Patches containing quercetin microcapsules to ameliorate dermal herpes simplex virus injuries in mice

Abstract

This study aimed to develop patches containing quercetin-loaded microcapsules and to evaluate their in vitro and in vivo safety and efficacy in preclinical surveys. A set of in vitro experiments evidenced the virucidal activity of quercetin against the HSV-1-KOS (sensitive to acyclovir) and HSV-1-AR (resistant to acyclovir) strains, with improved outcomes upon the first. The patches presented a homogeneous aspect, were easily handled, had a suitable bioadhesion, and possessed mechanical properties of soft and weak material, besides a pH compatible with human skin. The in vitro release profile of quercetin showed an initial burst release, followed by a controlled release rate, which was best described by Gompertz kinetics (R² of 0.93). Using quercetin-loaded patches for treating HSV-1-KOS-induced injuries was feasible since they were well tolerated in the in vivo skin irritation test and significantly decreased the injury scores until the fourth out of eight days of treatment in mice compared to acyclovir cream (50 mg/g). Altogether, the in vitro and in vivo antiviral assays indicate that this flavonol acts in the earlier stage of the infection, likely impairing the HSV-1 adsorption to the cell. The anti-inflammatory capacity of the quercetin-loaded patches was noteworthy as evidenced by histological analysis. These findings bring prospects for safer and more effective management of mucocutaneous HSV-1 injuries.

Highlights

Herpes simplex virus (HSV-1) infections have no cure and cause discomfort and pain.

Quercetin was effective against HSV-1-KOS and HSV-1-AR strains in vitro.

Quercetin-loaded bioadhesive patches ameliorated HSV-1-KOS infection in mice.

The polymeric patches enabled a controlled release of quercetin.

The safety of the patches was confirmed by an in vivo dermal irritation test.

Introduction

The World Health Organization (WHO) estimated that 3.8 billion people under the age of 50, equivalent to 64.2 % of the global population, were infected with the herpes simplex virus type 1 (HSV-1) in 2020 [1]. The herpetic infection has neither cure nor vaccines, with acyclovir being the reference drug for treatment [2]. However, managing HSV infections is even more challenging due to increasing strain resistance to this drug [3].

An alternative to conventional treatments consists of using natural products with antiviral activity [4], [5], [6]. Quercetin is an aglycone flavonoid (flavonol) present in our daily diet that has several biological activities and is acknowledged as an antiviral [7], owing to its efficacy in inhibiting various viruses such as influenza A, B, dengue, hepatitis C, rhinovirus, Zika, Ebola, poliovirus type 1, and SARS-CoV-2 [7], [8]. The in vitro anti-HSV-1 activity of quercetin has been evidenced previously [9], indicating inhibition of viral expression in the initial stages such as adsorption and penetration, which brings prospects for this phytochemical in herpetic treatment.

Topical products used in herpes treatment are often semi-solid formulations (e.g., ointments, and creams) having limited residence time in the administration site and conventional drug release profile, thus requiring several administrations daily [10], [11]. The development of patches (bioadhesive polymeric films) for drug delivery has currently gained attention since they can circumvent such limitations [12].

Depending on their composition and architecture, this pharmaceutical technology can bring several advantages such as ease of manufacture and self-administration, the capacity to absorb exudates, a higher dosage accuracy, posological flexibility, less potential for irritation, and the possibility of immediate interruption of treatment due to a side effect [13], [14]. Moreover, the lower need for repeated administration related to bioadhesion and the ability to promote targeted and controlled drug release at the treatment site emerge as potential advances brought by these patches to patients suffering from herpetic injuries across the globe.

To the best of our knowledge, the feasibility of using patches containing quercetin for treating HSV-1 injuries remains uncharted, thus, herein we report on the outcomes of various preclinical in vitro and in vivo assessments addressing this concern. The patches also underwent in vivo safety assessment, in vitro physicochemical quality control analysis, evaluation of mechanical properties, in vitro drug release studies, and short-term stability assessments (drug content and folding endurance).

Materials

Quercetin (95 % purity) was obtained from Sanrisil (Itaquaquecetuba, São Paulo, Brazil); Kollicoat® IR, polyvinylpyrrolidone (PVP), and poloxamer 407 (P407) were from BASF®️ (São Paulo, São Paulo, Brazil); casein was from Vetec® (Duque de Caxias, Rio de Janeiro); pectin from CP Kelco® (Limeira, São Paulo, Brazil); dimethyl sulfoxide (DMSO), sodium hydroxide, glycerol, and sodium chloride from Anidrol (Diadema, São Paulo, Brazil); absolute ethanol, Tween®️ 20.

Jéssica Bassetto Carra, Maria Laura Goussain Darido, Camila Felix Vecchi, Mariana Carla de Oliveira, Ricardo Luís Nascimento de Matos, Pietra Mitiko Tateyama Pattini, Bianca Larissa Masquetti, Beatriz da Silva Tavares, Marcos Luciano Bruschi, Ana Paula Frederico Rodrigues Loureiro Bracarense, Renê Oliveira do Couto, Rubia Casagrande, Sandra Regina Georgetti, Waldiceu A. Verri, Ligia Carla Faccin Faccin-Galhardi, Marcela Maria Baracat, Patches containing quercetin microcapsules to ameliorate dermal herpes simplex virus injuries in mice, European Journal of Pharmaceutics and Biopharmaceutics, 2025, 114631, ISSN 0939-6411, https://doi.org/10.1016/j.ejpb.2025.114631.