Phenolic glycosides and flavonoids with antioxidant and anticancer activities from Desmodium caudatum

Descaudatine A (1), an undescribed phenolic glycoside, along with a known analogue (2) and ten flavonoids (3-12), were isolated from the whole plant of Desmodium caudatum. Compounds 1 and 4 exhibited potent antioxidant activities with the IC₅₀ of 58.59 μM and 31.31 μM, respectively, which were approached to that of the positive control Vitamin C (IC₅₀ = 46.32 μM). Meanwhile, 12 showed moderate antioxidant activity with the IC₅₀ of 173.9 μM. Besides, compounds 3 and 6 inhibited the proliferation of HeLa cells with IC₅₀ values of 56.14 μM and 69.04 μM, respectively. Further studies indicated that 3 and 6 could dose-dependently induce PARP cleavage and might trigger caspase-3, 8, 9 activation to induce apoptosis. RXRα is an ideal anticancer target of nuclear receptor. The reporter gene assay of RXRα indicated that 3 and 6 could inhibited the 9-cis-RA induced RXRα transcription in a concentration-dependent manner.