(E)-[2-(4-Methylsulphonylphenyl)-1-cyclopentenyl-1-methyliden](arylmethyloxy)amines. Methyleneaminoxymethyl (MAOM) analogues of diarylcyclopentenyl cyclooxygenase-2 inhibitors: synthesis and biological properties

The (E)-[2-(4-Methylsulphonylphenyl)-1-cyclopentenyl-1-methyliden](methyloxy)amine (5) and (arylmethyloxy)amines (6-12) were designed in order to verify the effects on the biological properties of the substitution of an aryl of selective diarylcyclopentenyl cyclooxygenase-2 (COX-2) inhibitors of type 3 with a methyleneaminoxymethyl moiety (MAOMM). Compounds 5-12 were tested in vitro for their inhibitory activity towards COX-1 and COX-2 by measuring prostaglandin E2 (PGE2) production in U937 cell lines and activated J774.2 macrophages, respectively. The compound with the highest in vitro activity towards COX-2 (9) was also assayed in vivo for its antiinflammatory activity by means of the carrageenan-induced paw edema test in rats. Some of the new compounds showed an appreciable in vitro COX-2 inhibitory activity, with IC(50) values in the microM (6,7,9,10,11) range. Compound 9 also exhibited an appreciable in vivo activity (29% inhibition at a dose of 30 mg kg(-1)) when administered intraperitoneally. The structural parameters of 9 were determined by X-ray crystallographic analysis.     

Aryl-substituted methyleneaminoxymethyl (MAOM) analogues of diarylcyclopentenyl cyclooxygenase-2 inhibitors: effects of some structural modifications on their biological properties

The (E)-[2-(4-aminosulfonylphenyl)-1-cyclopentenyl-1-methyliden]-(arylmethyloxy)amines (6a,b), which are the sulfonamidic analogues of the previously described methylsulfonyl derivatives 5a,b, and their corresponding sulfides (7a,b) and sulfoxides (8a,b) were synthesised in order to obtain information about the role played by these different sulphur-containing groups in the cyclooxygenase-2 inhibitory activity of this class of compounds. In addition, other chemical manipulations concerning the oxime-ether substituent of this type of derivatives were affected by preparing compounds 9a,b, which present a methyl group on the oximic carbon of the oxime-ether chain of 5a,b, and compounds 10 and 11, in which the atomic sequence (C=NOCH(2)) of the MAOMM of 8b and 5b, respectively, is inverted. Compounds 6-11 were tested in vitro for their inhibitory activity towards COX-1 and COX-2 by measuring prostaglandin E2 (PGE2) production in U937 cell lines and activated J774.2 macrophages, respectively. Some of the new compounds showed an appreciable in vitro COX-2 inhibitory activity, with IC(50) values in the microM (7a,b, 8a and 9b) or sub-microM (8b) range. This last compound was also assayed in vivo for its antiinflammatory activity by means of the carrageenan-induced paw edema test in rats. No inhibitory effects were detected up to dose of 30 mg kg(-1) orally administered.     

Synthesis and biological evaluation of N-substituted-3,5-diphenyl-2-pyrazoline derivatives as cyclooxygenase (COX-2) inhibitors

Eighteen new 1-N-substituted-3,5-diphenyl-2-pyrazoline derivatives have been synthesized and cyclooxygenase (COX-1 and COX-2) inhibitory activities have been evaluated. The results of these biological assays showed that all of new derivatives are not endowed with improved anti-inflammatory activity against COX-1, but some of them showed a good activity against COX-2. To evaluate the binding mode of the most significative compounds (2d, 2f, 2g and 2k) docking studies were carried out. These studies confirmed biological data, in fact these compounds were able to fit into the active site of COX-2.     

Synthesis and biological evaluation of some thiazolyl and thiadiazolyl derivatives of 1H-pyrazole as anti-inflammatory antimicrobial agents

