Bioactive compounds and leaf anatomy of yerba mate morphotypes

Abstract

The objective of this work was to evaluate the bioactive compounds and foliar anatomy of yerba mate (Ilex paraguariensis) morphotypes. The antioxidant capacity, total phenolic compounds, methylxanthines, and caffeoylquinic acids were determined from the aqueous extract of leaves of the following yerba mate morphotypes: “sassafras”, dark green, dull green, gray, and “peludinha”. Light microscopy and scanning electron microscopy were used to observe the anatomical differentiations. The dark-green morphotype showed the highest contents of caffeine (20.4 mg g^-1), differing significantly only from the “peludinha” morphotype (8.8 mg g^-1). All morphotypes showed similar and high antioxidant activity (886.0 and 588.1 μmol Trolox equivalent antioxidant activity per gram of sample for ABTS and DPPH, respectively), as well as high total phenolic compounds content (73.9 mg gallic acid equivalent  per gram of sample). Although the anatomy of the leaf mesophyll is similar, the wax deposition and cuticle striation configuration on the adaxial surface differ between all five morphotypes.