Advertisement

Chemistry Africa

, Volume 2, Issue 1, pp 1–14 | Cite as

Synthesis, Characterization and Antifungal Study of Five New Derivatives of E-1-(2-Hydroxyphenyl)chalcone

  • Kayode L. Amole
  • Isaac A. Bello
  • Adebayo O. OyewaleEmail author
Original Article
  • 201 Downloads

Abstract

In an attempt to search for new and efficient antifungal agents, five chalcones namely (E)-3-(4′-diethylaminophenyl), (E)-3-(2′-ethoxyphenyl), (E)-3-(3′,4′-diethoxyphenyl), (E)-3-(2′,3′-dihydrobenzofuran-5-yl) and (E)-3-(3′,5′-bis[trifluoromethyl]phenyl)-1-(2-hydroxyphenyl) prop-2-en-1-one were synthesized from 2-hydroxyacetophenone with the corresponding substituted benzaldehydes. The synthesized chalcones were characterized by GC–MS, FTIR, 1H NMR and 13C NMR spectra analysis. The antifungal activities of these chalcone derivatives were evaluated against five candida species using the agar diffusion method. All the compounds showed varying degrees of activity against the fungi with the compounds containing the 4′-(diethylamino)phenyl and 2′-ethoxyphenyl moieties being the most potent in the series against the pathogens with MIC between 25 and 50 µg mL−1. Results clearly revealed the electronic effect of substituents on the B-ring of the chalcone on its antimicrobial activity with the compound containing the 4′-(diethylamino) substituent which is a strong electron releasing substituent, showing the highest activity while the compound containing the 3′,5′-bis[trifluoromethyl] substituent, which is a strong electron withdrawing substituent, showing a lower potency against the tested candida species.

Keywords

Flavonoids Chalcones Synthesis Candida and antifungal 

1 Introduction

Despite several researches on flavonoid derivatives to evaluate their therapeutic values, the rapid increase of multi-drug resistant microorganisms and at the same time, the nature of new emerging infections is becoming a major global public health problem [1]. Hence, the urgent need for designing and synthesizing new potent drugs with selective and shorter length treatments to help in the battle against both the drug-resistant and the new emerging microbial pathogens. One of the most frequently encountered groups of organic compounds in medicinal chemistry are chalcones and their derivatives. Chalcone is a generic term given to compounds bearing the 1,3-diphenylprop-2-en-1-one framework, which can be functionalized in the propane chain by the presence of olefinic, keto and/or hydroxyl groups (1) [2].

Chalcones are readily synthesized by Claisen–Schmidt condensation of equimolar concentration of acetophenones and benzaldehydes. The reactions are generally base-catalysed but several other procedures which involve the modification of the general procedure and more especially, the use of mechanical (grinding) and microwave assisted methods have been reported [3]. Chalcones have a wide range of biological activities such as cytotoxic [4], anticancer [5, 6], antioxidant [7], antimicrobial [8, 9], anti-leishmanial [10], anti-inflammatory [10, 11], antimalarial [12], antitubercular [13], antifibrogenic [14], analgesic [11], antiplatelet [15], and antihyperglycemic [16].

Substitution on chalcones moieties have shown varied biological activities and the wide range of these pharmacological activities depend on the nature, number, and the position of the substituent(s) on both benzene rings of the chalcone [17]. For example, pyrimidinyl substitution on chalcone displayed high antitumor properties [6], quinolone substitution on chalcone exhibited great antimalarial activity [18, 19] and thiophenol on chalcone showed potent anti-breast cancer property [19, 20].

This study focuses on the synthesis and biological evaluation of some new 2-hydroxychalcone derivatives as anti-candidiasis and the effect of the substituents on B-ring against candida species.

