1. Introduction

Natural and synthetic coumarins have drawn much attention due to its broad pharmacological activities. Literature review reveals that coumarin (2-oxo-2Hchromene) and its derivatives represent one of the most active classes of heterocyclic compounds which possess a wide spectrum of biological activities [1–9]: antitumor [1, 2], antibacterial [3, 4], antifungal [5–7], anticoagulant [8], antioxidant [9], and anti-inflammatory [10].

#### 1.1 Coumarins as antimicrobial agents

Over the past few decades, the search for newer antimicrobials remains an area of intensive investigation in the field of medicinal chemistry due to resistance developed by microorganism to conventional antibiotics. Antimicrobials are one of most significant weapons in fighting bacterial infections. Throughout history, there has been a continual battle between humans and the multitude of microorganisms that cause infection and disease [11, 12]. Coumarin derivatives have a wide range of structural modifications [13], and they can serve as molecular templates for new drugs. Coumarin derivatives are also considered as potential antimicrobial agents [14].

Medimagh-Saidana et al. reported synthesis and antimicrobial activity of some coumarin esters (1) (Figure 1). These compounds showed good activity against

Bacillus sp. and moderate activity against Aspergillus niger. For the data of the antibacterial activity, these compounds were found to be active against Pseudomonas sp. [15].

Al-Amiery et al. have synthesized some coumarin derivatives, and their antifungal activity was determined based on the growth inhibition rates of the mycelia of strains of Aspergillus niger and Candida albicans in Potato Dextrose Broth (PDB) medium against concentrations ranging from 10 to 100 μg/ml. The compound (2) (Figure 1) showed good activity as antifungals against fluconazole as standard drug [16].

Behrami et al. synthesized 8-amino-4,7-dihydroxy-chromen-2-one coumarin derivatives. The antibacterial activities of all the compounds and standard streptomycin and cefalexine at concentrations of 2, 3, and 5 mg/ml were studied against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. One compound (3) (Figure 1) was more active than cefalexine and lesser active than streptomycin, and it was most active among synthesized compounds [17].

Some coumarin derivatives containing thiazolidin-4-one ring were synthesized by Rama Ganesh et al. and were screened for their antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis and Gram-negative bacteria Klebsiella pneumonia and Escherichia coli at the concentration of 0.001 mol/ml compared with the standard drug ciprofloxacin. Zone of inhibition of highly active compound (4) (Figure 1) was 20 mm against Staphylococcus aureus and Bacillus subtilis [18].

#### 1.2 Coumarins as antioxidant agents

Free radicals are molecular species capable of independent existence that contain an unpaired electron in an atomic orbital; they are usually unstable and very reactive. These species are normally produced in the human body from essential metabolic processes, but they may also occur from external sources such as exposure to X-rays, ozone, cigarette smoking, air pollutants, and industrial chemicals [19].

sources [20]. As improved antioxidant status helps to minimize the oxidative damage and thus delays or prevents pathological changes, potential antioxidant therapy should be included either as natural free-radical-scavenging antioxidant enzymes or as an agent which is capable of augmenting the activity of antioxidant

Coumarin Derivatives with Antimicrobial and Antioxidant Activities

DOI: http://dx.doi.org/10.5772/intechopen.88096

The human organism possesses natural systems to annihilate these species, but when the body's ability to regulate them is overwhelmed, a condition known as oxidative stress appears, free radicals attacking important macromolecules leading

Many coumarin derivatives have a special ability to scavenge reactive oxygen

some coumarin derivatives with a heterocyclic ring (7, 8) (Figure 2). All these

benzothiazole, and they were evaluated for antioxidant activity by DPPH radical scavenging activity. The test compound (9) (Figure 2) showed good in vitro

Looking to the medicinal importance of the coumarin ring, we employed coumarin as a naturally occurring skeleton for the construction of new derivatives which might exhibit promising antimicrobial and antioxidant activities [27].

toacetate/ethylbutyrylacetate in the presence of H2SO4 concentrate [28].

The starting materials, 4-methyl/propyl-7-hydroxycoumarin, were prepared by Pechmann synthesis which involved the condensation of resorcinol and ethylace-

Maja et al. synthesized a series of carbohydrazide with coumarin ring (5, 6) and

species and to influence processes involving free radical injury [23, 24].

Shivani et al. synthesized new coumarin-substituted derivatives of

enzymes [21].

Figure 2.

antioxidant activity [26].

