Optimized Benzalkonium Chloride Gel: A Potential Vaginal Microbicides

Objective To develop an optimized BZK gel with good pharmaceutical effect and less toxicity to vaginal mucosa. Methods Four methods as below were used to research the spermicidal activity of BZK gel： 1） in vitro spermicidal test; 2） in vivo spermicidal test in rabbits; 3） anti-fertility test in rabbits; 4） contraceptive test in rabbits. Mucosal irritation test was used in rats to evaluate the safety of optimized BZK gel. Microbiological assessments were used to research anti-STI pathogens （including treponema pallidum, neisseria gonorrhoeae, trichomona vaginalis, candida albicans, ureaplama urealyticum, herpes simplex virus type-2, chlamydiae trachomatis） effect of optimized BZK gel. Results In vitro spermicidal test, EC50 of BZK gel was 0.029mg/ml, a little higher than that of N-9 （0.019mg/ml）. The MIC of BZK gel was 0.25mg/ml, similar to that of N-9 （0.20mg/ml）. The vaginal mucosal irritation test in rats showed that 0.429% BZK gel showed only minimal vaginal irritation, and did not damage the vaginal epithelium or cause local inflammation in rats. Microbiological assessments showed that optimized BZK gel could inhibit or inactivate common ST1 pathogens even after 3-fold or 5-fold dilution. Conclusion Optimized BZK gel was an effective microbicides.

Cytoprotective effect of amniotic membrane extracts on human corneal epithelial cells exposed to benzalkonium chloride in vitro

Background:The goal was to explore the protective effect and potential mechanism of amniotic membrane extracts(AME)on the ocular surface exposed to benzalkonium chloride(BAC).Methods:The human corneal epithelial cell(HCEC)line SD-HCEC1s was cultured in 5 groups:normal control(NC),NC+AME,BAC,BAC+NC,and BAC+AME.Cell viability analysis,flow cytometry analysis,real-time polymerase chain reaction(PCR),and western blot were employed to measure changes in cell function.Matrix metalloproteinases(MMPs)and inflammatory cytokines were assayed by enzyme-linked immunosorbent assay(ELISA)and activity assays.Results:Real-time PCR and western blot analysis demonstrated that the expressional level of caspase-8 was increased while the levels of Muc1,Muc4,and Muc16 were decreased after treatment with 0.02%BAC for 1 h.When the SD-HCEC1s were withdrawn from the BAC and switched to media containing 10%AME for 2 days,the expression level of capsase-8 was decreased while the levels of Muc1,Muc4,and Muc16 were increased.Real-time PCR and ELISA demonstrated that the mRNA and protein levels of MMP-1,MMP-3,MMP-13,CXCL1,interleukin(IL)-1β,IL-6,and tumor necrosis factor-alpha(TNF-α)were significantly increased after treatment with 0.02%BAC,whereas those of MMP-8 were decreased.When the 0.02%BAC was withdrawn and the SD-HCEC1s were cultured in 10%AME,the mRNA and protein levels of MMP-1,MMP-3,MMP-13,CXCL1,IL-1β,IL-6,and TNF-αwere decreased,while those of MMP-8 were increased.MMP-8 activity assays confirmed that IL-1βand TNF-αdownregulated the protein levels of MMP-8.Conclusions:AME protects SD-HCEC1s when stressed in BAC via upregulation of MMP-8 and downregulation of IL-1βand TNF-α.AME may have the potential functions to be employed as a topical adjunctive therapy in eyes chronically exposed to BAC.

Science Letters:Determination of benzalkonium chloride in viscous ophthalmic drops of azithromycin by high-performance liquid chromatography

A high-performance liquid chromatography （HPLC） system was used in the reversed phase mode for the determination ofbenzalkonium chloride （BKC） in azithromycin viscous ophthalmic drops. A Venusil-XBP（L）-C18 （150 mm×4.6 mm, 5 gm） column was used at 50℃. The mobile phase consisted of a mixture of methanol-potassium phosphate （16：5, v/v）. Two sample preparation methods were compared. The results suggested that, compared with an extraction procedure, a deproteinization procedure was much quicker and more convenient. Using the deproteinization procedure for sample preparation, calibration curves were linear in the range 5.0-50μg/ml. The within-day and inter-day coefficients of variation were less than 10%. The average recoveries were determined as 96.70%, 98.52%, and 97.96% at concentrations of 10.0, 30.0, and 50.0 μg/ml, respectively. Variability in precision did not exceed 5%. In conclusion, this HPLC method using a simple sample treatment procedure appears suitable for monitoring BKC content in azithromycin viscous ophthalmic drops.

