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Au et al. found that when the aqueous and methanol extracts of twenty Chinese herbs were screened for anti-HIV-1-integrase activity, most exhibited strong inhibition.  Furthermore, Au et al found that the inhibitor substance in these herbs was most likely a tannin (using a similar technique to Liu), and most lost their anti-integrase activity when the tannin was removed.  However, to herbs in particular, Paeonia suffruticosa (PS) and Prunella vulgaris (PV), still exerted potent inhibition of HIV-1 integrate even with the tannin removed.

The details of the study:

• The viral enzyme integrase is necessary for HIV to complete it's life cycle.  Specifically, it is needed to integrate viral DNA (constructed during earlier steps of the lifecycle) into the host's DNA
• The dried herbs used in this study were obtained from local Hong-Kong vendors.  The herbs used included the following: The dried herbs were obtained from local vendors. For Viola yedoensis, Andrographis paniculata, Senecio scandens and Oldenlandia diffusa, the whole plant was used. For Fritillaria cirrhosa, Coptis chinesis, Woodwardia unigemmata and Spatholobus suberectus, therhizome was used. For Sophora flavescens, Radix notoginseng, Polygonum multiflorum and Paeonia suffruticosa, the root was used. For Chrysanthemum indicum, Chrysanthemum morifolium, Prunella vulgaris and Lonicera japonica, the flower was used. For Arctium lappa and Ligustrum lucidum , the seed was used. For Lithospermum erythrorhizon both root and seed were used, respectively.₁₄
• HIV-1 integrase was produced by expression plasmids in E.Coli, then purified into solution
• Researchers used a ELIZA-based technique as follows:
• Wells were coated with standard lab target DNA
• Integrase was added to well, along with biotin-labeled donor DNA, and herb extract.  This mixture was incubated for one hour.  During this time, integrase would attach the biotin-labeled DNA to the target DNA, unless inhibited by the herbal extract.
• Wells were then washed with distilled water and an enzyme that would react with the biotin-labeled donor DNA to produce a fluorescence that could be measured by spectrophotometry.
• Thus, a strong fluorescent reaction would indicate that the biotin-label DNA was present, which meant that integrase had done its job.  On the other hand, a low fluorescent reaction would mean that the herbal extract successful inhibited integrase.
• Inhibition was measured before and after the researcher used additional techniques to separate tannins from each extract.
• Results for the aqueous extracts are shown graphically below:
• 
• Fig. 1. The inhibitory effects of aqueous herb extracts (mean 6 S. D.) on the activity of HIV-1 integrase before (h) and after (j) passing through the polyamide resin mini-column. Each data represented a mean of three separate measurements. The vertical bars indicate the standard deviations.

• PV and PS extracts continued to show HIV-1-integrase inhibition despite having the tannins removed
• 

• Study Conclusion: Several Chinese herbs (see above for names) contain potent anti HIV-1-integrase activity.  The active compounds are likely tannins, supported by the fall in their anti-integrase activity after the tannin was removed.  However, to herbs in particular, Paeonia suffruticosa (PS) and Prunella vulgaris (PV), still exerted potent inhibition of HIV-1 integrate even with the tannin removed, suggesting a unrelated compound within these often-use Chinese herbs that displays anti-integrase activity.

• Critique of Au