This study aimed to evaluate the antioxidant properties of royal jelly (RJ) collected from larvae of different ages that were transferred in artificial bee queen cells for 24, 48, and 72 h. RJ harvested from the 1 day old larvae 24 h after the graft displayed predominant antioxidant properties, including scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, inhibition of linoleic acid peroxidation, and reducing power. Regardless of the initial larval age, lower antioxidant activities were observed in the RJ harvested later than 24 h except for the activity of superoxide dismutase. In addition, higher contents of proteins and polyphenolic compounds were determined in the RJ harvested 24 h than that harvested 48 or 72 h after the graft. It implied that the polyphenolic compounds may be the major component for giving the antioxidant activities in RJ. In summary, the time of harvest and the initial larval age did affect the antioxidant potencies in RJ, and RJ collected 24 h after the larval transfer showed the most substantial antioxidant activities.

BackgroundRoyal jelly (RJ), the exclusive food for the larva of queen honeybee, is regarded as the novel supplement to promote human health. The function of RJ may be attributed to its major and unique fatty acid, 10-hydroxy-2-decenoic acid (10-HDA). The current study investigated the anti-inflammory function of 10-HDA on human colon cancer cells, WiDr, as well as its effect on the growth of pathogenic bacterium.MethodsThe pro-inflammatory cytokines, receptor antagonist cytokine (IL-1ra) and nuclear factor-kappa B (NF-κB) in WiDr cells was analyzed by Enzyme-linked immunosorbent assay (ELISA) or western blot. The growth inhibition of 10-HDA on bacterium was evaluated by determination of minimal inhibitory concentrations (MIC) and minimal bactericide concentrations (MBC).ResultsThe production of pro-inflammatory cytokines, Interleukin (IL)-8, IL-1β and tumor necrosis factor-alpha (TNF-α) in WiDr cells was modulated by 10-HDA. IL-8 were dramatically declined by 10-HDA at 3 mM, while IL-1β and TNF-α were significantly decreased. 10-HDA increased IL-1ra in a dose manner. NF-κB pathway is primarily in response to prototypical pro-inflammatory cytokines, and NF-κB was reduced after 10-HDA treatment. 10-HDA acted as potent bactericide against animal- or human-specific pathogens, including Staphylococcus aureus, Streptococcus alactolyticus, Staphylococcus intermedius B, Staphylococcus xylosus, Salmonella cholearasuis, Vibro parahaemolyticus and Escherichia coli (hemolytic).ConclusionsThe current study showed that in vitro 10-HDA from RJ exhibited anti-inflammatory activity in WiDr cells, as well as anti-bacterial activity against animal pathogens. 10-HDA showed its potential as anti-imflammtory agent and bactericide to benefit human gastrointestinal tract.

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