| Summary: | 碩士 === 實踐大學 === 食品營養與保健生技學系碩士班 === 103 === Allantoin is a common intermediate of purine metabolism in higher plant, which involved in the nitrogen transport and storage. Based on the effective efficacy of allantoin on (1) Temporary protection of minor cuts, scrapes, burns and sunburn; (2) Prevention and protection of the skin and lips against chapping, scrapes, burns the wind ; and (3) Relieve skin dryness, fever blisters and soften cold sores, allantoin has been classified, by The US Food and Drug Administration (FDA), as safe and effective skin protectant, and allowed to be used as non-prescriptive active ingredients (0.5-2.0%)in cosmetics such as skin creams. Recent studies have found that compared to other plant yam contain higher amount of allantoin, however, these studies have shown that not only large amount of solvent is used for extraction, but also a time consuming process for allantoin isolation. In Taiwan, the yam is a very high value cash crops, there are seven Dioscorea species commonly cultivated and found in the marked. However, there is no quantitative data of allantoin contents in all these yam varieties. The purpose of this study is to develop a rapid isolation and quantitation method for allantoin in the yam, and quantitate the contents the tuber of the commonly grown seven Dioscorea species in Taiwan. The yam tubers were peeled and the meat and skin were shredded, frozen, and vacuum dried. Methanol is used as extraction solvent in a solvent/yam powder ratio 4/1. The powder was mixed with the solvent thoroughly and extracted with shaking (500 rpm) at 60 ℃ for one hour twice. After the extraction the two extracts were mixed together and subjected to centrifugation (20,000 rpm). The supernatant of the allantoin isolate was then analyzed by high performance liquid chromatography (HPLC). The HPLC analysis was also validated by the authentic allantoin. Results showed that the allantoin recovery (recovery%) ranging from 99.2 to 102.7%, the coefficient of variation (CV%) ranging from 0.98 to 3.70, revealed the validation of this HPLC analytical method, and The analysis of contents of Dioscorea species commonly cultivated in Taiwan shown that D. alata tubers showed a higher allantoin content (mg/g wet weight in meat/skin 133.43 ± 2.95 / 172.93 ± 9.26), followed by D. Japonica var. pseudojaponica (118.76 ± 3.28 / 161.01 ± 1.97 mg/g wet weight), and the contents of allantoin in the tuber skin was higher than that in the meat in all varieties.
The extraction procedure we developed for allantoin is easy and rapid, it takes only about two hours. Results of HPLC analysis is precise and accurate. Overall, the method reduces the cost and time for the analysis of allantoin, and could be used in qualitative and quantitative analysis of allantoin in Dioscorea tuber.
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