Effect of Australian Propolis from Stingless Bees (Tetragonula carbonaria)

Discussion in 'Bee News' started by Americasbeekeeper, Nov 20, 2013.

  1. Americasbeekeeper

    Americasbeekeeper New Member

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    Effect of Australian Propolis from Stingless Bees (Tetragonula carbonaria) on Pre-Contracted Human and Porcine Isolated Arteries
    Bee propolis is a mixture of plant resins and bee secretions. While bioactivity of honeybee propolis has been reported previously, information is limited on propolis from Australian stingless bees (Tetragonula carbonaria). The aim of this study was to investigate possible vasomodulatory effects of propolis in KCl-precontracted porcine coronary arteries using an ex vivo tissue bath assay. Polar extracts of propolis produced a dose-dependent relaxant response (EC[SUB]50[/SUB]=44.7±7.0 μg/ml), which was unaffected by endothelial denudation, suggesting a direct effect on smooth muscle. Propolis markedly attenuated a contractile response to Ca[SUP]2+[/SUP] in vessels that were depolarised with 60 mM KCl, in Ca[SUP]2+[/SUP]-free Krebs solution. Propolis (160 µg/ml) reduced vascular tone in KCl pre-contracted vessels to near-baseline levels over 90 min, and this effect was partially reversible with 6h washout. Some loss in membrane integrity, but no loss in mitochondrial function was detected after 90 min exposure of human cultured umbilical vein endothelial cells to 160 µg/ml propolis. We conclude that Australian stingless bee (T. carbonaria) propolis relaxes porcine coronary artery in an endothelial-independent manner that involves inhibition of voltage-gated Ca[SUP]2+[/SUP] channels. This effect is partially and slowly reversible upon washout. Further studies are required to determine the therapeutic potential of Australian stingless bee propolis for conditions in which vascular supply is compromised.
    http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081297
     
  2. efmesch

    efmesch Active Member

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    This aspect of the discussion is worthy of mention: (emphasis by enlarged bold script was my addition)
    The potency of stingless bee propolis preparations was not significantly different to that determined for an ethanolic tincture of New Zealand honeybee propolis in porcine coronary artery (IC50, 87.3 µg/ml; this study). Interestingly, the potency of New Zealand propolis determined in our study was lower than that determined for an ethanolic extract of Brazilian green propolis (IC50,15.0 µg/ml) and a flavonoid-rich sub-fraction of that ethanolic extract (IC50, 4.4 µg/ml) in spontaneously hypertensive rat aorta [10]. Differences may be related to the chemical composition of each sample of propolis (botanical origin), species of animal (pig, rat) and/or tissue type (coronary artery, aorta).

    As I understand it, the differences are probably greater because of the plant source of the propolis than the bee species producing it.
     

  3. ApisBees

    ApisBees Active Member

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    I would also expect that you would find a difference also from propolis collected by the bees at different times of the year even if they were from the same source. The energy and resources sent up the tree in early spring to support vigorous vegetation growth and leaf verses in the fall when the tree are going dormant for winter.