Food-inspired peptides from spinach Rubisco endowed with antioxidant, antinociceptive and anti-inflammatory properties

Rubiscolin-6 (amino acid sequence: YPLDLF) is a selective δ-opioid receptor peptide isolated from spinach Rubisco. Its synthetic analogue, peptide YPMDIV is the most potent described so far for its increased opioid activity, thus in this work it was considered as lead compound for the design of twelve new analogues e.g. LMAS1-12. Firstly all the novel compounds have been tested for their antinociceptive and anti-inflammatory capacity in vitro and in vivo in order to evaluate their ability to maintain or loss the original activity. Among them peptides LMAS5-8 gave the best results, thus their antioxidant properties have been investigated along with their enzymatic inhibitory ability. Peptide LMAS6 shows a strong antioxidant (154.25 mg TE/g CUPRAC) and inhibitor activity on tyrosinase (84.49 mg KAE/g), indicating a potential role in food industry as anti-browning agent, while peptides LMAS5 and LMAS7 possess a modest cholinesterase inhibitory activity suggesting a conceivable use for nutraceuticals production.