2 Results and Discussion

2.1 Synthesis of E-1-(2-Hydroxylphenyl)prop-2-en-1-one Derivatives

The synthetic approach to the targeted compounds is illustrated in Scheme 1. The compounds were obtained as different shades of yellow with the exception of compound CKD which was red in colour. The red colouration as opposed to the commonly observed yellow colour for chalcones might be due to increased conjugation and the strong complementary electronic effect of the amino substituent at the para position of the B-ring. The yields obtained for the compounds were between 54 and 81% (Table 1). Compound CKM gave the lowest yield which might be due to the bulky nature of the meta bis-trifluoromethyl substituents on the B-ring that may hinder proper condensation of the reactants.
Scheme 1

Reaction scheme for the synthesis of chalcones

Table 1

Physical data of the 2-hydroxychalcone derivatives

Code

B-ring

M.F

M.W (g)

Colour

Rf

M.P range (oC)

Yield (%)

CKD

4′-(Diethylamino)phenyl

C19H21O2N

295

Red

0.55

124.4–124.8

79

CKE

2′-Ethoxyphenyl

C17H16O3

268

Yellow

0.60

81.7–82.9

81

CKH

3′,4′-Diethoxyphenyl

C19H20O4

312

Yellow

0.43

120.6–122.1

64

CKM

3′,5′-Bis[trifluoromethyl]phenyl

C17H10 F6O2

360

Pale yellow

0.73

138.7–141.3

54

CKQ

2′,3′-Dihydrobenzofuran

C17H14O3

266

Deep yellow

0.50

132.1–133.7

74

M.F. molecular formula, M.W. molecular weight (theoretical), Rf retardation factor, M.P. melting point

The carbon spectra showed highly deshielded carbon resonance in the range of 192.56–193.94 ppm for the carbonyl carbon, the shifts in the range of 162.41–163.80 ppm for C-2 (C–OH), the carbon resonance in the range of 118.57–123.87 ppm for α-C and 140.17–146.68 ppm for β-C of the conjugated chromophores (Table 2).
Table 2

Characteristic 13C NMR shift values of 2-hydroxychalcone derivatives

Code

B-ring

C–OH δ (ppm)

C=O δ (ppm)

α-C δ (ppm)

β-C δ (ppm)

CKD

4′-(Diethylamino)phenyl

163.45

193.41

118.57

146.68

CKE

2′-Ethoxyphenyl

163.80

192.56

123.51

141.52

CKH

3′,4′-Diethoxyphenyl

162.91

192.99

118.15

145.25

CKM

3′,5′-Bis[trifluoromethyl]phenyl

162.41

193.94

123.87

141.51

CKQ

2′,3′-Dihydrobenzofuran

163.55

193.64

118.71

145.86

δ chemical shift value

For 1HNMR spectra, the observed doublets for α-C and β-C with the coupling constants in the range of 15–19 Hz confirmed the α-H and β-H of the conjugated chromophores is trans.

The FTIR spectra showed broad peaks with intensities between 3380 and 3436 cm−1 confirming the presence of hydrogen bonded hydroxyl groups. The bands range from 1632 to1688 cm−1 for C=Ostr, 2996 and 3004 cm−1 for aromatic C–Hstr, 2914 and 2933 cm−1 aliphatic C–Hstr and 1438 and 1606 cm−1 for Cα=Cβ stretching of the chromophores. The m/z values of all the compounds equivalent to their respective theoretical molecular weights confirm the products.

2.2 Antifungal Evaluation

The five synthesized (E)-1-(2-hydroxylphenyl)-chalcone derivatives showed varying degrees of antifungal activities against the tested candida species based on the observed zones of inhibition which ranged from 21 to 27 mm (Table 3). The activities of the compounds were less than that of the standard drug, Fluconazole. The compounds that showed positive activity were further tested to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) (Table 4). Compound containing 4′-(diethylamino) substituent on the ring-B showed significant antifungal activity against the tested candida species at concentration between 25 and 50 µg mL−1 while compounds with 2-ethoxy substituent exhibited potency against the tested candida species except C. stellatoidea, compound with 3′,4′-diethoxyl substituent was active against three of the five tested microbes while compounds containing 2′,3′-dihydrobenzofuran moiety and 3′,5′-bis[trifluoromethyl] substituents were the least active at the same ranges of MIC.
Table 3

Mean zone of inhibition (mm) of prepared 2-hydroxychalcone derivatives (m ± s)

