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IRIDOID GLYCOSIDES
Aucubin and Catalpol are both iridoid glycosides (containing glucose as the sugar: Glc) found in many plants belonging to the Plantain Family. Aucubin is detailed elsewhere under both Spotted Laurel (Aucuba japonica from which it gets its name) and Woodruff, for it also occurs widely in the Bedstraw Family. The Catalpol is present at a concentration of 0.16% with Aucubin a little lower at 0.11%. Of all the UK Plantains, Catalpol is only absent in Buck's-horn Plantain. Catalpol is also present in plants belonging to the Figwort, Buddleja and Dead-Nettle Families. In animals it stimulates the adrenal glands, and also seems to inhibit oxidative damage to the brain, and in particular neuron apoptosis, caused by hydrogen peroxide produced under certain circumstances within the body, particularly within the mitochodria. Catalpol may be a useful pharmaceutical in the treatment of Parkinsons disease. The major difference between Aucubin and Catalpol is the epoxy group on the cyclopentane ring which presumably opens up in the presence of hydrogen peroxide and snatches one of the oxygen atoms from it, neutralising it.
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