Cytotoxic peptide obtained by enzymatic hydrolysis from Ditaxis heterantha seeds

Ditaxis heterantha is a plant from Euphorbiacea originally from semiarid zones in Mexico. Its seeds are composed of 20% of protein. The protein was fractionated by solubility in albumins globulins and glutelins. Antitumoral activity was evaluated for each fraction in mice BALB/c administrated by oral via, where glutelins fraction showed antitumoral activity against lymphoma L5178Y of 59%. Glutelins fraction was hydrolyzate using gastrointestinal proteases sequentially obtaining a hydrolyzate. This hydrolyzate was separated and purified by FPLC and to each purified peptide fraction was evaluated by cytotoxic activity against lymphoma L5178Y cells in vitro. A peptide was selected with a molecular weight of approximately 6.5 kDa and pI close to 4. This peptide showed cytotoxic activity of 54±7% in Annexin V (+) cells at 0.04µg/mL on lymphoma L5178Y in control of healthy untreated splenocyte cells obtained 29±0.0%. For the propidium iodide (IP) test the murine lymphoma at 0.04µg/mL was obtained 72±1% of IP (+) and for healthy untreated cells it showed 25±0.0% cyclophosphamide positive control at 10µg/mL was used. The cytotoxic activity of this peptide can be attributed to an alteration on cell cycle in lymphoma L5178Y cells. An N-terminal assay showed that the amino acids analysis of peptides shared similarity with the chain E sequence of the trypsin-binding domain of Bowman-Birk type protease inhibitor and its interaction with trypsin.