PHOTOCOCARCINOGENESIS STUDY OF ALOE VERA [CAS NO. 481-72-1 (Aloe-emodin)] IN SKH-1 MICE (SIMULATED SOLAR LIGHT AND TOPICAL APPLICATION STUDY)

Background Extracts from the Aloe vera plant are widely used in skin care products. We studied the effects of synthetic solar light on the skin of hairless mice that had been treated with creams containing various Aloe vera extracts. Methods We applied creams containing Aloe vera plant extracts (aloe gel, whole leaf, or decolorized whole leaf) or aloe-emodin to groups of 36 male and female hairless mice in the morning; other groups received creams containing no aloe. In the afternoon groups of animals were exposed to synthetic solar light for four hours. Other groups were not exposed to light and were control groups. The treatments and exposures were performed five days per week for 40 weeks, during which the animals were monitored for development of skin cancers. Results Mice exposed to synthetic solar light developed significant increases in squamous cell neoplasms and squamous cell nonneoplastic lesions of the skin whether or not they received treatment with cream. Female mice, but not male mice, treated with aloe gel or aloe-emodin and exposed to simulated solar light had increased numbers of squamous cell neoplasms when compared with mice treated with the carrier cream without the aloe gel or aloe-emodin and exposed to the same intensity of light. For both male and female mice, inclusion of aloe whole leaf extract or decolorized leaf extract in the cream increased the number of squamous cell neoplasms when the animals were exposed to simulated solar light. Conclusions We conclude that aloe gel or aloe-emodin had a weak enhancing effect on the photocarcinogenic activity of simulated solar light in female but not male hairless mice. We conclude that aloe whole leaf extract and decolorized leaf extract had a weak enhancing effect on the photocarcinogenic activity of simulated solar light in both male and female hairless mice.