Evaluation of Cynanchum otophyllum glucan sulfate against human immunodeficiency virus and herpes simplex virus as a microbicide agent

OBJECTIVE: The root of Cynanchum otophyllum—also known as Qing Yang Sheng—is a traditional ethnical Chinese medicine. The objective of this study was to evaluate in vitro activities and safety of C. otophyllum glucan sulfate (PS20) against Human Immunodeficiency Virus (HIV) and Herpes Simplex Virus (HSV). MATERIALS AND METHODS: Anti-HIV activity was detected with syncytial formation assay and quantitative P24 Enzyme-Linked Immunosorbent Assay (ELISA). Anti-HSV activity was detected with plaque reduction assay; cytotoxicity was tested with MTT colorimetric assay; and anti-bacterial activity was tested with microdilution method. Anti-HIV mechanism was investigated with fusion inhibition, time of addition, and pretreatment. RESULTS: The 50% Inhibition Concentration (IC(50)) of PS20 for HIV-1(IIIB), HIV-(Ada-M), HIV-1(Bal), HSV-I, and -II were 0.26 ± 0.02 mM, 0.46 ± 0.02 mM, 0.90 ± 0.04 mM, 3.45 ± 0.85 μM, and 0.70 ± 0.22 mM, respectively. Selectivity Indices (SI) were 653, 50, 39, 85, and 362, respectively. Studies on anti-HIV mechanism of PS20 showed that the target molecule should be the envelope protein. The 50% Cytotoxicity Concentrations (CC(50)) of PS20 for HeLa and ME-180 cell lines and human foreskin fibroblast cells was more than 70 μM. The Minimum Inhibitory Concentration (MIC) for vaginal lactobacilli was more than 1000 μM. CONCLUSION: PS20 possesses anti-HIV and HSV effect and low cytotoxicity to epithelium cells and vaginal lactobacilli. It may be considered as a potential microbicide agent for further investigation.