Flavonoid Compositions and Antioxidant Activity of Immature Kumquat in Different Flowering Periods

不同開花期未成熟金柑之類黃酮組成及抗氧化活性

簡亦翎(Yi-Ling Jian) ； 李怡萱(Yi-Hsuan Lee) ； 黃家德(Jia-De Huang) ； 何其儻(Chi-Tang Ho) ； 駱錫能(Shyi-Neng Lou)

《臺灣農業化學與食品科學》 58卷1期 (2020/02) Pp. 27-34

https://doi.org/10.6578/TJACFS.202002_58(1).0004

摘要

Immature kumquat has been demonstrated to exhibit antioxidant function, which might be attributed to its flavonoid compounds. The flavonoid compositions and antioxidant activity of immature kumquat are higher than mature kumquat. In this study, changes in flavonoid compositions and antioxidant activity of immature kumquat with different flowering periods were investigated. The results showed that total phenolic contents of immature kumquat in April (based on flowering month) were higher than that in June, July and August. However, the highest total flavonoid compositions (10923.5 mg/100g dry extract) of immature kumquat were found in June. The major flavonoids were C-glycosides, included 3',5'-di-C-β-glucopyranosylphloretin (DGPP), margaritene, and isomargaritene, which revealed the highest contents in June. And the best antioxidant activities, DPPH scavenging potency and ORAC potency, were also observed in June. However, there is no significant difference between the sample in June and April. This hinted that high level of flavonoid compounds of immature kumquat are well correlated to the good antioxidant activity. According to the climate data, the highest sunshine time was recorded during flowering time to harvest for the immature kumquat of flowering month in June (901.6 h), while in April was 828.7 h. Collectively, it could be proposed that high sunshine time during growing might lead to the production of more flavonoid compounds of immature kumquat. Consequently, the highest flavonoid compounds might result in good antioxidant activity. DGPP might be the major effective antioxidant flavonoid in immature kumquat.

關鍵字

Immature kumquat ； Flavonoid compositions ； Antioxidant activity ； Climate condition ； 3',5'- di-C-β-glucopyranosylphloretin (DGPP)

並列摘要

未成熟金柑的類黃酮成分和抗氧化活性皆高於成熟金柑，且其抗氧化活性與類黃酮組成分有關。本研究探討不同開花期未成熟金柑之類黃酮化合物組成和抗氧化活性的變化。結果顯示，4月份開花之未成熟金柑的總酚含量高於開花期在6月、7月和8月份者。然而，6月份開花之未成熟金柑的總黃酮類含量則最高（10923.5mg／100g乾萃取物）。其中主要皆為C－醣苷鍵的類黃酮，包括有3',5'－di－C－β－glucopyranosylphloretin（DGPP, 金柑素）、margaritene和isomargaritene等，其成分含量、DPPH自由基清除能力和氧自由基吸收能力（ORAC）皆以開花期6月份者為最高，然而其與4月份的未成熟金柑並無顯著差異。顯然未成熟金柑的類黃酮化合物含量與抗氧化活性有良好的正相關。此外，根據氣象資料，6月份開花期的未成熟金柑有最高的日照時間（901.6小時），4月份次高（828.7小時）。綜合以上，顯示金柑在生長過程中，高日照時間可能促使其產生更多的類黃酮化合物，因而導致其良好的抗氧化活性，而其中的金柑素（DGPP）可能是未成熟金柑中主要的有效抗氧化類黃酮。

並列關鍵字

未成熟金柑 ； 類黃酮組成 ； 抗氧化活性 ； 氣候條件 ； 金柑素