Synthesis, Antibacterial Activity and Molecular Docking of Phospholidinones in Stigmastane Series.

INTRODUCTION: Steroid compounds are widely distributed in nature throughout scientific history. Living organisms such as animals and vegetables have steroids that show a significant effect on their vital activities. Sterols are key components of all eukaryotic cell membranes. METHODS: Steroidal compounds; 3ß-oxo-[1',3',2'-oxathiaphos-phalidine-2'-one] stigmast-5-ene and 3ß- oxo[1`,3`,2`-dioxaphosphalidine-2`-one]-stigmast-5-ene were successfully prepared using easily accessible 3ß-hydroxy stigmast-5-ene with phosphorous oxychloride (POCl3), 2- mercaptoethanol/ethylene glycol and triethylamine (Et3N) in dry diethyl ether. Products were obtained in semi-solid state and characterized using physicochemical techniques. RESULTS: The results of the bioassay showed that the synthesized compound containing the sulfur atom had antibacterial activity. Molecular docking was also done in order to show in silico antibacterial activity and to make out the probable binding mode of compound with the amino acid residues of protein. CONCLUSION: The results of the docking study showed that synthesized compound 2 had minimal binding energy with substantial affinity for the active site.

New Bioactive Semisynthetic Derivatives of 31-Norlanostenol and Obtusifoliol from Euphorbia officinarum.

Fifteen semisynthetic terpenoid derivatives from the major latex components of Euphorbia officinarum have been evaluated against the insect pest Spodoptera littoralis, two species of protozoan parasites, Trypanosoma cruzi and Leishmania infantum, and also against insect Sf9 and mammalian CHO cells to test their selective cytotoxicity. Our results showed that 40% of the test substances were postingestive toxicants to S. littoralis. All the tested derivatives had cytotoxic effects on insect-derived Sf9 cells, whereas mammalian CHO cells were affected by a lower number of compounds (47%). Furthermore, 87% of the test compounds had antiparasitic effects on both L. infantum and T. cruzi, with some of them being selective parasite toxicants.

Synthesis of FF-MAS from lithocholic acid.

An effective synthesis of 4,4 dimethyl-cholest-8,14,24-trien-3beta-ol (FF-MAS) from lithocholic acid is described, utilising a double oxidation and regioselective Wittig reaction as key steps.

Synthesis of [3alpha-3H]cholesta-5,8-dien-3beta-ol and tritium-labeled forms of other sterols of potential importance in the Smith-Lemli-Optiz syndrome.

Five unsaturated sterols relevant to the Smith-Lemli-Opitz syndrome have been prepared in high radiochemical purity with a tritium label at the 3alpha position. Swern oxidation of cholesta-5,8-dien-3beta-ol and other unlabeled C27 sterols afforded the corresponding 3-ketosteroids, and reduction with tritiated NaBH4 gave the desired 3alpha-3H sterols, with double bonds at the delta(5,8), delta(5,8(14)), delta(6,8), delta(6,8(14)), and delta8 positions. High radiochemical purity of the tritiated sterols was demonstrated by normal phase, reversed phase, and silver-ion (Ag+) high-performance liquid chromatography (HPLC). In the course of this work, we developed a medium-pressure variant of Ag+-HPLC for purifying radiolabeled samples, documented significant isotopic fractionation of the 3alpha-tritiated sterols and their acetates on Ag+-HPLC, and discovered unexpected effects of a delta(8(14)) bond on the conformation of 3-keto-delta5-steroids. The synthetic and analytical methodologies described herein should provide a sound basis for investigating the origin and metabolism of sterols involved in the Smith-Lemli-Opitz syndrome and in late stages of cholesterol biosynthesis.

Plant sterol biosynthesis: 7-oxo-obtusifoliol analogues as potential selective inhibitors of cytochrome P-450 dependent obtusifoliol 14 alpha-demethylase.

A series of 7-oxo-obtusifoliol analogues have been synthetized and investigated as potential inhibitors of cytochrome P-450 dependent obtusifoliol 14 alpha-demethylase (P-450OBT.14DM) from higher plant microsomes. 7-Oxo-24 xi(24')-dihydro-obtusifoliol and 7-oxo-24(25)-dihydro-29-nor-lanosterol were potent competitive inhibitors for P-450OBT.14DM, binding 125-200 times more tightly than the substrates obtusifoliol and 24(25)-dihydro-29-nor-lanosterol. Inhibition of P-450OBT.14DM by these analogues showed strict structural requirements including the 8-en-7-one system which was compulsory for binding. 7-Oxo-24(25)-dihydro-lanosterol possessing an additional 4 beta-methyl substituent, did not have such inhibitory effects. Treatment of cultures of suspended bramble cells with 7-oxo-24(25)-dihydro-29-nor-lanosterol resulted in a strong decrease of [14C]acetate incorporation into the demethylsterols fraction and in an accumulation of [14C]obtusifoliol. This confirms that P-450OBT.14DM is the main in vivo target of 7-oxo-24(25)-dihydro-29-nor-lanosterol in the sterol-biosynthetic pathway.

