Phytochemical screening, nutritional properties and biological activities of sweet and conventional potato planted in Morocco

This study aimed at studying phytochemical composition, nutritional properties and biological activities (antioxidant and anti-inflammatory) of two potato varieties (sweet potato (SP): Ipomoea batatas L. and conventional potato (CP): Solanum tuberosum L.) planted and consumed in Morocco. For this, potato samples (SP and CP) were firstly subjected to phytochemical and nutritional analysis, including water content, total and reducing sugars, proteins, lipids, vitamin C, carotenoids, phenolic compounds and flavonoids. Secondly, phenolic compounds extracts were subjected to biological activities namely antioxidant and invitro anti-inflammatory. Potato extracts antioxidant activity was tested by DPPH and total antioxidant capacity (TAC) methods. Proteins and lipids contents were found much higher in SP (5.21 ± 0.26 and 0.29 ± 0.02 g/100g DW) respectively than in CP (2.93 ± 0.15 and 0.11 ± 0.01 g/100g DW) respectively. Besides, total and reducing sugars contents were 16.65 and 2.53 g/100g DW in the CP, and 12.47 and 2.13 g/100g DW in the SP, respectively. The antioxidant activity of different SP extracts was found to be higher than those of CP, by using DPPH and TAC methods. These findings could be explained by SP richness in carotenoids (212 ± 10.60 mg/100g DW), phenolic compounds (130.11 ± 6.51 mg GAE/100g DW), flavonoids (85.03 ± 4.2 5mg QE/100g DW) and vitamin C (471.33 ± 23.57 mg/100g DW). Exclusion chromatography done by Sephadex G50 showed that polymeric phenolic compounds in SP were more abundant when compared to monomeric ones. This difference was consistent with the anti-inflammatory activity assessed in vitro.