Morphological changes of the skin caused by a photosensitizer emulsion based on furanocoumarins of Sosnovsky’s hogweed’s

Furanocoumarins are natural photosensitizers and can be effectively used as drugs for the treatment of skin diseases, including superficial tumors. There are quite old and rare studies of the skin and systemic toxic effects of furanocoumarins, however, at present there are no data on the photosensitizing effect of furanocoumarins from Sosnovsky's Hogweed's and other giant hogweeds. There is also no convenient and easily dosed form of furanocoumarins due to the fact that furanocoumarins are rather lipophilic substances and easily form water-insoluble needle-like crystals. The purpose of the study was to evaluate the photosensitizing effect of a new emulsion form of furanocoumarins from Sosnovsky's Hogweed's on the skin of laboratory animals. In the course of the study, an emulsion of furanocoumarins extracted from Sosnovsky's Hogweed's and stabilized with tween-80 with a concentration of 8-methoxypsoralen 1 mg/ml was obtained. The emulsion was injected intravenously once to white laboratory rats at a dose of 8-methoxypsoralen 3 mg/kg. An area of rat skin after injection of the emulsion was subjected to ultraviolet irradiation at a dose of 44 joules/cm2 with a wavelength of 365 nm. After 7 days, a histological examination of skin biopsies at the site of irradiation was performed. Macroscopically, in rats after the introduction of the emulsion and ultraviolet irradiation, signs of second-degree burns were observed. Microscopically, damage to the epidermis up to the papillary dermis was revealed, accompanied by atrophy of the hair follicles, bullous sub-epidermal cavities, and leukocyte infiltration of the sub-epidermal zone. The emulsion form of furanocoumarins of Sosnovsky's Hogweed's with intravenous injection and the photo activating effect of irradiation causes the same degree of burn as with contact exposure, the depth of the cytotoxic effect is limited solely by the penetrating ability of ultraviolet radiation with a wavelength of 365 nm. Intact animals that received only ultraviolet irradiation without emulsion injection had no skin lesions. Thus, the resulting emulsion of furanocoumarins, when injected intravenously, exhibits a photosensitizing effect.