A Study of the Biological Activity of Bee Venom and its Fractions With Regard to Cosmetic Science and Immunology

Abstract

Apis mellifera venom has been used since antiquity to treat various ailments but sci-entific evidence to justify its therapeutic claims is incomplete. The venom has recent-ly entered cosmetic usage as a mimetic ingredient to alleviate signs of facial aging. This study investigated the potential of bee venom (BV) as a source of cosmetic and immunomodulatory agents for use in skin anti-ageing applications and as a vaccine adjuvant, respectively. BV fractions were obtained by reversed phase preparative chromatography and characterised by LC-MS and NMR techniques. The fractions were assayed for antimicrobial and cytotoxic activities against a range of microbes (Mycobacterium marinum, Norcardia farcinia and Trypanosoma brucei brucei) and human cell lines [NCTC2544 (normal keratinocytes), PNT2A (normal epithelial cells), and HS27 (normal fibroblasts)] respectively. Immunomodulatory effects were investigated in PMA-differentiated U937 cells with and without LPS co-stimulation. The aqueous stability of the venom and its susceptibility to protease action were as-sessed by LC-MS assays. An LC-MS method was also developed and validated for the assay of BV in commercial creams using the melittin signal as an indicator of BV content. Of the 4 BV fractions (F-1 to F-4), the largest, containing melittin, showed the most activity against N. farcinia (25-50μg/mL) and T. b. brucei (0.78-1.56μg/mL), but was not very active against M. marinum (>100μg/mL). The melittin fraction (96% pure) was the most cytotoxic against keratinocytes, fibroblasts and epi-thelial cells, with IC50 ≥ 2.5-4.0μg/mL. All fractions significantly enhanced IL-1β release, while only F-4, a lipophilic fraction, enhanced TNF-α release. F-4, which was revealed through NMR elucidation to contain (Z)-9-eicosen-1-ol, produced sig-nificant inhibition of IL-6 release. Melittin in aqueous solutions of BV, but not of the melittin fraction alone, underwent a temperature-dependent spontaneous degradation within the 21Lys-22Arg-23Lys-24Arg sequence due to a serine carboxypeptidase-like activity attributed to the BV allergen, Api m9. Taken together, these results suggest that a formulation matching the 3.2–37.2ppm content of melittin assayed in commer-cial creams would be safe for skin application based on IC50 values in human cells. The immunomodulatory effects observed in U937 cells highlight the potential of BV as a possible source of vaccine adjuvants.