Advances in the Propolis Chemical Composition between 2013 and 2018: A Review

Propolis or sometimes called “bee glue” is a lipophilic, adhesive, gummy, and resinous substance collected by different species of bees, including honeybees (e.g. Apis mellifera L.) and stingless bees (e.g. Tetragonisca angustula Illiger). Bees use it to seal holes in their hives, smooth out the internal walls, and protect the entrance against intruders. It also acts as a natural antibiotic to prevent bacterial, viral, or fungal infections within the hive [1–4]. Bees collect the resin from the cracks in the bark and leaf buds of different trees, including different species of poplars, conifers (e.g. pines and cypress), birches, alders, willows, palms, chestnuts, and even trees like eucalyptus, acacia, Clusia spp., and Baccharis dracunculifolia DC. Bees add salivary enzymes to the collected resin, mix it with beeswax and use this partially digested material in their hives [5–9].