乾燥溫度、時間及基因型對番石榴葉片萃取物抗氧化能力與α-澱粉酶抑制活性的影響

番石榴是台灣重要的經濟果樹之一。除了果實，其葉片富含抗氧化物質，具有預防退化性疾病的潛力。本研究的目的在了解乾燥溫度和時間對番石榴葉幼葉與成熟葉的總酚含量和抗氧化能力的影響，也探討基因型間總酚含量、抗氧化力和α-澱粉酶抑制率的變異。共分析了36個基因型，包括6個栽培種、5個引進或收集的品種(品系)、23個育種品系以及2個近緣種。結果顯示，在40℃下乾燥48小時幼葉通常在所有處理中具有最高的總酚含量和抗氧化能力，而在40℃的這些結果和處理與50℃乾燥12小時無顯著差異。葉片以50℃乾燥12小時，發現基因型間總酚含量、FRAP、DPPH清除力和α-澱粉酶抑制活性皆有顯著差異，而幼葉的總酚含量和抗氧化力優於成熟葉。基因型間幼葉的總酚含量、FRAP、DPPH清除能力和α-澱粉酶抑制率範圍分別為197.89至94.52 mg GAE / g、34.42至9.78 g Vitamin C / g、45.62至13.52 g Trolox / g和79.0％至13.7％。不論葉齡為何，總酚含量與FRAP和DPPH清除能力兩者均有高度顯著相關。從所分析的基因型中可篩選出總酚含量、抗氧化力和α-澱粉酶抑制率比常見的栽培種好的基因型，其可用於育種改良或保健產品的開發。

關鍵字

總酚含量；鐵還原抗氧化能力(FRAP) ； DPPH清除力

並列摘要

Guava is one of the important economic fruit trees in Taiwan. In addition to its fruits, its leaves are rich in antioxidant components and have the potential for the prevention of degenerative diseases. The aim of the present study was to understand the effects of drying temperature and duration on the total phenolic content and antioxidant capacity of guava leaves at young and mature stages. The variations of total phenolic content, antioxidant capacity and α-amylase inhibitory rate among genotypes were also investigated. In total, 36 genotypes were evaluated including six cultivars, five introduced or collected cultivars (line), 23 breeding lines and two related species. The results showed that drying young leaves at 40°C for 48 hours generally had the highest total phenolic content and antioxidant capacity among treatments. However, no significant difference was found between treatments at 40°C and at 50°C for 12 hours. When drying leaves at 50°C for 12 hours, it was found that there were significant variations in total phenolic content, FRAP, DPPH radical-scavenging power and α-amylase inhibitory activity among genotypes. Young leaves were better than mature leaves in terms of total phenolic content and antioxidant capacity. The total phenolic content, FRAP, DPPH scavenging power and α-amylase inhibition rate of the young leaves of the genotypes ranged from 197.89 to 94.52 mg GAE/g, 34.42 to 9.78 g Vitamin C/g, 45.62 to 13.52 g Trolox/g and 79.0% to 13.7%, respectively. Regardless of the leaf ages, total phenolic content is highly significantly correlated with both FRAP and DPPH scavenging power. Genotypes show better quality than the commonly grown cultivars in total phenolic content, antioxidant capacity and α-amylase inhibition rate have been selected. They can be used for further breeding or healthy product development.