Properties and structural requirements for substrate specificity of cytochrome P-450-dependent obtusifoliol 14 alpha-demethylase from maize (Zea mays) seedlings.

The biochemical properties of cytochrome P-450-dependent obtusifoliol 14 alpha-demthylase (P-450OBT.14DM) from maize (Zea mays) seedlings were defined. In particular, the enzyme was shown by differential centrifugation to be localized in the endoplasmic reticulum. P-450OBT.14DM had an apparent Km of 160 +/- 5 microM and an apparent Vmax of 65 +/- 5 pmol/min per mg of protein for its best substrate, obtusifoliol. The substrate specificity of P-450OBT.14DM was thoroughly investigated by comparing the demethylation of obtusifoliol with that of a series of 15 natural or novel synthetic analogues of obtusifoliol. The results obtained clearly indicate that three distinct domains of the sterol substrate are governing obtusifoliol demethylation by P-450OBT.14DM. They revealed that (i) P-450OBT.14DM has probably a specific apolar binding site for the side chain, (ii) the delta 8-double bond is an absolute requirement for substrate demethylation and (iii) the 3-hydroxy group plays a critical role in the enzyme-substrate interaction. Interestingly the binding site, beyond the C-3 position, contains a cleft which cannot accommodate a 4 beta-methyl substituent present in lanosterol or eburicol, the precursors of 14-desmethylsterols respectively in mammals and yeast. This result indicates that P-450OBT.14DM is a novel constitutive cytochrome P-450 with a high degree of substrate and product specificity.

Concerning the structure of 3 beta-benzoyloxy-5 beta-cholesta-8,14-diene, a major byproduct in the chemical synthesis of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one.

The X-ray crystal structure of 3 beta-(p-bromobenzoyloxy)-5 beta-cholesta-8,14-diene (space group P21, a = 10.698 A, b = 9.487 A, c = 15.024 A, beta = 96.05 degrees, Z = 2) was determined by the heavy atom method and refined to R = 0.075. This heavy atom derivative was synthesized from 5 beta-cholesta-8,14-diene-3 beta-ol, the benzoate ester of which was previously shown to be the major byproduct in the low-temperature isomerization of 7-dehydrocholesteryl benzoate in HCl/chloroform. The work presented here establishes unequivocally that the configuration of this isomerization byproduct at C-5 is 5 beta-H and that the configuration at C-17 was unchanged.

Synthesis of 14 beta-cholesta-5,7-dien-3 beta-ol.

5,7-Cholestadien-3 beta-ol was transformed into 14 beta-cholesta-5,7-dien-3 beta-ol in six steps. The inversion of the stereochemistry at C-14 was obtained by a selective protection of the delta 5 and the elaboration of the delta 7 double bond.

Chemical synthesis, spectral properties, and chromatography of 4alpha-methyl and 4beta-methyl isomers of (24R)-24-ethyl-5alpha-cholestan-3beta-ol and (24S)-24-ethyl-cholesta-5,22-dien-3beta-ol.

Described herein are chemical syntheses of the following compounds: 4-methyl-(24S)-24-ethyl-cholesta-4,22-dien-3-one, 4,4-dimethyl-(24S)-24-ethyl-cholesta-5,22-dien-3-one, 4beta-methyl-(24R)-24-ethyl-5alpha-cholestan-3beta-ol, 4alpha-methyl-(24R)-24-ethyl-5alpha-cholestan-3beta-ol, 4alpha-methyl-(24S)-24-ethyl-5alpha-cholest-22-en-3beta-ol, 4-methyl-6beta-bromo-(24S)-24-ethyl-cholesta-4,22-dien-3-one, 4alpha-methyl-(24S)-24-ethyl-cholesta-5,22-dien-3beta-ol, 4alpha,5alpha-epoxy-(24S)-24-ethyl-cholesta-4,22-dien-3beta-yl acetate, 4beta-methyl-(24S)-24-ethyl-cholest-22-en-3beta,5alpha-diol, 4beta-methyl-5alpha-hydroxy-(24S)-24-ethyl-cholest-22-en-3beta-yl acetate, 4beta-methyl-(24S)-24-ethyl-cholesta-5,22-dien-3beta-yl acetate and 4beta-methyl-(24S)-24-ethyl-cholesta-5,22-dien-3beta-ol. Chromatographic, nuclear magnetic resonance, and mass spectral data are presented for the compounds under consideration.