Solvent-free synthesis of 6β-phenylamino-cholestan-3β,5α-diol and (25R)-6β-phenylaminospirostan-3β,5α-diol as potential antiproliferative agents

Synthesis of fully functionalized spirostanic 1,2,3-triazoles by the three component reaction of diosgenin azides with acetophenones and aryl aldehydes and their biological evaluation as antiproliferative agents

Diosgenin is of significant interest due to its biological activity and synthetic application. In this study, we report the synthesis of a series of spirostanic 1,4,5-trisubstituted 1,2,3-triazoles by the three component reaction of (25R)-6-azidospirostan-3,5-diols with acetophenones and aryl aldehydes. The one-pot two step synthesis proceeds through the in situ formation of (E)-chalcones and copper catalyzed reaction with organic azides in DMF medium. Structural diversity was achieved by varying the aldehyde and acetophenone nature as well as the spirostanic azide stereochemistry. The results of in vitro biological assays showed that fully decorated spirostanic 1,2,3-triazoles exerted significant and selective antiproliferative activity against MCF-7, glioblastoma (SNB-19, T98G, A-172) and neuroblastoma (IMR-32, SH-SYSY) (HCT116) cell lines (GI₅₀ in the single-digit micromolar range). The data revealed that benzoyl and aryl substitutions in the triazole ring introduced at the 6β-position significantly improved the anti-tumor activity of (25R)-6-azidospirostan-3β,5α-diols. This position on the spirostan core may be the favourable to synthesize of potent anticancer leads from diosgenin.

Highly regioselective ring-opening of epoxides with amines: a metal- and solvent-free protocol for the synthesis of β-amino alcohols

We herein report a metal- and solvent-free acetic acid-mediated ring-opening reaction of epoxides with amines. This process provides β-amino alcohols in high yields with excellent regioselectivity. Importantly, this epoxide ring-opening protocol can be used for the introduction of amines in natural products during late-stage transformations.

6-(4'-Aryl-1',2',3'-triazolyl)-spirostan-3,5-diols and 6-(4'-Aryl-1',2',3'-triazolyl)-7-hydroxyspirosta-1,4-dien-3-ones: Synthesis and analysis of their cytotoxicity

In an endeavour to develop potent anti-tumor agents from diosgenin, a series of C-6 derived 1,2,3-triazolyl derivatives were designed and synthesized by employing Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition reaction of novel azides - (22R,25R)-6β-azidospirostan-3β,5α-diol and 6β-azido-7α-hydroxyspirosta-1,4-dien-3-one with aryl(hetaryl)alkynes. All the derivatives were evaluated for cytotoxic activity by MTT assay against eight different human cancer cell lines: T-cellular leucosis (CEM-13), human monocytes (U-937), breast (MDA-MB-231, BT-474), prostate (DU-145) and glioblastoma (U-87MG, SNB-19, T98G). The results of this study suggested that 6-(4'-aryl-1',2',3'-triazolyl)spirostan-3,5-diols 2, 3, 4, 5 and 6 possessed a promising cytotoxic potential. The corresponding 6-substituted 7-hydroxy-1,4-spirostadien-3-ones shown less cytotoxity on the human cancer cells. Compounds 2, 3, 4, and 5 which demonstrated high grown inhibition against glioma cancer cells U-87 and T98G, and also on the human-derived N118669 primary glioblastoma cell line (with GI₅₀ values in the range of 5-9 μM), were not affected the growth of SNB-19 cells. The data revealed that phenyl, 4-methoxyphenyl, 4-fluorophenyl, 3,4,5-trimethoxyphenyl or 2-pyridinyl substituent in the triazole moiety at the C-6 position significantly improved the anti-tumor activity. The mentioned position at the spirostan core may be favourable for the synthesis of potent anticancer leads from diosgenin.

Bioprospecting of whole-cell biocatalysts for cholesterol biotransformation

Microorganisms were isolated from industrial wool scouring effluents and from the soil adjacent to the wastewater treatment lagoon, both sterols-rich environments, in order to search for novel biocatalysts able to transform cholesterol. The isolates were identified on the basis of morphological and biochemical characteristics and phylogenetic analysis. Furthermore, a rapid and accurate bacteria identification by matrix assisted laser desorption/ionization-time-of-flight mass spectrometry was carried out. Bacteria and fungi including representatives of the genera Fusarium, Talaromyces, Trichoderma, Mucor, Aspergillus, Citrobacter, Proteus, Klebsiella, Exiguobacterium, Acinetobacter, Tsukamurella, Bacillus, and Streptomyces were found and evaluated for their ability to biotransform cholesterol by whole-cell treatment system. The results show that a Trichoderma koningiopsis strain, as well as two strains of Mucor circinelloides were able to transform cholesterol into value-added products. The major products were characterized as 7β-hydroxycholesterol, 4-cholesten-3-one, 5α,6α-epoxycholestan-3β-ol and 5β,6β-epoxycholestan-3β-ol. To the best of our knowledge, the present study is the first report of cholesterol biotransformation by representatives of Trichoderma and Mucor genera.

Cholesterol-Based Compounds: Recent Advances in Synthesis and Applications

This review reports on the latest developments (since 2014) in the chemistry of cholesterol and its applications in different research fields. These applications range from drug delivery or bioimaging applications to cholesterol-based liquid crystals and gelators. A brief overview of the most recent synthetic procedures to obtain new cholesterol derivatives is also provided, as well as the latest anticancer, antimicrobial, and antioxidant new cholesterol-based derivatives. This review discusses not only the synthetic details of the preparation of new cholesterol derivatives or conjugates, but also gives a short summary concerning the specific application of such compounds.