Ixorapeptide I and ixorapeptide II, bioactive peptides isolated from Ixora coccinea

Two novel derivatized peptides, designated as ixorapeptide I (1) and ixorapeptide II (2), in addition to 28 other known compounds, were isolated from the MeOH extract of Ixora coccinea using bioassay-guided fractionation. The structures of metabolites 1 and 2 were determined by interpretation of the spectroscopic data and Marfey’s method. Compound 1 exhibited selective potency against Hep3B liver cancer cell line with an IC50 value of 3.36 μg/mL, and compound 2 did not show notable cytotoxicity toward cancer cell lines but could inhibit superoxide anion generation and elastase release with IC50 values of 0.21 and 0.27 μg/mL, respectively. Moreover, kaempferol and luteolin from this plant showed inhibition with IC50 values of 3.55 and 2.56 μg/mL, respectively on platelet aggregation induced by collagen.

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