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Inorganic Chemistry Communications

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Short communication

Synthesis and characterization of novel quaternized 2, 3-(diethylmethylamino)phenoxy tetrasubstituted Indium and Galliumphthalocyanines and comparison of their antimicrobial and antioxidantproperties with different phthalocyanines

Neslihan Sakia,⁎, Mustafa Akina, Armağan Atsayb, H.R. Pekbelgin Karaoglub,Makbule Burkut Kocakb,⁎

a Department of Chemistry, Kocaeli University, TR41380 İzmit, Kocaeli, TurkeybDepartment of Chemistry, İstanbul Technical University, TR34469 Maslak, İstanbul, Turkey

G R A P H I C A L A B S T R A C T

A B S T R A C T

In this work, we describe the synthesis and characterization of tetra-substituted 2,9(10),16(17),23(24)-tetrakis-[3-(diethylmethylamino)phenoxy) phthalocyanina-tochlorogallium (III) tetraiodide and 2,9(10),16(17),23(24)-tetrakis-[3-(diethylmethylamino)phenoxy) phthalocyaninatochloroindium (III) tetraiodide and com-parision of their antioxidant and antimicrobial activities with previously synthesized metallo- or metal-free octa-substituted phthalocyanines bearing diethylami-nophenoxy groups at peripheral positions. Antioxidant activities of the compounds were investigated by using DPPH free radical scavenging assay, β-carotene/linoleic acid bleaching assay and reducing power assay and no significant difference was observed between metal-containing and metal-free phthalocyanine com-pounds. Disc diffusion and macro dilution methods were used to determine the antimicrobial activities of the PCs on Gram-negative and Gram-positive bacteria andnewly synthesized tetra-cationic gallium (PC6) and indium (PC7) phthalocyanines showed antimicrobial activity against all tested microorganisms. Antibacterialactivity of neutral compounds was considerably lower or even negligible than that of cationic ones.

1. Introduction

Phthalocyanine (PC) derivatives are an attractive class of

macrocyclic compounds and have become increasingly important inmany application fields [1,2]; such as dyes and pigments [3], medicalapplications [4,5], photodynamic therapy (PDT) [6,7]. In addition to

https://doi.org/10.1016/j.inoche.2018.07.010Received 9 April 2018; Received in revised form 5 July 2018; Accepted 9 July 2018

⁎ Corresponding authors.E-mail addresses: sakineslihan1@gmail.com (N. Saki), mkocak@itu.edu.tr (M.B. Kocak).

Inorganic Chemistry Communications 95 (2018) 122–129

Available online 17 July 20181387-7003/ © 2018 Elsevier B.V. All rights reserved.

T

the unique electronic, optical and structural behaviours; their anti-fungal [8], antibacterial [9,10] and antioxidant [11–14] propertieshave been also explored. Both synthetic and natural antioxidants havegreat help to the human body by reducing free radicals which cause theoxidative damages. Free radicals being very reactive oxygen speciescause various diseases including atherosclerosis, inflammatory injury,cancer and cardiovascular disease [15]. PC complexes having a goodsolubility without aggregation in common organic solvents show pro-mising properties for antioxidant activity and studies have indicatedthat there are significant differences between metallo and non-metalloPCs in this respect [12,16].

In recent years, multidrug resistance has developed in human pa-thogenic microorganisms due to the broad use of commercial anti-microbial drugs commonly used in the treatment of infectious diseases.This situation has lead researchers to find new antimicrobial substances[17]. Thus, synthesis of PCs (with or without metal) carrying differentfunctional groups and investigation of their biological activities havebeen studied in many researches [18–20]. Especially cationic phthalo-cyanines are reported as the good antimicrobial agents when comparedto the neutral ones [14,21].

In the proposed work, we described the antioxidant and anti-microbial properties of five metallo and two metal-free PC molecules.The study was performed by varying the structure and the number ofthe substituents and, therefore; modulating the overall positive chargeof the molecules. During the study, two new PC compounds were syn-thesized and characterized and antioxidant and antimicrobial activitiesof these two compounds were compared to previously synthesized fiveocta-substituted PCs. DPPH (1,1-diphenyl-2-picrylhydrazyl) free radicalscavenging activity, β-carotene/linoleic acid bleaching and ferric re-ducing capacity assays were used to determine the antioxidant activ-ities of all tested PCs. Moreover, the antimicrobial properties of thesemolecules were explored by using disc-diffusion and macro dilutionmethods.