Four series of pyrazolyl benzenesulfonamide derivatives have been synthesized. The first series was prepared by cyclization of the intermediate N,N-dimethylaminomethylene-4[3-phenyl-4-(substituted thiosemicarbamoyl hydrazonomethyl)-1H-pyrazol-1-yl]benzenesulfonamide 2a-c with ethyl bromoacetate to afford the corresponding thiazolidinyl derivatives 3a-c. The second series was prepared by cyclization of the key intermediates 2a-c with 4-bromophenacyl bromide giving rise to thiazolinyl derivatives 4a-c. Thiadiazolyl derivatives 5a-c were obtained by heating 2a-c with 2M FeCl(3) solution. Refluxing the intermediates 2a-c in acetic anhydride yielded the corresponding thiadiazolinyl derivatives 6a-c. All the target compounds showed anti-inflammatory activity and three of them 3b, 3c and 4c surpassed that of indomethacin both locally and systemically in the cotton pellet granuloma and rat paw edema bioassay. The active compounds showed selective inhibitory activity towards COX-2 enzyme as revealed by the in vitro enzymatic assay. All the tested compounds proved to have superior gastrointestinal (GI) safety profiles as compared to indomethacin, when tested for their ulcerogenic effects. The acute toxicity study of compounds having promising anti-inflammatory activity (3b, 3c and 4c) indicated that they are well tolerated both orally and parenterally. Antimicrobial activity tests expressed as minimal inhibitory concentrations (MIC), revealed that compounds 3b and 4a showed comparable antibacterial activity to that of ampicillin against Escherichia coli, while compounds 3a, 3c and 4a possessed about half the activity of ampicillin against Staphylococcus aureus. On the other hand, the results showed that all the tested compounds have weak or no antifungal activity against Candida albicans except for compounds 6b and 6c that showed half the activity of the control antifungal drug used (clotrimazole).     

Synthesis and serotonergic activity of variously substituted (3-amido)phenylpiperazine derivatives and benzothiophene-4-piperazine derivatives: novel antagonists for the vascular 5-HT1B receptor

The synthesis and vascular 5-HT(1B) receptor activity of a novel series of substituted 3-amido phenylpiperazine and 4-(4-methyl-1-piperazinyl)-1-benzo[b]thiophene derivatives is described. Modifications to the amido linked sidechains of the 3-amidophenyl-piperazine derivatives and to the 2-sidechain of the 1-benzo[b]thiophene derivatives have been explored. Several compounds were identified which exhibited affinity at the vascular 5-HT(1B) receptor of pK(B) > 7.0. From the 3-amidophenyl-piperazine series, N-(4-(4-chlorophenyl)thiazol-2-yl-3-(4-methyl-1-piperazinyl)benzamide (30) and from the benzo[b]thiophene-4-piperazine series N-(2-ethylphenyl)-4-(4-methyl-1- piperazinyl)-1-benzo[b]thiophene-2-carboxamide (38) were identified as a highly potent, silent (as judged by the inability of angiotensin II to unmask 5-HT(1B) receptor mediated agonist activity in the rabbit femoral artery) and competitive vascular 5-HT(1B) receptor antagonist. The affinity of compounds from these two series of compounds for the vascular 5-HT(1B) receptor is discussed as well as a proposed mode of binding to the receptor pharmacophore.     

Synthesis of some 1-(2-naphthyl)-2-(imidazole-1-yl)ethanone oxime and oxime ether derivatives and their anticonvulsant and antimicrobial activities.

In this study, oxime and oxime ether derivatives of anticonvulsant nafimidone [1-(2-naphthyl)-2-(imidozole-1-yl)ethanone] were prepared as potential anticonvulsant compounds. Nafimidone oxime was synthesized by the reaction of nafimidone and hydroxylamine hydrochloride. O-Alkylation of the oxime by various alkyl halides gave the oxime ether derivatives. Anticonvulsant activity of the compounds was determined by maximal electroshock (MES) and subcutaneous metrazole (scMet) tests in mice and rats according to procedures of the Antiepileptic Drug Development (ADD) program of the National Institutes of Health (NIH). In addition to anticonvulsant evaluation, compounds were also screened for possible antibacterial and antifungal activities because of the structural resemblance to the azole antifungals, especially to oxiconazole. All compounds were evaluated against three human pathogenic fungi and four bacteria using the microdilution method. Most of the compounds exhibited both anticonvulsant and antimicrobial activities; the O-alkyl substituted compounds (2, 3, 4 and 5) were found to be more active than the O-arylalkyl substituted compounds in both screening paradigms.     

Enantiopure 3-(arylmethylidene)aminoxy-2-methylpropionic acids: synthesis and antiinflammatory properties.

