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Toxicity
Angelicin, being the angular isomer of the furocoumarins, can have phototoxic and photomutagenic effects in contact with skin. It also highly enhances the toxicity of UV light on skin. This happens usually when the skin after getting in contact with angelicin, is exposed to sunlight. This leads possibly to severe skin damage, including erythema and blisters. Upon irradiation with UV light of longer wave-length, angular furoncoumarins like angelicin are supposed to form DNA-monoadducts, which can be a cause of skin cancer, although linear furoncoumarins like psoralen are reported to be five to ten times more active than angelicin and to form additionally the even more dangerous and lethal DNA cross-links. Psoralen can be used in a therapeutic way to suppress DNA replication in cancerous cells and introduce apoptosis – as mentioned in the section Medicine – but in healthy cells it can also cause severe skin problems, with photodermatitis being one of the least consequences. Experiments with animals and the research of cases where humans were treated with furocoumarin in combination with UV light (as used, i.e. in PUVA therapy) can result in different types of dermal tumors even years after successful treatment.

According to, to cause an acute toxicity by oral intake the LD50 is around 322 mg/kg (for rats). The possible consequences are alteration in sleep time and righting reflex, ataxia and analgesia.

In cells of mammalian culture, both linear (i.e., psoralen) and angular (i.e., angelicin) furoncoumarins have also shown to have mutagenic and cytotoxic effects, while they also serve as strong inhibitors of drug metabolism. The inhibition works due to the fact that furoncoumarins get in the way of the activity and expression of CYP1A1, which is regulated by aryl hydrocarbon receptors (AhR). There are mainly three points to consider : However, it is fairly difficult to discriminate with precision which type of furanocoumarin poses the highest risk in terms of phototoxicity and photomutagenicity, as the compounds occur always as a mixture of different types of furanocoumarin in plants and for most of the compounds there is not much data on the potency of their toxicity available yet.
 * 1) Furoncoumarins are able to inhibit the catalytic activity performed by CYP1A1 with and even without the presence of light.
 * 2) Furoncoumarins can trigger the gene expression of CYP1A1 when light is not available by activation the AhR.
 * 3) Furoncoumarins can trigger the gene expression of CYP1A1 when light is not available by activation the AhR.

Furthermore, furanocoumarins like angelicin have successfully been used as natural pesticides as treatment against microbes because of their phototoxic properties.