 (C-3),135.1 (C-4),116.8 (C-5),132.1(C-6),173.7 (-COOH)。通過比較化合物和標準品anthranilic acid 在薄層色譜上的顯色情況和Rf值[兩種展開系統(tǒng):正丁醇-醋酸-水(BAW)(4∶1∶5)上層;正己烷6 mL,乙酸乙酯3 mL,另加兩滴冰醋酸]確定化合物為anthranilic acid。
化合物11 淺黃色晶體(甲醇)。ESI-MS m/z 183[M+H]+,HR-ESI-MS (m/z:183.0646 [M +H]+,calcd.for C9H11O4183.0652);1H NMR (600 MHz,CD3OD)δ:6.19 (1H,s,H-5),2.44 (3H,s,3-CH3),2.04 (3H,s,6-CH3)。以上數(shù)據(jù)和antibase中3-methylorsellinic acid (2,4-dihydroxy-3,6-dimethyl-benzoic acid)以及文獻中數(shù)據(jù)一致[15]。
化合物12 無色結(jié)晶(甲醇)。ESI-MS m/z:183[M+H]+;1H NMR(DMSO-d6,600 MHz):δ3.37(2H,ddd,J=4.5,5.6,11.2 Hz),3.45 (2H,ddd,J=3.6,8.5,8.8 Hz),3.57(2H,t,J=7.6 Hz),3.60(2H,dd,J=11.0,8.8,3.6 Hz),4.08 (2H,d,J=7.0 Hz,OH),4.26 (2H,t,J=5.5 Hz,OH),4.34(2H,d,J=5.6 Hz,OH)。以上數(shù)據(jù)通過和標準品在薄層色譜上比較進一步確定mannitol。
化合物13 黃色粉末(氯仿)。ESI-MS (m/z):527[M-H]-,551[M+Na]+,1055[2M-H]-,1079[2M+Na]+,573[M+HCOO]-,1101[2M +HCOO]-;HR-ESI-MS (m/z:529.2687 [M+H]+,calcd.for C32H37N2O5529.2695);1H NMR (CDCl3,600 MHz)δ:7.03 (1H,s,H-2'),3.75 (1H,br d,J=6.0 Hz,H-3),7.47 (1H,d,J=7.6 Hz,H-4'),1.88 (1H,d,J=4.4 Hz,H-5),7.12 [1H,t(dd),J=8.4 Hz,H-5'],7.18 [1H,t(dd),J=8.4 Hz,H-6'],2.73 (1H,d,J=4.6 Hz,H-7),7.34(1H,d,J=8.0 Hz,H-7'),2.12(1H,br d,J=13.6 Hz,H-8),2.94(2H,dd,J=14.0,4.0 Hz,H-10α),2.65(1H,dd,J=14.0,7.5 Hz,H-10β),1.14(3H,d,J=4.4 Hz,H-11),1.26(3H,s,H-12),6.04(1H,dd,J=15.0,10.0 Hz,H-13),5.22 (1H,m,H-14),2.23(1H,br d,J=15.0 Hz,H-15),2.49(1H,m,H-16),0.97(3H,d,J=6.6 Hz,16-CH3),5.54(1H,d,J=9.0 Hz,H-17),1.23(3H,s,18-CH3),5.03(1H,d,J=4.4 Hz,H-19),6.49(1H,d,J=16.6 Hz,H-21),7.67 (1H,d,J=16.6 Hz,H-22)。以上數(shù)據(jù)和文獻中數(shù)據(jù)一致[16],確定化合物為chaetoglobosin A。
化合物14 黃色結(jié)晶(甲醇)。ESI-MS m/z:433.1[M+H]+;1H NMR(400 MHz,DMSO-d6)δ:8.59(1H,s,H-1),6.75(1H,s,H-4),6.25(1H,d,J=15.9 Hz,H-9),6.68(1H,dd,J=15.9,8.2 Hz,H-10),2.27(1H,m,H-11),1.39(2H,m,H-12),0.89(3H,t,J=7.2,H-13),1.64(3H,s,7-Me),1.10(3H,d,J=6.6 Hz,11-Me),3.46(1H,m,H-4'),3.66(1H,m,H-5'),1.06(3H,d,J=6.6 Hz,H-6'),1.04(3H,d,J=7.2,4'-Me);13C NMR(400 MHz,DMSO-d6)δ:150.7(C-1),157.0(C-3),105.0(C-4),140.1(C-4a),109.8(C-5),183.1(C-6),87.3(C-7),164.8(C-8),111.0(C-8a),120.2(C-9),146.9 (C-10),40.1 (C-11),29.0 (C-12),12.1 (C-13),29.8 (7-Me),19.1 (11-Me),167.9 (C-1'),125.8(C-2'),200.8(C-3'),50.5(C-4'),69.5(C-5'),21.4(C-6'),12.9(4'-Me)。以上數(shù)據(jù)和文獻中數(shù)據(jù)相似[17],確定化合物為5'-epichaetovirdin A。
化合物13 為毛殼屬真菌產(chǎn)生的細胞松弛素類生物堿,該類生物堿被報道具有強烈的抗腫瘤,抗真菌等生物活性[18];化合物14 屬于真菌來源的azaphilone 類色素,目前報道的天然azaphilone 類化合物具有抗腫瘤,抗病原細菌等多種生物活性[19]。細胞毒活性測試結(jié)果顯示:10 μg/mL 濃度下,處理24 h 后,化合物13 對豐年蝦幼蟲顯示了明顯的毒性,致死率為83.4%;化合物14 也顯示了中等強度的毒性,致死率為54.3%。陽性對照化合物ganodermanontriol 在該濃度下的死亡率為91.2%。已經(jīng)發(fā)現(xiàn)的這兩類真菌代謝產(chǎn)物結(jié)構(gòu)新穎多變,活性顯著。值得通過擴大發(fā)酵規(guī)模、改變培養(yǎng)基組成、培養(yǎng)條件及加入激發(fā)子等手段來進一步提高其化學(xué)多樣性,從中發(fā)現(xiàn)細胞毒性更強的新化合物。
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