Some optically active 3-(arylmethylidene)aminoxy- (3a-g, 4a-g) and fluorenylideneaminoxy-2-methylpropionic acids (5, 6), were prepared as analogues of the antiinflammatory arylpropionic acids of type B, in which the aromatic group is substituted by an MAOM moiety. Some of the new compounds, tested in vivo for their antiinflammatory properties by means of the carrageenan-induced paw edema method in rats, exhibited activity indices similar to that shown in the same test by ibuprofen. Compounds 3a,b and 4a,b, for which at least one of the two enantiomers had shown an inhibition value higher than 40% in the in vivo test, were assayed for their in vitro enzymatic inhibitory activity, showing percentage inhibition values between 40 and 50% at a concentration of 10 microM against COX-2; at the same concentration, they appeared to be devoid of any activity towards COX-1. Compounds 3a,b and 4a,b also proved to possess a similar toxicity. The lack of enantioselectivity shown by compounds 3-6 was tentatively explained in terms of a conformational freedom of the enantiomers which allows their quasi-superimposition.     

Synthesis of 2-amino-3-heteroaroylthiophenes and evaluation of their activity as potential allosteric enhancers at the human A1 receptor

2-Amino-3-benzoylthiophenes are allosteric enhancers of agonist binding to the adenosine A(1) receptor. New compounds bearing an heteroaroyl instead of the benzoyl moiety at the 3-position of the thiophene were synthesized. The phenyl ring was replaced with heterocycles that possess heteroatoms able to form hydrogen bonds (2-furanyl, 2-benzofuranyl, 2-pyridinyl in compounds 2-13) or with a thienyl moiety as isoster of the phenyl ring (2-thienyl, 3-thienyl and 5-halo-2-thienyl in compounds 14-29). The effect of several alkyl substituents at positions 4 and 5 of the thiophene ring to increase enhancer activity was determined. The ability of the new molecules to reduce the cAMP content in CHO cells expressing the human adenosine A(1) receptor was evaluated. Compounds 2-13 with hydrogen bond-forming heteroatoms did not show significant activity as allosteric enhancers. On the other hand, compounds 15-16 and 19-20 with an unsubstituted thienyl moiety as replacement for the phenyl ring were nearly as efficacious as PD 81,723, the prototypical A(1) allosteric enhancer. Alkyl substituents at positions 4 and 5 of the thiophene ring were tolerated while a substituted piperidine ring was not tolerated. We conclude that hydrogen bonds could not be formed in the domain of the receptor that accommodates the phenyl ring of 2-amino-3-benzoylthiophene derivatives, indicating that this domain is hydrophobic.     

Synthesis and biological evaluation of some thiazolylpyrazole derivatives as dual anti-inflammatory antimicrobial agents

The synthesis of a novel series of 4-thiazolylpyrazolyl derivatives is described in the present report. All the newly synthesized compounds were examined for their anti-inflammatory activity using cotton pellet-induced granuloma and carrageenan-induced rat paw edema bioassays. Their inhibitory activities of cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2), ulcerogenic effect and acute toxicity were also determined. Furthermore, all compounds were evaluated for their in vitro antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans. A docking pose for compounds 8b, 10a and 10b separately in the active site of the human COX-2 enzyme and DNA-gyrase B was also obtained. The results revealed that compounds 8b, 10a and 10b exhibited good anti-inflammatory activity with no or minimal ulcerogenic effect and good safety margin. Compounds 10a and 10b were found to be the most potent anti-inflammatory agents in the present study. Meanwhile, 10a and 10b displayed higher selective inhibitory activity towards COX-2 compared to indomethacin. Moreover, compounds 10a and 10b exhibited promising antibacterial against both E. coli and S. aureus. Docking studies for 8b, 10a and 10b with COX-2 (PDB ID: 1CX2) and DNA-gyrase B (PDB ID: 1EI1) showed good binding profile.     

Design and synthesis of some substituted 1H-pyrazolyl-thiazolo[4,5-d]pyrimidines as anti-inflammatory-antimicrobial Agents

