Chemical composition and antioxidant properties of Thai propolis: Role of caffeic acid phenethyl ester (CAPE)

Propolis, a resinous substance produced by Apis mellifera, is rich in polyphenols and flavonoids and exhibits diverse biological activities, including antioxidant and antimicrobial effects. This study aimed to characterize the chemical composition of Thai propolis and evaluate its free radical scavenging activity. Ethanolic (EEP) and aqueous (WEP) extracts were prepared and analyzed. Gas chromatography-mass spectrometry (GC-MS) identified major constituents of EEP, including phenolic acids, flavonoids, and sugars. Antioxidant activities were assessed using DPPH and hydrogen peroxide scavenging assays. EEP exhibited significantly higher radical scavenging activity than WEP, with maximum DPPH inhibition of 87.46% at 5 mg/mL. CAPE effectively scavenged superoxide and hydroxyl radicals and protected plasmid DNA from oxidative damage. These results highlight CAPE as bioactive compound contributing to the antioxidant properties of Thai propolis. Thai propolis, particularly its ethanolic extract, represents a promising natural source of antioxidants for potential applications in nutraceuticals, functional foods, and oxidative stress-related disease prevention.