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Monographs of essential oils that have caused contact allergy / allergic contact dermatitis
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Currently, psoralens are (largely) removed from the crude oil before being used in fragrances and other cosmetics, including bronzing and sun-protecting products (which should not contain bergapten in quantities >1 ppm in the European Union). There are no regulations, however, for its content in essential oils used in aromatherapy. Indeed, several cases of phototoxicity from such use have been reported (12,13). One patient developed phototoxicity from bath oil, which was shown to contain 5-methoxypsoralen (12). Two patients developed bullous phototoxic dermatitis from aromatherapy with bergamot oil, of which one from its use in a sauna. One of the preparations used proved to contain 2400 ppm (0.24%) bergapten (13). Two cases of photoallergy from bergamot oil were reported from Italy (11).
Photochemotherapy
Published in Henry W. Lim, Nicholas A. Soter, Clinical Photomedicine, 2018
Psoralens belong to the furocoumarin group of compounds. The parent compound psoralen, and many of its derivatives, are widely distributed in plants and fruit such as limes, celery, figs, and lemons. Thus, psoralens are ingested in small quantities in a normal diet; the biological significance of this is unknown. Four psoralens are used for therapeutic purposes (Fig. 1). Methoxsalen, or 8-methoxypsoralen, which is obtained from the seeds of a plant called Ammi majus that grows in the Nile Valley, is the most commonly used psoralen. Trioxsalen, or 4, 5′-8-trimethylpsoralen, is a synthetic compound used for the treatment of vitiligo. Bergapten, or 5-methoxypsoralen, is available in Europe and is now undergoing trials in the United States to confirm its efficacy in psoriasis. Psoralen is used in some Mediterranean countries for the treatment of psoriasis and vitiligo.
Psoralens
Published in Sarah H. Wakelin, Howard I. Maibach, Clive B. Archer, Handbook of Systemic Drug Treatment in Dermatology, 2015
Gillian Murphy, Veronika Dvorakova
Psoralens are naturally occurring furocoumarins that are found in several plant species. They appear to have a protective role against microbes, and inhibit germination of seeds. These aromatic molecules strongly absorb certain ultraviolet (UV) wavelengths (220–400 nm) and act as photosensitizers when administered orally or topically. Synthetic psoralens have been used therapeutically in dermatology since the 1970s in conjunction with UVA in psoralen-UVA photochemotherapy (PUVA). Three psoralens are in use in dermatology: 8-methoxypsoralen (8-MOP; Methoxsalen), 5-methoxypsoralen (5-MOP; Bergapten) and 4,5,8-trimethylpsoralen (TMP).
Molecular mechanisms of hepatotoxicity induced by compounds occurring in Evodiae Fructus
Published in Drug Metabolism Reviews, 2023
Caiqin Yan, Ting Peng, Tingting Zhang, Yuan Wang, Na Li, Kai Wang, Xijuan Jiang
5-Methoxypsoralen (5-MOP) (Table 1) serves as a good example. 5-MOP is a linear furocoumarin, also known as bergapten, which could be easily obtained from numerous plant sources. Since the psoralen ultraviolet A (PUVA) radiation was developed in the 1970s to treat psoriasis, hitherto multiple case reports and studies have established that psoralen and its derivatives are hepatotoxic in combination with UVA light exposure (Bjellerup et al. 1979; Pariser and Wyles 1980). During the clinical application in the past decades, 5-MOP intake was always correlated with a high incidence of cholestatic liver injury. After 40 times of treatments with 5-MOP and photochemotherapy over three months, a 55-year-old woman was reported to develop cholestatic hepatitis as indicated by increased level of bilirubin (Stephens and Cooper 1999). In addition, results of histological examination showed that 5-MOP treatment caused distinct hypertrophy of centrolobular hepatocytes in mice (Diawara et al. 2000).
Mechanism-based inactivation of cytochrome P450 enzymes by natural products based on metabolic activation
Published in Drug Metabolism Reviews, 2020
Tingting Zhang, Jinqiu Rao, Wei Li, Kai Wang, Feng Qiu
Many natural compounds have been reported to be mechanism-based inactivators of P450 enzymes. The best-known example could be furanocoumarins in grapefruit juice, which can interact with many prescription medications, such as ethinylestradiol, cyclosporin, midazolam, triazolam, and terfenadine (Guo and Yamazoe 2004). The main furanocoumarins bergamottin, bergaptol, dihydroxybergamottin, paradisin A, and paradisin B have been characterized as strong mechanism-based inactivators of CYP3A4 (Tassaneeyakul et al. 2000; Girennavar et al. 2007). Furanocoumarins are known as natural toxins that are widely distributed in numerous herbal medicines and have inhibitory effects on different P450 enzymes. Imperatorin and isoimperatorin, mainly found in Angelica dahurica, as well as psoralen and isopsoralen, isolated from Psoralea corylifolia, can mechanistically inactivate the activity of CYP2B6 (Cao et al. 2015; Ji et al. 2015; Zheng et al. 2015; Lu et al. 2016). In addition, psoralen and its derivatives, 5-methoxypsoralen and 8-methoxypsoralen, are mechanism-based inactivators of CYP2B1 and CYP2A6 (Koenigs and Trager 1998). Metabolic activation of the furan moiety is a key step in MBI. Furanocoumarins undergo oxidative metabolism to form furanoepoxide and/or γ-ketoenal intermediates, which are electrophilic and can further react with the nucleophilic sites of P450 enzymes (Zheng et al. 2015).
Safety of the current drug treatments for vitiligo
Published in Expert Opinion on Drug Safety, 2020
Torello Lotti, Komal Agarwal, Indrashis Podder, Francesca Satolli, Martin Kassir, Robert A Schwartz, Uwe Wollina, Stephan Grabbe, Alexander A Navarini, Simon M Mueller, Mohamad Goldust
Psoralens, derived from the plant Psoraleacorylifolia, have been used for the treatment of vitiligo for a long time. The derivative most widely used in photochemotherapy is 8-methoxypsoralen (8MOP) which is principally of plant origin but also available as a synthetic drug. 4, 5, 8-trimethyl psoralen (TMP) is a synthetic compound, less phototoxic and is primarily used for the treatment of vitiligo [7].5-methoxypsoralen is the newest congener of this molecule under research. Acute side effects of psoralen include erythema, pruritus, nausea, headache, drug eruptions; whereas chronic side effects may be chronic phototoxicity, xerosis, hypertrichosis, hyperpigmentation, cutaneous malignancies, etc. Psoralens are absolutely contraindicated in xeroderma pigmentosum, lupus erythematosus, bullous pemphigoid, history of idiosyncratic reaction to psoralens and are relatively contraindicated in conditions like cardiac, liver, renal disease, family history of melanoma, very young children. The criteria for patient selection are age 12 or over, ability to follow the protocol, availability for 12–24 months of continuous therapy, ophthalmological examination, and vitiligo other than acro-facial variant [7]. It is a pregnancy category C drug and is excreted in breast milk.