Validation of a simple chromatographic method for naringenin quantification in skin permeation experiments.

Naringenin is a flavonoid that can be found in citrus fruits (e.g., Citrus sp). This natural compound is known for its antioxidant activity, antitumor, and neuroprotective potential, also acting directly in controlling the inflammatory response. Topical and transdermal routes are attractive alternatives that could circumvent the low oral bioavailability. However, a simple analytical method capable of determining naringenin in skin layers is still demanded. Thus, this work aimed to validate a selective and straightforward chromatographic method for naringenin determination in skin permeation studies. The developed method uses a reversed-phase C18 column as stationary phase and a mobile phase composed of methanol/phosphoric acid 0.01 M (65:35, v/v), eluted at a flow rate of 0.6 mL/min with detection at 290 nm. The method was linear (r2 > 0.99) in a broad concentration range of 0.5-10.0 µg/mL, precise with an overall variation coefficient lower than 2%, and accurate with naringenin recovery from the skin layers higher than 85%. Additionally, the method was sensitive (LD = 0.10 µg/mL, LQ = 0.20 µg/mL), selective against skin matrices as well as naringenin degradation products, and robust regarding methodology parameters. Therefore, the method was suitable to be used in skin permeation studies employing naringenin.

Anti-inflammatory effect evaluation of naringenin and its incorporation into a chitosan-based film for transdermal delivery.

Naringenin is a bioflavonoid mainly found in citrus fruits. It presents many pharmacological benefits, including a remarkable anti-inflammatory activity, but its oral bioavailability is poor. To overcome this drawback, this work proposes a transdermal administration of such bioflavonoid, considering its use in the chronic treatment of inflammatory conditions. For this, it aims to develop a chitosan-based film that guarantees a consistent transdermal delivery of the drug. First, naringenin's in vitro anti-inflammatory effect on T-cell proliferation was evaluated, followed by research on the modulation of gene expression for inflammatory factors in peripheral blood mononuclear cells. Chitosan films were then prepared and characterized. Afterward, naringenin release profile from a selected film was determined as well as the drug permeation across porcine skin provided by the film. Naringenin induced the expression of the anti-inflammatory factors IL-10 and TGF-ß1 while inhibiting the expression of the pro-inflammatory cytokine IL-1ß and limiting T-cell proliferation. The chitosan film was successfully developed, and the drug was progressively released to the physiological media following both first order and Korsmeyer-Peppas kinetics. When topically applied, the chitosan film guaranteed a constant and continuous diffusion of naringenin across the skin over 72 h. Indeed, the permeation flux of naringenin was 0.30 ± 0.01 µg/cm2/h, which means a concentration in the receptor solution 14-fold (p < 0.05) higher than that provided by the drug solution. Thus, the chitosan film represents a promising transdermal alternative for the long-term treatment of inflammatory conditions using naringenin.