Microbes

CKD

CKE

CKH

CKM

CKQ

FLU

C. albicans

24.0 ± 0.82

23.3 ± 1.32

25.3 ± 1.32

25.0 ± 0.82

30.0 ± 0.82

C. krusei

20.7 ± 1.32

24.7 ± 1.32

25.0 ± 0.82

21.7 ± 1.32

31.0 ± 0.82

C. stellatoidea

25.3 ± 1.32

24.0 ± 0.82

30.0 ± 0.82

C. tropicalis

27.0 ± 0.82

24.0 ± 0.82

21.0 ± 0.82

30.0 ± 0.82

C. pseudotropicalis

23.0 ± 0.82

23.7 ± 1.32

25.7 ± 1.32

31.0 ± 0.82

FLU fluconazole, m mean zone of inhibition, s standard deviation

Table 4

MIC and MFC (µg mL−1) regimes of prepared 2-hydroxylchalcone derivatives

Microbe

CKD

CKE

CKH

CKM

CKQ

MIC

MFC

MIC

MFC

MIC

MFC

MIC

MFC

MIC

MFC

C. albicans

50

200

50

200

50

200

50

100

C. krusei

50

100

50

100

50

100

50

100

C. stellatoidea

50

100

50

100

C. tropicalis

25

100

50

100

50

200

C. pseudotropicalis

50

200

25

100

50

100

MIC minimum inhibition concentration, MFC minimum fungicidal concentration

These results may be due to electronic effect of substituents on the ring-B with the compound containing 4′-(diethylamino) substituent a strong electron releasing group and at the para position of the ring, being seen as the most active compound against tested candida species while the negative inductive effect of the compound containing trifluoromethyl substituent may be responsible for its lower activity. It has been reported that the negative inductive effect of substituents on the benzene ring of a compound reduces its antifungal activities [21].

3 Conclusion

Derivatives of (E)-1-(2-hydroxylphenyl)chalcone with 4′-(diethylamino)phenyl, 2′-ethoxyphenyl, 3′,4′-diethoxyphenyl, 2′,3′-dihydrobenzofuran and 3′,5′-bis[trifluoromethyl]phenyl moieties were successfully synthesized in good yields by a modified Claisen–Schmidt condensation and characterized. Antifungal evaluation of these chalcone derivatives were carried out against C. albicans, C. krusei, C. stellatoidea, C. tropicalis and C. pseudotropicalis. Results showed that inductive effect of substituents especially on the ring-B of the chalcones plays a major role on its antimicrobial activity with the compound CKD containing strong electron releasing substituent exhibiting the highest activity while compound CKM with strong electron withdrawing substituent showing a lower potency against the tested candida species.

4 Experiment

4.1 Synthesis

Five derivatives of 2-hydroxychalcone were synthesized by refluxing 2-hydroxyacetophenone each with 4-(N,N-diethylamino)benzaldehyde, 2-ethoxyl benzaldehyde, 3,4-diethoxylbenzaldehyde, 2,3-dihydrobenzofuran-5-carbaldehyde and 3,5-bis[trifluoromethyl]benzaldehyde.

Completion of the reactions were monitored with TLC aluminium sheet pre-coated plate from Merck (silica gel 60 F254, layer thickness 0.2 mm). The plate was also used to monitor the separation of compounds and determine the retardation factor (Rf) values. Spots were viewed at 254 nm and 366 nm (Model UVGL-58).

The compounds were purified using open column chromatography on silica gel 60 from Merck (60–120 mesh). The columns were packed wet with n-hexane and the compounds were dissolved in dichloromethane and dry loaded.

Proton decoupled Bruker 400 MHz spectrometer was used to measure the NMR spectra. The spectra were recorded with internal standard residual resonance signal of the respective deuterated chloroform and, for some dimethylsulphoxide (DMSO) as indicated on the spectra. All spectra measurement was carried out at room temperature.

The mass spectra were recorded on Agilent technology GC–MS 7890A coupled with MSD 5975C, with GC ALS as injection source. Injection volume (2 µL), over maximum temperature of 325 °C and equilibrium time of 0.25 min. Column size 30 m × 320 µm × 0.25 µm, initial temperature of 110 °C and flow rate of 1.6282 mL min−1. The samples were derivatised using N-methyl-bis[trifluoroacetamide] in methanol as solvent.

The melting point (uncorrected) were determined using Stuart SMP40 automated melting point apparatus (ramp rate 5 °C per minute, start temperature 50 °C and automatic stop). All the solid products were recrystallized from 98% ethanol.

The IR spectra were recorded on a FTIR-ATR spectrometer (Cary 630) using finely grounded sample.

