Endophytic fungi represent a virtually inexhaustible and sustainable resource of bioactive and chemically novel natural products with potential for utilization in the medical field [1]. Our systemic investigation of secondary metabolites from this fungi led to the discovery of (3R,4S)-6,8-dihydroxy-3,4,5,7-tetramethylisochroman (1), decarboxydihydrocitrinin (2), alternethanoxin A (3), 2,3,4-trimethyl-5,7-dihydroxy-2,3-dihydrobenzofuran (4), penicitrinone A (5), penicitrinol A (6), citrinolactone B (7), -diversonolic ester (8), emodin (9), citreorosein (10), 2,3,5-trimethyl-6-(3-oxobutan-2-yl)-4H-pyran-4one (11), kojic acid (12), and phenol A (13). Herein, we report details on the isolation and structural elucidation of these compounds. The fungus Penicillium citrinum BM7 (strain No. JX966317) was isolated from inner tissue fragments of the plant species Saccharum arundinaceum Retz. collected in Yichang, Hubei Province in April 2011 and identified based on morphological traits and internal transcribed spacer rDNA-ITS sequence analysis. The fungus was grown on solid rice medium at room temperature under static conditions for 30 days, and the metabolites were extracted with EtOAc. The crude extracts (60 g) were repeatedly chromatographed on silica gel columns and extensive reversed-phase semipreparative HPLC to afford the title compounds. The structures of these compounds were identified by extensive analysis of their spectroscopic data, which were in good agreement with literature data. Alternethanoxin A (3) and 2,3,5-trimethyl-6-(3-oxobutan-2-yl)-4H-pyran-4-one (11) have been isolated from the Penicillium citrinum for the first time. (3R,4S)-6,8-Dihydroxy-3,4,5,7-tetramethylisochroman (1). Yellow powder, C13H18O3. ESI-MS m/z 245 [M + Na]+ [2]. Decarboxydihydrocitrinin (2). Yellow powder, C12H16O3. ESI-MS m/z 209 [M + H]+ [3]. Alternethanoxin A (3). Yellow powder, C16H14O6. ESI-MS m/z 303 [M + H] +. 1H NMR (400 MHz, CDCl3, , ppm, J/Hz): 9.09 (1H, s, 6-OH), 7.50 (1H, dd, J = 7.7, 1.0, H-8), 7.35 (1H, dd, J = 8.0, 7.7, H-9), 7.13 (1H, dd, J = 8.0, 1.0, H-10), 6.23 (2H, s, H-3, 6), 3.65 (3H, s, 7-OCH3), 2.24 (3H, s, COCH3). 13C NMR (100 MHz, CDCl3, , ppm): 198.9 (COCH3), 167.0 (C-7), 160.2 (C-4, 5), 153.6 (C-6a), 148.8 (C-1), 130.9 (C-9), 130.3 (C-10a), 129.0 (C-2), 122.1 (C-8), 121.4 (C-10), 109.7 (C-11), 109.4 (C-3, 6), 52.7 (7-COH3), 22.1 (COCH3) [4]. 2,3,4-Trimethyl-5,7-dihydroxy-2,3-dihydrobenzofuran (4). Yellow powder, C11H14O3. ESI-MS m/z 195 [M + H] + [5]. Penicitrinone A (5). Yellow powder, C23H24O5. ESI-MS m/z 381 [M + H]+ [3]. Penicitrinol A (6). Yellow powder, C23H26O5. ESI-MS m/z 383 [M + H]+ [3].

中文翻译：

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来自内生真菌 Penicillium citrinum 的次级代谢产物

内生真菌是一种几乎取之不尽、可持续的生物活性和化学新型天然产物资源，具有在医学领域的应用潜力[1]。我们对该真菌次生代谢物的系统研究导致发现了 (3R,4S)-6,8-dihydroxy-3,4,5,7-tetramethylisochroman (1)、decarboxydihydrocitrinin (2)、alternethanoxin A (3)、 2,3,4-trimethyl-5,7-dihydroxy-2,3-dihydrobenzofuran (4), penicitrinone A (5), penicitrinol A (6), citrinolactone B (7), -diversonolic酯 (8), 大黄素 ( 9), citreorosein (10), 2,3,5-trimethyl-6-(3-oxobutan-2-yl)-4H-pyran-4one (11), 曲酸 (12), 和酚 A (13)。在此，我们报告了这些化合物的分离和结构解析的详细信息。真菌Penicillium citrinum BM7（菌株No. JX966317) 是从植物 Saccharum arundinaceum Retz 的内部组织碎片中分离出来的。2011年4月采集于湖北宜昌，基于形态特征和内部转录间隔区rDNA-ITS序列分析鉴定。真菌在室温和静态条件下在固体稻米培养基上生长 30 天，代谢物用 EtOAc 萃取。粗提物（60 g）在硅胶柱上反复色谱分离，并通过广泛的反相半制备型 HPLC 得到标题化合物。这些化合物的结构是通过对其光谱数据的广泛分析来确定的，这与文献数据非常吻合。交替烟碱 A (3) 和 2,3, 5-trimethyl-6-(3-oxobutan-2-yl)-4H-pyran-4-one (11) 已首次从柑橘青霉中分离出来。(3R,4S)-6,8-二羟基-3,4,5,7-四甲基异色满 (1)。黄色粉末，C13H18O3。ESI-MS m/z 245 [M + Na]+ [2]。脱羧二氢桔霉素 (2)。黄色粉末，C12H16O3。ESI-MS m/z 209 [M + H]+ [3]。交替烟碱 A (3)。黄色粉末，C16H14O6。ESI-MS m/z 303 [M + H] +。1H NMR (400 MHz,CDCl3,..., ppm, J/Hz): 9.09 (1H, s, 6-OH), 7.50 (1H, dd, J = 7.7, 1.0, H-8), 7.35 (1H, dd, J = 8.0, 7.7, H-9), 7.13 (1H, dd, J = 8.0, 1.0, H-10), 6.23 (2H, s, H-3, 6), 3.65 (3H, s, 7-OCH3 ), 2.24 (3H, s, COCH3)。13C NMR (100 MHz,CDCl3, , ppm): 198.9 (COCH3), 167.0 (C-7), 160.2 (C-4, 5), 153.6 (C-6a), 148.8 (C-1), 130.9 (C -9), 130.3 (C-10a), 129.0 (C-2), 122.1 (C-8), 121.4 (C-10), 109.7 (C-11), 109.4 (C-3, 6), 52.7 ( 7-COH3), 22.1 (COCH3) [4]。2,3, 4-三甲基-5,7-二羟基-2,3-二氢苯并呋喃 (4)。黄色粉末，C11H14O3。ESI-MS m/z 195 [M + H] + [5]。青霉素 A (5)。黄色粉末，C23H24O5。ESI-MS m/z 381 [M + H]+ [3]。青三醇 A (6)。黄色粉末，C23H26O5。ESI-MS m/z 383 [M + H]+ [3]。