Caccamese Salvatore, Bianca Salvatore, Santo Davide
Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6, 95125 Catania, Italy.
J Agric Food Chem. 2007 May 16;55(10):3816-22. doi: 10.1021/jf063355w. Epub 2007 Apr 7.
Naringin is the major flavanone-7-O-glycoside of sour orange, and it is mainly responsible for the bitter taste of the fruit. The relative content of (2S)- and (2R)-naringin in the albedo of sour oranges during maturation in the entire season was determined by normal phase HPLC using Chiralcel OD-H as chiral stationary phase and n-hexane/ethanol doped with 0.5% of TFA as mobile phase. HPLC traces were complicated by the presence of (2S)-neohesperidin, and a software-guided analysis was developed to assess the relative amount of the C-2 diastereomers of naringin. A sigmoid curve was obtained showing variation from 94% of (2S)-naringin in very immature fruits to 69.7% in mature fruit samples. Spontaneous epimerization of (2S)-naringin in the ethanolic solutions of the albedo was noted after prolonged keeping for less acid samples. The separation of the C-2 diastereomers of other flavanoid-7-O-glycosides present in Citrus (neoeriocitrin, neohesperidin, and eriocitrin) was also obtained by chiral HPLC and afforded the identification, including stereochemistry, of the eluting peaks in the HPLC traces of the albedo extracts.
柚皮苷是酸橙中的主要黄烷酮 -7-O-糖苷，它是造成该水果苦味的主要原因。使用Chiralcel OD-H作为手性固定相，以掺杂0.5%三氟乙酸的正己烷/乙醇作为流动相，通过正相高效液相色谱法测定了整个季节中酸橙内果皮成熟过程中（2S）-和（2R）-柚皮苷的相对含量。（2S）-新橙皮苷的存在使高效液相色谱图变得复杂，因此开发了一种软件引导分析方法来评估柚皮苷C-2非对映异构体的相对含量。得到了一条S形曲线，显示从极不成熟果实中94%的（2S）-柚皮苷到成熟果实样品中69.7%的变化。对于酸性较低的样品，在长时间保存后，观察到内果皮乙醇溶液中的（2S）-柚皮苷发生了自发差向异构化。通过手性高效液相色谱法还分离了柑橘中存在的其他黄酮类 -7-O-糖苷（新橙皮苷二氢查耳酮、新橙皮苷和橙皮苷二氢查耳酮）的C-2非对映异构体，并对其在内果皮提取物的高效液相色谱图中的洗脱峰进行了鉴定，包括立体化学。
