Compounds from Lonicera fulvotomentosa could be potential HIV protease inhibitors - GreenMedInfo Summary

In this study, we isolated nine compounds from the acid hydrolysate of the flower buds ofHsu et S. C. Cheng and characterized their chemical structures usingH-NMR,C-NMR, and electron ionization mass spectroscopy (EI-MS). These compounds were identified asβ-sitosterol (), 5,5'-dibutoxy-2,2'-bifuran (), nonacosane-10-ol (), ethyl (3β)-3,23-dihydroxyolean-12-en-28-oate (), oleanolic acid (), ethyl caffeate (), caffeic acid (), isovanillin (), and hederagenin (), withas a new triterpene compound. Inhibitory activity against human immunodeficiency virus (HIV) protease was also evaluated for the compounds, and only ethyl caffeate, caffeic acid, and isovanillin (,, and) exhibited inhibitory effects, with ICvalues of 1.0μM, 1.5 μM, and 3.5 μM, respectively. Molecular docking with energy minimization and subsequent molecular dynamic (MD) simulation showed that ethyl caffeate and caffeic acid bound to the active site of HIV protease, while isovanillin drifted out from the active site and dissociated into bulk water during MD simulations, and most of the binding residues of HIV protease have been previously identified for HIV protease inhibitors. These results suggest that caffeic acid derivatives may possess inhibitory activities towards HIV protease other than previously reported inhibitory activities against HIV integrase, and thus ethyl caffeate and caffeic acid could be used as lead compounds in developing potential HIV protease inhibitors, and possibly even dual-function inhibitors against HIV.