馬氏濱藜 (Atriplex maximowicziana) 衍生真菌株Alternaria alstroemeriae Km2286之成分研究

Abstract

本研究自金門蓮湖採集藥用植物馬氏濱藜 (Atriplex maximowicziana Makino)，從中分離出1,249株真菌，並藉由抑菌活性和抗病毒活性平台進行初步的篩選。最終選出具有抗人類疱疹病毒 (Epstein-Barr virus, EBV) 效果的真菌株Alternaria alstroemeriae Km2286，使用海水PDY培養液曝氣醱酵14天，再以乙酸乙酯分配萃取醱酵液。將萃取物以管柱層析 (CC) 和高效液相層析儀 (HPLC) 進行分析、分離與純化，所得純質使用核磁共振儀 (NMR)、紅外光譜 (IR)、紫外光譜 (UV) 及旋光度 (optical rotation) 進行結構鑑定，並藉由ChemBio3D分子模型的建構與ECD的計算確認化合物的相對立體與絕對立體。本次實驗一共獲得9個化合物，包含4個新perylenequinone衍生物altertromins A – D (1 – 4)，以及5個已知化合物altertoxin IV (5)、altertoxin VIII (6)、stemphyperylenol (7)、tenuazonic acid (8) 和allo-tenuazonic acid (9)，其中，化合物2、3和6在結構上含有氯原子，化合物4則同時含有氯原子與mercaptolactate，為真菌天然物中極罕見的結構。後續將所得純質以活性平台進行評估，發現化合物1 – 6具有抗EBV之效果，其EC50值介於0.17 ± 0.07至3.13 ± 0.31 μM，且化合物1 – 5的選擇指數 (selectivity index) 皆大於10。在抗發炎活性評估中，化合物1、2、3、4、6和7對BV-2細胞產生之一氧化氮具有顯著的抑制效果，其IC50值介於0.33 ± 0.04至4.08 ± 0.53 μM，化合物8則具有些微的抑制效果，且所有化合物在10 μM皆無表現出顯著的細胞毒性。至今為止，這是第一篇有關於perylenequinone衍生物抗EBV與抗發炎的研究。

In this study, 1,249 fungal strains isolated from Atriplex maximowicziana Makino, an important medicinal herb in Kinmen, were preliminary screening in the antimicrobial and antiviral tests. Alternaria alstroemeriae Km2286, showed antiviral activity against EBV (Epstein-Barr virus), was cultivated in salty PDY medium with aeration equipment for fourteen days. The liquid fermented broth was partitioned with EtOAc. The crude extract was separated and purified by column chromatography and HPLC, and resulted in the isolation of nine compounds, including four new perylenequinone derivatives, altertromins A – D (1 – 4), together with five known natural products, altertoxin IV (5), altertoxin VIII (6), stemphyperylenol (7), tenuazonic acid (8) and allo-tenuazonic acid (9). Compounds 2, 3 and 6 have chlorine at the C-8 of perylenequinone framework, while compound 4 has both of chlorine and mercaptolactate in perylenequinone structure, which was quite rare in natural products. Their structures were unambiguously deduced by spectroscopic data including HRESIMS, NMR, IR, UV, and optical rotation. The relative and absolute configurations were determined by the molecular modelling (ChemBio3D Ultra 14.0) and DFT-ECD calculations, respectively. Compounds 1 – 6 exhibited antiviral activities against EBV, with the EC50 values of 1.21 ± 0.10, 1.51 ± 0.29, 2.42 ± 0.56, 0.17 ± 0.07, 1.34 ± 0.01 and 3.13 ± 0.31 μM, respectively. In the anti-inflammatory bioassay, compounds 1, 2, 3, 4, 6 and 7 showed the significant inhibition of NO production in LPS-induced BV-2 cells, with the IC50 values of 2.73 ± 1.06, 0.73 ± 0.18, 4.08 ± 0.53, 0.33 ± 0.04, 2.06 ± 0.53 and 3.25 ± 1.21 μM, respectively. All the isolates showed no significant cytotoxicity against BV-2 cells at 10 μM. This is the first report to describe perylenequinone derivatives with anti-EBV and anti-inflammatory activities.