Antifungal activity of some mono, bis and quaternary Mannich bases derived from acetophenone

The development of resistance to current antifungal therapeutics drives search for new effective agents. Some Mannich bases have antifungal activity, but no information is available regarding the antifungal activity of acetophenone derived Mannich bases. Mono Mannich bases of acetophenone 1-3 were synthesized and converted into their corresponding bis derivatives, 5-7. Representative quaternary derivatives 4 and 8 were also synthesized. Antifungal activities of the compounds were evaluated using some yeasts and dermatophytes in vitro. Mono Mannich base 3 and quaternary compounds 4 and 8 were found to be 2-16 times more potent than the reference compound amphotericin B against dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes, and Microsporum canis. Compounds 4 and 8 were also found to be 2 times more effective compared with amphotericin B against the yeast Saccharomyces cerevisiae. Quaternization procedure improved the biological activity dramatically, whereas conversion of mono Mannich bases to corresponding bis derivatives generally did not affect antifungal activity. Our results suggest that acetophenone derived mono Mannich base 3 and quaternary derivatives 4 and 8 may serve as leading compounds for further studies to develop new antifungal agents with their highly potent antifungal activity.     

Synthesis and anticonvulsant evaluation of semicarbazones of acetophenone Mannich bases

Several semicarbazones of acetophenone and p-chloroacetophenone Mannich bases were designed and synthesized to meet the pharmacophore requirements essential for anticonvulsant activity. Mannich bases of acetophenone and p-chloroacetophenone were prepared by reacting formaldehyde with various secondary amines and then condensed with several aryl semicarbazides to yield the corresponding semicarbazones. All compounds were evaluated for their anticonvulsant activity by maximal electroshock (MES) and by subcutaneous metrazole (ScMet) and strychnine (ScSty) induced seizure methods, and their neurotoxic effects were determined using the rotorod test. The title compounds were also investigated for antidepressant and sedative-hypnotic potentiation properties. It is established that 3-[3-chlorophenyl(β-dimethylaminopropiophenone)semicarbazone] has excellent anticonvulsant activity in MES, ScSty, and ScMet tests and exhibits a potent antidepressant effect in the absence of sedative-hypnotic potentiation. The present study has proved our earlier hypothesis concerning the pharmacophore model with essential binding sites for semicarbazones. The inclusion of an additional moiety (CH₂-CH₂-N<) at the electron donor acceptor group retained the anticonvulsant activity. Published in Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 6, pp. 15–19, June, 2007.     

Cytotoxic activities of some mono and bis Mannich bases derived from acetophenone in brine shrimp bioassay

Some mono Mannich bases (1-phenyl-3-amino-1-propanone salts) and bis Mannich bases (1-phenyl-3-amino-2-amino-methyl-1-propanone salts) derived from acetophenone and a few representative quaternary derivatives were synthesised and their cytotoxicity was tested using the brine shrimp bioassay. This assay may serve as an intermediate test before further in vivo animal experiments in large scale, since brine shrimp nauplii as whole organisms were used in this test. Mono Mannich bases were generally more cytotoxic than their corresponding bis Mannich bases. Mannich bases synthesised were cytotoxic in both brine shrimp bioassay in this study and cell culture tests using Jurkat and Renca cells in a previous study. However, the order of the cytotoxic potency of the compounds were reverse, which may result from faster deamination of bis derivatives than optimal level, and different species and test media used in the two test systems. Faster deamination of bis derivatives might have led to elimination of active metabolites before reaching its target. The cytotoxicity of the compounds might have been altered by amino acids and proteins present in cell culture medium but not in sea water used in brine shrimp bioassay affecting their transport through the cell membrane and metabolism in the cell by binding with the compounds. With higher cytotoxic activity compared with 5-fluorouracil (CAS 51-21-8) in brine shrimp bioassay, mono Mannich base 1 and its quaternary derivative 4 and quaternary bis derivative 8 seem to be candidate compounds for further drug design.     

