Attenuation of carrageenan-induced hind paw edema and plasma TNF-α level by Philippine stingless bee (Tetragonula biroi Friese) propolis

Despite decades-long existence of the Philippine stingless bee industry, the biological activity of propolis from this native bee species (Tetragonula biroi Friese) remains poorly understood and sparingly investigated. Herein, we examined the potential anti-inflammatory efficacy of Philippine stingless bee propolis using the lambda (λ)-carrageenan-induced mice model of hind paw edema. Thirty (30), six-week-old, male ICR mice were randomly assigned into three treatment groups (n=10/group) as follows: distilled water group, diclofenac sodium group (10 mg/kg), and propolis group (100 mg/kg). All treatment were administered an hour prior to the injection of the phlogistic agent. As observed at 3 h post-injection, λ-carrageenan remarkably evoked the classical signs of hind paw edema exemplified grossly by swelling and hyperemia. The ameliorative effect of propolis became apparent at the onset of 6 h post-injection with a statistically significant finding evident at the 24-h period. This gross attenuation histologically correlated to a considerable and specific reduction of the dermal edema, which mirrored those of the diclofenac sodium group. Furthermore, both propolis and diclofenac sodium significantly attenuated the λ-carrageenan-induced increase in the protein expression levels of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) depicting more than two-fold decrement relative to the distilled water group. Altogether, these suggest that Philippine stingless bee propolis also exhibited a promising in vivo anti-inflammatory property, which can be partly mediated through the inhibition of TNF-α.