While it only turns into a handsome prince in fairy tales, the homely bullfrog may harbour a valuable anti-ageing substance for humans, South Korean researchers say.

A team led by Professor Kim Se-kwon of Pukyong University in Busan says it isolated a peptide with antioxidant properties from bullfrog skin.

Because of the properties, the material is useful in removing free radicals -- molecules that hasten the ageing process of human cells.

Alpha-tocopherol, also known as Vitamin E, is traditionally considered as the most active antioxidant in humans and widely used in medicines and health supplements.

But its price keeps rising because of surging world demand.

"The new substance can provide an economic alternative to tocopherol," Kim told reporters Tuesday, referring to another antioxidant. The team's discovery was published by Bioresource Technology, an international journal, last year.

"Because it is water-soluble, the substance may be consumed in much more diverse ways than the oil-soluble tocopherol. You may put it in soft drinks, for example," he said.

The newly found material is also 10 percent more efficient than tocopherol in curbing oxidisation, he added.

尽管丑陋的牛蛙只有在童话故事里才能变身英俊的王子，但韩国研究人员近日称，牛蛙体内可能含有一种能用于人类抗衰老的珍贵物质。

釜山釜庆大学金胜勋教授领导的研究小组称，他们从牛蛙的皮肤中分离出了一种具有抗氧化特性的生化肽。

由于这一特性，该物质可用于去除自由基——一种加速人体细胞衰老进程的分子。

“α-生育酚”——也就是我们通常所说的“维生素E”，历来被认为是人体内最活跃的抗氧化物质，并被广泛用于各类药品和保健品中。

但随着全球市场需求的不断增加，其价格也持续上涨。

金教授于本周二接受记者采访时提到新发现的抗氧化剂时说“这种新物质能够成为生育酚的经济替代品。”该研究小组的这一发现于去年在《生物资源技术》国际期刊上发表。

金教授介绍说：“由于该物质具有水溶性，所以它的用途比油溶性的生育酚更加多样化。比如，你可以在无醇饮料中添加该物质。”

他还提到，这种新发现的物质的抗氧化功效比生育酚高出10%。