Stark Timo D, Salger Mathias, Frank Oliver, Balemba Onesmo B, Wakamatsu Junichiro, Hofmann Thomas
Lehrstuhl für Lebensmittelchemie und Molekulare Sensorik, Technische Universität München , Lise-Meitner-Straße 34, 85354 Freising, Germany.
J Nat Prod. 2015 Feb 27;78(2):234-40. doi: 10.1021/np5007873. Epub 2015 Jan 27.
An aqueous ethanolic extract of the stem bark of Garcinia buchananii showed strong antioxidative activity using H2O2 scavenging, oxygen radical absorbance capacity (ORAC), and Trolox equivalent antioxidant capacity (TEAC) assays. Activity-guided fractionation afforded three new compounds, isomanniflavanone (1), an ent-eriodictyol-(3α→6)-dihydroquercetin-linked biflavanone, 1,5-dimethoxyajacareubin (2), and the depsidone garcinisidone-G (3), and six known compounds, (2″R,3″R)-preussianon, euxanthone, 2-isoprenyl-1,3,5,6-tetrahydroxyxanthone, jacareubin, isogarcinol, and garcinol. All compounds were described for the first time in Garcinia buchananii. The absolute configurations were determined by a combination of NMR, ECD spectroscopy, and polarimetry. These natural products showed high in vitro antioxidative power, especially isomanniflavanone, with an EC50 value of 8.5 μM (H2O2 scavenging), 3.50/4.95 mmol TE/mmol (H/L-TEAC), and 7.54/14.56 mmol TE/mmol (H/L-ORAC).
布氏藤黄茎皮的乙醇水提取物通过过氧化氢清除、氧自由基吸收能力（ORAC）和Trolox当量抗氧化能力（TEAC）测定显示出很强的抗氧化活性。活性导向分馏得到了三种新化合物，异芒果黄酮（1），一种ent-圣草酚-（3α→6）-二氢槲皮素连接的双黄酮，1,5-二甲氧基阿扎卡红素（2），以及缩酚酸酮藤黄苷-G（3），还有六种已知化合物，（2″R,3″R）-普鲁士蓝酮、呫吨酮、2-异戊烯基-1,3,5,6-四羟基呫吨酮、阿扎卡红素、异藤黄醇和藤黄醇。所有化合物均首次在布氏藤黄中被描述。通过核磁共振、电子圆二色光谱和旋光测定相结合的方法确定了绝对构型。这些天然产物表现出很高的体外抗氧化能力，尤其是异芒果黄酮，其EC50值为8.5 μM（过氧化氢清除），3.50/4.95 mmol TE/mmol（H/L-TEAC），以及7.54/14.56 mmol TE/mmol（H/L-ORAC）。
