不同品种荔枝壳中原花青素的鉴定及其体外抗氧化活性研究

Identification of Procyanidins in the Pericarps of Different Litchi Cultivars and Their in Vitro Antioxidant Activities

为筛选适合开发天然抗氧化产品的荔枝优良品种,本研究对7个不同品种荔枝壳中总酚、总原花青素、总黄酮含量及A型低聚原花青素组分进行了分析,采用DPPH、ABTS+自由基清除法及FRAP法测定其体外抗氧化活性。结果表明,褐毛荔果壳提取物中所含抗氧化活性成分如总酚、总原花青素、总黄酮以及总A型低聚原花青素含量均为最高。经电喷雾液质联用四级杆飞行时间质谱(HPLC-Q-TOF-MS/MS)分析鉴定,得到所含物质的一级及二级质谱。质谱结果显示荔枝壳中含有的低聚原花青素组分主要为表儿茶素、原花青素A2、原花青素A4、A型三聚体及四聚体,不同品种荔枝壳中原花青素含量具有差异性(P<0.05)。褐毛荔果壳提取物表现出较强的自由基清除活性(DPPH·:1144.60μmol Trolox/g DW,ABTS^(+)·:2905.56μmol Trolox/g DW,FRAP:868.84μmol Trolox/g DW)。经皮尔逊相关性分析,原花青素单体、二聚体、三聚体含量与抗氧化活性具有显著相关性(P<0.05)。综合分析,与其他品种相比,褐毛荔果壳提取物中A型低聚原花青素含量最高,体外抗氧化活性方面表现最佳,可作为开发天然抗氧化产品的新型潜在原料加以利用。

To screen eminent litchi varieties suitable for the development of natural antioxidant products,the total phenol,total proanthocyanidin,total flavonoid contents and A-type oligomeric procyanidin fractions in the pericarps of seven diverse litchi cultivars were analyzed.The in vitro antioxidant activities including DPPH,ABTS+free radical scavenging and FRAP were determined.The results demonstrated that the total phenols,total proanthocyanidins,total flavonoids as well as total A-type oligomeric procyanidins contained in the pericarp extract of'Hemaoli'were the highest.In addition,the primary and secondary mass spectra of the contained substances were analyzed and identified by electrospray liquid-mass spectrometry with quadrupole time-of-flight mass spectrometry(HPLC-Q-TOF-MS/MS).The mass spectrometry results demonstrated that the oligomeric procyanidin fractions contained in litchi pericarps were mainly epicatechin,procyanidin A2,procyanidin A4,A-type trimer and tetramer.Moreover,the content of A-type oligomeric procyanidins in litchi pericarp varied significantly(P<0.05)among diverse cultivars.The pericarp extract of'Hemaoli'possessed potent free radical scavenging activity(DPPH∙:1144.60μmol Trolox/g DW,ABTS+∙:2905.56μmol Trolox/g DW,FRAP:868.84μmol Trolox/g DW).The contents of A-type procyanidin monomer,dimer and trimer were significantly correlated with antioxidant activity by Pearson's correlation analysis(P<0.05).In summary,a comprehensive analysis indicated that the pericarp extract of'Hemaoli'contained the highest content of A-type oligomeric procyanidins as well as remarkable antioxidant activity compared to other cultivars.Therefore,'Hemaoli'could be utilized as a novel potential material for the development of natural antioxidant products.