The most common medications for the treatment of zoonotic toxoplasmosis are pyrimethamine and sulfadiazine, which may cause serious undesirable side effects. Thus, there is an urgent need to develop novel therapeutics. Baicalein (BAI, C₁₅H₁₀O₅) has been shown to perform well against protozoan parasites including Leishmania and Cryptosporidium. In this study, the inhibition efficacy of BAI on Toxoplasma gondii was evaluated using plaque, invasion, and intracellular proliferation assays. BAI effectively inhibited T. gondii (half-maximum inhibitory concentration (IC₅₀)=6.457×10^-5 mol/L), with a reduced invasion rate (33.56%) and intracellular proliferation, and exhibited low cytotoxicity (half-maximum toxicity concentration (TC₅₀)=5.929×10^-4 mol/L). Further investigation using a mouse model shed light on the inhibitory efficacy of BAI against T. gondii, as well as the potential mechanisms underlying its anti-parasitic effects. The survival time of T. gondii-infected ICR mice treated with BAI was remarkably extended, and their parasite burdens in the liver and spleen were greatly reduced compared with those of the negative control group. Histopathological examination of live sections revealed effective therapeutic outcomes in the treatment groups, with no notable pathological alterations observed. Furthermore, alterations in cytokine levels indicated that BAI not only effectively suppressed the growth of T. gondii but also prevented excessive inflammation in mice. Collectively, these findings underscore the significant inhibitory efficacy of BAI against T. gondii, positioning it as a promising alternative therapeutic agent for toxoplasmosis.
Animals ; Toxoplasma/drug effects* ; Flavanones/therapeutic use* ; Mice ; Antiparasitic Agents/therapeutic use* ; Mice, Inbred ICR ; Toxoplasmosis/drug therapy* ; Female

Objective:A camelid natural nanobody library was screened to target S100 calcium-binding protein B (S100B) for obtaining high-affinity and specific nanobodies (Nbs), which provided a molecular basis for the early diagnosis and prognostic treatment of malignant melanoma.Methods:In this study, affinity panning was employed to isolate S100B-specific nanobodies with unique complementarity-determining region 3 (CDR3) sequences from a camelid natural nanobody library. The selected Nbs were expressed in a prokaryotic system and purified via Ni-NTA affinity chromatography. The affinity, specificity, and diagnostic potential of the Nbs were evaluated using enzyme-linked immunosorbent assay (ELISA), western blot, and bio-layer interferometry (BLI).Results:A camelid natural anti-S100B nanobody library with a capacity of 1.91×10 8 CFU was successfully constructed. Affinity panning yielded 30 S100B-specific Nbs, among which Nb107, Nb122, Nb212, and Nb324 with distinct CDR3 sequences were selected for expression. Following Ni-NTA purification, all four anti-S100B Nbs exhibited high purity. Western blot analysis confirmed their ability to recognize recombinant S100B. ELISA and BLI analyses revealed that Nb212 demonstrated high affinity (1.96×10 -11 mol). Additionally, Nb107, Nb122, and Nb212 exhibited broad-spectrum recognition capabilities, binding to various tumor cell lines (Hepa1-6, GL261, 4T1, CT26) as well as murine/human melanoma cells. These Nbs also effectively bound to native murine/human antigens in serum samples from melanoma (A375, B16F10) mouse models. Conclusions:Specific anti-S100B Nbs are successfully screened and expressed, demonstrating not only recognition of native conformational antigens but also broad-spectrum binding and high affinity. These findings highlight their significant potential for developing early diagnostic assays and broad-spectrum targeted vaccines or therapeutics against diverse tumor cells.

Objective:A camelid natural nanobody library was screened to target S100 calcium-binding protein B (S100B) for obtaining high-affinity and specific nanobodies (Nbs), which provided a molecular basis for the early diagnosis and prognostic treatment of malignant melanoma.Methods:In this study, affinity panning was employed to isolate S100B-specific nanobodies with unique complementarity-determining region 3 (CDR3) sequences from a camelid natural nanobody library. The selected Nbs were expressed in a prokaryotic system and purified via Ni-NTA affinity chromatography. The affinity, specificity, and diagnostic potential of the Nbs were evaluated using enzyme-linked immunosorbent assay (ELISA), western blot, and bio-layer interferometry (BLI).Results:A camelid natural anti-S100B nanobody library with a capacity of 1.91×10 8 CFU was successfully constructed. Affinity panning yielded 30 S100B-specific Nbs, among which Nb107, Nb122, Nb212, and Nb324 with distinct CDR3 sequences were selected for expression. Following Ni-NTA purification, all four anti-S100B Nbs exhibited high purity. Western blot analysis confirmed their ability to recognize recombinant S100B. ELISA and BLI analyses revealed that Nb212 demonstrated high affinity (1.96×10 -11 mol). Additionally, Nb107, Nb122, and Nb212 exhibited broad-spectrum recognition capabilities, binding to various tumor cell lines (Hepa1-6, GL261, 4T1, CT26) as well as murine/human melanoma cells. These Nbs also effectively bound to native murine/human antigens in serum samples from melanoma (A375, B16F10) mouse models. Conclusions:Specific anti-S100B Nbs are successfully screened and expressed, demonstrating not only recognition of native conformational antigens but also broad-spectrum binding and high affinity. These findings highlight their significant potential for developing early diagnostic assays and broad-spectrum targeted vaccines or therapeutics against diverse tumor cells.