Various crystalline forms of realgar exhibit differentiated anti-abscess and anticancer effects based on a PXRD analysis and biological evaluation.

Ethnopharmacological Relevance: Realgar is a mineral medicine with a long history that can be used externally or internally. It is often used to treat skin diseases and leukemia in clinical practice. Realgar exhibits a polycrystalline phenomenon, and it remains unknown whether there is a difference in the efficacies of the different realgar crystalline forms.
Purpose: The aim of this study is to investigate the pharmacodynamic differences of the different realgar crystalline forms (α-As ₄ S ₄ and β-As ₄ S ₄ ) using in vivo and in vitro experiments.
Material and Methods: The in realgar crystalline patterns were initially identified using a powder x-ray diffractometer (PXRD). The antimicrobial activities of α-As ₄ S ₄ and β-As ₄ S ₄ were then assessed in vitro to elucidate their effectiveness against bacteria. Transdermal absorption and pharmacokinetic experiments were used to investigate the variances in the bioavailabilities between the in vitro and in vivo conditions. The effects of α-As ₄ S ₄ and β-As ₄ S ₄ for skin abscess healing were studied in mice using a subcutaneous injection of Staphylococcus aureus (S. aureus). HL-60 cells were exposed to a serum that contained different crystalline forms of realgar to evaluate the potential differences in the therapeutic effects of α-As ₄ S ₄ and β-As ₄ S ₄ on leukemia.
Results: Realgar is composed of α-As ₄ S ₄ and β-As ₄ S ₄ crystalline forms. The soluble arsenic content in α-As ₄ S ₄ generally exceeded that of β-As ₄ S ₄ , and the antimicrobial activity showed a positive correlation with the soluble arsenic content. α-As ₄ S ₄ demonstrated a higher in vivo and in vitro bioavailability and a faster elimination rate in vivo compared to β-As ₄ S ₄ . The pharmacodynamic experimental investigations showed that α-As ₄ S ₄ exhibited a superior healing effect on subcutaneous abscesses. Furthermore, serum pharmacology experiments revealed that α-As ₄ S ₄ induced significantly higher membrane damage and apoptosis in HL-60 cells compared to β-As ₄ S ₄ .
Conclusion: The different realgar crystalline forms had distinct pharmacodynamics. α-As ₄ S ₄ demonstrated higher bioavailability in vitro and in vivo and superior effects on skin abscess healing compared to β-As ₄ S ₄ . It also possessed anti-leukemia properties. It is the first time to report the differences in the efficacy between two crystalline forms of realgar, which is helpful to improve the knowledge of the real chemical substances for realgar.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024. Published by Elsevier B.V.)