Synthesis of some Mannich bases with dimethylamine and their hydrazones and evaluation of their cytotoxicity against Jurkat cells

1-Aryl-3-dimethylamino-1-propanone hydrochlorides type mono Mannich bases, D series, and corresponding hydrazone derivatives, K series, were synthesized and their cytotoxicity was tested against Jurkat cells (transformed human T-lymphocytes). The aryl part was changed as phenyl in D1 and K1, 4-methylphenyl in D2 and K2, 4-methoxyphenyl in D3 and K3, 4-hydroxyphenyl in D4 and K4, 4-chlorophenyl in D5 and K5, 3-methoxyphenyl in D6 and K6, 4-fluorophenyl in D7 and K7, 4-bromophenyl in D8 and K8, 3-hydroxyphenyl in D9 and K9, and 2-acetylthiophene in D10 and K10. Of the compounds synthesized, K2, K3, K5, K6, K7, K8, K9, and K10 are reported for the first time. Cytotoxic activities of the D and K series were compared with each other to see alterations in bioactivity depending on the chemical structures in Jurkat cells. Cytotoxicities of the compounds synthesized were also compared with the reference compound, 5-fluorouracil (CAS 148-82-3). Mono Mannich bases, D1 (3.60 times), D2 (4.45 times), D3 (2.46 times), D4 (3.52 times), D5 (5.18 times), D6 (3.20 times), D7 (3.23 times), D8 (3.95 times), D9 (3.36 times) and D10 (3.99 times) had 2.46-5.18 times higher cytotoxic potency than the reference compound 5-fluorouracil against Jurkat cells, while hydrazones K1 (4.92 times), K2 (4.65 times), K3 (6.04 times), K4 (6.34 times), K5 (4.67 times), K6 (5.12 times), K7 (5.39 times), K8 (8.31 times), K9 (4.65 times) and K10 (8.65 times) had 4.65-8.65 times higher cytotoxic potency than the reference compound 5-fluorouracil against the same cell line. On the other hand, hydrazone compounds K1 (1.37 times), K3 (2.46 times), K4 (1.80 times), K6 (1.60 times), K7 (1.67 times), K8 (2.11 times), K9 (1.38 times), and K10 (2.17 times) had 1.37-2.46 times higher cytotoxic potency than their corresponding mono Mannich bases. The results of this study suggest that hydrazones were better compounds compared with the corresponding mono Mannich bases in terms of cytotoxicity, and they may serve as model compounds to develop new cytotoxic agents for further studies.     

Syntheses and stability studies of some Mannich bases of acetophenones and evaluation of their cytotoxicity against Jurkat cells

Mannich bases, namely 1-aryl-3-dimethylamino-1-propanone hydrochlorides (Ia-f) as mono-Mannich bases (series I), bis(beta-aroylethyl)ethylamine hydrochlorides (IIa, IIb, IId, IIe) as bis-Mannich bases (series II), 3-aroyl-4-aryl-1-ethyl-4-piperidinol hydrochlorides (series III), which are structural isomers of bis derivatives and some representative quaternary salts (Ig, IIIf, IIIg), were synthesized to investigate the effect of chemical structure and ring substituents on cytotoxic activity in Jurkat cells. Stability studies of some representative compounds have also been realised. Compounds IIb, IId, IIe, and IIIe were reported for the first time. Id-g, IIa, IId, IIe, IIIf,g were 1.25-6.55 times more potent than 5-fluorouracil (CAS 51-21-8). However, the cytotoxic activity of the most potent compounds. Ig and IIIf, were one fifth of that of melphalan (CAS 148-82-3). The formation of compound IV during the stability studies of Ig, IIa, and IIIf suggested that they may be thiol alkylators. Bis-Mannich base IIa in nonsubstituted derivatives, piperidinol derivative IIIb in methyl substituted compounds, mono derivative Id in chloro substituted compounds were the most potent compounds when the cytotoxicity of the compound series which have the same substituents in benzene ring are compared. Replacement of the benzene with thiophene improved the cytotoxicity in both series I and II. Quaternization procedure also increased the cytotoxicity in both series I and III. Quaternary derivatives seem to be promising compounds for further studies to develop new anticancer drugs.     