The synthesis of two novel series of structurally related 1H-pyrazolyl derivatives of thiazolo[4,5-d]pyrimidines is described. All the newly synthesised compounds were examined for their in vivo anti-inflammatory activity in two different bioassays namely; cotton pellet-induced granuloma and carrageenan-induced paw edema in rats. The in vitro inhibitory activity of the most active compounds towards human COX-1 and COX-2 enzymes was also estimated. In addition, the ulcerogenic effects and acute toxicity (LD(50)) values of these compounds were determined. The same compounds were evaluated for their in vitro antimicrobial activity against Escherichia coli, as an example of Gram negative bacteria, Staphylococcus aureus as an example of Gram positive bacteria, and Candida albicans as a representative of fungi. The results revealed that compounds 5a, 9a, 9b, 10b and 12a exhibited anti-inflammatory activity comparable to that of indomethacin in both local and systemic in vivo animal models with no or minimal ulcerogenic effects (0-10%) and high safety margin (LD(50) > 500 mg kg(-1)). In addition, most of them displayed appreciable antibacterial activities when compared with ampicillin, especially against S. aureus. Compounds 9a and 12a are the most distinctive derivatives identified in the present study because of their remarkable in vivo and in vitro anti-inflammatory activity in addition to their pronounced antibacterial activities comparable to ampicillin against Gram positive and -negative bacteria. Therefore, they are considered as successful dual anti-inflammatory-antimicrobial candidates.     

Potential cancer-chemopreventive activities of wine stilbenoids and flavans extracted from grape (Vitis vinifera) cell cultures

Moderate consumption of wine is associated with a reduced risk of cancer. Grape plant cell cultures were used to purify 12 phenols: the stilbenoids trans-astringin, trans-piceid (2), trans-resveratroloside, trans-resveratrol, trans-piceatannol, cis-resveratroloside, cis-piceid, and cis-resveratrol; the flavans (+)-catechin, (-)-epicatechin, and epicatechin 3-O-gallate; and the flavan dimer procyanidin B2 3'-O-gallate. These compounds were evaluated for potential to inhibit cyclooxygenases and preneoplastic lesion formation in carcinogen-treated mouse mammary glands in organ culture. At 10 micrograms/ml, trans-astringin and trans-piceatannol inhibited development of 7,12-dimethylbenz[a]anthracene-induced preneoplastic lesions in mouse mammary glands with 68.8% and 76.9% inhibition, respectively, compared with untreated glands. The latter compound was the most potent of the 12 compounds tested in this assay, with the exception of trans-resveratrol (87.5% inhibition). In the cyclooxygenase (COX)-1 assay, trans isomers of the stilbenoids appear to be more active than cis isomers: trans-resveratrol [50% inhibitory concentration (IC50) = 14.9 microM, 96%] vs. cis-resveratrol (IC50 = 55.4 microM). In the COX-2 assay, among the compounds tested, only trans- and cis-resveratrol exhibited significant inhibitory activity (IC50 = 32.2 and 50.2 microM, respectively). This is the first report showing the potential cancer-chemopreventive activity of trans-astringin, a plant stilbenoid recently found in wine. trans-Astringin and its aglycone trans-piceatannol were active in the mouse mammary gland organ culture assay but did not exhibit activity in COX-1 and COX-2 assays. trans-Resveratrol was active in all three of the bioassays used in this investigation. These findings suggest that trans-astringin and trans-piceatannol may function as potential cancer-chemopreventive agents by a mechanism different from that of trans-resveratrol.     

Synthesis, crystal structure and biological evaluation of novel 2-(5-(hydroxymethyl)-3-phenyl-1H-pyrazol-1-yl)-1-phenylethanol derivatives

A series of novel 2-(5-(hydroxymethyl)-3-phenyl-1H-pyrazol-1-yl)-1-phenylethanol derivatives (4) was synthesized from ethyl 1-(2-oxo-2-phenylethyl)-3-phenyl-1H-pyrazole-5-carboxylate derivatives (3) and characterized by means of IR, 1H NMR, HRMS and X-ray crystal diffraction. Structures of 4a, 4d, 4e and 4f were also determined by 13C NMR. Isomeric intermediates, 3a and 5a, were unambiguously confirmed by X-ray crystal structure analysis and successfully differentiated with 1H NMR chemical shifts of methylene bonded to pyrazole ring. Preliminary biological evaluation showed that compounds 4d and 4e could suppress A549 lung cancer cell growth through cell cycle arrest and autophagy.     