2. Materials and methods

2.1. Chemicals

All reagents and solvents used for the synthesis of PC moleculeswere of reagent grade quality obtained from commercial suppliers. β-Carotene, chloroform, linoleic acid, tween 40 (polyoxyethylene sor-bitan monopalmitate), 1,1-diphenyl-2-picrylhydrazyl (DPPH), trolox,sodium carbonate, sodium nitrate, aluminum chloride monohydrate,sodium hydroxide, sodium phosphate, potassium ferricyanide, tri-chloroacetic acid (TCA), ferric chloride, butylated hydroxytoluene(BHT) and butylated hydroxyanisole (BHA) were obtained from SigmaChemical Co. Mueller Hinton Agar (MHA), Mueller Hinton Broth(MHB), methanol, ethanol, ethyl acetate and n-hexane were purchasedfrom Merck. Blanc and antibiotic loaded discs were purchased fromBioanalyse LTD.

2.2. Metallo- (MPCs) and metal-free phthalocyanines (PCs)

The first five (PC1, PC2, PC3, PC4 and PC5) have been previouslypublished [22,23] and the other two (PC6 and PC7) newly synthesizedand characterized for this study (see supporting information for ex-perimental details). The chemical structures of all tested molecules aregiven in Fig. 1.

2.3. PC stock solution

500mg/mL stock solution was used for antioxidant activity studies.CHCl3 was used as dissolving medium for compounds from PC1 to PC5and DMSO was used as dissolving medium for compounds PC6 and PC7.All stock solutions were prepared in DMSO for antimicrobial assays.0.005M stock solution was used for disc diffusion assay while 1024 μg/

mL stock solution was used for macro dilution assay.

2.4. DPPH free radical scavenging assay

DPPH free radical scavenging activity of the compounds was mea-sured by the method described in Pascoal et al. [24]. Different con-centrations of PCs in DMSO and a positive control Trolox in methanolwere prepared as the test solutions. 1 mL of each molecule with pre-pared concentrations was taken into test tubes and 0.5 mL of 1mMDPPH solution in methanol was added. These solutions were incubatedfor 1 h at room temperature and the absorbance was read at 517 nmusing UV–VIS spectrophotometer (Optimizer). The DPPH radicalscavenging activity percentage was calculated by using the followingformula:

=

−

×

A AA

DPPH radical scavenging activity (%) 100control sample

control

where Acontrol is the absorbance of the control reaction mixture, Asample is the absorbance of the sample.

For each PC compound and standard; IC50 (mg/mL) values, theconcentration of the compound (mg/mL) which reduces the DPPH ab-sorbance by 50%, was also calculated for comparison.

2.5. β-Carotene/linoleic acid bleaching assay

Total antioxidant activity was determined according to the methodof Macro [25] with slight modifications. β-Carotene (0.5 mg) in 1mL ofCHCl3 was added to 25 μL of linoleic acid and 200mg of Tween 40emulsifier mixture. Then the solvent evaporated by vigorous shakingand 100mL of distilled water saturated with oxygen was added to themixture. 160 μL of this mixture was transferred into 40 μL of the sam-ples at different concentrations. As soon as the emulsion was added into each tube, the zero time absorbance was measured at 470 nm usingan Optimizer UV visible spectrophotometer. After incubation for 2 h at50 °C, the absorbance was read again at the same wavelength. Ethanolwas used as a control while BHT was the positive control.

The bleaching rate (R) of β-carotene was calculated according to thefollowing equation:

=Rt

ab

In

in where ln is the natural log, a is the absorbance at zero time, and b isthe absorbance at the time t (120min). Antioxidant activity was cal-culated in terms of percentage inhibition relative to the control usingthe following equation:

=

−

×

R RR

Antioxidant activity (%) 100control sample

control

2.6. Determination of reducing power

Reducing power was determined according to the method describedbefore [24]. 1 mL of sample was further mixed with 2.5 mL of 200mMsodium phosphate buffer (pH 6.6) and 2,5 mL of 1% potassium ferri-cyanide, and the mixture was incubated at 50 °C for 20min. Then,2.5 mL of 10% trichloroacetic acid was added, and the mixture wascentrifuged at 3000 rpm for 10min. The upper layer (2.5 mL) wasmixed with 2.5mL of deionized water and 0.5 mL of 0.1% ferricchloride. Finally, the absorbance was measured at 700 nm usingUV–VIS spectrophotometer (Optimizer). BHA was used as the control.