4.2 General Procedure for the Synthesis of E-1-(2-Hydroxyphenyl)-3-(substituted phenyl)-2-propen-1-one

A mixture of the respective benzaldehyde derivatives (5 mmol), 2-hydroxyacetophenones (5 mmol) in 98% ethanol (20 mL) was well stirred in a round bottom flask and 50% NaOH solution (2 mL) was added gradually with constant stirring under reflux for about 5 h. After completion of the reaction as confirmed by TLC (20% ethyl acetate in hexane), the reaction mixture (coloured solution) was allowed to cool to room temperature, then poured over crushed ice, acidified with 10% HCl until the reaction mixtures was slightly acidic and allowed to stand overnight in an ice bath. The product formed was filtered using a vacuum pump, then washed several times with cold distilled water, dried and recrystallized from absolute ethanol. The progress of the reaction was monitored by ascending thin layer chromatography hexane:ethyl acetate (9:1) and the purity of the product was revealed either by reactivity toward iodine vapour or by irradiation with UV254 light.

4.2.1 (E)-3-(4′-Diethylaminophenyl)-1-(2-hydroxy phenyl)prop-2-en-1-one (CKD)

The title compound (1.17 g, 0.005 mol) was prepared from 2-hydroxyacetophenone (0.68 g, 0.005 mol) and 4-(diethylamino)benzaldehyde (0.89 g, 0.005 mol) as a red crystalline solid, m.pt 124.4–124.6 °C, yield = 79%. GCMS m/z = 295, 253, 227, 207, 185,129, 109,83,55 (Fig. 1a).
Fig. 1

a Mass spectrum (MS) of compound CKD. b Infrared (IR) of compound CKD. c1H nuclear magnetic resonance (NMR) of compound CKD. d13C nuclear magnetic resonance (NMR) of compound CKD

FTIR-ATR (v cm−1) = 1688 (C=O), 3421 (–OH), 2996 (Ar C–H), 2914 (Alip C–H), 1461 (Alip C=C) (Fig. 1b); 1H-NMR: (400 MHz, CDCl3) δ (ppm) = 1.12 (6H, t, CH3), 3.32 (4H, m, CH2), 13.23 (1H, s, –OH), 6.56 (2H, d,), 6.81–6.93 (2H, m), 7.32–7.38(3H, m), 7.45 (1H, d), 7.81–7.84 (2H,m) (Fig. 1c); 13C-NMR: (100 MHz, DMSO) δ (ppm) = 12.60 (2C, CH3), 44.56 (2C, CH2), 111.24 (C3′, C5′), 113.42 (C3), 118.42 (C5), 118.57 (α-C), 120.42 (C1, Cq), 121.45 (C1′, Cq), 129.34 (C6), 131.29(C2′, C6′), 135.57 (C4), 146.68 (β-C), 150.07 (C4′, C–N), 163.45 (C2, C–OH), 193.41 (C=O) (Fig. 1d).

4.2.2 (E)-3-(2′-Ethoxyphenyl)-1-(2-hydroxyphenyl) prop-2-en-1-one (CKE)

The title compound (1.09 g, 0.005 mol) was prepared from 2-hydroxyacetophenone (0.68 g, 0.005 mol) and 2-ethoxybenzaldehyde (0.75 g, 0.005 mol) as a yellow crystalline solid, m.pt 81.7–82.9 °C, yield =81%. GCMS m/z = 268, 239, 221, 197,165, 133, 121, 91, 65 (Fig. 2a); FTIR-ATR (v cm−1) = 1689 (C=O), 3381 (–OH), 2982 (Ar C–H), 2933 (Alip C–H), 1606 (Alip C=C) (Fig. 2b); 1H-NMR: (400 MHz, CDCl3) δ (ppm) = 1.46 (3H, t, CH3), 4.01 (2H, q, CH3), 13.08 (1H, s, –OH), 6.83–6.93 (2H, m), 7.00–7.42 (3H, m), 7.43–7.81 (2H, m), 7.86–7.92 (2H, m), 8.19 (1H, d, J = 19.00) (Fig. 2c); 13C-NMR: (100 MHz, DMSO) δ (ppm) = 14.78 (1C, CH3), 63.71(1C, CH2), 112.18 (C3′), 118.27 (C3), 118.88 (C5), 121.16 (C5′), 121.50 (C1, Cq), 123.5 (α-C), 126.51 (C1′, Cq), 127.14 (C6′), 129.45 (C6), 130.45 (C4′), 136.21 (C4), 141.52 (β-C), 158.67 (C1′, C–O), 163.80 (C2, C–OH), 192.56 (C=O) (Fig. 2d).
Fig. 2

a Mass spectrum (MS) of compound CKE. b Infrared (IR) spectrum of compound CKE. c1H nuclear magnetic resonance (NMR) of compound CKE. d13C nuclear magnetic resonance (NMR) of compound CKE

