Name: Baldorj Pagmadulam
Affiliation: Research Unit for Innovative medicine, NRCPD
Position: Foreign Visiting Researcher
Term: June 2022 – October 2022
Host researcher: Prof. Yoshifumi Nishikawa (English /Japanese)
Circumstances of application:
I received my Ph.D. degree in NRCPD from the Obihiro University of Agriculture and Veterinary medicine. My doctoral research focused on antiprotozoal compounds producing actinobacterial strains from Mongolian natural resources (soil bacteria). Currently, drug screening and development against various infections from natural resources and chemical synthesis of natural products are challenging in the world. I wanted to continue my research on drug screening from natural resources at NRCPD. Thus, I applied for this position to pursue my research at the NRCPD which would give me the opportunity to finish my study.
Research activity in NRCPD:
The objective of the current study was to purify and identify anti-protozoan compounds from actinobacteria (Streptomyces sp.) which were isolated from Mongolian soils. The crude extracts were extracted from actinobacteria (Streptomyces sp.) by using solvents (ethyl acetate) and evaluated their antibacterial activities (E. coli and Bacillus cereus). Based on antibacterial activities, 26 crude extracts were selected and evaluated against Toxoplasma gondii (RH-GFP) and Plasmodium falciparum (3D7 and K1) growth in vitro. The in vitro inhibitory effect of 9 crude extracts was >90% on P. falciparum growth and 7 crude extracts inhibited T. gondii growth by >100%. The ethyl acetate 4 crude extracts (D1, D10, D12, D14) were selected for this study due to their low cytotoxicity and potential anti-protozoan activities. Crude extract D1 and D10 had significant anti-protozoan activities against P. falciparum 3D7 (chloroquine-sensitive strain) with IC50: 137.1 ng/ml (SI:>781) and IC50: 21.9 ng/ml (SI:>205.4). Also, crude extract D12 and D14 inhibited P. falciparum 3D7 growth with IC50: 50.6 ng/ml (SI:47) andIC50: 6.8 µg/ml, respectively. The crude extract D1 and D10 inhibited P. falciparum K1 (multidrug-resistant strain) growth IC50: 144.1 ng/ml and IC50: 93.8 ng/ml. Moreover, the crude extract D12 and d14 inhibited P. falciparum K1 growth with IC50: 523.4 ng/ml and IC50:19.2µg/ml, respectively.
The crude extract D1, D10, and D12 inhibited T. gondii growth with IC50: 4.8 µg/ml, IC50: 0.5 µg/ml, and IC50: 16.06 µg/ml. The phylogenetic analysis of crude extracts (D1, D10, D12, D14) based on 16S rRNA gene sequencing revealed that had the highest similarity with Streptomyces badius (D1), Streptomyces bacillaris (D12), streptomyces sp. (D10) and Streptomyces sp. (D14). The purification of bioactive fractions from ethyl acetate 4 crude extracts has been done by thin-layer chromatography (TLC) and column chromatography. The 14 samples (C1-C14) were purified by column chromatography and thin layer chromatography from crude extract D1, D10, D12, and D14. Among 14 samples, 5 samples were inhibited by T. gondii growth >50%, and 3 samples were inhibited by > 40%. The purified samples C11 and C2 were most active against P. falciparum 3D7 growth with IC50: 2.1 ng/ml and IC50: 219 ng/ml, respectively. The 10 purified samples inhibited P. falciparum 3D7 growth ranging from 0.4 µg/ml to 50.4 µg/ml. Further, the purified 14 candidate compounds will be subjected to Nuclear Magnetic resonance spectroscopy analysis (MNR) to identify compounds.
Future prospects:
I would like to express my sincere thanks to my supervisor Prof. Yoshifumi Nishikawa for his valuable support and could give me a chance to finish my research. Also, I wish to thank all the professors and members of NRCPD, especially Dr. Nanang Rudianto Ariefta. This foreign visiting research position at NRCPD allowed me to continue more deeply investigating my research field by using advanced research techniques. Having knowledge and results in parasitology and toxicology will be beneficial for my future research work and also give me a chance to make an international network with foreign researchers.