Cytotoxic activities of mono and bis Mannich bases derived from acetophenone against Renca and Jurkat cells

Mannich bases of acetophenones have been disclosed to have antitumour and cytotoxic activities. 1-Phenyl-3-dimethylaminopropan-1-one hydrochloride, 1, and related piperidino, 2, and morpholino, 3, derivatives, and compound 4, which is a quaternary form of 1, were synthesized as mono Mannich bases derived from acetophenone. They were converted to corresponding bis Mannich bases, 5-8, to see whether it increases the bioactivity. The biological activity of the compounds was examined by cytotoxicity against mouse renal carcinoma (Renca) and transformed human T-lymphocyte (Jurkat) cell lines. Conversion of mono Mannich bases to corresponding bis Mannich bases remarkably increased the cytotoxicity in most cases. Quaternization procedure also improved the bioactivity in mono derivatives against Jurkat cells. Bis mannich bases 5-7 were found to be more active than 5-fluorouracil (6-23 fold) and melphalan (1.25-5 fold) against Renca cells. Except 2 and 8, the compounds synthesised were found to be more active than 5-fluorouracil (1.2-33 fold) against Jurkat cells.     

Cytotoxicity of some azines of acetophenone derived mono-Mannich bases against Jurkat cells

Acetophenone derived mono-Mannich bases (Ig1-Ig4), 1-aryl-3-amino-1-propanone hydrochlorides, which are known to have cytotoxicity in Jurkat cells, were synthesized. Then, they were converted to corresponding azine derivatives (D1-D4), N, N'-bis(3-amino-1-aryl-propylidene)hydrazine dihydrochlorides, which are bifunctional agents. The aryl part was replaced by phenyl in Ig1, Ig2, Ig3, D1, D2, and D3, and by p-hydroxyphenyl in Ig4 and D4. The amine part was replaced by dimethylamine in Ig1, D1, Ig4 and D4, by piperidine in Ig2 and D2, and by morpholine in Ig3 and D3. The aim of this study was to investigate whether the modification in chemical structure, converting the mono-Mannich base to a corresponding azine derivative, improves the cytotoxicity. In addition, the effect of the representative compound, D3, N, N'-bis(3-morpholine-4-yl-1-phenylpropylidene)hydrazine dihydrochloride, on cellular glutathione level after 1 h exposure in phosphate buffer at 37 degrees C was also determined to provide information on a possible mechanism of cytotoxic action. Compounds D2-D4 are reported for the first time in this study. Except for Ig2 and D2, the cytotoxicity of mono-Mannich bases, Ig1, Ig3 and Ig4 and corresponding azine derivatives, D1, D3 and D4 were higher than the reference compound 5-FU. Azine derivatives D1 and D4 had almost equal cytotoxic potency with corresponding mono-Mannich bases Ig1 and Ig4, respectively. On the other hand, azine derivatives D2 and D3, had 1.28 and 1.90-times less cytotoxicity in Jurkat cells compared with the mono-Mannich bases, Ig2 and Ig3, respectively, from which they are derived. Azine derivative D3 dose-dependently decreased the total cellular glutathione level, suggesting that azine derivatives may exert cytotoxicity by thiol alkylation. Azine derivatives with equal or less cytotoxic potency compared to the mono-Mannich bases they are derived from seemed to be less suitable derivatives for the development of new cytotoxic compounds.     

Evaluation of cytotoxicity of some Mannich bases of various aryl and arylidene ketones and their corresponding arylhydrazones.

Mannich bases were synthesized and converted to the corresponding arylhydrazones. X-ray analysis of a ketone (1a) and a hydrazone (4d) revealed structural features of interest. All of the compounds showed cytotoxicity toward murine lymphocytic leukemia L1210 cells in the 4.9-25.0-microM range. The correlation coefficients generated by plotting the IC50 values (the concentrations of compounds that inhibit the growth of tumors by 50%) of some hydrazones against certain electronic, hydrophobic, and steric constants of the aryl substituents indicated only weak correlations. A few ketones and hydrazones displayed significant cytotoxicity to the WiDr human colon cancer cells, and these derivatives, especially the ketones, may serve as prototypes for future drug development. The KB tumor (a human epidermoid carcinoma of the nasopharynx) was somewhat refractory to selected compounds. In an in vitro assay conducted by the National Cancer Institute and involving approximately 53 tumor cell lines originating from eight neoplastic diseases, 65% of the compounds showed some selectivity toward one or more groups of cancers, principally leukemia, melanoma, and colon cancer. The bioevaluation of the ketones and hydrazones against the L1210, WiDr, and KB tumors, as well as evidence from proton nuclear magnetic resonance studies did not support the suggestion that hydrazones may be prodrugs of the corresponding ketones.     