2.7. Antimicrobial activity

Escherichia coli ATCC 25922 (Gram −), Staphylococcus aureus ATCC25923 (Gram +), Bacillus subtilis ATCC 6633 (Gram +), Bacillus cereus

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ATCC 14579 (Gram +), Bacillus subtilis ATCC 6051 (Gram +) bacteriawere used for antimicrobial activity studies. These were obtained fromInstitute of Hıfzısıhha, Istanbul-Turkey. All antimicrobial activity stu-dies were performed under fluorescent light for 30min.

2.7.1. Disc diffusion assayThe antimicrobial activity of PC compounds was investigated

against the representative microorganisms using disc diffusion method[26]. Bacterial cultures were incubated overnight at 37 °C in theMueller-Hinton Broth (MHB) medium. Incubated microorganisms wereadded to sterile tubes containing 5mL purified water and adjusted to0.5 McFarland standards (1.5× 108 CFU/mL of bacteria) by spectro-photometrically. The cultures taken from tubes by using sterile swabwere inoculated on petri dish containing Mueller Hinton agar. Testcompounds, on the other hand, were dissolved in DMSO to a finalconcentration of 0.005M. The discs were impregnated with 5, 10, 15and 20 μL of prepared solutions and placed on the inoculated agar.Blank discs were impregnated with DMSO (20 μL for each blank disc) asnegative control. Ampicillin (10 μg/disc), Cefotaxime (30 μg/disc) andOfloxacin (10 μg/disc) were used as positive reference standards. Fi-nally, inoculated petri dishes incubated at 37 °C for 24 h at incubatorand antimicrobial activities were evaluated by measuring the zone ofinhibition against the test organisms.

2.7.2. Macro dilution assayMinimum inhibitory concentration (MIC) and minimal bactericidal

concentration (MBC) values of PC compounds against bacterial strainswere determined based on macro dilution method [27]. The inocula ofmicroorganisms were prepared from 12-h broth cultures and suspen-sions were adjusted to 1× 108 CFU/mL. Standard dilutions were madeat the 1024 μg/mL stock solution with a concentration of each moleculeof 512–2 μg /L.

1mL MHB to each tube and 1mL of stock antibiotic solution only tothe first tube were added. 1mL sample from the first tube was trans-ferred to the second tube making a serial dilutions and 1mL is removedfrom the final tube. Finally standard inoculum of microorganism wasadded to the each tube including the control tube which did not containantibiotics and was a reproductive indicator.

Tubes were incubated at 37 °C for 18 h and the MIC and MBC weredetermined as the lowest concentration of molecule to result in nogrowth of the inoculum and the lowest concentration of moleculeneeded to kill 99.9% of the initial organism inoculum, respectively.

2.8. Statistical analysis

All the assays were carried out in triplicate. The results were ex-pressed as mean values and standard deviation (SD).

Cl H

Fig. 1. Structure of PCs and particular substituents.

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3. Result and discussion

3.1. Synthesis and characterization

The synthesis of PC6 and PC7 achieved in two steps starting from 3-(diethylamino)phenoxy) phthalonitrile. First, synthesis of non-qua-ternized derivatives of PC6 and PC7 by cyclotetramerization of 3-(diethylamino)phenoxy)phthalonitrile in the presence of metal salts(InCl3, GaCl3) in quinolone under microwave irradiation. Second, the

quaternization of the products with excess methyl iodide in chloroformin dark gave desired water soluble PC6 and PC7. The reaction stirred for2 weeks to achieve complete quaternization. The obtained PC6 and PC7are soluble in DMSO, DMF and water. Q band absorption of PC6 andPC7 are observed at 651 and 652 nm in water, whereas at 687 and692 nm in DMSO. The blueshift and relatively low intensity of the Qband in water when compared to DMSO solution is a clear indication ofaggregation in aqueous media for PC6 and PC7 [28].

Proton NMR spectra of tetra-substituted phthalocyanines givescomplex signals due to four different mixture of regioisomers, whichare expected to give chemical shifts that differ slightly from each other[29]. Examination of the 1H NMR spectra of PC6 and PC7 in DMSO‑d6showed aromatic protons as complex multiplets 9.73–7.6 and 9.54–7.6regions, respectively. N-CH3 protons of quaternization are observed asmultiple signals around 3.62 ppm for PC6 and 3.59 ppm for PC7. Ali-phatic N-CH2 protons of PC6 are observed as two separate signals at 4.2and 3.96 ppm for PC6 and at 4.14 and 3.91 ppm for PC7.

