Medicinal Chemistry - Volume 9, Issue 5, 2013

Cinnamic acid derivatives can be found in plant material, and they possess a remarkable variety of biological effects. In the present study, we have investigated the cytotoxic effects of representative cinnamic acid esters and amides. The cytotoxicity was determined by MTT test on human cervix adenocarcinoma (HeLa), myelogenous leukemia (K562), malignant melanoma (Fem-x), and estrogen-receptor-positive breast cancer (MCF-7) cells, versus peripheral blood mononuclear cells (PBMCs) without or with the addition of the plant lectin phytohemaglutinin (PHA). The compounds tested showed significant cytotoxicity (IC50s between 42 and 166 µM) and furthermore selectivity of these cytotoxic effects on the malignant cell lines versus the PBMCs was also seen, especially when electron-withdrawing groups, such as a cyano group (compound 5), were present on the aromatic rings of the alcohol or amine parts of the cinnamic acid derivatives. The additional study on cell cycle phase distribution indicated that novel cinnamic acid derivatives inhibit cell growth by induction of cell death. Thus, cinnamic acids derivatives represent important lead compounds for further development of antineoplastic agents.

Tubulin is the one of the most useful and strategic molecular targets for anticancer drugs. Agents that bind in Colchicine-binding site of tubulin include Phenstatin, Combretastatin A-4, Colchicine, Steganacin, Podophyllotoxin and certain other synthetic analogues of these compounds. Arylidene pyrollo and pyrido [2,1- b] quinazolones (isoindigatone and its synthetic analogues) have been earlier reported to be tubulin inhibitors evidenced by tubulin polymerization assay. The present study is an extension of the library of the isoindigatone and its synthetic analogues to generate the structure activity relationship. The study explores the role of the arylidene ring and also provides some intresting observations such as the placement of bicyclic ring such as naphylidene for potential activity. Some of the important interactions of KNH- 3 and KNH-11 with the amino acid residues of active site of Tubulin have also been observed by molecular modeling.

As a continuation of our efforts to develop the benzimidazole-PBD conjugates as potential anticancer agents, a series of heteroaryl substituted benzimidazole linked PBD conjugates has been synthesized and evaluated for their anticancer potential in 60 human cancer cell lines. Most of the compounds exhibited promising anticancer activity and interestingly, compounds 4c and 4d displayed significant activity in most of the cell lines tested. Whereas, compound 4e showed selectivity in renal cancer cells with GI50 values of < 10 and 70 nM against RXF 393 and UO-31 cell lines, respectively. Further, these compounds also showed significant DNA-binding affinity by thermal denaturation study using duplex form of calf thymus (CT) DNA.

A series of peptidomimetic containing bidentate pTyr mimetics (9a-w) are reported as potent and selective PTP1B inhibitors. Compounds (9p and 9q) showed excellent selectivity towards PTP1B over various PTPs, including TCPTP (in vitro), which confirms discovery of highly potent and selective PTP1B inhibitors.

SBA-15 type ordered silicas possessing amino groups attached onto their surfaces were prepared by using two different functionalization methodologies. These matrices were used for the cephalexin adsorption from aqueous solution and further kinetic study of its release into physiological solution. The materials were characterized by nitrogen adsorption/ desorption, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-Ray photoelectron spectrometry (XPS) and thermo analytical methods (TG/DSC). UV–visible spectroscopy at 262 nm was used for quantitative determination of cephalexin present in liquid media. Results reveal that drug adsorption capacities and the corresponding release profiles are dependent on the number of loaded amino groups and their location, which in turn is determined by the functionalization procedure used. It was concluded that amino post-functionalization could enhance long-term cephalexin delivery in comparison with co-functionalization procedure.

Oxindole derivatives 3-25 have been synthesized from commercially available oxindole by refluxing with different aromatic aldehydes in good yields. Their in vitro antiglycation potential has been evaluated. They showed a varying degree of antiglycation activity with IC50 values ranging between 150.4 - 856.7 µM. 3-[(3-Chlorophenyl)methylidene]- 1,3-dihydro-2H-indol-2-one (IC50 = 150.4 ± 2.5 µM) is the most active compound among the series, better than the standard rutin with an IC50 value 294.5 ± 1.50 µM. The structures of the compounds were elucidated by 1H-NMR and mass spectroscopy and elemental analysis. A limited structure-activity relationship has been developed.

