| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 104 === Abstract
This study focused on antioxidant activity of hot water extract for ten kinds of herbal tea (Verbena officinalis, Melissa officinalis, Achillea millefolium, Hyssopus officinalis, Salvia officinalis, Urtica dioica, Hemerocallis fulva, Citrus maxima, Citrus limon, Ficus formosana ). First, total polyphenol content and total flavonoids were measured to evaluate the antioxidant components of hot water extracted material. Followed by in vitro experiments including DPPH and ABTS radicals scavenging activity, reducing and chelating power, and total antioxidant activity were selected to investigate antioxidant capacities. Furthermore, HPLC was used to identify antioxidant compound..
The amount of total polyphenol content in Melissa officinalis (388.51 mg/g) was much higher than other hotwater extracts, followed by Hyssopus officinalis (164.85 mg/g) and Salvia officinalis (149.34 mg/g). Urtica dioica was the lowest (20.52 mg/g). The total flavonoid contents were abundant in Hemerocallis fulva (41.99 mg/g), Verbena officinalis (37.61mg/g) and Hyssopus officinalis (36.47 mg/g). Citrus limon was the lowest (9.59 mg/g). In terms of antioxidant capacity, Melissa officinalis, Hyssopus officinalis and Salvia officinalis had the highest DPPH radical scavenging capacity and reducing power. For ABTS radical scavenging capacity, Melissa officinalis, Hyssopus officinalis and Hemerocallis fulva had the highest capacity. For chelating effect, Urtica dioica, Achillea millefolium and Verbena officinalis had the highest effect. For total antioxidant capacity, Melissa officinalis, Hemerocallis fulva and Verbena officinalis had the best capacity. Total polyphenol contents correlated well with four antioxidant activities (DPPH radical scavenging capacity, reducing power, ABTS radical scavenging capacity, and total antioxidant capacity). Only Citrus maxima and Ficus formosana had the inhibitory effect of the tyrosinase activity. The Melissa officinalis had the best results at 0.5 mg/ml (55.7%) against xanthine oxidase activity.
The six kinds of hot water extracts of herbal tea (Verbena officinalis, Melissa officinalis, Achillea millefolium, Hyssopus officinalis, Salvia officinalis and Hemerocallis fulva) which have better antioxidant activities were selected for HPLC analysis. Three compounds (caffeic acid, rosmarinic acid and luteolin) were found to be present in the extract. The total amount of these compounds in samples was 0.83-63.66 mg/g.
Keywords: antioxidative, HPLC, herbal tea, extract
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