3.2. Antioxidant activity

Three different test systems, namely DPPH free radical scavenging,β-carotene/linoleic acid systems and ferric reducing antioxidant powerwere used for screening antioxidant activities of PC molecules.

Fig. 2. Free radical scavenging activity of compounds (%). Vertical bars represent the SD.

Table 1IC50 values of PC compounds for DPPH scavenging assay.

Compounds/standards IC50 mg/mL

DPPH

Trolox 0.0029 ± 0.012PC1 0.01592 ± 0.017PC2 0.01196 ± 0.03PC3 0.01514 ± 0.19PC4 0.01168 ± 0.005PC5 0.01322 ± 0.023PC6 0.01698 ± 0.004PC7 0.01326 ± 0.017

Table 2Antioxidant activities of compounds (%) by using the β-carotene/linoleic acid method.

mg/mL β-Carotene/linoleic acid assay

100 200 300 400 500

MoleculesPC5 19.76 ± 1.43 22.11 ± 1.71 30.09 ± 2.07 45.78 ± 0.65 71.83 ± 1.62PC3 ND ND ND 36.71 ± 2.37 68.14 ± 4.12PC4 17.22 ± 0.15 25.43 ± 1.23 33.76 ± 0.75 48.19 ± 0.38 59.02 ± 1.92PC2 14.30 ± 0.03 21.70 ± 0.13 29.46 ± 0.55 41.33 ± 0.47 54.71 ± 2.36PC7 11.44 ± 0.51 18.83 ± 3.65 26.05 ± 1.27 32.11 ± 2.38 51.73 ± 1.09PC6 8.56 ± 2.27 9.71 ± 3.09 9.92 ± 2.79 ND NDPC1 8.66 ± 0.97 17.98 ± 1.41 23.86 ± 2.44 25.94 ± 0.73 NDBHTa 29.46 ± 0.51 44.34 ± 0.94 58.07 ± 1.67 89.51 ± 2.04 98.72 ± 1.12

Values are expressed as the means ± SD of triplicate measurements. ND not detected.a Reference compounds.

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3.2.1. DPPH free radical scavenging activityTo determine the radical scavenging activities of molecules, stan-

dard free radical DPPH has been used. DPPH has a characteristic ab-sorption at 517 nm and antioxidant effect of inhibitor molecules cause adecrease in the absorbance. This decrease in absorbance is taken as ameasure of the extent of radical scavenging [30]. Free radical-scaven-ging capacities of the PC compounds measured by DPPH assay are givenin Fig. 2. Increasing the concentration improved the scavenging activityof all compounds and the highest scavenging activity was obtained withPC4 at 600mg/mL concentration (58.37 ± 0.14%), while PC6 showedthe lowest one (38.02 ± 1.07%) at the same concentration. The des-cending order of radical scavenging effect of PC compounds was4 > 2 > 5 > 7 > 3 > 1 > 6. The antioxidant behavior of phtha-locyanines is directly related to the resonance of localized electrons.Some factors, such as the connected substituent and the centrally lo-cated metal atom, the electrovalent character, have a direct effect onthe Π electron density [31]. Accordingly, the increase in redox activityof the central metal in the PCs also increases the antioxidant property.When this property is considered; PC4 may have exhibited higher DPPHactivity when compared to PC3 and PC5 having the same functionalgroups because the metal atom in the structure has redox activity. Inaddition, PC7 has showed higher activity than PC6 and this can also beexplained by the redox activity of central metal atoms.

When the molecules with and without metal are compared; theactivity of PC4 was found to be higher than metal-free PC2, PC5 andPC3. In general studies, among the molecules having the same

substituents, metal-containing molecules exhibited better activity thanmetal-free molecules [13,16]. On the other hand; in our study, metal-free PC2 showed better activity than PC3 and PC5 due to the differencesbetween the substituents and the comparison between the metal-freemolecules has showed that chlorine substituent in PC1 has a negativeaffect on the activity.

No significant difference was observed between the metal-con-taining and metal-free PCs. At all concentrations tested, Trolox showedabout 50% more DPPH removal activity than PC molecules.

The concentration of antioxidant needed to decrease the initialDPPH concentration by 50% (IC50) is a parameter widely used tomeasure the antioxidant activity and a lower IC50 value correspondswith a higher antioxidant power [32]. Calculated IC50 values gaveproportional results with DPPH scavenging activities (Table 1).