Evaluation of some azines of aminomethylacetophenones and related quaternary ammonium compounds versus the EMT6 tumour

Azines derived from 3-dimethylamino-1-phenyl-1-propanone hydrochloride and two ring dimethylaminomethyl-acetophenones as well as the related quaternary ammonium iodides were synthesized. In phosphate buffer ph 7.4/37 degrees C 3-dimethylamino-1-phenyl-1-propanone azine dimethoiodide (2) formed 1-phenyl-3-(3-phenyl-2-pyrazolin-1-yl)-1-propanone. In the presence of a biomimetic thiol, 2-mercaptoethanol, compound 2 gave a bis S-alkylated product namely 3-(2-hydroxyethylthio)-1-phenyl-1-propanone azine. New products were not observed when two quaternary ammonium compounds derived from ring aminomethylacetophenone azines were examined under similar conditions. Six derivatives had moderate activity against the EMT6 tumour in vitro at concentrations of 250-500 mumol.1(-1) and greatest potency was noted with the ring dimethylaminomethylacetophenone azines and related quaternary ammonium compounds at these concentrations.     

Evaluation of the cytotoxicity of some mono-mannich bases and their corresponding azine derivatives against androgen-independent prostate cancer cells

Mono-Mannich bases derived from acetophenones, 1-aryl-3-amino- 1 -propanone hydrochlorides (Igl-Ig4), and their corresponding azine derivatives, N, N'-bis(3-amino-l-aryl-propylidene) hydrazine dihydrochlorides (DI-D4), were designed and synthesized as cellular thiol alkylating agents. The aryl portion was replaced by a phenyl group in Ig1, Ig2, Ig3, D1, D2, and D3, and by a p-hydroxyphenyl group in Ig4 and D4. The amine side chain was replaced by a dimethylamine group in Igl, D1, Ig4 and D4, by a piperidine group in Ig2 and D2, and by a morpholine group in Ig3 and D3. The cytotoxic activity of the compounds was tested against the androgen-independent prostate cancer cell line PC-3. The relationship between cytotoxicity and pKa value of the amine group and partition coefficients of the compounds was also investigated. Azine derivative D4 was found to be the most potent among all the compounds tested and the cytotoxicity increased 1.73 fold compared with the mono-Mannich base Ig4 in PC-3 cells. On the other hand, conversion of mono-Mannich bases Igl-Ig3 to their corresponding azine derivatives DI-D3 decreased the cytotoxicity considerably. Substitution of the hydroxyl group at the para position of the aromatic ring in azine derivative D4 increased the cytotoxicity, and a rational explanation in this regard is described in length. The results emerged from this investigation guide the future expansion of these series of compounds.     

Evaluation of some Mannich bases derived from substituted acetophenones against P-388 lymphocytic leukemia and on respiration in isolated rat liver mitochondria

Series of 3-dimethylamino-1-aryl-1-propanone hydrobromides (IV) and 3-dimethylamino-2-dimethylaminomethyl-1-aryl-1-propanone dihydrobromides (V) were synthesized. Evaluation of these derivatives against P-388 lymphocytic leukemia growth revealed that two compounds show promise as antineoplastic agents. Compounds of the V series were unstable in phosphate buffer (in contrast to series IV), and when the same nuclear substituent was present in both series of compounds, V was approximately 100 times more active than IV in both the stimulation and inhibition of respiration of mitochondria isolated from rat liver cells. Representatives from both series showed that respiration in mitochondria was affected by changing the pH of the aqueous buffer from 7.4 to 6.9 or 6.4 and by reducing the temperature from 37 degrees to 20 degrees. The compounds showed reactivity toward a biomimetic thiol.     

Anticonvulsant properties of some Mannich bases of conjugated arylidene ketones.

Thirty 1-aryl-5-dimethylamino-1-penten-3-one hydrohalides and related compounds were prepared as candidate anticonvulsants and evaluated in maximal electroshock seizure (MES), subcutaneous pentylenetetrazole threshold, and neurotoxicity screens. Following administration by the intraperitoneal route, many of the compounds were active in the MES screen, whereas only 10% of the Mannich bases afforded protection in the subcutaneous pentylenetetrazole test. Quantitation of half of the compounds prepared revealed that many had activity comparable with that of clinically useful drugs in the MES screen. The anticonvulsant properties of eight of the compounds following oral administration were reduced considerably or abolished compared with those following intraperitoneal administration. Various synthetic strategies for future development of potential anticonvulsants are outlined.     

