To investigate the in vitro inhibitory mechanism of Nymphaea candida total flavonoids(NCTF)against Staphylococcus aureus(S.aureus)and its safety in mice,this study first deter-mined the antibacterial effect of NCTF on the clinically isolated strain S.aureus-C1.Subsequently,the inhibitory mechanism of NCTF on S.aureus-C1 was explored by measuring its effects on bac-terial growth curves,microstructure,intracellular AKP and LDH levels,and biofilm formation.Safety evaluation included determination of LD50 and MDT in mice,as well as analysis of serum biochemical parameters,organ indices,and histopathological observations.Results showed that NCTF effectively inhibited S.aureus-C1 proliferation,with an inhibition zone diameter of(18.98±0.67)mm and a MIC of 6.25 g/L.A concentration of 2×MIC nearly completely suppressed bacte-rial growth.Scanning electron microscopy revealed structural damage to bacterial cells,including collapse and shrinkage.AKP and LDH assays indicated significantly increased AKP activity(P＜0.05)and decreased intracellular LDH activity(P＜0.05)in the supernatant of drug-treated groups,demonstrating NCTF-induced disruption of cell walls and membranes leading to leakage of AKP and LDH.Crystal violet staining of biofilms showed significant inhibition rates of(43.77±9.16)％and(61.71±9.82)％at 2 × MIC and 4 × MIC concentrations,respectively(P＜0.05).Safe-ty assessments indicated low toxicity of NCTF in mice,with transient effects that returned to nor-mal levels within a short period.These findings demonstrate that NCTF exhibits potent antibacte-rial activity against S.aureus-C1 by damaging bacterial cell structures,increasing cell wall/mem-brane permeability,reducing biofilm formation,and displaying low toxicity.This study provides scientific evidence for clinical drug screening against bovine mastitis and the development of Nym-phaea candida resources.

Polylactic acid-glycolic acid copolymer(PLGA)is a widely used and studied drug delivery system.The favorable characteristics of PLGA,such as good bioavailability,controlled release,and excellent safety due to the biodegradable polymer skeleton,have allowed PLGA to be approved by authorities as a human drug delivery platform.Immunoprophylaxis will be one of the most poten-tial and ideal prevention and control measures to control the epidemic of parasitic diseases.Howev-er,vaccines often have many limitations,such as relatively weak immunogenicity,easy degrada-tion,dose and mode of administration challenges,stability and storage issues.The use of PLGA as a vaccine carrier can improve the stability of the vaccine,reduce the storage and transportation prob-lems of the vaccine and reduce the number of doses,improve the therapeutic effect and reduce the side effects;These characteristics make PLGA an ideal platform for vaccine delivery.This paper re-views the latest progress,feasibility and challenges of PLGA in the field of parasite immunopro-phylaxis,in order to provide new ideas for the development and development of more effective pre-vention and treatment strategies for parasitic diseases.

To investigate the in vitro inhibitory mechanism of Nymphaea candida total flavonoids(NCTF)against Staphylococcus aureus(S.aureus)and its safety in mice,this study first deter-mined the antibacterial effect of NCTF on the clinically isolated strain S.aureus-C1.Subsequently,the inhibitory mechanism of NCTF on S.aureus-C1 was explored by measuring its effects on bac-terial growth curves,microstructure,intracellular AKP and LDH levels,and biofilm formation.Safety evaluation included determination of LD50 and MDT in mice,as well as analysis of serum biochemical parameters,organ indices,and histopathological observations.Results showed that NCTF effectively inhibited S.aureus-C1 proliferation,with an inhibition zone diameter of(18.98±0.67)mm and a MIC of 6.25 g/L.A concentration of 2×MIC nearly completely suppressed bacte-rial growth.Scanning electron microscopy revealed structural damage to bacterial cells,including collapse and shrinkage.AKP and LDH assays indicated significantly increased AKP activity(P＜0.05)and decreased intracellular LDH activity(P＜0.05)in the supernatant of drug-treated groups,demonstrating NCTF-induced disruption of cell walls and membranes leading to leakage of AKP and LDH.Crystal violet staining of biofilms showed significant inhibition rates of(43.77±9.16)％and(61.71±9.82)％at 2 × MIC and 4 × MIC concentrations,respectively(P＜0.05).Safe-ty assessments indicated low toxicity of NCTF in mice,with transient effects that returned to nor-mal levels within a short period.These findings demonstrate that NCTF exhibits potent antibacte-rial activity against S.aureus-C1 by damaging bacterial cell structures,increasing cell wall/mem-brane permeability,reducing biofilm formation,and displaying low toxicity.This study provides scientific evidence for clinical drug screening against bovine mastitis and the development of Nym-phaea candida resources.

Polylactic acid-glycolic acid copolymer(PLGA)is a widely used and studied drug delivery system.The favorable characteristics of PLGA,such as good bioavailability,controlled release,and excellent safety due to the biodegradable polymer skeleton,have allowed PLGA to be approved by authorities as a human drug delivery platform.Immunoprophylaxis will be one of the most poten-tial and ideal prevention and control measures to control the epidemic of parasitic diseases.Howev-er,vaccines often have many limitations,such as relatively weak immunogenicity,easy degrada-tion,dose and mode of administration challenges,stability and storage issues.The use of PLGA as a vaccine carrier can improve the stability of the vaccine,reduce the storage and transportation prob-lems of the vaccine and reduce the number of doses,improve the therapeutic effect and reduce the side effects;These characteristics make PLGA an ideal platform for vaccine delivery.This paper re-views the latest progress,feasibility and challenges of PLGA in the field of parasite immunopro-phylaxis,in order to provide new ideas for the development and development of more effective pre-vention and treatment strategies for parasitic diseases.