Purification and characterization of a novel antifungal protein with antiproliferation and anti-HIV-1 reverse transcriptase activities from Peganum harmala seeds

A novel antifungal protein, designated as PHP, was isolated from the seeds of Peganum harmala, by cationic exchange chromatography on Resource S column and gel filtration on Sephadex 75 10/300 GL column. PHP was found to form a homodimer of about 16 kDa. Isoelectric focusing polyacrylamide gel electrophoresis analysis showed that the isoelectric point of PHP was approximate to 8.4. The N-terminal 20-amino acid sequence of PHP, ITCPQVTQSLAPCVPYLISG, resembles the non-specific lipid transfer proteins in certain plants. PHP exhibited lipid-binding activity. Furthermore, PHP exerted antifungal activity against Alternaria alternate, Penicillium degitatum, Rhizopus stuolonifer, and Magnaporthe grisea, and its antifungal activity was stable in the temperature range 460C, and in the pH range 410. It inhibited the mycelial growth in A. alternate, P. degitatum, R. stuolonifer, and M. grisea with 50 inhibitory concentration (IC50) of 1.5, 37.5, 8.44, and 12.19 M, respectively. PHP was also able to inhibit the proliferation of esophagus carcinoma (Eca-109), cervical carcinoma (HeLa), gastric carcinoma (MGC-7), and melanoma (B16) cells with IC50 of 0.7, 2.74, 3.13, and 1.47 M, respectively. Moreover, PHP significantly inhibited HIV-1 reverse transcriptase (RT) with an IC50 of 1.26 M. It did not have hemagglutinating and antibacterial activities. In conclusion, a novel antifungal protein with antiproliferation and anti-HIV-1 RT activities was obtained from P. harmala seeds.