Novel Pd(II) complexes of 1-N-substituted 3-phenyl-2-pyrazoline derivatives and evaluation of antiamoebic activity

Cyclization of Mannich base with N(4)-substituted thiosemicarbazides by different aliphatic, aromatic and cyclic amines afforded a series of new 1-N-substituted cyclised pyrazoline analogues of thiosemicarbazones (PYZ-TSC) 1-10. Reaction of [Pd(DMSO)(2)Cl(2)] with pyrazoline derivatives led to new palladium(II) complexes [Pd(PYZ-TSC)Cl(2)] 1a-10a. The structures of all the compounds were characterized by spectroscopic methods. It was concluded that the pyrazoline thiosemicarbazone derivatives have two chelating arms, one attached at the 2-position of the pyrazole ring (that is, N donor) and other (S donor) linked to the thiosemicarbazone branch. The determination of antiamoebic activity of all the compounds was done using HM1:IMSS strain of Entamoeba histolytica, among all the complexes, 8a showed the most promising IC(50)=0.37 microM vs. IC(50)=1.81 microM of metronidazole, the reference drug. MTT assay showed that the compounds are non-toxic to human kidney epithelial cell line.     

Adamantane derivatives of thiazolyl-N-substituted amide, as possible non-steroidal anti-inflammatory agents

A series of adamantane derivatives of thiazolyl-N-substituted amides were synthesized in a three-step reaction and tested for anti-inflammatory activity as well as lipoxygenase and cycloxygenase inhibitory actions. Theoretical calculation of their lipophilicity, as ClogP was performed. The effect of the synthesized compounds on inflammation, using the carrageenin-induced mouse paw oedema model was studied and compared to indomethacin. In general, the studied compounds were found to be potent anti-inflammatory agents (29.6-81.5%). Anti-inflammatory activity was influenced by some structural characteristics of the synthesized compounds. The lipoxygenase inhibitory activity was tested by the conversion of sodium linoleate to 13-hydroperoxylinoleic acid. Low inhibitory activity was observed. Evaluation of COX-1 and COX-2 inhibitory activities of the compounds revealed a COX-1 inhibitory potential, comparable to that of naproxen for some of the compounds and a low to moderate COX-2 inhibitory potential. Comparison of the in vivo and in vitro results leads to the conclusion that most compounds of this series may be involved in other mechanisms of inflammation, too.     

Synthesis and antimicrobial properties of 2-(benzylidene-amino)-benzo[d]isothiazol-3-ones

The in vitro antimicrobial activity of 2-amino-benzo[d]isothiazol-3-one and of several 2-arylideneamino derivatives carrying in the second position a substituted or unsubstituted aromatic ring or an arylalkenylidene moiety was determined by the broth dilution method against several strains selected to define their spectrum and potency. All the compounds demonstrated good antibacterial properties against Bacillus subtilis, streptococci, enterococci and staphylococci including penicillin-resistant clinical isolates. Several compounds showed excellent inhibitory properties against Streptococcus pyogenes, which is the most sensitive microorganism tested. Many benzisothiazolones exhibited good activity against Gram-negative Haemophilus influenzae. As regards antifungal activity, several of the tested compounds inhibited Saccharomyces cerevisiae at concentrations of 3-6 microg ml-1. In all cases the parent 2-amino-benzo[d]isothiazol-3-one was the most effective agent, with minimum inhibitory concentration (MIC) values ranging from 0.07 to 6 microg ml-1. The results obtained indicate that most of these compounds are wide-spectrum antimicrobial substances and promising agents against penicillin-resistant staphylococci.     

Synthesis and antimicrobial activity of 1-(4-aryl-2-thiazolyl)-3-(2-thienyl)-5-aryl-2-pyrazoline derivatives

Several 1-(4-aryl-2-thiazolyl)-3-(2-thienyl)-5-aryl-2-pyrazoline derivatives were synthesized by reacting substituted 3-(2-thienyl)-5-aryl-1-thiocarbamoyl-2-pyrazolines with phenacyl bromides in ethanol. The structures of the synthesized compounds were confirmed by (1)H NMR, (13)C NMR, and EIMS spectral data. Their antimicrobial activities against Escherichia coli (NRRL B-3704), Staphylococcus aureus (NRLL B-767), Salmonella typhimurium (NRRL B-4420), Bacillus cereus (NRRL B-3711), Streptococcus faecalis (NRRL B-14617), Aeromonas hydrophila (Ankara Uni. Fac. of Veterinary), Candida albicans and Candida glabrata (isolates obtained from Osmangazi Uni. Fac. of Medicine) were investigated. A significant level of activity was observed.     

Synthesis and vasorelaxing evaluation of alpha-methylidene-gamma-butyrolactone bearing quinolin-2(1H)-one and 3,4-dihydroquinolin-2(1H)-one derivatives.