141

to cell damage and homeostatic disruption [22].

Coumarin derivatives with antioxidant activity.

compounds prove a good antioxidant activity [25].

2. Synthesis of coumarin derivatives

There is an increasing interest in antioxidants, particularly in those intended to prevent the presumed deleterious effects of free radicals in the human body and to prevent the deterioration of fats and other constituents of food stuffs. In both cases, there is a preference for antioxidants from natural rather than from synthetic

Figure 1. Coumarin derivatives with antimicrobial activity.

Coumarin Derivatives with Antimicrobial and Antioxidant Activities DOI: http://dx.doi.org/10.5772/intechopen.88096

Figure 2. Coumarin derivatives with antioxidant activity.

Bacillus sp. and moderate activity against Aspergillus niger. For the data of the antibacterial activity, these compounds were found to be active against Pseudomonas

Al-Amiery et al. have synthesized some coumarin derivatives, and their antifungal activity was determined based on the growth inhibition rates of the mycelia of strains of Aspergillus niger and Candida albicans in Potato Dextrose Broth (PDB) medium against concentrations ranging from 10 to 100 μg/ml. The compound (2) (Figure 1) showed good activity as antifungals against fluconazole as standard drug

Behrami et al. synthesized 8-amino-4,7-dihydroxy-chromen-2-one coumarin derivatives. The antibacterial activities of all the compounds and standard streptomycin and cefalexine at concentrations of 2, 3, and 5 mg/ml were studied against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. One compound (3) (Figure 1) was more active than cefalexine and lesser active than streptomycin, and

Some coumarin derivatives containing thiazolidin-4-one ring were synthesized by Rama Ganesh et al. and were screened for their antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis and Gram-negative

Free radicals are molecular species capable of independent existence that contain an unpaired electron in an atomic orbital; they are usually unstable and very reactive. These species are normally produced in the human body from essential metabolic processes, but they may also occur from external sources such as exposure to X-rays, ozone, cigarette smoking, air pollutants, and industrial chemicals [19]. There is an increasing interest in antioxidants, particularly in those intended to prevent the presumed deleterious effects of free radicals in the human body and to prevent the deterioration of fats and other constituents of food stuffs. In both cases, there is a preference for antioxidants from natural rather than from synthetic

0.001 mol/ml compared with the standard drug ciprofloxacin. Zone of inhibition of highly active compound (4) (Figure 1) was 20 mm against Staphylococcus aureus

bacteria Klebsiella pneumonia and Escherichia coli at the concentration of

it was most active among synthesized compounds [17].

sp. [15].

Phytochemicals in Human Health

[16].

and Bacillus subtilis [18].

Figure 1.

140

Coumarin derivatives with antimicrobial activity.

1.2 Coumarins as antioxidant agents

sources [20]. As improved antioxidant status helps to minimize the oxidative damage and thus delays or prevents pathological changes, potential antioxidant therapy should be included either as natural free-radical-scavenging antioxidant enzymes or as an agent which is capable of augmenting the activity of antioxidant enzymes [21].

The human organism possesses natural systems to annihilate these species, but when the body's ability to regulate them is overwhelmed, a condition known as oxidative stress appears, free radicals attacking important macromolecules leading to cell damage and homeostatic disruption [22].

Many coumarin derivatives have a special ability to scavenge reactive oxygen species and to influence processes involving free radical injury [23, 24].

Maja et al. synthesized a series of carbohydrazide with coumarin ring (5, 6) and some coumarin derivatives with a heterocyclic ring (7, 8) (Figure 2). All these compounds prove a good antioxidant activity [25].

Shivani et al. synthesized new coumarin-substituted derivatives of benzothiazole, and they were evaluated for antioxidant activity by DPPH radical scavenging activity. The test compound (9) (Figure 2) showed good in vitro antioxidant activity [26].

## 2. Synthesis of coumarin derivatives

Looking to the medicinal importance of the coumarin ring, we employed coumarin as a naturally occurring skeleton for the construction of new derivatives which might exhibit promising antimicrobial and antioxidant activities [27].

The starting materials, 4-methyl/propyl-7-hydroxycoumarin, were prepared by Pechmann synthesis which involved the condensation of resorcinol and ethylacetoacetate/ethylbutyrylacetate in the presence of H2SO4 concentrate [28].