4.2.3 (E)-3-(3′,4′-Diethoxyphenyl)-1-(2-hydroxy phenyl)prop-2-en-1-one (CKH)

The title compound (1.00 g, 0.005 mol) was prepared from 2-hydroxyacetophenone (0.68 g, 0.005 mol) and 3,4-diethoxybenzaldehyde (0.97 g, 0.005 mol) as a yellow crystalline solid, m.pt 120.6–122.1 °C, yield = 64%. GCMS m/z = 312, 283, 255, 227, 192, 136, 115, 92, 55 (Fig. 3a); FTIR-ATR (v cm−1) = 1632.6 (C=O), 3399 (–OH), 2985 (Ar C–H), 2918 (Alip C–H), 1561 (Alip C=C) (Fig. 3b); 1H-NMR: (400 MHz, CDCl3) δ (ppm) = 1.36 (3H, m, CH3), 1.52 (3H, m, CH3), 4.01 (2H, m, CH2), 4.02 (2H, m, CH2), 12.83 (1H, s, –OH), 6.77–6.88 (3H, m), 6.60–7.10 (2H, m), 7.35–7.38 (2H, m), 7.72–7.79 (2H, m) (Fig. 3c); 13C-NMR: (100 MHz, DMSO) δ (ppm) = 14.07–14.18 (2C, CH3), 63.88–64.14 (2C, CH2), 111.83 (C2′), 111.93 (C5′), 116.86 (C3), 117.97 (C1, Cq), 118.15 (α-C), 119.47 (C5), 123.08 (C6′), 126.73 (C1′), 128.94 (C6), 135.55 (C4,), 145.25 (β-C), 148.16 (C3′, C–O), 151.03 (C4′, C–O), 162.91 (C2, C–OH), 192.99 (C=O) (Fig. 3d).
Fig. 3

a Mass spectrum (MS) of compound CKH. b Infrared (IR) spectrum of compound CKH. c1H nuclear magnetic resonance (NMR) of compound CKH. d13C nuclear magnetic resonance (NMR) of compound CKH

4.2.4 (E)-3-(2′,3′-Dihydrobenzofuran-5-yl)-1-(2-hydroxyphenyl)prop-2-en-1-one (CKQ)

The title compound (0.98 g, 0.005 mol) was prepared from 2-hydroxyacetophenone (0.68 g, 0.005 mol) and 2′,3′-dihydrobenzofuran-5-carbaldehyde (0.74 g, 0.005 mol) as a deep yellow crystalline solid, m.pt 132.1–133.7 °C, yield =74%. GCMS m/z = 266, 238,173, 146, 115, 92, 63 (Fig. 4a); FTIR-ATR (v cm−1) = 1662 (C=O), 3436 (–OH), 2997 (Ar C–H), 2915 (Alip C–H), 1438 (Alip C=C) (Fig. 4b); 1H-NMR: (400 MHz, CDCl3) δ (ppm) = 3.26 (2H, t, J = 8.71 Hz, CH2), 4.65 (2H, t, J = 8.73 Hz, CH2), 12.97 (1H, s, –OH), 6.83 (1H, d, J = 8.29 Hz), 6.93 (1H, ddd, J = 1.15 Hz, 7.22 Hz, 8.20 Hz), 7.02 (1H, dd, J = 1.01 Hz, 8.39 Hz), 7.49 (4H, m), 7.90 (2H, m) (Fig. 4c); 13C-NMR: (100 MHz, DMSO) δ (ppm) = 29.21 (1C, CH2), 70.03 (1C, CH2), 109.64 (C7′), 116.89 (C3), 118.58 (C5), 118.71 (α-C), 120.17 (C1, Cq,), 125.23 (C4′), 127.51(Cq, C–CH2), 128.35 (C5′), 129.49 (C6′), 130.57 (C6, Cq,) 136.06 (C4) 145.86 (β-C), 163.04 (C-O), 163.55 (C2, C–OH), 193.64 (C=O) (Fig. 4d).
Fig. 4

a Mass spectrum (MS) of compound CKQ. b Infrared (IR) spectrum of compound CKQ. c1H nuclear magnetic resonance (NMR) of compound CKQ. d13C nuclear magnetic resonance (NMR) of compound CKQ

