美国俄亥俄州立大学的研究人员发表的一篇报告指出，从褐藻中萃取出的褐藻多酚(BAPs)可以保护身体免于照射过量阳光造成的皮肤癌。
这项以小鼠进行试验的研究证实，褐藻多酚可以保护皮肤免于紫外线B(UVB)辐射造成的伤害。阳光中的UVB是导致非黑色素瘤皮肤癌的主因，美国每年大约有一百三十万起非黑色素瘤皮肤癌病例，而其中百分之90是由于日晒所造成的。
研究人员在无毛的小鼠皮肤上涂了BAPs，并且在饲料中添加BAPs喂食这些小鼠。褐藻多酚经由这二种用药途径，显著地减少了这些小鼠发生皮肤癌的数量达百分之60，以及使肿瘤大小减少了百分之43。同时也减少了皮肤发炎的比例。
这项研究将发表于12月15日的InternationalJournalofCancer中。这些化合物经由口服方式用药相当有效，只需小剂量就可以达到防止皮肤癌的效果。BAPs是强力的抗氧化剂，可能具有抗癌特性。此外，研究人员也发现饮食中添加BAPs可以使COX-2活性减少百分之74-82，局部涂抹用药可以减少百分之66-82。
英文原文：
CHEMICALS IN BROWN ALGAE MAY PROTECT AGAINST SKIN CANCER
COLUMBUS , Ohio – Substances extracted from a marine seaweed may protect against skin cancer caused by too much sun, new research suggests.
The animal study indicates that chemicals called brown algae polyphenols (BAPs), which are found in a type of brown marine seaweed, might protect against skin cancers caused by ultraviolet B (UVB) radiation.
Garry D. Stoner
UVB radiation in sunlight is thought responsible for 90 percent of the estimated 1.3 million cases of non-melanoma skin cancer diagnosed in the United States annually.
Researchers applied the BAPs to the skin of hairless mice and fed it to the animals in their diet. In both cases, the substances reduced the number of skin tumors by up to 60 percent and their size by up to 43 percent. They also reduced inflammation.
The study, led by researchers at the Ohio State University Comprehensive Cancer Center, is published in the Dec. 15 issue of the International Journal of Cancer.
“These compounds seemed to be dramatically effective at fairly low doses both orally and topically,” says principal investigator Gary D. Stoner, professor emeritus of internal medicine and a cancer chemoprevention researcher.
“These findings suggest that, even when eaten, these compounds get to skin cells and neutralize the cancer-causing oxygen radicals that are produced by UV exposure.”
Laboratory research has shown that BAPs are strong antioxidants and may have anticancer properties.
For this study, Stoner and his collaborators used a strain of hairless mice that are particularly susceptible to UVB-induced skin cancer. Nine experimental groups were used, each with 20 mice.
In two groups, BAPs were applied to the skin in concentrations of 3 milligrams or 6 milligrams in a mild solvent. In two other groups, BAPs made up 0.1 percent or 0.5 percent of the diet.
A group of untreated control mice was also exposed to UVB.
The remaining groups were additional controls: Two were fed the standard diet with and without UV exposure, and two had the BAP solvent applied to the skin with and without UV exposure.
The mice received the BAPs for two weeks before UVB exposure began, followed by 24 weeks of increasing UVB exposure according to a standardized schedule.
The researchers then counted the number of tumors in the treatment and control groups and calculated their size.
Animals exposed only to UVB developed an average of 8.5 skin tumors. The animals fed the lower and the higher dose of BAPs developed an average of 4.7 and 3.7 tumors respectively. Of those given the topical treatment, the lower and higher doses developed 3.4 and 4.6 tumors respectively.
In terms of tumor volume, the animals fed BAPs at the lower and higher doses had tumors that were 34 percent and 40 percent smaller than those in animals exposed to UVB alone. Of those given the topical treatment, the lower and higher dose animals had tumors that were 27 percent to 43 percent smaller than animals exposed to UVB alone.
In addition, the researchers compared the groups for skin levels of the enzyme cyclooxygenase-2 (COX-2) and of the hormone-like substance prostaglandin E2, both of which are strong indicators of inflammation, and for cell proliferation rates.
Animals treated with BAPs showed lower levels of both COX-2 and prostaglandin E2.
The researchers found that the dietary BAPs reduced COX-2 activity by 74-82 percent, and that the topical BAPs reduced it by 66-82 percent. They also measured lower rates of cell proliferation in BAP-treated animals.
“Both the oral and topical BAP treatment reduced COX-2 and prostaglandin E2 cell proliferation levels in the skin,” Stoner says, “which corresponds with fewer tumors and small tumors in the treated animals.”