The main objective of this investigation was to explore the vasorelaxing structure-activity relationships of alpha-methylidene-gamma-butyrolactone bearing quinolin-2(1H)-ones and their 3,4-dihydro derivatives. These target compounds were synthesised in two steps starting from aryl-OH which was treated with a bromomethyl ketone followed by a Reformatsky-type condensation. Quinolin-2(1H)-one alpha-methylidene-gamma-butyrolactones exhibited less vasorelaxing activity than their 3,4-dihydro counterparts. Compounds with a methyl or a phenyl group at the C(gamma) of the lactone were more vasorelaxant than the C(gamma)-fluorophenyl derivatives in the 3,4-dihydroquinolin-2(1H)-one series. When comparing the positional isomers, alpha-methylidene-gamma-butyrolactone substituted at the 7-position of the 3,4-dihydroquinolin-2(1H)-ones were more active than their 6-substituted counterparts, which in turn were more active than the 8-substituted derivatives. The vasorelaxing effect of these 3,4-dihydroquinolin-2(1H)-ones was proved to be dose dependent. Among them, 7-[(2,3,4,5-tetrahydro-4-methylidene-5-oxo-2-phenyfuran-2-yl)methoxy]-quinolin-2(1H)-one (10b) was the most potent with an IC(50) of 9.2 microM on the KCl-induced vasoconstriction of pig coronary arteries.     

Design, synthesis and pharmacological screening of novel nitric oxide donors containing 1,5-diarylpyrazolin-3-one as nontoxic NSAIDs

Various substituted 1,5-diarylpyrazol-3-one derivatives were synthesized and screened for analgesic, anti-inflammatory activities, ulcerogenic potential and for their ability to release nitric oxide. Most compounds exhibited significant analgesic and anti-inflammatory activities. It was interesting to note that out of ten compounds, 7j (59.64%) was found to have anti-inflammatory activity greater than the standard drug Indomethacin (57.89%), whereas compound 7b (57.89%) was found to be equipotent to that of standard, Indomethacin. The pharmacological studies suggested that the presence of 4-nitro and 2-methoxy on phenyl ring at C₅ of pyrazole has a significant anti-inflammatory activity and 4-chloro substitution on same phenyl ring was found to have decreased activity. However only a phenyl substituted derivative was found to have most potent activity. Compound 7j containing plane phenyl at C₅ of pyrazole was found to have significant analgesic activity (56.86%) in acetic acid induced writhing model. Compounds 7d and 7i having 4-chloro substituted phenyl ring showed least analgesic activity (10.78%) and (6.86%) respectively. The compounds also showed significantly reduced GI-ulcerogenicity and gastroprotective results in histopathological studies i.e. they were found to be causing no mucosal injury. All the synthesized compounds were found to exhibit significant nitric oxide releasing activity, in both in vitro and in vivo models. Molecular docking studies served to be an important tool for the study of binding of compounds with that of a COX-2 enzyme. The results of the docking studies were found to endorse the result of experimental work. Thus, the rationale used to design the NCEs was found to produce the promising results as anticipated. Therefore it can be said that the strategy employed can serve as an important tool in future for the design and development of novel therapeutic agents of various categories too.     

Acetylenic and allenic derivatives of 2-(5-methoxy-1-methylindolyl) alkylamines: Synthesis and evaluation as selective inhibitors of the monoamine oxidases A and B

We report the synthesis and in vitro studies as MAO-A and MAO-B inhibitors of a new series of 2-(5-methoxy-1-methylindolyl)alkylamines, including 2-(5-methoxy-1-methylindolyl)amine 9 and its N-methyl derivative 10, 1-[2-(5-methoxy-1-methylindolyl)]ethylamine 1 and its N-methyl derivative 2 and 3-[2-(5-methoxy-1-methylindolyl)propylamine 11 and its N-methyl derivative 12, so as some of the N-(2-propynyl), N-(2,3-butadienyl) and N-(2-butynyl) derivatives of 1, 2, 11 and 12 (compounds 3–8 and 13–18). All compounds were found to inhibit both MAO-A and MAO-B. Comparison with a previous series of 2-(5-methoxy-1-methylindolyl)methylamine derivatives (A1–A9) shows that in the new series, the inhibitory potency towards MAO-A generally decreases, whereas the inhibitory potency towards MAO-B generally increases, resulting in a loss of the selectivity for MAO-A seen in the reference compounds A1–A9. Structure-activity relationships are discussed.