Phytochemical investigations on n-butanol extract of Cephalaria balansae Raus. (Caprifoliaceae) led to the isolation of four previously undescribed triterpenoid saponins based on hederagenin type aglycone, namely, balansoides A-D, along with ten known compounds. Their structures were proposed based on 1D and 2D NMR spectroscopic data, HRESIMS analysis and chemical evidence as 3-O-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl hederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl hederagenin 28-O-β-D-glucopyranosyl ester, 3-O-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl hederagenin 28-O-β-D-galactopyranosyl-(1 → 6)-β-D-glucopyranosyl ester and 3-O-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl hederagenin 28-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosyl ester. The four saponins were evaluated for their potential cytotoxic activity against HEK-293, A-549, HeLa cells and for hemolytic properties on human blood cells. Balansoide A displayed significant inhibitory effects on cancerous A-549 and HeLa cells, and non-cancerous HEK-293 cells with IC50 values of 12, 15 and 8 μM, respectively. Balansoides A-D together with n-butanol extract exhibited considerable hemolysis in human erythrocyte cells. Immunomodulatory properties of balansoides A-D were also evaluated in activated whole blood cells by PMA plus ionomycin. While balansoides A-C increased IL-1β concentration with values of 1004.47, 991.57 and 966.50 pg/ml, only balansoide B augmented a slight IFN-γ secretion with value of 5219.14 pg/ml. None of the compounds changed IL-2 levels significantly.
Keywords: Caprifoliaceae; Cephalaria balansae; Cytotoxic activity; Hemolytic activity; Immunomodulatory activity; Triterpene glycoside.
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