Photodegradation of prednisolone under UVB solar irradiation. Role of photogenerated ROS in the degradation mechanism

Abstract

The use of biologically active substances with anti-inflammatory properties such as corticosteroids has increased considerably in the last few decades. Particularly, the compound we are interested in, prednisolone (Predn), is a glucocorticoid with high biological activity. This compound absorbs UV radiation and may participate in photochemical processes, which can result in its own decomposition. These processes could result in the formation of free radicals or reactive oxygen species (ROS). On these grounds, the kinetic and mechanistic aspects of the direct photodegradation of Predn have been studied in aqueous medium under different atmospheric conditions by stationary and time-resolved techniques. The mechanism involved in the photodegradation has been elucidated. Predn is capable of generating the excited triplet state Predn* as a result of UVB light absorption. In the presence of oxygen,Predn* allows the formation of ROS, of which O(Δ) (Φ = 0.014), HO and the radical OH˙ stand out. The latter is generated from the spontaneous dismutation of O˙ and subsequent homolytic cleavage, photochemically promoted, of HO. Predn undergoes unimolecular photodegradation reactions under an inert argon atmosphere. In this study we found that in the presence of oxygen, the Predn photo-consumption is improved. This implies that the attack by ROS involves a very important additional contribution to the photodegradation of Predn under aerobic conditions.

Photostability of Topical Agents Applied to the Skin: A Review

“…Glucocorticosteroids pregna-1,4-dien-3,20-diones [24] betamethasone and its esters [25,26] betamethasone-17 valerate [27] mometasone furoate [28] hydrocortisone 21-acetate [29] prednisolone [30] fluocinolone 16,17-acetonide [31,32] desonide [33,34] Retinoids vitamin A [35] tretinoin [36][37][38][39][40][41][42][43][44] isotretinoin [36,37,45] adapalene [46,47] tazarotene [48] Antifungal drugs clotrimazole [49,50] bifonazole [51] itraconazole [52,53] terbinafine [54] Non-steroidal antiinflammatory drugs piroxicam [55][56][57] naproxen [58][59][60][61] diclofenac [57,58,62] ketoprofen [63][64][65][66] ibuprofen …”

“…The experiment carried out by Cacciari et al showed that the presence of oxygen could have special significance to the rate of the photodegradation of corticosteroids. The photodegradation process of prednisolone under UVB irradiation was based on the two pathways: direct photolysis and self-sensitization via photogenerated reactive oxygen species [30]. The photogeneration of OH • , and then, their attack on the corticosteroid could be responsible for the photodegradation process of prednisolone, dexamethasone, triamcinolone 16,17-acetonide or fluocinolone 16,17-acetonide [30,31,86,87].…”

Natural degradation of ceftriaxone promoted by direct UVB light in aqueous media. Mechanistic analysis and cytotoxic effects on a eukaryotic cell line and on bacteria

“…In previous work, we evaluated the photodegradation processes of different widely used drugs and their corresponding toxicity studies, since the degradation of drugs can produce substances with greater or lesser toxicity with respect to that of the original molecule. [25][26][27][28][29] In the aforementioned studies, the drugs were degraded either by direct photolysis or by a photosensitized process with riboflavin, which is a natural pigment present in aquatic environments that can act as a photosensitizer. [30][31][32][33] In the case of the photosensitized degradation of vancomycin, we observed that the bactericidal activity against Staphylococcus aureus strains was affected by the photolysis, which means that the photoproducts do not preserve the antimicrobial properties of the original compound.…”

“…In previous work, we evaluated the photodegradation processes of different widely used drugs and their corresponding toxicity studies, since the degradation of drugs can produce substances with greater or lesser toxicity with respect to that of the original molecule. 25–29 In the aforementioned studies, the drugs were degraded either by direct photolysis or by a photosensitized process with riboflavin, which is a natural pigment present in aquatic environments that can act as a photosensitizer. 30–33…”

Removal of 26 corticosteroids, potential COVID-19 remedies, at environmentally relevant concentrations in water using UV/free chlorine, UV/monochloramine, and UV/hydrogen peroxide

“…5 Moreover, most of previous studies focused on a limited list of target CSs (5-6 CSs) at high method detection limits (>1 ng L −1 ). [21][22][23][24] To date, no comprehensive studies are available dealing with the transformation processes of a large group of CSs at environmental concentrations during UV-based AOPs. Systematic investigations on CS behavior during UV-based AOPs through sensitive analytical methods are urgently needed.…”