The smilagenin glycosides 42 47 with a cis fusion rings A and B were isolated from the roots of S. medica [25, 26].
Each individual trial lasted 19.2 s and trials were interleaved by 19.2 s blank periods during which only the fusion rings and the fixation cross were being presented.
The observations revealed the presence of centric fusions, rings and chromosomal breaks (Table 4).
The positive control (MMS) was found to induce statistically significant number of structural aberrations, mainly centric fusions, rings and chromosome breaks in bone marrow cells.
(2) The cis/trans fusion between rings A and B has no significant difference in terms of antifungal activities.
The sapogenin of spirostane glycosides 1 11 possess either a cis or a trans fusion between rings A and B, or a double bond between C-5 and C-6, leading to 5α (neotigogenin), 5β (sarsasapogenin), and Δ5 (narthogenin) subtypes (Fig. 2).
The variations of these sapogenins mainly comprise dehydrogenation between C-5 and C-6, carbonylation at C-6, hydroxylation at C-17 or C-27, and cis/trans fusion between rings A and B. Diosgenin glycosides 12 30 were characterized by a double bond between C-5 and C-6.
Western blot analysis showed a decrease in the protein levels of TRF2 (Fig. 6A), and karyotype analysis revealed chromosomal instability and breakage with structural abnormalities including end-to-end fusions, string, ring and triradial configurations.
Since the bridgehead stereocentre situated β to the ketone was of a fixed and stable configuration, the fact that cis ring fusion is both kinetically and thermodynamically stable with respect to trans ring fusion provides chiral stability to the bridgehead stereocentre that is situated α to the ketone.
However, while select on search('[R2&r9]') will select all the atoms not involved in the ring fusion, since now three rings will be found, and those central two atoms will be considered to be in three rings, not two.
