Emerging Adjuvant Therapy for Cancer: Propolis and its Constituents

Propolis is a bee-metabolized resinous substance (bee glue) from plant sap and gums. It has been in usage as a healing agent since antiquity, yet has not garnered global popularity as a health promoter. Its biological effects, which range from antimicrobial, antioxidant, anti-inflammatory, antidiabetic, dermatoprotective, anti-allergic, laxative and immunomodulatory to anticancer, have been validated. Propolis has shown efficacy against brain, head and neck, skin, breast, liver, pancreas, kidney, bladder, prostate, colon and blood cancers. The inhibition of matrix metalloproteinases, anti-angiogenesis, prevention of metastasis, cell-cycle arrest, induction of apoptosis and moderation of the chemotherapy-induced deleterious side effects have been deduced as the key mechanisms of cancer manipulation. The components conferring antitumor potentials have been identified as caffeic acid phenethyl ester, chrysin, artepillin C, nemorosone, galangin, cardanol, etc. These compounds target various genetic and biochemical pathways of cancer progression. Depending on the botanical sources and the geographical origin, biological activities of propolis vary. Despite phenomenal development in cancer research, conventional therapy falls short in complete malignancy management. The findings obtained so far build hope that propolis as a complementary medicine may address the lacunae. This review documents the recent advances and scope of amendement in cancer remediation with adequate emphasis on the mechanistic aspect of propolis.