Immunomodulatory proanthocyanidins from Ecdysanthera utilis

Two new A-type proanthocyanidins have been isolated from Ecdysanthera utilis and identified as epicatechin-(4beta-->8,2beta-->O-->7)-epicatechin-(4beta-->8)-epicatechin (5) and epicatechin-(4beta-->8)-epicatechin-(4beta-->8,2beta-->O-->7)-epicatechin-(4beta-->8)-epicatechin (6), respectively. The structure-related components epicatechin (1), procyanidin B2 (2), proanthocyanidin A1 (3), proanthocyanidin A2 (4), and aesculitannin C (7) were also isolated. All of these compounds were identified and evaluated for immunopharmacological activity. Human peripheral blood mononuclear cells (PBMC) were used as target cells, and cell proliferation was determined by (3)H-thymidine uptake. The results indicated that compound 3 suppressed PBMC proliferation activated with phytohemagglutinin (PHA). The inhibitory mechanisms may involve the blocking of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production, since compound 3 attenuated IL-2 and IFN-gamma production of PBMC in a dose-dependent manner. Therefore, it is suggested that immunomodulatory agents are present in E. utilis.