[en] In recent years, there has been an increasing interest in consumption of red fruits and vegetables due to its rich dietary sources of antioxidant, phenolics and anthocyanins. In this study, phytochemical and antioxidant properties of green and red lettuce cultivars were studied. Particularly, the effect of leaf position on these properties was compared. Eight conventionally grown cultivars of lettuce (Lactuca sativa L.), with four green (Fonseca, Freckles, Krizet and Filipus) and four red (Versai, Nation, Paradai and Cherokee) cultivars were studied. Their leaves were divided into three groups; outer, middle and inner part. Total antioxidant capacity (TAC) of each group of leaves was assessed by both trolox-equivalent antioxidant capacity (TEAC), and the ferric reducing antioxidant power (FRAP) assay. Leaf color, total soluble solids, total phenolics (TP), total anthocyanin (TACY), chlorophyll a and b were determined. The results demonstrated that outer leaves have the highest phytonutrient content and antioxidant properties. Outer leaves exhibited significantly higher TP and TAC than middle and inner leaves in both red and green color lettuce. The average TP content of red lettuce were 845, 297 and 195 μg gallic acid equivalent per gram fresh weight in the outer, middle and inner leaves, respectively. Also TAC of outer leaves was significantly higher than middle and inner leaves in both red and green color lettuce. The magnitude of difference between red and green cultivars was significant as determined by both TEAC and FRAP methods.

[es] En los &uacute;ltimos a&ntilde;os ha habido un inter&eacute;s creciente por consumir frutas y verduras de color rojo, por ser una fuente rica de antioxidantes, polifenoles y antocianinas. En este trabajo se estudiaron las propiedades fitoqu&iacute;micas y antioxidantes de cultivares de lechuga verdes y rojos, comparando, en particular, el efecto de la posici&oacute;n de la hoja sobre estas propiedades. Se estudiaron ocho cultivares convencionales de lechuga (Lactuca sativa L.), cuatro verdes (Fonseca, Freckles, Krizet y Filipus) y cuatro rojos (Versai, Nation, Paradai y Cherokee), dividiendo sus hojas en tres grupos: externas, medias e internas. Se evalu&oacute; la capacidad antioxidante total (TAC) de cada grupo de hojas, tanto la capacidad antioxidante equivalente de Trolox (TEAC), como el ensayo de potencia antioxidante reductora f&eacute;rrica (FRAP). Tambi&eacute;n se determin&oacute; el color, los s&oacute;lidos solubles totales, fenoles totales (TP), el total de antocianinas (TACY), y las clorofilas a y b de las hojas. Los resultados mostraron que las hojas externas ten&iacute;an un mayor contenido de fitonutrientes y antioxidantes, as&iacute; como TP y TAC significativamente mayores que las hojas medias e internas, tanto en lechugas rojas como verdes. El contenido promedio de TP en las lechugas rojas fue 845, 297 y 195 195 &mu;g de equivalentes de &aacute;cido g&aacute;lico por gramo de peso fresco en las hojas exteriores, medias e internas, respectivamente. Tambi&eacute;n el TAC de las hojas externas fue, en ambos tipos de lechuga, significativamente mayor que el de las hojas medias e internas. La diferencia entre los cultivares rojos y verdes fue significativa tanto con los m&eacute;todos TEAC como FRAP.