#### 2.1 Mechanism of the Pechmann condensation

The reaction is conducted with a strong Brønsted acid such as methanesulfonic acid or a Lewis acid such as AlCl3. The acid catalyzes transesterification as well as keto-enol tautomerization [29]. A Michael addition leads to the formation of the coumarin skeleton. This addition is followed by rearomatization and then by elimination of water which gives the product (Figure 3).

was heated for 4–6 h with hydrazine hydrate (two moles). After this period of time, the mixture was cooled at room temperature, and the precipitate was filtrated and

The reaction of the acid hydrazides (4-methyl/propyl-2-oxo-2H-benzopyran-7 oxyacetic acid hydrazide) with CS2 in ethanol containing KOH at room temperature has been presented in Figure 6. The corresponding potassium dithiocarbazate

The obtaining of coumarin derivatives with a thiadiazole ring has been described in Figure 7. Literature data show that pyrrole, pyrazole, thiadiazoles, and triazoles and their derivatives are very attractive targets due to their biological properties. In view of the above observations, we have synthesized compounds with thiadiazole ring in order

These compounds were obtained following the reaction between potassium 4 methyl/propyl-2-oxo-2H-benzopyranyl-7-oxymethyldithiocarbazate and acetic acid. The reaction occurred under refluxing. The solid product was separated by

In the synthesis of coumarin derivatives, elemental analysis and two basic spectroscopic techniques, infrared spectroscopy (IR) and nuclear magnetic resonance

to evaluate the potential antimicrobial and antioxidant activities.

Coumarin Derivatives with Antimicrobial and Antioxidant Activities

filtration and then purified by recrystallization from acetic acid [33, 34].

then purified by recrystallization (Figure 5).

DOI: http://dx.doi.org/10.5772/intechopen.88096

derivatives, IVa–IVb, are obtained [32].

Synthesis of coumarin acetohydrazides III(a-b).

Synthesis of coumarin potassium salts IV(a-b).

Synthesis of coumarin thiadiazoles derivatives V(a-b).

Figure 5.

Figure 6.

Figure 7.

143

The coumarin compounds have wide interest due to their diverse pharmacological properties. In particular, these biological activities make coumarin compounds more attractive and testing as novel therapeutic compounds.

As part of our aim in research of biologically active coumarin derivatives, the free hydroxyl group on the coumarin ring has allowed us to introduce some radicals that can improve the biological activity.

The fourth scheme describes the reactions of 4-methyl/propyl-7 hydroxycoumarin with ethyl bromoacetate. 2-Ethyl-((4-methy/propyl-2-oxo-2Hchromen-7-yl)oxy)acetate (IIa–IIb) was prepared by heating a mixture of 4 methyl/propyl-7-hydroxycoumarin and ethyl bromoacetate in the presence of K2CO3 anhydrous in dry acetone. After filtration, the solution was evaporated, and the solid products (IIa or IIb) were recrystallized from ethanol [30] (Figure 4).

The fifth scheme describes the reactions of compounds IIa–IIb with hydrazine hydrate. The chemistry of hydrazide and its derivatives has obtained great interest in both organic chemistry and biological science with remarkable impact. Hydrazides and hydrazones are possessing -NH-NH2 and -NH-N=CH- groups, respectively. The availability of proton in hydrazides constitutes them as an important class of compound for new drug discovery. Therefore, researchers have shown great interest in developing these compounds as target structures for evaluating new biological activities [31].

Hydrazinolysis of compounds IIa–IIb gave the corresponding acetohydrazides (IIIa–IIIb) in good yields [30, 32]. One mole of the compound IIa or IIb in ethanol

Figure 3. Mechanism of the Pechmann condensation.

Figure 4. Synthesis of coumarin esters II(a-b).

Coumarin Derivatives with Antimicrobial and Antioxidant Activities DOI: http://dx.doi.org/10.5772/intechopen.88096

2.1 Mechanism of the Pechmann condensation

Phytochemicals in Human Health

ination of water which gives the product (Figure 3).

that can improve the biological activity.

biological activities [31].

Figure 3.

Figure 4.

142

Mechanism of the Pechmann condensation.

Synthesis of coumarin esters II(a-b).

more attractive and testing as novel therapeutic compounds.

