Evaluation of multifunctional activity of bioactive peptide fractions from the leaves of Nauclea diderrichii (De Wild. and T. Durand) Merrill and Ixora brachypoda DC

Abstract

Bioactive peptides are known for health-promoting properties due to several pharmacological effects they modulate in physiological systems. Herein, the presence of peptides particularly cyclic peptides, was investigated in two Rubiaceae members; Nauclea diderichii (De Wild. and T. Durand) Merrill and Ixora brachypoda DC by thin layer chromatography (TLC) chemical detection, and their multifunctional bioactivity evaluated. Crude and pre-purified peptides were obtained from both plants using aqueous and solid-phase extractions, respectively. The peptide fraction of N. diderrichii showed good DPPH scavenging activity (IC50 = 3.43 μg/mL) compared to the standard Gallic acid (IC50 = 1.44 μg/mL). Peptide fractions of both plants displayed inhibitory effects (MIC = 6.25 μg/mL) against bacteria and fungi strains except Escherichia coli, relative to standard drugs (MIC = 0.31 μg/mL). Both displayed significant toxicity to brine shrimp nauplii (LC50≤ 220.8 μgmL-1) as well as MCF-7 and RD cancer cells (IC50 ≤ 34.0 μgmL-1). The enterovirus species B and C tested were remarkably susceptible to the peptide fractions (IC50 ≤ 3.20 μg/mL).