From the aerial parts of Astragalus suberi L., Fabaceae, seven saponins were isolated. Based on spectral data (IR, 1H and 13C NMR and HR-FABMS), the structures were established as 3-O-(β-ᴅ-glucopyranosyl)-soyasapogenol B (1); 3-O-(β-ᴅ-glucuronopyranosyl)- soyasapogenol B (2); 3-O-[β-ᴅ-galactopyranosyl (1→2)-β-ᴅ-glucopyranosyl]-soyasapogenol B (3); 3-O-[α-ʟ-rhamnopyranosyl (1→2)-β-ᴅ-galactopyranosyl (1→2)-β-ᴅ-glucopyranosyl]- soyasapogenol B (4); 3-O-[α-ʟ-rhamnopyranosyl (1→2)-β-ᴅ-galactopyranosyl (1→2)-β-ᴅ-glucopyranosyl]-11-hydroxy-soyasapogenol B (5); 3-O-[α-ʟ-rhamnopyranosyl (1→2)-β-ᴅ-galactopyranosyl (152)-β-ᴅ-glucuronopyranosyl]-soyasapogenol B (6) and 3-O-[α-ʟ-rhamnopyranosyl (1→2)-β-ᴅ-galactopyranosyl (1→2)-β-ᴅ-glucuronopyranosyl]-complogenin (7).
The isolated saponins exhibited antibacterial activities against Gram-positive and Gramnegative bacteria with minimum inhibitory concentration values > 100 μg/ml, antifungal activity against all the strains tested with minimum fungicidal concentration values between 25 and 50 μg/ml and inhibited the growth of Hep-2 (human carcinoma of larynx), with IC50 values between 50 μg/ml (compounds 5-7) and 100 μg/ml (compounds 1-4), and Hela (human carcinoma of cervix) cell lines in culture with different IC50 values [74 compound 7), 98 (compound 5) and 180 μg/ml (compounds 1-4 and 6)]
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