4.2.5 (E)-3-(3′,5′-Bis[trifluoromethyl]phenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (CKM)

The title compound (0.98 g, 0.005 mol) was prepared from 2-hydroxyacetophenone (0.68 g, 0.005 mol) and 3,5-bis[trifluoromethyl]benzaldehyde (1.21 g, 0.005 mol) as a pale yellow crystalline solid, m.pt 138.7–141.3 °C, yield = 54%. GCMS m/z = 360, 309, 270, 227, 165, 146, 111, 74 (Fig. 5a); FTIR-ATR (v cm−1) = 1655 (C=O), 3399 (–OH), 3004 (Ar C–H), 2918 (Alip C–H), 1438 (Alip C=C) (Fig. 5b); 1H-NMR: (400 MHz, DMSO) δ (ppm) = 12.36 (1H, Broad, –OH), 7.02 (1H, m), 7 7.59 (1H, m), 7.99 (1H, d, J = 15.67, α-H), 8.15 (1H,s), 8.34 (2H, m, β-H), 8.67 (2H, s) (Fig. 5c); 13C-NMR: (100 MHz, DMSO) δ (ppm) = 118.24 (C3), 119.67 (C5), 121.11 (C1, Cq), 123.69 (2C, d, J = 273.22 Hz, C-F3), 123.87 (α-C), 126.17 (C4′), 130.00 (C2′, C6′,), 131.39 (C3′, C5′, q, J = 32.97 Hz, Cq), 131.69 (C6), 137.23 (C4), 137.79 (C1′,Cq), 141.51 (β-C), 162.41 (C2, C–OH), 193.94 (C=O) (Fig. 5d).
Fig. 5

a Mass spectrum (MS) of compound CKM. b Infrared (IR) spectrum of compound CKM. c1H nuclear magnetic resonance (NMR) of compound CKM. d13C nuclear magnetic resonance (NMR) of compound CKM

4.3 Antifungal Evaluation

Test microbes are Candida albicans, Candida krusei, Candida tropicalis, Candida stellatoidea and Candida pseudotropicalis. All are clinical isolates were obtained from the Department of Medical Microbiology, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria.

4.4 Preparation of Culture Media and Compounds

Mueller–Hinton agar was used as the growth medium for the microbes. The dehydrated bacteriological culture media was weighed (36 g) and dissolved in distilled water (100 mL) according to the manufacturer’s specification. The resultant suspension was dispensed into clean conical flask and sterilized at 121 °C for 15 min in an Adelphi bench autoclave and then poured into sterilized petri dishes (sterilized at 121 °C for 15 min in an Adelphi bench autoclave). The plates were allowed to cool and solidify, initial concentration of each of the compounds (200 µg mL−1) was prepared by weighing the compound (0.002 g) and dissolved it in the DMSO (10 mL) to obtain a stock concentration of 200 µg mL−1 of the compound [22].

4.5 Antimicrobial Profile (Zone of Inhibition)

The antibacterial screening was carried out using the agar diffusion method [22]. The prepared medium was seeded with standard inoculums (0.1 mL) of the micro-organism. The inoculums were then spread evenly using a sterilized swab over the surface of the medium, seeded plates were allowed to dry at 37 °C for 30 min inside an incubator. A standard cork borer, 6 mm in diameter was used to cut a well at the centre of each seeded medium used and 0.1 mL of the solution of the compounds (200 µg mL−1) was then introduced into each hole on the surface of the medium. The plates were then incubated at 37 °C for 24 h, after which the plates were observed for zones of inhibition. The zones of inhibition were measured with a transparent ruler and the results were recorded in millimetre. All determinations were made in triplicate. Fluconazole (10 µg mL−1) was used as the standard drug.

