Efficient microwave assisted access to chiral O-(alpha-protected-aminoacyl)steroids

Microwave-assisted synthesis of a novel steroid-derived Schiff base chemosensor for detection of Al3+ in aqueous media

A novel steroid-derived Schiff base chemosensor, N′-(2-hydroxybenzylidene)-3α-hydroxy-cholanhydrazide (LA), has been designed and prepared via microwave irradiation. The sensor LA showed highly selective fluorescent sensing for Al3+ with a low detection limit of 34 nM in the pH range from 6.05 to 9.32 in ethanol/water (1:2, v/v) solution. The binding stoichiometry between LA and Al3+ was determined as 1:1 by Job’s plot and further verified with 1H NMR studies. Under a UV lamp, the fluorescence color changes could be easily detected by the naked eye. In addition, the sensor LA has been applied in detection of Al3+ in real water samples.

An Acid-Catalyzed Addition and Dehydration Sequence for the Synthesis of Heteroarylated Steroidal Dienes

Additions of heteroarenes to hormone steroids containing an α,β-unsaturated ketone are reported. Additions of a range of electron-rich heteroarene nucleophiles, including indoles, a pyrrole, and a thiophene, to a variety of commercially available steroids and subsequent dehydration formed 3-heteroarylated steroidal dienes in up to 93% yield. This atom-economical reaction sequence occurs under mild reaction conditions in the presence of catalytic bismuth triflate.

Rational approaches, design strategies, structure activity relationship and mechanistic insights for anticancer hybrids

A Hybrid drug which comprises the incorporation of two drug pharmacophores in one single molecule are basically designed to interact with multiple targets or to amplify its effect through action on another bio target as one single molecule or to counterbalance the known side effects associated with the other hybrid part(.) The present review article offers a detailed account of the design strategies employed for the synthesis of anticancer agents via molecular hybridization techniques. Over the years, the researchers have employed this technique to discover some promising chemical architectures displaying significant anticancer profiles. Molecular hybridization as a tool has been particularly utilized for targeting tubulin protein as exemplified through the number of research papers. The microtubule inhibitors such as taxol, colchicine, chalcones, combretasatin, phenstatins and vinca alkaloids have been utilized as one of the functionality of the hybrids and promising results have been obtained in most of the cases with some of the tubulin based hybrids exhibiting anticancer activity at nanomolar level. Linkage with steroids as biological carrier vector for anticancer drugs and the inclusion of pyrrolo [2,1-c] [1,4]benzodiazepines (PBDs), a family of DNA interactive antitumor antibiotics derived from Streptomyces species in hybrid structure based drug design has also emerged as a potential strategy. Various heteroaryl based hybrids in particular isatin and coumarins have also been designed and reported to posses' remarkable inhibitory potential. Apart from presenting the design strategies, the article also highlights the structure activity relationship along with mechanistic insights revealed during the biological evaluation of the hybrids.

Synthesis and anti-tumor evaluation of novel 25-hydroxyprotopanaxadiol analogs incorporating natural amino acids

In the current study, derivatives of 25-hydroxyprotopanaxadiol (25-OH-PPD) were prepared and their in vitro anti-tumor activities were tested on six different human tumor cell lines by standard MTT assay. The results showed that combining an ester group combined with the presence of an amino acid moiety led to a 10-fold improved anti-tumor activity. Compound 1c exhibited the best anti-tumor activity in the in vitro assays. Compounds 2c, 3c, 4c, 5c, 6c and 8b showed better anti-tumor activities compared to the parent compound 25-OH-PPD. The current results may provide useful data for researching and developing new anti-cancer agents.

Microwave-assisted synthesis and in vitro antibacterial activity of novel steroidal thiosemicarbazone derivatives

Herein, we reported the synthesis of 16 novel steroidal thiosemicarbazone derivatives via the condensation of steroidal ketones and substituted thiosemicarbazides under solvent-free conditions using microwave irradiation. The yields obtained are in the range of 84-96% using microwave method and 46-62% using conventional method. All the synthesized compounds (7a-p) have been characterized by (1)H NMR, ESI-MS, IR and elemental analyses. All the series compounds (7a-p) were evaluated for their antibacterial activity against and the results were compared with the standard drug Amoxicillin. Some of the compounds from the series like 7c, 7o and 7p were equipotent with Amoxicillin against Pseudomonas aeruginosa. Also compound 7h was better than Amoxicillin against Staphylococcus aureus and Bacillus subtilis.

Design, synthesis and stimuli responsive gelation of novel stigmasterol-amino acid conjugates

An efficient synthesis of three novel stigmasterol-amino acid (glycine, L-leucine and L-phenylalanine) conjugates as stimuli responsive gelators is reported. The gelation properties of the prepared compounds were investigated in a variety of organic as well as aqueous solvents. The most striking finding of our investigation was that the hydrochloride salts of the prepared conjugates acted as gelators, whereas the neutral conjugates were either non-gelators or formed only a weak gel in anisole. The hydrochloride salts of stigmasteryl glycinate and L-leucinate form gels in n-alcohols (n=4-10) and in ethane-1,2-diol, and that of stigmasteryl L-phenylalaninate forms gels in aromatic solvents and in tetrachloromethane. These unique properties of the gelators were explored to prepare stimuli responsive, "acid-base" triggered reversible sol-gel transitions. The gelators and their gels were characterized by liquid and solid-state NMR as well as FT-IR. The morphology of their corresponding xerogels was investigated by SEM.

Synthesis of New Deoxycholic Acid bis Thiocarbazones under Solvent-Free Conditions using Microwave Irradiation

A simple method for the synthesis of new deoxycholic acid bis thiocarbazones under solvent-free conditions using microwave irradiation has been developed. Its main advantages are short reaction times, good conversions and the environmentally friendly nature of the process. Their structures were characterised by 1H NMR, IR, ESI-MS spectra and elemental analysis. The preliminary results indicate that some of these compounds possess inhibitory effects against Escherichia coli.

Hybrid anticancer agents: isothiocyanate-progesterone conjugates as chemotherapeutic agents and insights into their cytotoxicities

New hybrid molecules of isothiocyanate and progesterone and their metal complexes were synthesized exhibiting promising anti-proliferative and pro-apoptotic activity against breast and prostate cancer cells. These metal complex compounds exploited an existing cellular transport pathway for delivery of cytotoxic isothiocyanate moiety across cell membrane resulting in the inhibition of cell viability and inducing apoptosis. The highest apoptotic action was shown by the copper complex, which was mediated through the inhibition of Akt signaling similar to the one shown by isothiocyanate compounds. Our results underscore the possible role of metal redox cycling, and thus it is likely will open newer avenues for further optimization for the synthesis of novel active compounds through appropriate isothiocyanate pharmacophores.

1-Benzotriazol-1-yl-3,3,3-trifluoro-2-methoxy-2- phenylpropan-1-ones: Mosher-Bt Reagents

Benzotriazole derivatives of 3,3,3-trifluoro-2-methoxy-2-phenylpropionic acid react with water-soluble amino acids and peptides in an acetonitrile/water (2:1) mixture to give the corresponding amides in quantitative yield.