Pyrrolizidine alkaloids from seven wild-growing Senecio species in Serbia and Montenegro

The genus Senecio (family Asteraceae) is one of the largest in the world. It comprises about 1100 species which are the rich source of pyrrolizidine alkaloids. Plants containing pyrrolizidine alkaloids are among the most important sources of human and animal exposure to plant toxins and carcinogens. The pyrrolizidine alkaloids of seven Senecio species (S. erucifolius, S. othonnae, S. wagneri, S. subalpinus, S. carpathicus, S. paludosus and S. rupestris) were studied. Fourteen alkaloids were isolated and their structures determined from spectroscopic data (1H- and 13C-NMR, IR and MS). Five of them were identified in S. erucifolius, four in S. othonnae, two in S. wagneri, four in S. subalpinus, two in S. carpathicus, three in S. paludosus and three in S. rupestris. Seven pyrrolizidine alkaloids were found for the first time in particular species. The results have chemotaxonomic importance. The cytotoxic activity and antimicrobial activity of some alkaloids were also studied

Antibacterial and cytotoxic activities of naphthoquinone pigments from Onosma visianii Clem

In this study, the antibacterial and cytotoxic activities of isolated compounds from the roots of Onosma visianii were investigated. By using different chromatographic techniques and appropriate spectroscopic methods, the seven naphthoquinones were described: deoxyshikonin (1), isobutyrylshikonin (2), α-methylbutyrylshikonin (3), acetylshikonin (4), ß-hydroxyisovalerylshikonin (5), 5,8-O-dimethyl isobutyrylshikonin (6) and 5,8-O-dimethyl deoxyshikonin (7). Among the tested compounds, 3 and 4 exhibited the highest antibacterial activities toward all tested bacterial species (MIC50 and MIC90 for gram positive bacteria: 6.40 µg/mL-12.79 µg/mL and 6.82 µg/mL-13.60 µg/mL, respectively; for gram negative bacteria: 4.27 µg/mL-8.53 µg/mL and 4.77 µg/mL-9.54 µg/mL, respectively). Also, naphthoquinones 3 and 4 exhibited strong cytotoxic activity against MDA-MB-231 cells (IC50 values 86.0 µg/mL and 80.2 µg/mL, respectively), while compounds 1, 3, 4 and 5 significantly decreased viability of HCT116 cells (IC50 values of 97.8 µg/mL, 15.2 µg/mL, 24.6 µg/mL and 30.9 µg/mL, respectively). Our results indicated that all tested naphthoquinone pigments are potential candidates for clinical uses as antibacterial and cytotoxic agents