Joubert Elizabeth, Manley Marena, Botha Mariza
ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599, South Africa.
Phytochem Anal. 2008 Mar-Apr;19(2):169-78. doi: 10.1002/pca.1033.
The potential of UV spectrophotometry and an aluminium chloride (AlCl(3)) colorimetric method to determine the dihydrochalcone (DHC) and mangiferin contents of green rooibos and honeybush (C. genistoides) extracts, respectively, was investigated. The DHC content of rooibos water extracts, determined using UV spectroscopy, correlated with the sum of the aspalathin and nothofagin contents as quantified using HPLC (r = 0.98). A correlation coefficient of 0.91 was obtained when correlating the mangiferin content of C. genistoides methanol extracts, determined by the AlCl(3) colorimetric method, with the results obtained by HPLC. Using the linear equations from the correlations it was possible to predict the DHC and mangiferin contents of extracts from the respective spectrophotometric measurements to a reasonable accuracy as an alternative to HPLC. The total polyphenol (TP) content of rooibos water extracts can also be determined using UV spectrophotometry and aspalathin as a standard (r = 0.99) as an alternative to the Folin-Ciocalteau method. The TP content of rooibos extracts correlated (r = 0.99) with its total antioxidant activity (TAA) as determined with the ABTS radical cation scavenging assay, but the TP content of C. genistoides water extracts is not a good indication of their TAA (r = 0.27). The aspalathin content of rooibos extracts correlated with their TAA (r = 0.96), but the mangiferin content of honeybush water extracts only gave a moderate correlation with their TAA (r = 0.75).
研究了紫外分光光度法和氯化铝（AlCl₃）比色法分别测定绿路易波士茶和蜜树茶（C. genistoides）提取物中二氢查耳酮（DHC）和芒果苷含量的潜力。使用紫外光谱法测定的路易波士茶水提取物中的DHC含量，与使用高效液相色谱法（HPLC）定量的阿斯巴甜和诺托菲金含量之和相关（r = 0.98）。将通过AlCl₃比色法测定的C. genistoides甲醇提取物中的芒果苷含量与HPLC获得的结果进行相关性分析时，得到的相关系数为0.91。利用相关性得到的线性方程，可以通过各自的分光光度测量结果合理准确地预测提取物中的DHC和芒果苷含量，作为HPLC的替代方法。路易波士茶水提取物中的总多酚（TP）含量也可以使用紫外分光光度法并以阿斯巴甜为标准进行测定（r = 0.99），作为福林 - 西奥卡勒法的替代方法。路易波士提取物的TP含量与其通过ABTS自由基阳离子清除试验测定的总抗氧化活性（TAA）相关（r = 0.99），但C. genistoides水提取物的TP含量并不能很好地指示其TAA（r = 0.27）。路易波士提取物中的阿斯巴甜含量与其TAA相关（r = 0.96），但蜜树茶水提取物中的芒果苷含量与其TAA的相关性仅为中等（r = 0.75）。
