Diversity of natural pigments and phytochemical compounds from exocarp and mesocarp of 27 Cucurbita pepo accessions

The accessions variability in crop species is crucial for crop improvement and consequently enables the development of more new valuable agricultural products. This study aimed to evaluate the ascorbic acid (AA), chlorophyll a (Chl-A), chlorophyll b (Chl-B), total phenolic compounds (TPC) as well as dry matter (DM) in different tissues (exocarp and mesocarp) of Cucurbita pepo fruits belonging to 27 morphologically diverse germplasm accessions (14 traditional accessions and 13 commercial hybrids from different countries). DM content ranged from 4.2 to 11.76%, while natural pigments were between 5.85 and 2602.2 mu g/g OW (corresponding to Chl-B and Chl-A, respectively). Other antioxidant compounds registered higher values, 0.47-1.29 mg/g DW for AA and 1.98-5.49 mg/g DW for TPC. Additionally, pattern-recognition techniques including distribution, principal component analysis (PCA) and dendogram cluster analysis were used to compare accessions. PCA revealed that the first two components represented 76% and 84% of the total variability in exocarp and mesocarp tissues, respectively; while clusters regrouped those accessions with greater similarity. Exocarp samples exhibited a significantly higher content in all compounds studied, thus positively suggesting the beneficial consumption of fruit peel. This work also highlights the potential contribution of 'zucchini' morphotype to dietary intake requirements, being moderate in 'vegetable marrow' and 'pumpkin'. Accessions rich in AA, Chl-A, Chl-B and TPC like those namely Ac-2, Ac-8, Ac-23 and Ac-27 could be exploited as potential donors for novel variety development in future breeding programmes. (C) 2015 Elsevier B.V. All rights reserved.