Inhibition effects of benzalkonium chloride on Chlorella vulgaris induced corrosion of carbon steel

In this work,a surfactant,benzalkonium chloride(BAC),was used to study its effects on both the growth of Chlorella vulgaris and the corrosion caused by its biofilm.Experimental results indicated that BAC at a low concentration of 3 mg/L suppressed C.vulgaris growth and achieved 81%corrosion inhibition based on weight loss reduction.The inhibition effects increased when the BAC dosage was increased.At 30 mg/L,the corrosion inhibition increased to 95%.Electrochemical results supported surface pitting analysis,weight loss results data and confirmed the corrosion inhibition.

Therapeutic Effects of Sodium Hyaluronate on Ocular Surface Damage Induced by Benzalkonium Chloride Preserved Anti-glaucoma Medications

Background： Long-term use of benzalkonium chloride （BAC）-preserved drugs is often associated with ocular surface toxicity. Ocular surface symptoms had a substantial impact on the glaucoma patients＇ quality of life and compliance. This study aimed to investigate the effects of sodium hyaluronate （SH） on ocular surface toxicity induced by BAC-preserved anti-glaucoma medications treatment. Methods： Filly-eight patients （101 eyes）, who received topical BAC-preserved anti-glaucoma medications treatment and met the severe dry eye criteria, were included in the analysis. All patients were maintained the original topical anti-glaucoma treatment. In the SH-treated group （56 eyes）, unpreserved 0.3% SH eye drops were administered with 3 times daily for 90 days. In the control group （55 eyes）, phosphate-butTered saline were administered with 3 times daily for 90 days. Ocular Surface Disease Index （OSDI） questionnaire, break-up time （BUT） test, corneal fluorescein staining, corneal and conjunctival rose Bengal staining, Schirmer test, and conjunctiva impression cytology were pertbrmed sequentially on days 0 and 91. Results： Compared with the control group, SH-treated group showed decrease in OSDI scores （Kruskal-Wallis test： H = 38.668, P 〈 0.001 ）, fluorescein and rose Bengal scores （Wilcoxon signed-ranks test： z = -3.843, P 〈 0.001, and z = 3.508, P 〈 0.001, respectively）, increase in tear fihn BUT （t-test： t - -10.994, P 〈 0.001 ） and aqueous tear production （t-test： t = -10.328, P 〈 0.001 ） on day 91. The goblet cell density was increased （t-test： t = -9.981, P 〈 0.001）, and the morphology of the conjunctival epithelium were also improved after SH treatment. Conclusions： SH significantly improved both symptoms and signs of ocular surface damage in patients with BAC-preserved anti-glaucoma medications treatment. SH could be proposed as a new attempt to reduce ocular surface toxicity, and alleviate symptoms of ocular surface damage in BAC-preserved anti-glaucoma medications treatment.

Pronounced temporal changes in soil microbial community and nitrogen transformation caused by benzalkonium chloride

As one typical cationic disinfectant, quaternary ammonium compounds(QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the surrounding environment. Concerningly, it is still unclear how the soil microbial community succession happens and the nitrogen(N)cycling processes alter when exposed to QACs. In this study, one common QAC(benzalkonium chloride(BAC) was selected as the target contaminant, and its effects on the temporal changes in soil microbial community structure and nitrogen transformation processes were determined by q PCR and 16S r RNA sequencing-based methods. The results showed that the aerobic microbial degradation of BAC in the two different soils followed first-order kinetics with a half-life(4.92 vs. 17.33 days) highly dependent on the properties of the soil. BAC activated the abundance of N fixation gene(nif H) and nitrification genes(AOA and AOB) in the soil and inhibited that of denitrification gene(nar G). BAC exposure resulted in the decrease of the alpha diversity of soil microbial community and the enrichment of Crenarchaeota and Proteobacteria. This study demonstrates that BAC degradation is accompanied by changes in soil microbial community structure and N transformation capacity.

Effect of combination of ultraviolet radiation and biocide on fungal-induced corrosion of high-strength 7075 aluminum alloy

The effect of ultraviolet(UV)radiation and biocide benzalkonium chloride(BKC)on fungal-induced corrosion of AA7075 induced by Aspergillus terreus(A.terreus)was deeply studied using analysis of biological activity,surface analysis,and electrochemical measurements.Results demonstrated that the planktonic and sessile spore concentrations decline by more than two orders of magnitude when UV radiation and BKC are combinedly used compared with the control.UV radiation can inhibit the biological activity of A.terreus and influence the stability of passive film of AA7075.Except for direct disinfection,the physical adsorption of BKC on the specimen can effectively inhibit the attachment of A.terreus.The combination of UV radiation and BKC can much more effectively inhibit the corrosion of AA,especially pitting corrosion,due to their synergistic effect.The combined application of UV radiation and BKC can be a good method to effectively inhibit fungal-induced corrosion.