The fourth scheme describes the reactions of 4-methyl/propyl-7-

The reaction is conducted with a strong Brønsted acid such as methanesulfonic acid or a Lewis acid such as AlCl3. The acid catalyzes transesterification as well as keto-enol tautomerization [29]. A Michael addition leads to the formation of the coumarin skeleton. This addition is followed by rearomatization and then by elim-

The coumarin compounds have wide interest due to their diverse pharmacological properties. In particular, these biological activities make coumarin compounds

As part of our aim in research of biologically active coumarin derivatives, the free hydroxyl group on the coumarin ring has allowed us to introduce some radicals

hydroxycoumarin with ethyl bromoacetate. 2-Ethyl-((4-methy/propyl-2-oxo-2Hchromen-7-yl)oxy)acetate (IIa–IIb) was prepared by heating a mixture of 4 methyl/propyl-7-hydroxycoumarin and ethyl bromoacetate in the presence of K2CO3 anhydrous in dry acetone. After filtration, the solution was evaporated, and the solid products (IIa or IIb) were recrystallized from ethanol [30] (Figure 4). The fifth scheme describes the reactions of compounds IIa–IIb with hydrazine hydrate. The chemistry of hydrazide and its derivatives has obtained great interest in both organic chemistry and biological science with remarkable impact. Hydrazides and hydrazones are possessing -NH-NH2 and -NH-N=CH- groups, respectively. The availability of proton in hydrazides constitutes them as an important class of compound for new drug discovery. Therefore, researchers have shown great interest in developing these compounds as target structures for evaluating new

Hydrazinolysis of compounds IIa–IIb gave the corresponding acetohydrazides (IIIa–IIIb) in good yields [30, 32]. One mole of the compound IIa or IIb in ethanol was heated for 4–6 h with hydrazine hydrate (two moles). After this period of time, the mixture was cooled at room temperature, and the precipitate was filtrated and then purified by recrystallization (Figure 5).

The reaction of the acid hydrazides (4-methyl/propyl-2-oxo-2H-benzopyran-7 oxyacetic acid hydrazide) with CS2 in ethanol containing KOH at room temperature has been presented in Figure 6. The corresponding potassium dithiocarbazate derivatives, IVa–IVb, are obtained [32].

The obtaining of coumarin derivatives with a thiadiazole ring has been described in Figure 7. Literature data show that pyrrole, pyrazole, thiadiazoles, and triazoles and their derivatives are very attractive targets due to their biological properties. In view of the above observations, we have synthesized compounds with thiadiazole ring in order to evaluate the potential antimicrobial and antioxidant activities.

These compounds were obtained following the reaction between potassium 4 methyl/propyl-2-oxo-2H-benzopyranyl-7-oxymethyldithiocarbazate and acetic acid. The reaction occurred under refluxing. The solid product was separated by filtration and then purified by recrystallization from acetic acid [33, 34].

In the synthesis of coumarin derivatives, elemental analysis and two basic spectroscopic techniques, infrared spectroscopy (IR) and nuclear magnetic resonance

Figure 5. Synthesis of coumarin acetohydrazides III(a-b).

Figure 6. Synthesis of coumarin potassium salts IV(a-b).

Figure 7. Synthesis of coumarin thiadiazoles derivatives V(a-b).

spectroscopy (NMR), were used to characterize the structures of the target compounds [35].

The physical constants and analytical data of compounds Ia–Ib, IIa–IIb, IIIa–IIIb, IVa–IVb, and Va–Vb have been given in Tables 1–5.


Table 1.

Physical constants and analytical data of compounds Ia–Ib.

The IR spectra of all synthesized compounds showed some characteristic peaks

H-NMR spectra of the synthesized compounds are in accordance with the assigned structures (Table 11). The aliphatic protons resonated in the range of 1.20–4.77 ppm. It can be seen that all the compounds exhibited the respected proton

Compd. R υO-H cm<sup>1</sup> υC-H aliph cm<sup>1</sup> υC=O lactone cm<sup>1</sup> υC-O cm<sup>1</sup> Ia H3C▬ 3280 2950 1680 1150 Ib H3C▬CH2▬CH2▬ 3195 2970 1695 1140

Compd. R MP °C Molecular formula Analysis found (calculated) (%)

Compd. R MP °C Molecular formula Analysis found (calculated) (%)

IVa H3C▬ 184 C13H11N2O4KS2 43.08

Coumarin Derivatives with Antimicrobial and Antioxidant Activities

DOI: http://dx.doi.org/10.5772/intechopen.88096

IVb H3C▬CH2▬CH2▬ 176–178 C15H15N2O4KS2 46.13

Physical constants and analytical data of compounds IVa–IVb.

