Singlet molecular oxygen-mediated photo-oxidation of tetracyclines: kinetics, mechanism and microbiological implications

Miskoski, Sandra; Sánchez, Eduardo I.; Garavano, Marcela; López, Mercedes; Soltermann, Arnaldo T.; Garcı́a, Norman A.

doi:10.1016/s1011-1344(98)00104-3

Cited by 49 publications

(31 citation statements)

References 23 publications

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“…3 indicates that 1 O 2 was generated upon irradiation of TC solutions at the pH range of 2.7-8.3. The results confirmed that 1 O 2 could be generated by irradiation of TC not only in the fully protonated form [13], but also in the deprotonated forms of TC over the natural pH range; the results were different from the work by Miskoski et al [14]. In our study the TC solution was excited in the ESR cavity by the third harmonic light of a pulsed Nd:YAG laser at 355 nm, which coincides with the maximum absorbance of TC, while Miskoski et al employed 532 nm as the excited wavelength at which the TC solution shows no appreciable absorption.…”

Section: Mechanism On Photolysis Of Tccontrasting

confidence: 67%

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Photodegradation of tetracycline and formation of reactive oxygen species in aqueous tetracycline solution under simulated sunlight irradiation

Chen

et al. 2008

Journal of Photochemistry and Photobiology A: Chemistry

257

102

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The photochemical kinetics and mechanism of the antibiotic compound tetracycline (TC) was investigated in aqueous solution under simulated sunlight irradiation. The study of the electron spin resonance revealed that the singlet oxygen ( 1 O 2 ) was generated and the formation rate decreased with increasing pH in illuminated TC solution. Also, it was found that the H 2 O 2 was produced and increased with increasing pH under the simulated sunlight irradiation. The results verified that TC could be sunlight excited and induced the formation of reactive oxygen species. Moreover, the contributions of oxidation reaction to photodegradation of TC were clarified by the role of different radical scavengers. The kinetic model elucidated the involvement of TC photoinduced singlet oxygen on the photodegradation of TC. It was verified that the photodegradation of TC was predominantly attributed to direct photolysis. The quantum yields of direct photolysis increases with increasing pH in the range of 6.0-9.0, varying from 3.4 × 10 −4 to 1.1 × 10 −2 . The indirect photolysis of TC was carried out in the presence of nitrate, bicarbonate, ferric ions and humic acid (HA), respectively. The results verified that the photodegradation of tetracycline was not obviously affected by these photosensitizers except ferric ions, indicating that the direct photolysis of TC was predominant process.

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Section: Mechanism On Photolysis Of Tccontrasting

confidence: 67%

“…During the research of phototoxicity for tetracyclines (TCs), Hasan and Khan observed the photosensitized emission of singlet oxygen in TC solution [13]. However, the later study indicated that TCs did not generate 1 O 2 to any considerable extent [14]. Equally, the superoxide anion (O 2…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of tetracycline and formation of reactive oxygen species in aqueous tetracycline solution under simulated sunlight irradiation

Chen

et al. 2008

Journal of Photochemistry and Photobiology A: Chemistry

257

102

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“…Several mechanisms have been proposed to explain this phenomenon including photo-oxidation or an oxygen-dependent pathway that involves a tetracycline photoproduct and a singlet oxygen after absorption of UV radiation by the tetracycline molecule (27). There are many structural elements of the molecular structure of tetracycline, including its phenolic ring, tertiary amino groups, and various conjugated double bonds, which may serve as reactive sites for singlet molecular oxygen-mediated photo-oxidation (28). However, Col-3 contains only a phenolic ring in its tetracycline backbone and lacks the other aforementioned sites that could potentially react with a singlet oxygen.…”

Section: Discussionmentioning

confidence: 99%

A Phase I and Pharmacokinetic Study of Col-3 (Metastat), an Oral Tetracycline Derivative with Potent Matrix Metalloproteinase and Antitumor Properties

