Total Reactive Antioxidant Potential (TRAP) and Total Antioxidant Reactivity (TAR) of Medicinal Plants Used in Southwest Amazonia (Bolivia and Peru)

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Abstract
The charge (relative concentration) of antioxidants in different extracts of medicinal plants used in southwest Amazonia regions of Beni (Bolivia) and Madre de Dios (Peru) was determined employing a procedure based on the quenching of luminol-enhanced chemiluminescence derived from the thermolysis of 2,2'-azo- bis (2-amidinopropane) (ABAP) as the free radical source. Total reactive antioxidant potential (TRAP) and total antioxidant reactivity (TAR) values were determined (in Trolox equivalents) using this method, and 65 extracts showed antioxidant activity. Of these, 46 demonstrated TRAP values > 100 µM. The highest activity was noted in a methanol bark extract of Copaifera reticulata (TRAP = 7500 µM). On the other hand, the highest TAR value was obtained in the methanol root extract of Dracontium loretense. IC 50 and eficiency (compared to Trolox) values were also calculated. The results obtained indicate that the large antioxidant capacity of some medicinal plants may be due to the presence of both very reactive and low reactive antioxidants, the later in rather high concentrations, and that the therapeutic action claimed for some of these plants could be due, in part, to their capacity for scavenging oxygen free radicals which are involved in many diseases. The use of luminol-enhanced chemiluminescence proved to be a simple, sensitive and reproducible method that can be used to determine the antioxidant capacity in complex mixtures such as plant extracts.