Efficacy and safety of newly developed preservative-free latanoprost 0.005% eye drops versus preserved latanoprost 0.005% in open angle glaucoma and ocular hypertension: 12-week results of a randomized,multicenter, controlled phase Ⅲ trial

AIM: To evaluate the therapeutic efficacy, safety and tolerability of newly developed preservative-free(PF) latanoprost generic [TJO-002] and compare it with benzalkonium chloride(BAK)-preserved latanoprost [Xalatan?] in patients with primary open angle glaucoma(POAG) and ocular hypertension(OHT).METHODS: Included patients were aged ≥19 y with POAG/OHT. After a washout period, patients with IOP 21-35 mm Hg at 9 a.m. were enrolled. After a full ophthalmic and glaucoma examination, 144 patients with POAG and OHT participated in this study. Subjects were randomly assigned either PF latanoprost(74 eyes) or BAK-preserved latanoprost(70 eyes). All subjects were examined at 4, 8, and 12 wk after first administration. At each follow-up visit,IOP was measured at 9 a.m. and 5 p.m. and compliance was assessed. Throughout the study, all adverse events were recorded and monitored by the masked investigators who measured IOP.RESULTS: Both groups showed a statistically significant decrease of average diurnal IOP at 12 wk compared to baseline(-7.21±3.10 mm Hg in the PF latanoprost group and-7.02±3.17 mm Hg in the BAK latanoprost group, both P<0.0001). There was no statistically significant diurnal IOP variation between the groups. In terms of tolerability, pruritus, burning/stinging, and sticky eye sensation, severity was significantly lower in the PF latanoprost group than in the BAK latanoprost group(P<0.05). CONCLUSION: PF latanoprost has at least similar efficacy in terms of IOP reduction and better tolerability compared with BAK latanoprost.

Preventive effect of Angelica gigas Nakai extract oral administration on dry eye syndrome

Objective:To identify the preventive effect of Angelica gigas Nakai(A.gigas Nakai)extract in a benzalkonium chloride-induced dry eye model.Methods:A total of 28 mice were divided into 4 groups:1)Normal group:mice received only saline;2)positive control group:mice received an oral solution without A.gigas Nakai extract at 10:00 a.m.and 0.2%benzalkonium chloride eye drops at 2:00 p.m.;3)A.gigas Nakai extract(5 mg);4)A.gigas Nakai extract(10 mg).Both group 3)and group 4)received an oral solution with A.gigas Nakai extract(either 5 mg/kg or 10 mg/kg)at 10:00 a.m.and 0.2%benzalkonium chloride eye drops at2:00 p.m.After 14 d of follow-up,tear volume measurement and fluorescein staining were evaluated for the recovery effects on ocular surface.Histologic analysis was conducted by hematoxylin and eosin staining.Apoptosis on ocular epithelium layer was examined using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining.Expression of TNF-a was also measured using western blot analysis.Results:An increase in both the tear volume and the sustained fluorescein staining scores was observed,demonstrating the preventive effects of A.gigas Nakai extract.Structure changes such as irregularity of the epithelial layer and corneal epithelial cell death were inhibited in the A.gigas Nakai extract groups.Expression of TNF-αmoderately declined;however,its expression level was still higher,compared to the normal group.Conclusions:Results from the current study show the significant preventive effect of A.gigas Nakai extract in a mouse model of benzalkonium chloride-induced dry eye syndrome.Thus,A.gigas Nakai extract could be considered as an oral preventive agent for dry eye syndrome in the future.

A core–shell-structured zeolitic imidazolate framework@cationic antimicrobial agent templated silica nanocomposite for tackling antibiotic resistant bacteria infection

Bacterial infection is a major threat to public health.Nanotechnology offers a solu-tion by combining nanomaterials with antibacterial agents.The development of an effective nanocomposite against drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus(MRSA)is highly important yet challenging.Here,an anti-MRSA core–shell structure is designed,containing antibacterial zeolitic imidazolate framework-8(ZIF-8)as the core and bactericidal benzalkonium chloride(BAC)templated rough-surface mesostructured silica nanocomposite(RMSN)as the shell.The resultant ZIF-8@RMSN nanocomposite exhibits sustained release of BAC and zinc ions,effective disruption of the bacterial membrane,generation of oxidative damage of bacterial DNA,leakage of intracellular components,andfinally bacte-rial death.Furthermore,the synergistic antibacterial mechanisms lead to enhanced biofilm elimination performance.In addition,the ZIF-8@RMSN-modified band-aid effectively combats MRSA infection in vivo.This work has provided a promising nanocomposite against MRSA-related infections.