Y. Kashiwada et al., ANTI-AIDS AGENTS .18. SODIUM AND POTASSIUM-SALTS OF CAFFEIC ACID TETRAMERS FROM ARNEBIA-EUCHROMA AS ANTI-HIV AGENTS, Journal of natural products, 58(3), 1995, pp. 392-400
Monosodium and monopotassium salts [2-4] of isomeric caffeic acid tetr
amers were isolated from Arnebia euchroma as anti-HIV agents. Mixtures
of dipotassium and disodium salts [1] of a caffeic acid tetramer and
dipotassium and potassium-sodium salts [5] of a caffeic acid tetramer
glucoside were also isolated from the active fraction. The structures
of 1-5 were characterized by chemical and spectral evidence. Compounds
2-4 demonstrated potent anti-HIV activity with EC(50) values of 2.8,
4.0, and 1.5 mu g/ml, respectively. Treatment of 1-4 with dilute HCl y
ielded known caffeic acid tetramers [8 and 9], which were found to be
less active, indicating the importance of the sodium and potassium sal
ts to the enhanced anti-HIV activity.