Comparison of the free radical-scavenging activity of Thai stingless bee propolis

Propolis has been wildly applied as medicine and dietary supplement because of its broad biological activities including anti-inflammatory, immunomodulatory and antioxidant activity. Propolis from the stingless bees (Apoidae) such as Lepidotrigona ventralis Smith, Lepidotrigona terminata Smith, and Tetragonula pagdeni Schwarz, has been used as indigenous medicine and marketed in several preparations in Thailand. However, the biological activities of each type of propolis generally depend on the bee species. Thus, in this study, free radical scavenging activities of the propolis from these three stingless bee species in the same area of mangosteen garden were performed by FRAP, ABTS and DPPH assay. All extracts were observed as viscous crude and amber products. The propolis extracts from the stingless bee were able to exhibit free radical scavenging activity. The extract from T. pagdeni illustrated significant highest activity with FRAP value 389.07 ± 26.02 µmol Fe 2+ /g extract, and IC 50 values were 59.52 ± 10.76, and 122.71 ± 11.76 µg/mL using ABTS and DPPH assay, respectively. In addition, the major compounds from T. pagdeni propolis extract was separated and identified as alpha mangostin and gamma mangostin that may be play an important role in the biological activity of the propolis. Therefore, T. pagdeni propolis was suggested as a suitable raw material for indigenous usage and further development as pharmaceutical products.