C H

C H

3.06 3.01

3.87 3.76

3.29 3.06

4.22 4.12

42.87

46.02

50.63

53.33

indicating the presence of particular groups (Tables 6–10). <sup>1</sup>

Physical constants and analytical data of compounds Va–Vb.

Va H3C▬ 267–268 C13H10N2O3S2 50.97

Vb H3C▬CH2▬CH2▬ 172 C15H14N2O3S2 53.87

chemical shifts in the same range.

IR spectral data of compounds Ia–Ib.

Table 4.

Table 5.

Table 6.

145

#### Table 2.

Physical constants and analytical data of compounds IIa–IIb.


Table 3.

Physical constants and analytical data of compounds IIIa–IIIb.

Compd. R MP °C Molecular formula Analysis found (calculated) (%) C H IVa H3C▬ 184 C13H11N2O4KS2 43.08 42.87 3.06 3.01 IVb H3C▬CH2▬CH2▬ 176–178 C15H15N2O4KS2 46.13 46.02 3.87 3.76

#### Table 4.

spectroscopy (NMR), were used to characterize the structures of the target com-

Compd. R MP °C Molecular formula Analysis found (calculated) (%)

Compd. R MP °C Molecular formula Analysis found (calculated) (%)

Compd. R MP °C Molecular formula Analysis found (calculated) (%)

C H

C H

C H

4.87 4.80

5.84 5.76

4.58 4.55

5.92 5.69

5.38 5.22

6.25 6.05

68.02

70.21

64.10

65.89

57.98

60.56

The physical constants and analytical data of compounds Ia–Ib, IIa–IIb,

IIIa–IIIb, IVa–IVb, and Va–Vb have been given in Tables 1–5.

Ia H3C▬ 185 C10H8O3 68.18

Ib H3C▬CH2▬CH2▬ 130 C12H12O3 70.57

IIa H3C▬ 100–102 C14H14O5 64.12

IIb H3C▬CH2▬CH2▬ 98 C16H18O5 66.19

IIIa H3C▬ 204–205 C12H12N2O4 58.06

IIIb H3C▬CH2▬CH2▬ 147–148 C14H16N2O4 60.86

Physical constants and analytical data of compounds IIIa–IIIb.

Physical constants and analytical data of compounds Ia–Ib.

Physical constants and analytical data of compounds IIa–IIb.

pounds [35].

Phytochemicals in Human Health

Table 1.

Table 2.

Table 3.

144

Physical constants and analytical data of compounds IVa–IVb.


#### Table 5.

Physical constants and analytical data of compounds Va–Vb.

The IR spectra of all synthesized compounds showed some characteristic peaks indicating the presence of particular groups (Tables 6–10). <sup>1</sup>

H-NMR spectra of the synthesized compounds are in accordance with the assigned structures (Table 11). The aliphatic protons resonated in the range of 1.20–4.77 ppm. It can be seen that all the compounds exhibited the respected proton chemical shifts in the same range.


#### Table 6.

IR spectral data of compounds Ia–Ib.



#### Table 7.

IR spectral data of compounds IIa–IIb.


#### Table 8.

IR spectral data of compounds IIIa–IIIb.

Compd. R υN-H cm<sup>1</sup> υC=S cm<sup>1</sup> IVa H3C▬ 3210 1240 IVb H3C▬CH2▬CH2▬ 3150 1210

#### Table 9.

IR spectral data of compounds IVa–IVb.

3. Pharmacological activities of coumarin derivatives

Compd. R Chemical shift (δ ppm) 500 MHz

Coumarin Derivatives with Antimicrobial and Antioxidant Activities

DOI: http://dx.doi.org/10.5772/intechopen.88096

Ia H3C▬ 2.73 ppm s, 3H: CH3; 6.04 ppm s, H3; 6.72 ppm s, H8; 6.83–6.85 ppm d, H6,

Ib H3C▬CH2▬CH2▬ 1.20 ppm t, 3H: CH3 (12); 1.66 ppm m, 2H: CH2 (11); 2.81–2.84 ppm m,

IIa H3C▬ 1.26–1.28 ppm t, 3H: CH3 (14); 2.73 ppm s, 3H: CH3; 4.25–4.28 ppm m,

IIb H3C▬CH2▬CH2▬ 0.95–0.98 ppm t, 3H: CH3 (17); 1.20–1.23 ppm t, 3H: CH3 (14); 1.60–

IIIa H3C▬ 2.74 ppm s, 3H: CH3; 3.86 ppm s, 2H: NH2 (13); 4.42 ppm s, 2H: CH2 (10);

