Antiophidic Solanidane Steroidal Alkaloids from Solanum campaniforme

Abstract

Three new solanidane alkaloids bearing a 22,23-epoxy ring (1-3) and four known compounds were isolated from leaves of Solanum campaniforme. The structures were determined using spectroscopic techniques, including 1D and 2D NMR, and HRESIMS experiments. The antiophidic activity of the alkaloids was tested against Bothrops pauloensis venom. Compounds 1-3 completely inhibited myotoxicity without inhibiting phospholipase A2 activity of the venom, while hemorrhage and skin necrosis were significantly reduced in the presence of alkaloids 1 and 2.

Solanidane and iminosolanidane alkaloids from Solanum campaniforme

“…The 13 C NMR-CPD and DEPT spectra displayed signals for 27 carbon atoms, among which there was one carbonyl at d 189.0 (C-3), four olefinic resonances at d 173.5 (C-5), 159.5 (C-1), 127.8 (C-2) and 124.2 (C-4), as well as signals for sp 3 nitrogenated [d 72.2 (C-16) and 45.9 (C-26)] and oxygenated [d 62.7 (C-23)] carbon atoms (Lawson et al, 1997). These data were in agreement with a structure of a solanidane alkaloid similar to that of 22a,23a-epoxy-solanida-1,4-dien-3-one (1a) previously isolated from S. campaniforme (Torres et al, 2011). A detailed comparison of the 1 H and 13 C NMR spectroscopic data of 1, to those of 1a, clearly established differences that justified a b-position for the epoxy ring in contrast to the previously 22a,23a-epoxy-solanidane alkaloid (1a) [1: d H /d C 1.10 (H-21), 3.16 (H-23), 1.97 and 1.53 (2H-24)/16.3 (C-21), 95.8 (C-22), 62.7 (C-23) and 41.5 (C-24); 1a: d H /d C 1.27 (H-21), 3.12 (H-23), 2.16 and 1.38 (2H-24)/19.0 (C-21), 93.7 (C-22), 60.1 (C-23) and 45.6 (C-24)].…”

“…6a and b). These results suggest a synergistic or additive action of the alkaloids, and the involvement of the three major alkaloids previously isolated from the EtOAc fraction (Torres et al, 2011) that were also found in the CH 2 Cl 2 fraction. This can explain the greater inhibitions obtained using the crude extract and the CH 2 Cl 2 fraction.…”

“…3). This indicated the presence of an imino system, thereby explaining the shielding of the carbon atoms at d 115.3 (C-2), 176.5 (C-3), 115.9 (C-4) and 165.5 (C-5) when compared with the equivalent carbons of 2a, caused by the smaller eletronegativity of the nitrogen atom compared to oxygen (Torres et al, 2011). In the NOESY experiment, the dipolar interaction between the olefinic proton (H-2) and the imino-methylene protons (2H-8 0 ) allowed inference of an E configuration to the carbon-nitrogen double bond (Fig.…”

“…Due the medicinal importance of these plants in traditional medicine in the northeast region of Brazil, efforts have been dedicated to investigation of some species from the Solanaceae, especially those of the genera Acnistus and Solanum (Rocha et al, 2012;Pinto et al, 2011;Veras et al, 2004). A preliminary study of Solanum campaniforme resulted in the isolation of three major solanidane alkaloids from the EtOAc fraction of the EtOH extract, these being active against the Bothrops pauloensis venom (Torres et al, 2011). The study was then extended herein to the dichloromethane fraction of the same EtOH extract, from which were isolated several new minor solanidane alkaloids.…”

One pot rhodium catalysed three component dehydrogenation route to fused and spiro-heterocycles

“…We initially surveyed a range of catalysts based on Pd, Ru, Rh and identified Rh(PPh 3 ) 3 Cl as an effective catalyst for this transformation. 13 Initially we carried out a model e reaction of 2-bromoacetophenone (1 mmol) with piperidine (1 mmol) and triethylamine (1 mmol) in toluene (20 mL) at room temperature.…”