Antioxidant and Photoprotective Activity of Apigenin and its Potassium Salt Derivative in Human Keratinocytes and Absorption in Caco-2 Cell Monolayers.

Sánchez-Marzo Sánchez-Marzo,Herranz-López Herranz-López,Pérez-Sánchez Pérez-Sánchez,Ruiz-Torres Ruiz-Torres,Castillo Castillo,Barrajón-Catalán Barrajón-Catalán,Martínez-Tébar Martínez-Tébar

doi:10.3390/ijms20092148

Abstract

Ultraviolet (UV) radiation, especially types A (UVA) and B (UVB), is one of the main causes of skin disorders, including photoaging and skin cancer. Ultraviolent radiation causes oxidative stress, inflammation, p53 induction, DNA damage, mutagenesis, and oxidation of various molecules such as lipids and proteins. In recent decades, the use of polyphenols as molecules with an antioxidant and anti-inflammatory capacity has increased. However, some of these compounds are poorly soluble, and information regarding their absorption and bioavailability is scarce. The main objective of this study was to compare the intestinal absorption and biological activity of apigenin and its more soluble potassium salt (apigenin-K) in terms of antioxidant and photoprotective capacity. Photoprotective effects against UVA and UVB radiation were studied in human keratinocytes, and antioxidant capacity was determined by different methods, including trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays. Finally, the intestinal absorption of both apigenins was determined using an in vitro Caco-2 cell model. Apigenin showed a slightly higher antioxidant capacity in antioxidant activity assays when compared with apigenin-K. However, no significant differences were obtained for their photoprotective capacities against UVA or UVB. Results indicated that both apigenins protected cell viability in approximately 50% at 5 J/m2 of UVA and 90% at 500 J/m2 of UVB radiation. Regarding intestinal absorption, both apigenins showed similar apparent permeabilities (Papp), 1.81 × 10−5 cm/s and 1.78 × 10−5 cm/s, respectively. Taken together, these results suggest that both apigenins may be interesting candidates for the development of oral (nutraceutical) and topical photoprotective ingredients against UVA and UVB-induced skin damage, but the increased water solubility of apigenin-K makes it the best candidate for further development.

Highlights

The skin is the largest organ of the body acting as a physical and chemical barrier to protect the body against harmful external agents such as ultraviolet (UV) radiation, dehydration, temperature changes, and pathogens [1,2,3]
Photoprotective effects against UVA and UVB radiation were studied in human keratinocytes, and antioxidant capacity was determined by different methods, including trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays
UV radiation has an array of harmful effects, and chronic exposure to sunlight is the main cause of photoaging and skin carcinogenesis

Summary

Introduction

The skin is the largest organ of the body acting as a physical and chemical barrier to protect the body against harmful external agents such as ultraviolet (UV) radiation, dehydration, temperature changes, and pathogens [1,2,3]. UV radiation exposure is a main factor for age-related changes, including immunosuppression and allergy disorders, degenerative aging, inflammation, extracellular matrix (ECM) degeneration, DNA damage, oxidative stress, and carcinogenesis [4,5]. These effects are included in the term photoaging, which resumes the biological consequences of UV exposure, on skin, and in the whole organism. Excessive ROS formation, after UVA and following UVB overexposure, can oxidize several DNA repair proteins, compromising their efficiency [11]

Objectives

Methods

Results

Conclusion