Metabolite extract of Streptomyces hygroscopicus Hygroscopicus inhibit the growth of Plasmodium berghei through inhibition of ubiquitin - proteasome system.

Streptomyces hygroscopicus Hygroscopicus, a member of family of Actinomycetes produces eponemycin a proteasome inhibitor that can inhibit Ubiquitin-Proteasome System (UPS) function in eukaryotic cell. Previous study showed that coronamycin, an active substrate isolated from Streptomyces sp. can act as anti-plasmodial, antibacterial, and antifungal, however the research did not show the mechanism of coronamycin in inhibiting the growth of Plasmodium. This research was done to reveal if eponemycin that is contained in metabolite extract of S. hygroscopicus can inhibit UPS function of Plasmodium berghei. This study was an experimental study using P. berghei infected Balb/C mice as malaria model. Samples were divided into 1 control group (group infected with P. berghei without treatment) and 3 treatment groups (mice infected with P. berghei and treated intra-peritoneal with metabolite extract of S. hygroscopicus dose 130 μg/kgBW, 580 μg/kgBW, and 2600 μg/kgBW for 5 days). The degree of parasitemia and morphology of the parasite were measured from the first day of malaria induction until the last treatment. The accumulation level of polyubiquitin was measured using Western blot and ELISA method. The degree of parasitemia on day 6 showed significant differences among treatment groups and control (p=0,000). Percentage of inhibition showed significant differences between control and group treated with metabolite extract of S. hygroscopicus 2600 μg/kgBW. An increasing dose of extract of S. hygroscopicus followed by an increasing of inhibition in parasite growth (r=0,850). Probit analysis showed that ED50 was 9.418 μg/kgBW. There was a change in morphology of the parasite after treatment. Parasite morphology became crisis form. There was an accumulation of polyubiquitinated protein in the group treated with metabolite extract of S. hygroscopicus 2600 μg/kgBW. It can be concluded that analog eponemycin in metabolite of S. hygroscopicus is a potential candidate for new malarial drug by inhibiting UPS function of the parasite and cause stress and dead of the parasite.