The descending order of IC50 values of PC compounds was4 > 2 > 5 > 7 > 3 > 1 > 6.

3.2.2. β-Carotene/linoleic acid assayThe antioxidant activity of carotenoids is based on the radical ad-

ducts of carotenoids with free radicals from linoleic acid. The linoleicacid free radical attacks the highly unsaturated β-carotene models. Thepresence of different antioxidants can hinder the extent of β-carotene-bleaching by neutralizing the linoleate-free radical and other free ra-dicals formed in the system [33]. Using the β-carotene/linoleic acidmethod; seven different PC derivative molecules showed differentpatterns of antioxidant activities (Table 2). With the increased

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Abso

rban

ce 7

00 n

m

100 200 300 400 500mg/mL

PC1

PC6

PC7

PC2

PC4

PC3

PC5

BHA

Fig. 3. Reducing power assay of PC compounds at different concentrations. Vertical bars represent the SD.

Table 3Antioxidant activities of phthalocyanine molecules from the literature.

Molecule Concentration Scavenging effect of DPPH radical(%)

Ferrous ion-chelating activity(%)

Reference

[Tetrakis (3,4,5-trimethoxybenzyloxy) phthalocyaninato] cobalt(II) 100mg/mL 67.9 – [11]4-(3,4,5-Trimethoxybenzyloxy)phthalonitrile 100mg/mL – 96.7[Co] 2(3),9(10),16(17),23(24)-Tetrakis(4-(methylthio) phenylthio)

phthalocyanine500 μg/mL 54 – [13]

2(3),9(10),16(17),23(24)-Tetrakis(4-(methylthio)phenylthio) phthalocyaninatometal free

100 μg/mL – 79.86

1(4),8(11),15(18),22(25)-Tetrakis-3′-(thiophen-3-ylmethoxy)phthalocyaninatocobalt (II)

100mg/mL 37.94 – [16]

2(3),9(10),16(17),23(24)-Tetrakis-4′-(thiophen-3-ylmethoxy)phthalocyaninatocobalt (II)

500 μg/mL – 81

2,10,16,24-Tetrakis[methyl 2-(oxy)-2,2-diphenylacetate phthalocyaninato]Cobalt (II)

100mg/mL 29.3 – [28]

2,10,16,24-Tetrakis[methyl 2-(oxy)-2,2-diphenylacetate phthalocyaninato]Nickel (II)

100mg/mL – 87.1

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concentration, the antioxidant activity was also increased. The per-centage inhibition of the molecules ranged from 71.83 to 51.73 at500mg/mL concentration on peroxidation in linoleic acid system. Po-sitive control BHT showed 98.72% inhibition activity at this con-centration. PC5 showed the highest antioxidant activity against li-noleate free radicals. The descending order of antioxidant activities ofPC compounds was 5 > 3 > 4 > 2 > 7 > 6 > 1.

3.2.3. Reducing powerThe reducing capacity of a compound may serve as a significant

indicator of its potential antioxidant activity. The presence of re-ductants in the environment converts Fe3+/ferricyanide complex usedin this process to ferrous form. Thus, the concentration of Fe2+ is de-termined by measuring the absorbance at 700 nm [34]. The results ofthe reducing power assay of tested molecules are summarized in Fig. 3.High absorbance indicated the high reducing power and BHA was usedas the positive control. According to the results at 500mg/mL con-centration, the highest activities were measured at 0.562 nm for controlBHA followed by PC5 as 0.391, PC3 as 0.3, PC4 as 0.283, PC2 as 0.219,PC7 as 0.198, PC6 as 0.187 and PC1 as 0.145, respectively.

According to the these results it is possible to say that metallo-PCsshowed better activity than nonmetallo-PCs. Redox-inert zinc (Zn) isthe most abundant metal in the brain and an essential component of

numerous proteins involved in biological defense mechanisms againstoxidative stress [35] and this can explain the higher lipid peroxidationactivity of PC5. Lipids are oxidized in vitro by several different me-chanisms and one potential and widely studied mechanism involves thetransition metal-dependent LDL oxidation. Recent studies showed thatthe interaction of transition metals with some antioxidants is a crucialrole in the protection of LDL against oxidation [36].

The antioxidant properties of PC compounds with different che-mical structures investigated in several studies are summarized inTable 3.