Nerve agents such as sarin, VX and tabun are organophosphorus compounds able to inhibit an enzyme acetylcholinesterase (AChE). AChE reactivators and anticholinergics are generally used as antidotes in the case of intoxication with these agents. None from the known AChE reactivators is able to reactivate AChE inhibited by all kinds of nerve agents. In this work, reactivation potency of seventeen structurally different AChE reactivators was tested in vitro and subsequently, relationship between their chemical structure and biological activity was outlined. VX was chosen as appropriate member of the nerve agent family.

The study aimed to synthesize and evaluate substituted 4-methyl-2-oxo-2H-chromen-7-yl phenylcarbamates as potent acetylcholinesterase (AChE) inhibitors and anti-amnestic agents. The compounds were evaluated for AChE and butyrylcholinesterase (BuChE) inhibitory activity in rat brain homogenate and plasma, respectively. The most potent test compound 4d was evaluated for memory testing in scopolamine-induced amnesia. The phenylcarbamate substituted coumarins (4a-4h) demonstrated more potent AChE inhibitory as compared to parent 7-hydroxy-4-methylcoumarin. The introduction of phenylcarbamate moiety to coumarin template also significantly increased BuChE inhibitory activity, albeit less than AChE inhibitory activity with approximate BuChE/AChE selectivity ratio of 20. The compound 4d displayed the most potent AChE inhibitory activity with IC50 = 13.5 ± 1.7 nM, along with amelioration of amnesia in mice in terms of restoration of time spent in target quadrant and escap latency time. It is concluded that carbamate derivatives of coumarin may be employed as potential AChE inhibitors and anti-amnestic agents.

Acetylcholinesterase inhibitors are the most frequently prescribed anti-Alzheimer’s drugs. A series of 6-acetyl- 5H-thiazolo[3,2-a]pyrimidine derivatives as the novel acetylcholinesterase inhibitors were designed based on virtual screening methods. The target compounds which are not reported in the literature were synthesized with Biginelli reaction and Hantzsch-type condensation of dihydropyrimidines with substituted phenacyl chlorides, and were characterized with elemental analysis, IR, MS, 1H-NMR and 13C-NMR. The biological evaluation against human acetylcholinesterase in vitro showed most of the target compounds exhibited varying inhibition at 10 µM using the Ellman method. The results provide a starting point for the development of novel drugs to treat Alzheimer’s disease, and a foundation in search for improved acetylcholinesterase inhibitors with the novel scaffolds. The preliminary structure-activity relationships were the 2-hydroxyethoxy group at the phenyl ring at C4 position of the parent nucleus played significant roles in the AChE inhibitory activity of the target compounds.

A series of (Z)-N-(1-(2-(2-amino-3-((dimethylamino) methyl) phenyl)-5-phenyl-1,3,4,oxadiazol-3(2H)- yl)ethanone derivatives was prepared and studied for its antimicrobial and antioxidant activities. Among the synthesized derivatives, compounds (7c) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4-oxadiazol-3(2H)- yl)ethylidene)-4-chloroaniline, (7g) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4-oxadiazol- 3(2H)-yl)ethylidene)-4-nitroaniline and (7i) (Z)-N-(1-(2-(2-amino-3-((dimethylamino)methyl)phenyl)-5-phenyl-1,3,4- oxadiazol-3(2H)-yl)ethylidene)-4-methoxyaniline were found to be the most effective antimicrobial compounds. While the compounds 7c and 7g were the most potent antioxidant compounds with significant hydrogen peroxide scavenging activity.

A new series of 4,5-dihydro-2H-indazoles was synthesized and evaluated for anti-inflammatory activity using formalin-induced paw edema and turpentine oil-induced granuloma pouch bioassays. In addition, the inhibitory activity of cyclooxygenase, ulcerogenic effect, and acute toxicity (ALD50) values were also determined. Compounds 10, 13, 15, 16, 18 and 22 were proved to display distinctive anti-inflammatory profiles with a fast onset of action. They revealed super GI safety profile and are well tolerated by the experimental animals with high safety margin (ALD50 > 300 mg / Kg). The same active compounds exhibited moderate to powerful selectivity profile towards the inhibition of COX-2 enzyme. Docking poses for the most active compounds separately in the active site of human COX-2 enzyme were also obtained.

