Abstract

Aim of the study

Previously, we reported that the petroleum ether fraction, RC-1, and EtOAc fraction, RC-2, of the medicinal plant Rhus chinensis showed potent anti-HIV-1 activities. To address anti-HIV-1 constituents of RC-1 and RC-2, 17 compounds were isolated. Anti-HIV-1 activities and possible action mechanisms of these compounds were investigated.

Methods

The syncytial formation induced by HIV-1 was determined under the inverted microscope, cellular toxicity and protection assay were assessed by MTT method, reduction of p24 antigen expression level and RT activity were measured by ELISA, and inhibition of recombinant HIV-1 PR was monitored by the fluorescent signal.

Results

The compounds 1 and 13 inhibited HIV-1-induced syncytium formation potently with TI value of 42.31 and 19.07, respectively. Compounds 4, 5, 6, 9 and 10 were less potent with TI value of 8.94, 8.22, 4.14, 5.11 and 5.34, respectively. Compound 1, a benzofuranone-type compound, previously reported as a novel anti-HIV-1 agent, might target late-steps of HIV-1 life cycle. Compound 13 inhibited HIV-1 replication with EC₅₀ of 7.16 μg/ml and might target at/before integration step.

Conclusion

These compounds might contribute to anti-HIV-1 activities extracts of the medicinal plant Rhus chinensis.

Keywords: Rhus chinensis; HIV-1; Benzofuranone; Anti-HIV agents; Botanicals

Abbreviations: AIDS, acquired immunodeficiency syndrome; ART, antiretroviral therapy; CAPE, caffeic acid phenylethyl ester; CC₅₀, 50% cytotoxic concentration; CPE, the cytopathic effect; EC₅₀, 50% effective concentration; HIV, human immunodeficiency virus; HRP, horseradish peroxidase; M.O.I., multiplicity of infection; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; PR, protease; RC-1, petroleum ether fraction of Rhus chinensis; RC-2, EtOAc fraction of Rhus chinensis; RT, reverse transcriptase; TCID₅₀, the 50% HIV-1 tissue culture infectious dose; TI, therapy index

Article Outline

1. Introduction

2. Materials and methods

2.1. Reagents and chemicals

2.2. Species collection

2.3. Extraction and isolation

2.4. Compounds structural identification

2.5. Cells and virus

2.6. MTT-based cytotoxicity assay

2.7. Syncytial assay

2.8. Protection for HIV-1-induced lytic effects

2.9. Inhibition of HIV-1 p24 antigen production in chronically infected H9

2.10. Inhibition assay of recombinant HIV-1 RT activity

2.11. Inhibition assay of recombinant HIV-1 protease activity

3. Results

3.1. Anti-HIV-1 activities of compounds in cellular assays

3.2. Inhibition of compounds on recombinant HIV-1 RT activity

3.3. Inhibition of compounds on recombinant HIV-1 PR activity

4. Discussion and conclusions

Acknowledgements

References