Hot water extract of chlorella (WEC) increased the lifespan of superoxide dismutase (SOD1)mutant adults of Drosophila melanogaster in a dose dependent manner (200–800 µg/mL). Compounds in WEC were successively fractionated by solid phase extraction using a Sep-Pak C18 cartridge and size exclusion chromatography (SEC). Amino compounds in SEC fractions were derivatized with 6-aminoquinolyl-N-hydroxylsuccinimidyl carbamate and analyzed by reversed phased-liquid chromatography-tandem mass spectrometry. Phenylalanine, phenethylamine, isopentylamine, and 2-methylbutylamine were identified in the SEC fraction, which increased the lifespan of the D. melanogaster mutant adults. Phenethylamine, at very low doses (6–60 ng/g of diet) that roughly corresponded to those of phenethylamine in WEC (200–800 μg/mL), increased the lifespan of the D. melanogaster adults, while isopentylamine did not exert the lifespan elongation activity. Since phenethylamine did not show SOD-like activity, it did not increase lifespan by direct antioxidant activity.

Bioactive peptides in the body after ingestion of plant protein hydrolysates have been speculated but not identified. We aimed to establish an approach to identify small amounts of food-derived peptides in humans after ingestion of non-extracellular matrix protein hydrolysates. Corn and wheat gluten hydrolysates were digested using pancreatin and leucine aminopeptidase; the resultant peptides were identified via size-exclusion chromatography and reverse-phase HPLC-tandem mass spectrometry (MS/MS). Structures of indigestible peptides were confirmed via LC-MS/MS in multi-reaction monitoring mode. All indigestible peptides in the exopeptidase digest were diprolyl and di- and tripyroglutamyl peptides. Blood collected from healthy volunteers (n = 4) before and after ingestion of 9 g of the hydrolysates was assessed for the indigestible peptides via LC-MS/MS. Six peptides (Pro-Ala, Pro-Gly, Pro-Gln, pyroGlu-Pro, pyroGlu-Leu-Pro, and pyroGlu-Gln-Pro) significantly increased in human plasma up to 10–100 nM compared to the baseline. This may hence be a powerful tool for identifying food-derived peptides in blood.