IIIb H3C▬CH2▬CH2▬ 0.95–0.98 ppm t, 3H: CH3 (16); 1.59–1.66 ppm m, 2H: CH2 (15); 2.72–

IVa H3C▬ 2.71–2.74 ppm d, 3H: CH3; 4.41–4.43 ppm s, 2H: CH2 (10); 6.02–6.05 ppm

IVb H3C▬CH2▬CH2▬ 1.20–1.22 ppm t, 3H: CH3 (18); 1.62–1.66 ppm m, 2H: CH2 (17);

Va H3C▬ 2.39 ppm s, 3H: CH3; 4.77 ppm s, 2H: CH2 (10); 6.23 ppm s, H3;

Vb H3C▬CH2▬CH2▬ 0.95–0.98 ppm t, 3H: CH3 (19); 1.60–1.65 ppm m, 2H: CH2 (18);

JH6,H5 = 7.5 Hz; 7.62–7.64 ppm d, H5, JH5,H6 = 7.5 Hz; 10.85 ppm s, 1H: OH

2H: CH2 (10); 6.11 ppm s, H3; 6.72 ppm s, H8; 6.84–6.85 ppm d, H6, JH6, H5 = 7.5 Hz; 7.63–7.65 ppm d, H5, JH5,H6 = 7.5 Hz; 10.86 ppm s, 1H: OH

2H: CH2 (13); 4.61 ppm s, 2H: CH2 (10); 6.04 ppm s, H3; 6.84 ppm s, H8; 7.05–7.07 ppm d H6; 7.62–7.64 ppm d, H5

1.65 ppm m, 2H: CH2 (16); 2.72–2.75 ppm t, 2H: CH2 (15); 4.15– 4.20 ppm m, 2H: CH2 (13); 4.92 ppm s, 2H: CH2 (10); 6.17 ppm s, H3; 6.98 ppm s, H8; 6.96–6.97 ppm d H6; 7.73–7.75 ppm d, H5

6.03 ppm s, H3; 6.83 ppm s, H8; 7.05–7.07 ppm d; 7.62–7.64 ppm d, H5; 8.02 ppm s, NH (12)

2.75 ppm t, 2H: CH2 (14); 4.35 ppm s, 2H: NH2 (13); 4.61 ppm s, 2H: CH2 (10); 6.17 ppm s, H3; 6.98 ppm s, H8; 6.99–7.00 ppm d H6; 7.74–7.76 ppm d, H5; 9.42 ppm s, NH (12)

q, H3; 6.82–6.84 ppm d, H8; 7.05–7.08 ppm q H6; 7.62–7.64 ppm d, H5; 9.94 ppm s, NH (12); 11.23 ppm s, NH (13)

2.79–2.82 ppm t, 2H: CH2 (16); 4.40 ppm s, 2H: CH2 (10); 6.10 ppm s, H3; 6.84 ppm s, H8; 7.04–7.08 ppm q H6; 7.62–7.66 ppm d, H5; 9.95 ppm s, NH (12); 11.25 ppm s, NH (13)

6.99 ppm s, H8; 7.02–7.04 ppm d H6; 7.70–7.72 ppm d, H5; 10.29 ppm s, SH (16)

2.72–2.75 ppm t, 2H: CH2 (17); 4.77 ppm s, 2H: CH2 (10); 6.17 ppm s, H3; 6.98 ppm s, H8; 6.99–7.00 ppm d H6; 7.75–7.76 ppm d, H5; 11.27 ppm s, SH (16)

The compounds were screened for their antibacterial and antifungal activity

The antimicrobial activity was studied using Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Sarcina lutea ATCC 9341, Bacillus cereus ATCC 14579), Gram-negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), and pathogenic yeasts (Candida albicans ATCC 10231, Candida glabrata ATCC MYA 2950, Candida parapsilosis ATCC 22019). All these strains were

obtained from the Culture Collection of the Department of Microbiology, Faculty of Pharmacy, "Grigore T. Popa" University of Medicine and Pharmacy, Iasi, Romania.

3.1 Antimicrobial activity

Table 11. 1

147

according to standard protocols [36].

H-NMR spectral data of compounds I–V.


#### Table 10.

IR spectral data of compounds Va–Vb.


Coumarin Derivatives with Antimicrobial and Antioxidant Activities DOI: http://dx.doi.org/10.5772/intechopen.88096

Table 11. 1 H-NMR spectral data of compounds I–V.