A relationship found among the reducing power, DPPH-scavengingactivity and β-carotene-bleaching extent indicates that the mechanismsof action of the PCs for the antioxidant activity may be identical. Inprevious studies, DPPH scavenging activity was ranged from 29.3 to67.9%. In our study, the highest activity was obtained at 50.32% andthe lowest at 34.81% for seven molecules examined. In all studiesstandard molecules were found to be more active than PCs at DPPHradical scavenging activities. β-Carotene /linoleic acid bleaching ac-tivity assay was performed for PC molecules for the first time in thisstudy and results were compatible with the other antioxidant studies. Ingeneral, tested PCs were found to have higher reducing power valuesthan the standard values of the reduction powers [37,38] although theeffects of molecules in our study were lower than the standards.

Table 4Antimicrobial activity of PCs (0.005M) against the bacterial strains tested based on disc-diffusionmethod. (A); Image of disc diffusion susceptibility test, (B); Inhibition zone of PCs (mm).

Staphylococcusaureus

Escherichiacoli

Bacillussubtilis

Bacilluscereus

Bacillussubtilis

aNC: negative control (DMSO). bAMP: ampicillin (10 μg/disc); OFX: ofloxacin (10 μg/disc); CFX: cefo-taxim (30 μg/disc) were used as positive reference standard antibiotic discs.

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3.3. Antimicrobial activity

Disc diffusion and macro dilution methods were used to determinethe antimicrobial activities of the phthalocyanine molecules against oneGram-negative (Escherichia coli ATCC 25922) and four Gram-positive(Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Bacilluscereus ATCC 14579, Bacillus subtilis ATCC 6051) bacteria.

Both for disc diffusion and macro dilution methods, PC6 and PC7showed an inhibition effect on all tested microorganisms. In disc dif-fusion method; the results obtained from PCs were in the range of0–17.5mm and these were lower than the standard drugs ampicillin,ofloxacin and cefotaxim when compared. Table 4 reveals that PC7showed the highest inhibitory activity against B. subtilis ATCC6633(17.5 mm), B. subtilis ATCC 6051(17mm), S. aureus (16mm), B.cereus (15mm) and E. coli (11mm) at 20 μL loading. Compound PC6, onthe other hand, showed the highest inhibitory activity against E. coli(16mm), B. subtilis and B. cereus (15mm) and S. aureus (14mm) at20 μL loading.

According to the test results obtained from macro dilution assay,MIC and MBC values of tested PCs were in the range of 16–128 μg/mLand 32–256 μg/mL, respectively (Table 5).

In this study Ga (Gallium) and In (Indium) metal containing PCcomplexes with cationic substituents at R groups showed antimicrobialactivity against all tested microorganisms. Mikula et al. investigated theantimicrobial activities of some novel PCs against E. coli and found thatpositively charged molecules showed inhibitory effect on bacteriumwhile negatively charged and neutral ones showed no inhibitory effect[39]. There are also other studies in which the antimicrobial activitiesof PCs against both gram (+) and gram (−) bacteria have been in-vestigated [40–42].

4. Conclusion

New water-soluble quaternized 2, 3-(diethylmethylamino)phenoxytetrasubstituted In and Ga phythalocyanines synthesized and char-acterized. Antioxidant and antimicrobial activities of these complexeswere compared with previously synthesized five metallo- or non-me-tallo octasubstituted PC derivatives bearing diethylaminophenoxy- andchloro-substituents at peripheral positions. Antioxidant activities weredetermined by using, DPPH free radical scavenging, β-carotene/linoleicacid systems and ferric reducing antioxidant power assays. The highestDPPH scavenging activity was obtained with PC4 at 400mg/mL con-centration (50.32 ± 0.17%), PC5 showed the highest antioxidant ac-tivity against linoleate free radicals as 71.83 ± 1.62% at 500mg/mLand the highest reducing power as 0.391 nm. In all antioxidant assayspositive control standards showed higher activities than investigatedphthalocyanines compounds. Antimicrobial activities of PCs were de-termined by using disc diffusion and macrodilution assays. Among allthe tested PC compounds, only positively charged quaternized phtha-locyanine molecules PC6 and PC7 showed antimicrobial activity on alltested microorganisms.

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PC6 PC7

ATCC code Microorganisms MIC MBC MIC MBC

25923 Staphylococcus aureus 128 256 32 6425922 Escherichia coli 32 64 64 1286051 Bacillus subtilis 128 256 16 646633 Bacillus subtilis 64 ND 16 3214579 Bacillus cereus 64 128 64 128

MBC: minimal bactericidal concentration (μg/mL); MIC: minimal inhibitionconcentration (μg/mL).

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