Paviosides A–H, eight new oleane type saponins from Aesculus pavia with cytotoxic activity

A phytochemical analysis of Aesculus pavia has led to the isolation of eight novel triterpenoid saponins, based on oleane type skeleton and named paviosides A–H (1a, 1b–4a, 4b). On the basis of chemical, and 2D NMR and mass spectrometry data, the structures of the new compounds were elucidated as 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-glucopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-tigloyl-22-acetyl barringtogenol C (1a), 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-glucopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-angeloyl-22-acetyl barringtogenol C (1b), 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-galactopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-tigloyl-22-acetyl barringtogenol C (2a), 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-galactopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-angeloyl-22-acetyl barringtogenol C (2b), 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-xylopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-tigloyl-22-acetyl barringtogenol C (3a), 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-xylopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-angeloyl-22-acetyl barringtogenol C (3b), 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-xylopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-tigloyl-22-acetyl protoaescigenin (4a), and 3-O-[β-d-xylopyranosyl (1→2)] [-β-d-xylopyranosyl (1→4)]-β-d-glucopyranosiduronic acid 21-angeloyl-22-acetyl protoaescigenin (4b). The compounds showed cytotoxic activity on J-774, murine monocyte/macrophage, and WEHI-164, murine fibrosarcoma, cell lines. Among them, paviosides E–H (3a, 3b and 4a, 4b) showed higher activity with values ranging from 2.1 to 3.6 μg/mL. Structure–activity relationship studies indicated the positive effect on the activity of xylose unit in the place of glucose, while a little detrimental effect is observed when glucose is substituted by galactose. The aglycone structure and the presence of a tigloyl or an angeloyl group at C-21 do not affect significantly the inhibitory activity on both tested cell lines.

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