4.6 Determination of Minimum Inhibitory Concentration (MIC)

MIC was carried out using broth dilution method [23, 24]. Mueller–Hinton broth was prepared and 10 mL was dispensed into test tubes and sterilized at 121 °C for 15 min, the broth was allowed to cool. Mac–Farland’s turbidity standard scale number 0.5 was prepared to give a turbid solution. Normal saline was prepared and 10 mL was dispensed into sterilized test tubes and the test micro-organism was inoculated and incubated at 37 °C for 6 h. After incubation, dilution of the micro-organism in normal saline was done until the turbidity matched that of the Mac–Farland scale by visual comparison, at this point the test micro-organisms have a concentration of about 1.5 × 108 cfu mL−1.

Two-fold serial dilution of the compound in the sterilized broth was done to obtain the concentration of 200, 100, 50, 25 and 12.5 µg mL−1, respectively. The initial concentration was obtained by dissolving 0.002 g of the compound in 10 mL of the sterile broth. From the suspension of the micro-organism in normal saline, 0.1 mL was inoculated into the different concentrations of the compound in the Mueller–Hinton broth. The broths were then incubated at 37 °C for 24 h, after which the test tubes were observed for turbidity (growth). The test tube with lowest concentration of the compound which showed no turbidity was recorded as the minimum inhibitory concentration (MIC).

4.7 Determination of Minimum Fungicidal Concentration (MFC)

MFC was carried out to check whether the test microbes were killed or only their growth were inhibited. Mueller–Hinton agar was prepared according to manufacturer’s instruction, sterilized at 121 °C for 15 min. It was poured into sterilized petri-dishes. The plates were allowed to cool and solidify. The content of the MIC test tubes in the serial dilution were sub-cultured on to the prepared plates. The plates were then incubated at 37 °C for 24 h, after which the plates were observed for colony growth. The MFC was the plate with lowest concentration of the compound without colony growth [23, 24].

Notes

Compliance with Ethical Standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

