Leaves werewashedwithcleanwater,cutintosmallpieces
(approximately 1cm×1 cm),andplacedinafreezedryer(model
7754511, LabconcoCorporation,KansasCity,Missouri,USA)for
48 h.Thefreeze–driedsamplesweregroundtoapowderbyusinga
stainless-steel grinderandstoredinafreezeruntiltheywereused