Powerful Plants: Antioxidant Capacity of Selected Plants
Christine Curiac, Jason Alvarodiaz, Langeda Bontemps, Luis Castellar, Jennifer Cerda, Ana Figuereo, Chelsea Trost, and Luis C. Fernandez-Torres
School of Science, Technology, and Engineering Management, St. Thomas University, Miami Gardens, FL 33054
Different cultures from around the world have used plants from their natural surroundings to treat different ailments. The action mechanisms of these natural remedies are diverse, yet many studies suggest their antioxidant properties bring about their effectiveness. This project presents the determination of the antioxidant capacity of selected plants, and comparing those results to a Trolox standard. The Briggs-Rauscher (BR) oscillating reaction was used to determine the antioxidant capacity of the samples. The antioxidant species scavenge free radicals formed in the BR reaction, lengthening the time intervals of the reaction’s oscillations; the higher the antioxidant capacity, the longer the oscillation delays. The samples consisted of aqueous and ethanolic extracts from the leaves of Annona muricata, Moringa oleifera, Petiveria alliacea, Hamelia patens, and Gynura bicolor. To analyze the results we used the Relative Antioxidant Performance (RAP), where the slopes of the samples were compared to the Trolox standard. Since most of these leaves are traditionally used in teas, we hypothesized that the aqueous extracts would exhibit the highest antioxidant capacity. Except for the aqueous extracts of Moringa oleifera and Petiveria alliacea, our hypothesis was proven correct, with Hamelia patens showing the highest RAP. These results were attributed to the solubility in water of the active antioxidant molecules versus their solubility in ethanol. These observations suggest that antioxidant properties are present, and could be a plausible pathway to their therapeutic properties. Furthermore, these extracts are complex mixtures of natural ingredients; therefore, we should not dismiss any potential synergistic effects between different ingredients.