References

  1. 1.
    Shaik AB, Yejella RP, Shaik S (2017) Synthesis, antimicrobial and computation evaluation of novel isobutylchalcones as antimicrobial agents. Int J Med chem 1:1–14Google Scholar
  2. 2.
    Sridhar S, Dinda SC, Prasad YR (2010) Synthesis and biological evaluation of some new chalcones containing 2,5-dimethyfuran moiety. E J Chem 8(2):541–546CrossRefGoogle Scholar
  3. 3.
    Rajat G, Abhijit D (2014) Synthesis and biological activities of chalcones and their heterocyclic derivatives: a review. World J Pharm Pharm Sci 3(3):578–595Google Scholar
  4. 4.
    Ahmed N, Konduru NK, Ahmad S, Owais M (2014) Synthesis of flavonoids based novel tetrahydropyran conjugates (Prins products) and their antiproliferative activity against human cancer cell lines. Eur J Med Chem 75:233–246CrossRefGoogle Scholar
  5. 5.
    Sankappa RU, Isloor AM, Pai KSR, Fun HK (2015) Synthesis and in vitro biological evaluation of new pyrazole chalcones and heterocyclic diamides as potential anticancer agents. Arab J Chem 8:317–321CrossRefGoogle Scholar
  6. 6.
    Jin C, Liang YJ, He H, Fu L (2013) Synthesis and antitumor activity of novel chalcone derivatives. Biomed Pharmacother 67:215–217CrossRefGoogle Scholar
  7. 7.
    Agati G, Azzarello E, Pollastri S, Tattini M (2012) Flavonoids as antioxidants in plants: location and functional significance. Plant Sci 196:67–76CrossRefGoogle Scholar
  8. 8.
    Bhuiyan MMH, Hossain MI, Mohammad Al-Amin MM (2011) Microwave-assisted efficient synthesis of chalcones as probes for antimicrobial activities. Chem J 1(1):21–28Google Scholar
  9. 9.
    Prasad YR, Rao AL, Rambabu RE (2008) Synthesis and antimicrobial activity of some chalcone derivatives. Eur J Chem 5(3):461–466Google Scholar
  10. 10.
    Nowakowaska Z (2007) A review of anti-infective and anti-inflammatory chalcones. Eur J Med Chem 42:125–137CrossRefGoogle Scholar
  11. 11.
    Wu X, Wilairat P, Go ML (2002) Antimalarial activity of ferrocenyl chalcones. Bioorg Med Chem Lett 12(17):2299–2302CrossRefGoogle Scholar
  12. 12.
    Lin Y, Zhou Y, Flavin MT, Zhou L, Nie W, Chen F (2002) Chalcones and flavonoids as anti-tuberculosis agents. Bioorg Med Chem 10:2795–2802CrossRefGoogle Scholar
  13. 13.
    Lee SH, Nan JX, Zhao YZ, Woo SW, Park EJ, Kang TH, Seo GS, Kim YC, Sohn DH (2003) The chalcone butein from Rhus verniciflua shows antifibrogenic activity. Planta Med 69(11):990–994CrossRefGoogle Scholar
  14. 14.
    Viana GS, Bandeira MA, Matos FJ (2003) Analgesic and antiinflammatory effects of chalcones isolated from Myracrodruon urundeuva allemão. Phytomedicine 10(2–3):189–195CrossRefGoogle Scholar
  15. 15.
    Ohkura N, Ohnishi K, Taniguchi M, Nakayama A, Usuba Y, Fujita M, Fujii A, Ishibashi K, Baba K, Atsumi G (2016) Anti-platelet effects of chalcones from Angelica keiskei Koidzumi (Ashitaba) in vivo. Pharmazie 71(11):651–654Google Scholar
  16. 16.
    Damazio RG, Zanatta AP, Cazarolli LH, Chiaradia LD, Mascarello A, Nunes RJ, Yunes RA, Barreto Silva FR (2010) Antihyperglycemic activity of naphthylchalcones. Eur J Med Chem 45(4):1332–1337CrossRefGoogle Scholar
  17. 17.
    Hasan SA, Elias AN, Jwaied AH, Khuodaer AR, Hussain SA (2012) Synthesis of new flourinated derivative with anti-inflammatory activity. Int J Pharm Sci 4(5):430–434Google Scholar
  18. 18.
    Li R, Kenyon GL, Cohen FE, Chen X, Gong B, Dominguez JN, Davidson E, Kurzban G, Miller RE, Nuzum O, Rosenthal PJ, McKerrow JH (1995) In vitro antimalarial activity of chalcones and their derivatives. J Med Chem 38:5031–5037CrossRefGoogle Scholar
  19. 19.
    Ahmed N et al (2015) Design, synthesis and antimicrobial activities of novel ferrocenyl and organic chalcone-based sulfones and bis-sulfones. Arab J Chem.  https://doi.org/10.1016/j.arabjc.2014.12.008 Google Scholar
  20. 20.
    Kumar A, Tripathi VD, Kumar P, Gupta LP, Trivedi R, Bid H, Nayak VL, Siddiqui JA, Chakravarti B, Saxena R, Dwivedi A, Siddiquee MI, Siddiqui U, Konwar R, Chattopadhyay N (2011) Design and synthesis of 1,3-biarylsulfanyl derivatives as new anti-breast cancer agents. Bioorg Med Chem 19:5409–5419CrossRefGoogle Scholar
  21. 21.
    Narain Y, Jhaumeer-Laulloo S, Bhowon MG (2010) Structure–activity relationship of Schiff base derivatives. Int J Biol Chem Sci 4(1):69–74Google Scholar
  22. 22.
    Lino A, Deogracios O (2006) The in vitro anti-bacterial activity of Annona senegalensis, Securidacca longipendiculata and Steanotaenia araliacea. Afr J Health Sci 1(6):31–35Google Scholar
  23. 23.
    Vollekova A, Kostalova S, Sochorova R (2001) Iso-quinoline Alkaloids from Mahonia aquifolium stem bark is active against Malassezia Sp. Folia Microbiol 46:107–111CrossRefGoogle Scholar
  24. 24.
    Usman H, Abdulrahman FT, Ladan AA (2007) Phytochemical and evaluation of tribulus terrestris L. (Zygophyllaceae) growing in Nigeria. Res J Biol Sci 2(3):244–247Google Scholar

Copyright information

© The Tunisian Chemical Society and Springer Nature Switzerland AG 2018

Authors and Affiliations

  • Kayode L. Amole
    • 1
  • Isaac A. Bello
    • 1
  • Adebayo O. Oyewale
    • 1
    Email author
  1. 1.Department of Chemistry, Faculty of Physical SciencesAhmadu Bello UniversityZariaNigeria

Personalised recommendations