Syed

Takimoto

Hidalgo

et al. 2004

Clinical Cancer Research

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Purpose: The purpose of this research was to assess the feasibility of administering Col-3, an oral chemically modified tetracycline derivative with potent inhibitory effects on matrix metalloproteinase activity and production, and recommend a dose on an uninterrupted once-daily schedule. The study also sought to characterize the pharmacokinetic behavior of Col-3 and seek evidence of anticancer activity.Experimental Design: Patients with advanced solid malignancies were treated with escalating doses of Col-3 with dose level assignment according to an accelerated titration scheme. Because photosensitivity skin reactions were being reported in concurrent trials of Col-3, patients were instructed to apply sunscreen rigorously throughout the trial. The maximum tolerated dose was defined as the highest dose at which <2 of the first 6 new patients experienced doselimiting toxicity. The pharmacokinetic behavior of Col-3 was characterized, and pharmacodynamic relationships were sought.Results: Thirty-three patients were treated with 73 courses of Col-3 at four dose levels ranging from 36 to 98 mg/m 2 /day. Unacceptably high incidences of photosensitivity skin reactions and malaise were noted in the first 28-day courses of patients treated with Col-3 at doses exceeding 50 mg/m 2 /day. At 50 mg/m 2 /day, severe toxicity occurred in 2 of 12 new patients in first courses, and no additional doselimiting toxicities were observed in subsequent courses. Other mild to modest adverse effects included nausea, vomiting, liver function tests abnormalities, diarrhea, mucositis, leukopenia, and thrombocytopenia. The pharmacokinetics of Col-3 were dose proportional, and mean trough concentrations at steady state were similar to biologically relevant concentrations in preclinical studies. Major responses did not occur, but durable disease stability was noted in 3 patients, one each with carcinosarcoma of the uterus, pancreas, and ovary, all of whom had experienced disease progression before Col-3 treatment.Conclusions: The recommended dose for Phase II studies of Col-3 administered once daily on an uninterrupted schedule is 50 mg/m 2 /day accompanied by efforts that promote adherence to the use of sunscreen and other photoprotective measures. Pharmacokinetic results indicate that plasma concentrations above biologically relevant concentrations are readily maintained at this dose, and additional disease-directed studies, particularly in patients with soft tissue sarcoma, should be considered.

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“…Side-chain degradations by deamination, desulfuration and dealkylation are typical of many photolytic processes [19][20][21][22]. Photodeamination occurs when tetracycline is irradiated with UV light [11][12][13]. The removal of volatile dimethylamine, which requires the loss of only 2 atoms of carbon with respect to the 22 atoms of tetracycline, explains the small variation of the TOC values reported in Figure 4.…”

Section: Mechanistic Aspectsmentioning

confidence: 97%

“…Absorption slowly decreases with irradiation time. The fall in the absorbance at 355 nm is accompanied by a very weak absorption in the visible region that can be attributed to the formation of 4a,12a-anhydro-4-oxo-4-dedimethylaminotetracycline [10,11]: Tetracycline photodecomposes easily and is converted to many decomposition compounds [11][12][13][14][15][16][17][18]. Side-chain degradations by deamination, desulfuration and dealkylation are typical of many photolytic processes [19][20][21][22].…”

Section: Mechanistic Aspectsmentioning

confidence: 99%

Removal of drugs in aqueous systems by photoassisted degradation

et al. 2005

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Aqueous solutions of tetracycline, lincomycin and ranitidine were irradiated with UV light in homogeneous and heterogeneous systems. Two commercial polycrystalline TiO 2 powders (Degussa P25 and Merck) were used as photocatalysts. After 5 h, an appreciable photolytic degradation of tetracycline and ranitidine was observed while the degradation of lincomycin was noticeably lower. As far as the mineralization is concerned, a small decrease of the TOC values was measured in the case of tetracycline whereas negligible variations were found for lincomycin or ranitidine. The presence of the photocatalysts greatly enhanced the degradation rates of the drugs with respect to those observed during the homogeneous experiments. The Langmuir-Hinshelwood kinetic model adequately describes the experimental results and both the pseudo-first order kinetic constants of the reactions and the adsorption constants were calculated. Merck TiO 2 was more active than P25 Degussa for the photodegradation of tetracycline and ranitidine, whereas both photocatalysts showed similar performances for lincomycin. In the presence of TiO 2 Degussa P25, tetracycline was almost completely mineralized, but the reduction of the initial TOC was ca. 60% in the case of lincomycin and ranitidine. A less significant mineralization was observed by using Merck TiO 2 .

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Singlet molecular oxygen-mediated photo-oxidation of tetracyclines: kinetics, mechanism and microbiological implications

Cited by 49 publications

References 23 publications

Photodegradation of tetracycline and formation of reactive oxygen species in aqueous tetracycline solution under simulated sunlight irradiation

Photodegradation of tetracycline and formation of reactive oxygen species in aqueous tetracycline solution under simulated sunlight irradiation

A Phase I and Pharmacokinetic Study of Col-3 (Metastat), an Oral Tetracycline Derivative with Potent Matrix Metalloproteinase and Antitumor Properties

Removal of drugs in aqueous systems by photoassisted degradation

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