Protective Effect of Hainosankyuto, a Traditional Japanese Medicine, on Streptococcus pyogenes Infection in Murine Model

BACKGROUND: Streptococcus pyogenes (S. pyogenes) causes various serious diseases including necrotizing fasciitis and streptococcal toxic shock syndrome. One serious problem observed recently with S. pyogenes therapy is attenuation of the antibiotic effect, especially penicillin treatment failure and macrolide resistance. Hainosankyuto, a traditional Japanese medicine based on ancient Chinese medicine, has been used for treatment of infectious purulent diseases in Japan. In this study, we investigated the protective and therapeutic efficacy of Hainosankyuto against S. pyogenes-skin infection. METHODOLOGY/PRINCIPAL FINDINGS: A broth microdilution method revealed that Hainosankyuto did not show a direct anti-bacterial effect against S. pyogenes. Force-feeding Hainosankyuto to infected mice for 4 consecutive days increased the survival rate and reduced the size of local skin lesions compared with mice fed PBS. Although we did not find the significant recovery of survival rate in Hainosankyuto administration only after S. pyogenes infection, the sizes of ulcer lesion were significant smaller after Hainosankyuto administration compared with mice fed PBS. No difference was observed in the anti-bacterial effect of Hainosankyuto between macrolide-susceptible and -resistant strains. Blood bactericidal assay showed that the survival rate of S. pyogenes using the blood from Hainosankyuto-treated mice was lower than that using the blood from untreated mice. We also found increased levels of IL-12, IFN-γ and a decreased level of TNF-α in the serum of S. pyogenes-infected mice treated with Hainosankyuto. Mouse peritoneal macrophage from Hainosankyuto-treated mice had significant phagocytic activity and increased mRNA levels of IL-12, IFN-γ and decreased mRNA level of TNF-α compared with control macrophage. CONCLUSIONS/SIGNIFICANCE: Hainosankyuto increased survival rate after S. pyogenes infection and up-regulated both blood bactericidal activity and macrophage phagocytic activity through modulation of inflammatory cytokines. Our data also suggest Hainosankyuto may be useful for the treatment of S. pyogenes infection more prophylactically than therapeutically

How can natural products serve as a viable source of lead compounds for the development of new/novel anti-malarials?

Malaria continues to be an enormous global health challenge, with millions of new infections and deaths reported annually. This is partly due to the development of resistance by the malaria parasite to the majority of established anti-malarial drugs, a situation that continues to hamper attempts at controlling the disease. This has spurred intensive drug discovery endeavours geared towards identifying novel, highly active anti-malarial drugs, and the identification of quality leads from natural sources would greatly augment these efforts. The current reality is that other than compounds that have their foundation in historic natural products, there are no other compounds in drug discovery as part of lead optimization projects and preclinical development or further that have originated from a natural product start-point in recent years. This paper briefly presents both classical as well as some more modern, but underutilized, approaches that have been applied outside the field of malaria, and which could be considered in enhancing the potential of natural products to provide or inspire the development of anti-malarial lead compounds

Do ethnobotanical and laboratory data predict clinical safety and efficacy of anti-malarial plants?

<p>Abstract</p> <p>Background</p> <p>Over 1200 plant species are reported in ethnobotanical studies for the treatment of malaria and fevers, so it is important to prioritize plants for further development of anti-malarials.</p> <p>Methods</p> <p>The “RITAM score” was designed to combine information from systematic literature searches of published ethnobotanical studies and laboratory pharmacological studies of efficacy and safety, in order to prioritize plants for further research. It was evaluated by correlating it with the results of clinical trials.</p> <p>Results and discussion</p> <p>The laboratory efficacy score correlated with clinical parasite clearance (r_s=0.7). The ethnobotanical component correlated weakly with clinical symptom clearance but not with parasite clearance. The safety component was difficult to validate as all plants entering clinical trials were generally considered safe, so there was no clinical data on toxic plants.</p> <p>Conclusion</p> <p>The RITAM score (especially the efficacy and safety components) can be used as part of the selection process for prioritising plants for further research as anti-malarial drug candidates. The validation in this study was limited by the very small number of available clinical studies, and the heterogeneity of patients included.</p

Resistance of a Rodent Malaria Parasite to a Thymidylate Synthase Inhibitor Induces an Apoptotic Parasite Death and Imposes a Huge Cost of Fitness

BACKGROUND: The greatest impediment to effective malaria control is drug resistance in Plasmodium falciparum, and thus understanding how resistance impacts on the parasite's fitness and pathogenicity may aid in malaria control strategy. METHODOLOGY/PRINCIPAL FINDINGS: To generate resistance, P. berghei NK65 was subjected to 5-fluoroorotate (FOA, an inhibitor of thymidylate synthase, TS) pressure in mice. After 15 generations of drug pressure, the 2% DT (the delay time for proliferation of parasites to 2% parasitaemia, relative to untreated wild-type controls) reduced from 8 days to 4, equalling the controls. Drug sensitivity studies confirmed that FOA-resistance was stable. During serial passaging in the absence of drug, resistant parasite maintained low growth rates (parasitaemia, 15.5%±2.9, 7 dpi) relative to the wild-type (45.6%±8.4), translating into resistance cost of fitness of 66.0%. The resistant parasite showed an apoptosis-like death, as confirmed by light and transmission electron microscopy and corroborated by oligonucleosomal DNA fragmentation. CONCLUSIONS/SIGNIFICANCE: The resistant parasite was less fit than the wild-type, which implies that in the absence of drug pressure in the field, the wild-type alleles may expand and allow drugs withdrawn due to resistance to be reintroduced. FOA resistance led to depleted dTTP pools, causing thymineless parasite death via apoptosis. This supports the tenet that unicellular eukaryotes, like metazoans, also undergo apoptosis. This is the first report where resistance to a chemical stimulus and not the stimulus itself is shown to induce apoptosis in a unicellular parasite. This finding is relevant in cancer therapy, since thymineless cell death induced by resistance to TS-inhibitors can further be optimized via inhibition of pyrimidine salvage enzymes, thus providing a synergistic impact. We conclude that since apoptosis is a process that can be pharmacologically modulated, the parasite's apoptotic machinery may be exploited as a novel drug target in malaria and other protozoan diseases of medical importance

Susceptibility and morbidity between male and female Swiss mice infected with Angiostrongylus costaricensis: Susceptibilidade e morbidade entre camundongos Swiss machos e fêmeas infectados com Angiostrongylus costaricensis

The gender of vertebrate hosts may affect the outcome of parasitic infections. An experimental murine infection with Angiostrongylus costaricensis was followed with determinations of body weight, fecal larval elimination, number and length of adult worms, number of macroscopic intestinal lesions, and mortality. Groups of male and female Swiss mice were infected with 10 3rd-stage A. costaricensis larvae per animal. The results indicate there are no significant differences related to gender of the host, except for higher length of worms developed in male mice.<br>O sexo dos hospedeiros vertebrados pode influenciar no resultado de infecções parasitárias. A infecção experimental de camundongos com Angiostrongylus costaricensis foi acompanhada com observação do peso corporal, eliminação de larvas nas fezes, número e comprimento dos vermes adultos, número de lesões macroscópicas nos intestinos e mortalidade. Grupos de camundongos Swiss machos e fêmeas foram infectados cada um com 10 larvas de terceiro estágio de A. costaricensis. Os resultados indicam que não há diferenças significativas relacionados ao sexo dos hospedeiros, exceto pelo maior comprimento dos vermes nos hospedeiros machos