Stingless Bee Propolis in Pharmacology: Some Applied Cellular and Molecular Mechanisms

Medicinal properties of propolis across a broad spectrum of diseases are ancestral knowledge constantly evidenced while slow to reveal mechanisms of action. Stingless bee propolis used in this review originated from the following stingless bees: Brazil (Melipona fasciculata, Melipona quadrifasciata quadrifasciata, Scaptotrigona sp., Scaptotrigona aff. postica, Tetragonisca angustula), India (Tetragonula sp.), Indonesia (Wallacetrigona incisa), the Philippines (Tetragonula biroi), Thailand (Tetragonula laeviceps, Tetrigona apicalis, Tetrigona melanoleuca), Vietnam (Lisotrigona furva). Five pathologies were selected for this review: cancer, dental plaque, microbial infections, glycemic imbalance, and respiratory disorders. Veterinary uses and in silico approaches were included. Cellular and molecular mechanisms of action elicited by propolis (granules, EEP, and HEP) involved the following: antiproliferative action, adhesion capacity, apoptosis, cell cycle arrest at the G0/G1 phase, cytostatic and cytotoxic action, inflammatory enzymes, inhibition of COX-2, integrity of cell wall and membrane, mRNA gene expression, p21 protein expression, and pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). A note on the geographical origin of propolis and a further note on stingless bee identifications are included. Finally, pharmacological propolis applications need propolis standardization, verified mechanisms of action, and more clinical trials to validate experimental findings. They all create opportunities for new research.