Biocidal activity of some Mannich base cationic derivatives

Article abstract of DOI:10.1016/j.bmc.2005.07.031

A novel series of cationic surfactants was prepared based on Mannich base (produced from the condensation of piperidine and/or morpholine as secondary amine and paraformaldehyde in the presence of 8-hydroxyquinoline). The chemical structures of the synthesized cationic surfactants were confirmed using elemental analyses, FTIR spectroscopy and ¹H NMR. Surface activities of the prepared surfactants were measured including: surface tension (γ), critical micelle concentration (CMC), effectiveness (π_CMC), efficiency (Pc₂₀), maximum surface excess (Γ_max), minimum surface area (A_min), interfacial tension (γ _IT), emulsification power and foaming power at 25°C. The structural influences on their surface activities and adsorption free energy were discussed. The synthesized cationic surfactants were evaluated for their biocidal activity towards Gram +ve bacteria (Staph. Cocu., Bacillus), Gram -ve bacteria (Salmonella, E. coli), fungi (A. terrus., A. flav.) and yeast (Candida) at 1.0, 2.5 and 5.0 mg/mL, respectively. The target compounds showed good inhibition towards Gram +ve bacteria, Gram -ve bacteria and yeast. Meanwhile, excellent fungicidal results were obtained against the various types of fungi under investigation.

Full text of DOI:10.1016/j.bmc.2005.07.031

Bioorganic & Medicinal Chemistry 13 (2005) 5921–5926
Biocidal activity of some Mannich base cationic derivatives
Nabel A. Negm,a,* Salwa M.I. Morsya and Medhat M. Saidb
aEgyptian Petroleum Research Institute, Applied Surfactant Laboratory, Petrochemicals Department, Cairo, Egypt
bNational Research Center, Giza, Egypt
Received 21 December 2004; revised 9 July 2005; accepted 11 July 2005
Available online 9 September 2005
Abstract—A novel series of cationic surfactants was prepared based on Mannich base (produced from the condensation of piper-
idine and/or morpholine as secondary amine and paraformaldehyde in the presence of 8-hydroxyquinoline). The chemical structures
of the synthesized cationic surfactants were confirmed using elemental analyses, FTIR spectroscopy and 1H NMR. Surface activities
of the prepared surfactants were measured including: surface tension (c), critical micelle concentration (CMC), effectiveness (pCMC),
efficiency (Pc20), maximum surface excess (Cmax), minimum surface area (Amin), interfacial tension (cIT), emulsification power and
foaming power at 25 ꢀC. The structural influences on their surface activities and adsorption free energy were discussed. The synthe-
sized cationic surfactants were evaluated for their biocidal activity towards Gram +ve bacteria (Staph. Cocu., Bacillus), Gram ꢀve
bacteria (Salmonella, E. coli), fungi (A. terrus., A. flav.) and yeast (Candida) at 1.0, 2.5 and 5.0 mg/mL, respectively. The target com-
pounds showed good inhibition towards Gram +ve bacteria, Gram ꢀve bacteria and yeast. Meanwhile, excellent fungicidal results
were obtained against the various types of fungi under investigation.
ꢁ 2005 Elsevier Ltd. All rights reserved.
1. Introduction
cyclic derivatives exhibit excellent corrosion inhibition
through their tendency towards adsorption at
interfaces.4
Mannich base is a condensation product of ammonia,
primary or secondary amine hydrochlorides with formal-
dehyde and reactive hydrogen containing compounds.1
The reaction proceeded according to the following:
A new trend in the Mannich base cationic surfactants
appeared in their biocidal activity towards various types
of microorganisms (bacteria and fungi). That biocidal
activity depends mainly on the chemical structure of
the Mannich base and the surface activity of their
cationic derivatives.5
RCOCH3 + CH2O + RNHꢁHCl ! RCOCH2CH2NR2
Mannich base is characterized by the presence of tertiary
nitrogen, which is capable of undergoing a quaterniza-
tion reaction in the presence of halocompounds to pro-
duce cationic compounds with a good surface activity.2
The surface activity of the produced compounds de-
pends mainly on the starting materials of secondary
amines, the active-hydrogen containing compounds
and the quaternizing agents. The long-chain derivatives
of Mannich base cationic surfactants play an important
role in the emulsification process,3 while the unsaturated
In this work, six Mannich base cationic surfactants were
synthesized through direct quaternization of (morphol-
ine and/or piperidine) Mannich bases, and dodecyl-,
hexadecyl- and octadecylbromoacetate. The produced
cationic surfactants, namely, 7-pipridinomethyl-8-hy-
droxy-N-methyl-carboxyalkyl quinolinium bromide (Pa–c)
and 7-morpholinomethyl-8-hydroxy-N-methylcarboxyalkyl
quinolinium bromide (Ma–c) were confirmed using
elemental analyses, FTIR-spectroscopy and H NMR
1
spectra. Their surface activities were measured including
surface tension (c), critical micelle concentration
(CMC), effectiveness (pCMC), efficiency (Pc20), maximum
surface excess (Cmax), minimum surface area (Amin),
interfacial tension (cIT), emulsification power and
foaming power at 25 ꢀC. The biocidal activities of the
synthesized cationic surfactants were tested against
Gram-positive bacteria, Gram-negative bacteria, yeast
Keywords: Mannich base; Surface tension; Interfacial tension; Critical
micelle concentration; Effectiveness; Efficiency; Surface pressure; Min-
imum surface area; Emulsification power; Free energy; Adsorption;
Micellization; Antibacteria; Antifungi; Antiyeast; Bactericidal; Biocidal
activity.
*
Corresponding author. Tel./fax: +2022233123; e-mail: nabelnegm@
hotmail.com
0968-0896/$ - see front matter ꢁ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2005.07.031

