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Hyaluronate depolymerization following thermal decomposition of oxytetracycline.
T Miyazaki1, C Yomota, S Okada
1National Institute of Health Sciences, Osaka, Japan. miyazaki@nihs.go.jp
Chemical & Pharmaceutical Bulletin
|February 24, 2001
Summary
Tetracyclines, like oxytetracycline hydrochloride (OTC), can depolymerize sodium hyaluronate (HA) without light. OTC decomposition in solution causes HA breakdown, a process influenced by temperature and oxygen availability.
Area of Science:
- Biochemistry
- Materials Science
Background:
- Sodium hyaluronate (HA) is a crucial glycosaminoglycan with various biological functions.
- Tetracyclines, such as oxytetracycline hydrochloride (OTC), are antibiotics with known photosensitizing properties.
- Previous research has indicated potential radical-related side effects of tetracyclines.
Purpose of the Study:
- To investigate the depolymerization of sodium hyaluronate (HA) by tetracyclines.
- To elucidate the mechanism and conditions influencing HA depolymerization by OTC.
- To identify the specific OTC derivative responsible for HA degradation.
Main Methods:
- Size exclusion chromatography with a low angle laser light scattering detector to measure HA molecular weight changes.
- Incubation of HA and OTC solutions at varying temperatures (37°C and below 25°C).
- Analysis of OTC decomposition products using reversed-phase HPLC and visible spectroscopy.
- Experiments under varying oxygen conditions (nitrogen saturation) and with radical scavengers (mannitol).
Main Results:
- Oxytetracycline hydrochloride (OTC) depolymerized sodium hyaluronate (HA) at 37°C in the dark, indicated by reduced HA molecular weight.
- OTC solution spontaneously discolored to reddish-brown at 37°C, correlating with HA depolymerization.
- Depolymerization and discoloration were significantly reduced below 25°C.
- Oxygen depletion and the presence of mannitol prevented HA depolymerization, though mannitol preserved HA from damage while OTC still decomposed.
- Anhydrooxytetracycline was proposed as the likely derivative responsible for HA depolymerization.
Conclusions:
- Tetracycline antibiotics, specifically OTC, can induce HA depolymerization through a non-photochemical mechanism.
- The degradation of OTC at physiological temperatures generates reactive species that break down HA.
- Temperature and oxygen are critical factors in OTC-induced HA depolymerization, suggesting a role for oxidative processes.