Abstract
Multidrug resistance in pathogenic bacteria has become a significant public health concern. As an alternative therapeutic option, antimicrobial photodynamic therapy (aPDT) can successfully eradicate antibiotic-resistant bacteria with a lower probability of developing resistance or systemic toxicity commonly associated with the standard antibiotic treatment. Parietin (PTN), also termed physcion, a natural anthraquinone, is a promising photosensitizer somewhat underrepresented in aPDT because of its poor water solubility and potential to aggregate in the biological environment. This study investigated whether the complexation of PTN with (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) could increase its solubility, enhance its photophysical properties, and improve its phototoxicity against bacteria. At first, the solubilization behavior and complexation constant of the PTN/HP-β-CD inclusion complexes were evaluated by the phase solubility method. Then, the formation and physicochemical properties of PTN/HP-β-CD complexes were analyzed and confirmed in various ways. At the same time, the photodynamic activity was assessed by the uric acid method. The blue light-mediated photodegradation of PTN in its free and complexed forms were compared. Complexation of PTN increased the aqueous solubility 28-fold and the photostability compared to free PTN. PTN/HP-β-CD complexes reduce the bacterial viability of Staphylococcus saprophyticus and Escherichia coli by > 4.8 log and > 1.0 log after irradiation, respectively. Overall, the low solubility, aggregation potential, and photoinstability of PTN were overcome by its complexation in HP-β-CD, potentially opening up new opportunities for treating infections caused by multidrug-resistant bacteria.
Highlights
The overuse of antibiotics has resulted in inexorable antibiotic resistance, which worsens day by day, extending hospital admissions, raising healthcare costs, and eventually leading to increased death rates
In 2020, more than 670,000 people were infected in Europe with antibiotic-resistant bacteria, with approximately 33,000 deaths
Qiu et al dealt with the complexation of anthraquinone, emodin, in HP-β-CD [34], and the authors presented a similar profile with 1:1 stoichiometry between emodin and HP-β-CD
Summary
The overuse of antibiotics has resulted in inexorable antibiotic resistance, which worsens day by day, extending hospital admissions, raising healthcare costs, and eventually leading to increased death rates. In 2020, more than 670,000 people were infected in Europe with antibiotic-resistant bacteria, with approximately 33,000 deaths. The total economic burden of antibiotic resistance in Europe is expected to be 1.1 billion Euros [1]. Pharmaceutics 2022, 14, 357 in economic output due to illness or death-related infection was estimated to surpass. The number of deaths caused by worldwide antibiotic resistance is expected to increase to 10 million per year by 2050, up from 700,000 in 2014 [3]. Scientific, economic, and regulatory, hinder the development of new antibiotics [5]. Alternative treatment strategies against resistant bacteria are urgently sought
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