Synthesis and Antiproliferative Activity of Some Steroidal Lactams

Using cholesterol as starting material, a series of 6-substituted-3-aza-A-homo-3-oxycholestanes and 6-substituted-4-aza-A-homo-3-oxycholestanes were synthesized by the oxidation, reduction, oximation, Beckman rearrangement and condensation reaction. These synthesized compounds displayed a distinct cytotoxicity against MGC 7901, HeLa and SMMC 7404 cancer cells. Our results revealed that the structures of functional groups at position-6 on the steroidal ring are crucial for the IC50 value of antiproliferative activities of these compounds and the cytotoxic activity against MGC 7901 and SMMC 7404 cells was not significantly different between 4-N-lactams and 3-N-lactams when its 6-substituted group was a carbonyl or a hydroximino, but all 3-N-lactams showed a higher cytotoxicity against HeLa cells than 4-N-lactams. In particular, compounds 6, 8, 9 (IC506: 6.5 μmol/L; 8: 7.7 μmol/L; 9: 5.6 μmol/L) were even more cytotoxic than cisplatin to HeLa cells (positive contrast, 10.1 μmol/L). The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs

Synthesis and Evaluation of Some Steroidal Oximes as Cytotoxic Agents: Structure/Activity Studies (II)

Hydroximinosteroids isolated from marine sponges display a variety of biological functions including cytotoxicity and anti-virus. In this study, we synthesized a series of hydroximinosteroid derivatives with a different functional group on the ring A or B and various side chains at position 17, and analyzed the cytotoxicity of these compounds against sk-Hep-1, H-292, PC-3 and Hey-1B cancer cells. Our results revealed that although a cholesterol-type side chain at position 17 is required for the biological activity of the compounds as we previously confirmed, elimination of the 4,5-double bond augmented the cytotoxic activity for the steroidal oximes. In addition, the presence of a hydroxy on 3- or 6-position of the steroidal nucleus resulted in a remarkable increase of cytotoxic activity. Our findings present more evidence showing the relationship between the chemical structure and biological function

Synthesis and Evaluation of Some Steroidal Oximes as Cytotoxic Agents: Structure/Activity Studies (II)

Hydroximinosteroids isolated from marine sponges display a variety of biological functions including cytotoxicity and anti-virus. In this study, we synthesized a series of hydroximinosteroid derivatives with a different functional group on the ring A or B and various side chains at position 17, and analyzed the cytotoxicity of these compounds against sk-Hep-1, H-292, PC-3 and Hey-1B cancer cells. Our results revealed that although a cholesterol-type side chain at position 17 is required for the biological activity of the compounds as we previously confirmed, elimination of the 4,5-double bond augmented the cytotoxic activity for the steroidal oximes. In addition, the presence of a hydroxy on 3- or 6-position of the steroidal nucleus resulted in a remarkable increase of cytotoxic activity. Our findings present more evidence showing the relationship between the chemical structure and biological function

Synthesis and Evaluation of Some Steroidal Oximes as Cytotoxic Agents: Structure/Activity Studies (II)

Hydroximinosteroids isolated from marine sponges display a variety of biological functions including cytotoxicity and anti-virus. In this study, we synthesized a series of hydroximinosteroid derivatives with a different functional group on the ring A or B and various side chains at position 17, and analyzed the cytotoxicity of these compounds against sk-Hep-1, H-292, PC-3 and Hey-1B cancer cells. Our results revealed that although a cholesterol-type side chain at position 17 is required for the biological activity of the compounds as we previously confirmed, elimination of the 4,5-double bond augmented the cytotoxic activity for the steroidal oximes. In addition, the presence of a hydroxy on 3- or 6-position of the steroidal nucleus resulted in a remarkable increase of cytotoxic activity. Our findings present more evidence showing the relationship between the chemical structure and biological function

Alternans in Genetically Modified Langendorff-Perfused Murine Hearts Modeling Catecholaminergic Polymorphic Ventricular Tachycardia

The relationship between alternans and arrhythmogenicity was studied in genetically modified murine hearts modeling catecholaminergic polymorphic ventricular tachycardia (CPVT) during Langendorff perfusion, before and after treatment with catecholamines and a β-adrenergic antagonist. Heterozygous (RyR2p/s) and homozygous (RyR2s/s) RyR2-P2328S hearts, and wild-type (WT) controls, were studied before and after treatment with epinephrine (100 nM and 1 μM) and propranolol (100 nM). Monophasic action potential recordings demonstrated significantly greater incidences of arrhythmia in RyR2p/s and RyR2s/s hearts as compared to WTs. Arrhythmogenicity in RyR2s/s hearts was associated with alternans, particularly at short baseline cycle lengths. Both phenomena were significantly accentuated by treatment with epinephrine and significantly diminished by treatment with propranolol, in full agreement with clinical expectations. These changes took place, however, despite an absence of changes in mean action potential durations, ventricular effective refractory periods or restitution curve characteristics. Furthermore pooled data from all hearts in which arrhythmia occurred demonstrated significantly greater alternans magnitudes, but similar restitution curve slopes, to hearts that did not demonstrate arrhythmia. These findings thus further validate the RyR2-P2328S murine heart as a model for human CPVT, confirming an alternans phenotype in common with murine genetic models of the Brugada syndrome and the congenital long-QT syndrome type 3. In contrast to these latter similarities, however, this report demonstrates the dissociation of alternans from changes in the properties of restitution curves for the first time in a murine model of a human arrhythmic syndrome