Abstract: Aim To investigate the chemical constituents from the twigs and leaves of Pithecellobium clypearia Benth and their immunomodulatory effects. Methods The constituents were separated and purified by various chromatographic methods and their structures were identified on the basis of spectral analysis. The immunomodulatory effects of all the compounds were examined by a Con A-induced T lymphocytes proliferation assay. Results Eight compounds were isolated and identified as (-)-epigallocatechin (1), (-)-5, 7, 3', 4', 5'-pentahydroxyflavan (2), (-)-epigallocatechin-7-gallate (3), (-)-5, 3', 4', 5'-tetrahydroxyflavan-7-gallate (4), quercitin-3-O-α-L-rhamnpyranoside (5), myricitin-3-O-α-L-rhamnpyranoside (6), gallic acid (7), and ethyl gallate (8), respectively. Conclusion Compounds 3 and 8 were isolated from this genus for the first time, and compound 1 was isolated from this species for the first time. Compound 3 exhibited a strong inhibition on the T lymphocytes proliferation induced by Con A with an IC50 of 4.4 μmol·L–1.

Key words: Pithecellobium clypearia, Pithecellobium clypearia, Flavonoids, Flavonoids, Flavane, Flavane, Lymphocytes proliferation, Lymphocytes proliferation