Effect of acetophenone derived Mannich bases on cellular glutathione level in Jurkat cells. A possible mechanism of action

The effect of the acetophenone derived mono Mannich bases 1-3 and bis Mannich base 7 (bis derivative of compound 3) on cellular glutathione level was investigated in Jurkat cells. The cells were exposed to the compounds in phosphate buffered saline for 1 h in 37 degrees C with gentle shaking and then glutathione level was measured. Especially, mono Mannich base 3 and its bis derivative 7 decreased total glutathione level in a dose-dependent manner. The results provide further support for the thiol alkylation mechanism explaining the cytotoxic activity of Mannich bases.     

Antimicrobial evaluation of some Mannich bases of acetophenones and representative quaternary derivatives

1-Aryl-3-dimethylamino-1-propanone hydrochlorides Ia-f (series I) as mono-Mannich bases bis(beta-aroylethyl)ethylamine hydrochlorides IIa, IIb, IId, IIe (series II) as bis-Mannich bases, 3-aroyl-4-aryl-1-ethyl-4-piperidinol hydrochlorides (structural isomer of bis derivatives IIIa-e, series III), and some of their representative quaternary salts (Ig, IIIf, IIIg) were synthesized. Antimicrobial activities of the compounds were evaluated against some bacteria and fungi. Series I and III showed antimicrobial activity against gram positive bacteria. All series demonstrated activity against fungi, however, they generally did not affect gram negative bacteria at the concentration range tested (2-64 micrograms/ml). Quaternisation procedure improved the bioactivity in compound IIIa for antibacterial activity and in compounds IIIa and IIIb for antifungal activity against Trichophyton rubrum and Mycosporium canis. There was no relationship between Hammett values of the aryl substituents and bioactivities in series III. The mono-Mannich bases of series I had better antimicrobial activities than bis-Mannich bases of series II. Compounds Ia, If, IIId had equal and compounds If and IIIf had higher antibacterial activities compared to the reference drug, streptomycin (CAS 57-92-1), against various gram positive bacteria. On the other hand, compounds Ia, IIIa, IIIc, IIIe, IIIf, and IIIg had equal and If, IIId, IIIf, IIIg had higher antifungal activity compared to the reference drug, amphotericin-B (CAS 1397-89-3), against various fungi. To conclude, the compounds of series III, having both marked antifungal and antibacterial activities, may serve as candidate compounds for further studies. Especially compound IIIf may serve as a model compound to develop new agents against dermatophytes.     

Anticonvulsant activity of indanylspirosuccinimide Mannich bases

A series of Mannich bases derived from spiro [indan-1,3'pyrrolidine-2',5'-dione] were evaluated for anticonvulsant activity. This activity varied as a function of the amine substituent and several compounds showed protective effects in both the maximal electroshock (MES) and subcutaneous pentylenetetrazol (scMet) assays. In addition, fluorenyl- and cyclopentyl-derived spirosuccinimides, as well as extended chain analogues, were tested and proved to be inactive. A time versus effect study was conducted employing the MES assay and the hydroxyethylpiperazine-derived Mannich base of spiro [indan-1,3 pyrrolidine-2',5',dione]. This compound acted rapidly and its protective half-life was increased as larger doses were administered.     

Synthesis and evaluation of anticonvulsant activities of some bis Mannich bases and corresponding piperidinols

Some acetophenone derived bis Mannich bases (B1-B5) and piperidinols (C1, C4), which are the structural isomers of B1 and B4, and also quaternary piperidine derivative C6 were synthesized and studied for anticonvulsant activity. Of the compounds, C6 was reported for the first time. Chemical structures of the compounds were confirmed by UV, IR, 1H-NMR, 13C-NMR, mass spectra and elemental analysis. Their anticonvulsant activities were determined by maximal electroshock (MES), subcutaneous metrazol (scMet) tests and rotarod test for neurological deficits. According to the activity studies, B2, B4, C1 and C4 derivatives were found to be protective against MES at 30 mg/kg and above. B1, B2, B3, B4, C4 and C6 derivatives were found to be protective against scMet. at different dose levels ranging from 30 to 300 mg/kg. Since no neurotoxicity was detected for the compounds B4 and C4, they seem to be candidate compounds for further synthesis and in vivo studies for their potential anticonvulsant activity.