3 Results 3.1 Quantification of AMPs LR14 The AMPs LR14 are a mixture of four peptides, and all the peptides have molecular masses <1 kDa. These peptides show considerable antimicrobial activity
against the indicator strain, M. luteus. The antimicrobial activity and protein concentration of the four INK1197 concentration peptides are as follows: peptide 1—12,500 AU/mL (500 μg/mL); peptide 2—25,000 AU/mL (450 μg/mL); peptide 3—25,000 AU/mL (700 μg/mL); and peptide 4—12,500 AU/mL (700 μg/mL). These peptides are different from other bacteriocins known in the database as well as plantaricin LR14-α and -β. Moreover, the retention time of any of these peptides (AMPs LR14) did not match with plantaricins LR14-α and -β, as confirmed by the high-performance liquid chromatography (HPLC) chromatogram . These peptides have been characterized
in terms of their heat and pH stability. They are tolerant to extremes of temperature ranging from boiling to freezing at −20 °C. They A-1155463 purchase are able to retain their activity in a wide range of pH values (pH 2–10), and are susceptible to proteolytic cleavage, which confirms their proteinaceous nature. 3.2 Evaluation of Anti-Plasmodial Activity of AMPs LR14 P. falciparum takes up Selleck Sepantronium hypoxanthine as part of its purine salvage pathway and its incorporation is a measure of growth and viability of the parasite. Thus, the viability of the parasite can be monitored by the extent of incorporation of [3H] hypoxanthine. As described in Sect. 2, the infected erythrocytes incubated Farnesyltransferase with different concentrations of AMPs LR14 along with [3H] hypoxanthine showed a dose-dependent decline in the radioactive counts, reflecting the effect on the viability of the parasite. Different concentrations of AMPs LR14 ranging from 0.6 to 42 μg/mL showed inhibition in the range of 1–99 % in comparison with an untreated control (considered as 100 % viable). From
the results obtained, IC50 was achieved in the chloroquine-sensitive strain (3D7) at 1.6 μg/mL and the chloroquine-resistant strain (RKL19) at 2.85 μg/mL of AMPs LR14. In comparison, the IC50 level of chloroquine (positive control) was 17.6 ng/mL for the chloroquine-sensitive strain (3D7) and 100 ng/mL for the chloroquine-resistant strain (RKL19). No hypoxanthine uptake could be detected beyond the maximum tested dose of 42 μg/mL, where 99 % inhibition was observed. Figure 1 depicts the percentage cell viability at different concentrations of AMPs LR14 used, in comparison to the control. Fig. 1 Effect of antimicrobial peptides (AMPs LR14) on the growth of Plasmodium falciparum: P. falciparum-infected erythrocytes (2 % final hematocrit and 1 % parasitemia) were incubated for 24 h at 37 °C in the presence of different dosages of AMPs LR14. The concentration of drug producing 50 % inhibition was assessed by measuring the [3H] incorporation into nucleic acid of P. falciparum cells. Experiments were performed with two strains of P.