The Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA.
Cancer Res. 2011 Apr 15;71(8):2809-14. doi: 10.1158/0008-5472.CAN-10-3756. Epub 2011 Apr 12.
Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is the principal pungent component in hot peppers, including red chili peppers, jalapeños, and habaneros. Consumed worldwide, capsaicin has a long and convoluted history of controversy about whether its consumption or topical application is entirely safe. Conflicting epidemiologic data and basic research study results suggest that capsaicin can act as a carcinogen or as a cancer preventive agent. Capsaicin is unique among naturally occurring irritant compounds because the initial neuronal excitation evoked is followed by a long-lasting refractory period, during which the previously excited neurons are no longer responsive to a broad range of stimuli. This process is referred to as desensitization and has been exploited for its therapeutic potential. Capsaicin-containing creams have been in clinical use for many years to relieve a variety of painful conditions. However, their effectiveness in pain relief is also highly debated and some adverse side effects have been reported. We have found that chronic, long-term topical application of capsaicin increased skin carcinogenesis in mice treated with a tumor promoter. These results might imply that caution should be exercised when using capsaicin-containing topical applications in the presence of a tumor promoter, such as, for example, sunlight.
辣椒素（反式-8-甲基-N-香草基-6-壬酰胺）是红辣椒、墨西哥胡椒和哈瓦那辣椒等热辣椒中的主要辣味成分。辣椒素在全球范围内被消费，其食用或局部应用是否完全安全存在着长期而复杂的争议。相互矛盾的流行病学数据和基础研究结果表明，辣椒素可能是一种致癌物质，也可能是一种癌症预防剂。辣椒素在天然刺激性化合物中是独一无二的，因为最初引起的神经元兴奋之后是一个长时间的不应期，在此期间，先前兴奋的神经元对广泛的刺激不再有反应。这个过程被称为脱敏，已经被用于其治疗潜力。含有辣椒素的乳膏已经在临床上使用多年，用于缓解各种疼痛症状。然而，其在缓解疼痛方面的有效性也存在很大争议，并且已经报道了一些不良反应。我们发现，在给予肿瘤促进剂的小鼠中，慢性、长期局部应用辣椒素会增加皮肤致癌作用。这些结果可能意味着，在存在肿瘤促进剂（例如阳光）的情况下，使用含有辣椒素的局部应用时应谨慎。
