Excessive iron accumulation can lead to liver damage in captive black rhinoceros (Diceros bicornis), thus dietary iron absorption must be regulated. A potential method of controlling iron absorption is to use foods that contain compounds that chelate metals. Carolina willow (Salix caroliniana) contains phenolic glycosides and condensed tannins, both of which chelate metals. Thus, we analyzed leaf samples for these compounds and measured iron binding of the leaf extracts. Quantities of a phenolic glycosides, salicin, was determined via HPLC, and EPI-MS was used to verify the peak identities. Fifty four samples of plant material were analyzed and the amounts of salicin ranged from 0.6 to 6.4ppt. There was a general inverse correlation between quantity of tannins and amounts of salicin. Earlier analyses showed that S. caroliniana leaves have tannins (up to 30%wt/wt) that could potentially chelate iron. However, the iron binding assays showed excess iron was delivered to the solution by the plant extracts.

What to feed the rhinoceros: Quantification of iron binding by Carolina willow leaf extracts

247th National Meeting (2014)

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