Phellopterin cream exerts an anti-inflammatory effect that facilitates diabetes-associated cutaneous wound healing via SIRT1

Abstract

Background: Diabetic ulcers, which are characterized by chronic nonhealing wounds with a long-lasting inflammatory state, are a typical symptom in individuals with diabetes, and there is still no effective treatment for these lesions. Angelica dahurica plays a critical role in inflammatory diseases. Among numerous monomeric compounds, phellopterin has been shown to have anti-inflammatory properties.

Purpose: To research the bioactive constituents in Angelica dahurica and their mechanism of action in treating diabetic ulcers.

Study design: Chemical research of Angelica dahurica led to the identification of a new coumarin, dahuricoumarin A (1), along with seven known compounds (2 - 8). All compounds were tested for anti-inflammatory activity, and phellopterin, compound (3), significantly decreased the expression of intercellular cell adhesion molecule-1 (ICAM-1), a representative indicator of inflammation. Phellopterin can also increase SIRT1 protein, a key target for inflammation. In our research, we confirmed the anti-inflammatory effects of phellopterin on diabetic ulcers and explored the underlying mechanism of action.

Methods: The expression of IFN-γ, SIRT1, and ICAM-1 in human diabetic ulcer tissues was studied using immunohistochemistry. Streptozotocin was used to induce a diabetic model in C57BL/6J mice, and ulcers were surgically introduced. After phellopterin treatment, the skin lesions of diabetic mice were observed over a period of time. The protein and mRNA expression levels of SIRT1 and ICAM-1 were measured using H&E, qRT-PCR and immunohistochemical staining. A HaCaT cell inflammatory model was induced by IFN-γ. Using a lentiviral packaging technique, MTT assay, and Western blotting, the effect of phellopterin on the proliferation of HaCaT cells and the expression of ICAM-1 was evaluated under normal and SIRT1 knockdown conditions.

Results: High levels of ICAM-1 and IFN-γ were identified, but low levels of SIRT1 were found in human diabetic ulcer tissues, and phellopterin showed therapeutic benefits in the healing process by attenuating chronic inflammation and promoting re-epithelialization, along with SIRT1 upregulation and ICAM-1 downregulation. However, inhibiting SIRT1 reversed its proliferative and anti-inflammatory effects.

Conclusion: In vitro and in vivo, phellopterin exerts anti-inflammatory and proliferative effects that promote diabetic wound healing, and the potential mechanism depends on SIRT1.

Keywords: Angelica dahurica; Diabetic ulcer; Inflammation; Phellopterin; SIRT1; Wound healing.