5922
N. A. Negm et al. / Bioorg. Med. Chem. 13 (2005) 5921–5926
and fungi. The modes of action of these compounds
against these microorganisms were discussed.
performed by vigorously stirring a mixture of 10 mL
(1%) surfactant solution and 10 mL of paraffin oil at
30 ꢀC. Emulsifying power (emulsion stability) was ex-
pressed as the time required for separation of 9 mL pure
water. While, foam power was measured after shaking
100 mL of 0.1% concentration of the surfactant solution
vigorously in a stoppered graduated 250 mL cylinder at
room temperature.9
2. Experimental procedures
2.1. Synthesis of Mannich base
To a cold suspension of 8-hydroxyquinoline (0.01 mol)
in acetic acid (30 mL), piperidine or morpholine
(0.011 mol) was added, followed by paraformaldehyde
(0.11 mol). The reaction mixture was then heated under
reflux for 4h and left overnight at room temperature.
After removing the acetic acid in a vacuum, the residue
was treated with dilute hydrochloric acid to dissolve the
Mannich base formed. The reaction mixture was filtered
and the cooled filtrate was made alkaline with ammoni-
um hydroxide. The product was filtered and recrystal-
lized twice from acetone to yield piperidine and
morpholine Mannich base, respectively.6
2.5. Biocidal activity
The antimicrobial activities of the surfactants were tested
according to the diffusion agar technique. They were
tested for their bactericidal activity against Gram +ve
bacteria (Staph. Cocu., Bacillus), Gram ꢀve bacteria
(Salmonella, E. coli) and for fungicidal activity against
(A. terrus., A. flav.) and yeast (Candida) at 1.0, 2.5 and
5.0 mg/mL.10
3. Results and discussion
3.1. Structure
2.2. Synthesis of the cationic form of Mannich base
Mannich base (0.1 mol) and 0.1 mol of the bromoesters
(dodecyl-, hexadecyl- or octadecyl bromoacetate) were
dissolved in ethyl alcohol (50 mL) and refluxed for
6 h.7 The produced crystalline product was filtered,
washed by petroleum ether (60–80 ꢀC) twice and dried
under vacuum at 50 ꢀC. Elemental analyses, FTIR and
1H NMR spectroscopic analyses confirmed the struc-
tures of the synthesized surfactants (Pa–c, Ma–c).
The chemical structures of the synthesized surfactants
were confirmed using microelemental analyses, which
showed good coincidence between the calculated and
found values of C, H, N and Br (%), Table 1.
FTIR spectra showed the following bands: mC@O at 1750–
1735 cmꢀ1, mCH at 2926 cmꢀ1, mCH at 2853 cmꢀ1, mC@C at
3
2
1667–1640 cmꢀ1, mC–N at 1250–1020 cmꢀ1 and mþN at
3040 cmꢀ1, which confirmed the expected functional
groups found in the synthesized molecules.
2.3. Surface tension and critical micelle concentration
Surface tension values of the synthesized cationic surfac-
tant solutions (Pa–c, Ma–c) were obtained at 25 ꢀC using
Du-Nouy Tensiometer (KRUSS K6 Type 4851) with a
platinum ring. Apparent surface tensions were measured
about five times for the sample within 2 min interval be-
tween each reading. The obtained data were plotted
against ꢀlogC without any correction. CMC values
were determined from the plot of surface tension versus
concentration.8
1H NMR analyses of compounds (Pa) and (Ma) as rep-
resentative samples showed the following; for (Pa): at
d = 2.3 ppm (t, 3H, CH3); at 1.25 ppm (m, 24H, CH2),
at 0.95 ppm (t, 2H, CH2CO) and at 2.0 ppm (d, 4H,
CH@CH). While, for (Ma): at d = 2.3 ppm (t, 3H,
CH3) at 0.95 ppm (t, 2H, CH2CO); at 2.1 ppm (d, 4H,
CH@CH) and at 1.25 ppm (m, 20H, CH2).
The spectral analyses confirmed the chemical structures
of the synthesized cationic surfactants, as shown in
Scheme 1.
2.4. Interfacial tension, emulsion stability and foaming
power
Interfacial tension was measured using Du Nouy Tensi-
ometer (KRUSS K6 type 8451). These measurements
were carried out by the addition of 5 mL of the synthe-
sized surfactant solution (0.1 M) and 5 mL of paraffin
oil at ambient temperature. The emulsion stability was
3.2. Surface properties
3.2.1. Surface tension (c), interfacial tension (cIT) and
critical micelle concentration (CMC). Figures 1 and 2
represent the variations of surface tension versus ꢀlogC
Table 1. Characterization of the Mannich base cationic compounds
Compound
M. wt
Solvent
Yield (%)
C%
H%
N%
Br%
Calcd
Found
Calcd
Found
Calcd
Found
Calcd
Found
Pa
Pb
549
605
633
551
607
635
Ethanol
Ethanol
Ethanol
Ethanol
Ethanol
Ethanol
79
75
72
68
65
65
63.38
65.45
66.35
60.98
63.26
64.25
63.36
65.42
65.34
60.96
63.25
64.23
8.56
8.76
9.01
7.80
8.40
8.66
8.55
8.74
9.00
7.78
8.39
8.65
5.10
4.62
4.42
5.08
4.61
4.40
5.09
4.62
4.42
5.08
4.60
4.40
14.57
13.22
12.63
14.51
13.17
12.59
14.56
13.20
12.60
14.48
13.09
12.52
Pc
Ma
Mb
Mc