Compounds with different sets of three of the four functional groups of (1R,2R,6S)-3-methyl-6-(prop-1-en-2- yl)cyclohex-3-ene-1,2-diol 1 possessing high antiparkinsonian activity were synthesized. The synthesized compounds were tested for the antiparkinsonian activity in vivo on a mouse model with MPTP neurotoxin. A pronounced antiparkinsonian effect of 1 can only be achieved if it contains all the four functional groups (two hydroxy groups and two double bonds). The 2-hydroxy group or the 3,4-double bond is not required for stimulating the exploratory activity of the animals.

Thirty etopside esters of malic acid were synthesized and have been shown to exhibit improved aqueous solubility and stability in neutral solution except for compounds 7Ia-c and 9Ia-c. Compounds 6Ia–c, 6IIb-c, 8Ia-b and 10Ib have been shown to function as prodrugs, whereas the other synthesized derivatives were too stable to reveal parent drugs in vivo. Among synthesized compounds, 8Ib, 4’-O-demethyl 4’-L-malyl epipodophyllotoxins showed the most potent anticancer activity and favorable stability in vitro.

Certain 4,5-diarylisoxazole derivatives have been found to possess broad biological effects, including antiinflammatory and anticancer activities. Recently, we have reported preparation of certain isoflavone derivatives and investigated for their anti-osteoporotic and antiproliferative activities in a detailed SAR study. The present report describes the conversion of isoflavones into novel 4,5-diphenylisoxazole derivatives by the treatment with NH2OH. Alkylation followed by amination of these 4,5-diphenylisoxazoles gave the desired aminoalkoxy substituted 4,5-diphenylisoxazole derivatives. These compounds were evaluated in vitro for the osteogenic differentiation and quantification of mineralization. Although 5-isopropoxy-2-[4-(4-methoxyphenyl)isoxazol-5-yl]phenol (3) exhibited approximately 2.8-fold more activity than the positive Ipriflavone in the promotion of osteoblast activity (277% mineralization), the low cell viability (6%) and high cytotoxicity (68%) prompted us to further pursue more suitable candidates. A series of aminoalkyl side chains were introduced with aims to decrease cytotoxicity. Among them, 5-{4-isopropoxy-2-[4-(pyrrolidin-1-yl)butoxy]phenyl}-4-(4- methoxyphenyl)isoxazole (7a) exhibited approximately 2-fold more activity than the positive Ipriflavone in the promotion of osteoblast activity (194% mineralization) with comparable cell viability (71% v.s. 77%). Compound 7a was non cytotoxic against hADSCs and therefore, was selected as a lead for further structural optimization.

The present study has been aimed to assess the antibacterial effects of the glucosinolate hydrolysis product phenyl isothiocyanate (PITC) against Escherichia coli and Staphylococcus aureus. Aspects on the antibacterial mode of action of PITC have also been characterized, such as the changes on surface physicochemical characteristics and membrane damage. The minimum inhibitory concentration of PITC was 1000 μg/mL, for both bacteria. The antimicrobial potential of PITC was compared with selected antibiotics (ciprofloxacin, erythromycin, streptomycin, tetracycline and spectinomycin), that reported a moderate effect. The combination of PITC with ciprofloxacin and erythromycin against S. aureus exhibited a good antimicrobial efficacy, due to an additive effect (the diameter of inhibition zones increased from 30 to 40 mm for ciprofloxacin and almost the double for erythromycin). The other combinations reported unsatisfactory results against both bacteria. The study of the physiological changes induced by PITC action demonstrated the interaction between the electrophilic compound and the bacterial cells at several points that causes changes in membrane properties (decreases negative surface charge, increases surface hydrophilicity and electron donor characteristics). PITC was also found to disturb membrane function, as manifested by phenomena such as cellular disruption and loss of membrane integrity, triggering cell death.