Antioxidant Activity, Inhibition of Nitric Oxide Overproduction, and In Vitro Antiproliferative Effect of Maple Sap and Syrup from Acer saccharum

Abstract Antioxidant activity, inhibition of nitric oxide (NO) overproduction, and antiproliferative effect of ethyl acetate extracts of maple sap and syrup from 30 producers were evaluated in regard to the period of harvest in three different regions of Quebec, Canada. Oxygen radical absorbance capacity (ORAC) values of maple sap and syrup extracts are, respectively, 12 ± 6 and 15 ± 5 μmol of Trolox equivalents (TE)/mg. The antioxidant activity was also confirmed by a cell-based assay. The period of harvest has no statistically significant incidence on the antioxidant activity of both extracts. The antioxidant activity of pure maple syrup was also determined using the ORAC assay. Results indicate that the ORAC value of pure maple syrup (8 ± 2 μmol of TE/mL) is lower than the ORAC value of blueberry juice (24 ± 1 μmol of TE/mL) but comparable to the ORAC values of strawberry (10.7 ± 0.4 μmol of TE/mL) and orange (10.8 ± 0.5 μmol of TE/mL) juices. Maple sap and syrup extracts showed to significantly inhibi...