oa The nutritional quality of grape leaves: Comparative study between leaves collected from arid and temperate regions in Palestine.

Grape leaves are widely consumed in Palestine, and many Mediterranean countries. This food item is considered as a delicacy in many cultures, and most consumers consider it as also a healthy food. Accordingly, we started two years ago a study to assess the nutritional quality of leaves collected from two grape varieties, namely Shami and Baituni, which were collected from two regions, namely Dahria (considered as an arid region) and Beit Umar (considered as temperate region). Leaves were collected during spring time in three replicates and directly grinded to powder in liquid nitrogen. To assess the nutritional quality, leaf extract were tested as anticancer agent, and tested further for the total antioxidants potential. Moreover, leaf extracts were subjected to detailed analysis for active compounds using GC-MS and LC-MS. Results show that leaves from Shami grapes clearly inhibited the proliferation of lung cancer cells. Concerning the influence of cultivation area, Shami leaves from the temperate region (Beit Umar) proved to be more effective that those collected from Dahria (the arid region). In addition, leaves from Baituni grapes proved to be ineffective against lung cancer. In contrast, the GC-MS analyses of primary metabolites show that leaves of both grape varieties, which were collected from the arid region, contain higher levels of a large set of compounds including alanine, valine, isoleucine, proline, serine, threonine, uracil, sorbose, malitol, quercetin, and maltotriose. This dramatic increase in these compounds may be attributed to osmotic adjustment of plants to cope with drought stress prevailed in that region compared to the temperate region. The analyses for secondary metabolites and total antioxidants potential are closed and will be represented, in connection with changes in primary metabolites and anticancer activity of grape leave extracts. In conclusion, results clearly show that consumption of grape leaves is very healthy, and its consumption may contribute to Mediterranean diet by preventing the occurrence of severe diseases. Moreover, detailed analyses using GC-MS, and LC-MS may reveal the active compounds behind the health-promoting impact of grape leaves. Further purification of these compounds may allow for future usage of leaf extract of Shami grapes as natural pharmaceuticals.