N. A. Negm et al. / Bioorg. Med. Chem. 13 (2005) 5921–5926
5923
+
-
N
Br
CH2
N
HO
CH2COOR
7-Pipridinomethyl-8-hydroxy -N-methylcarboxyalkyl quinolinium bromide
(Pa-c)
+
-
O
N
Br
CH2
N
HO
CH2COOR
7-Morphilinomethyl-8-hydroxy -N-methylcarboxyalkyl quinolinium bromide
(Ma-c)
Alkyl = a : dodecyl-, b : hexadecyl- and c : octadecyl-
Scheme 1. Mannich base cationic surfactants.
75
70
65
60
55
50
45
40
35
65
60
55
50
45
40
4.6
4.3
4
3.6
3.3
3
2.6
2.3
4.6
4.3
4
3.6
-log C
3.3
3
2.6
2.3
-log C
Figure 1. Surface tension isotherm of morpholine derivatives, Ç Ma; d
Mb; n Mc.
Figure 2. Surface tension isotherm of piperidine derivatives, Ç Pa; d
Pb; n Pc.
pholine cationic derivatives showed a reverse trend in
their surface tension and critical micelle concentration
values, which may be due to the presence of the oxygen
atom in their skeleton, and which decreases the water/
hydrophobe repulsion that occurred through hydrogen
bond formation between the morpholine ring and
hydrogen atoms in water molecule.15 This phenomenon
allows the molecules to be presented in the bulk of their
solutions, which corresponded to higher surface tension
values for their solutions at the critical micelle concen-
tration than piperidine derivatives.
of the synthesized cationic surfactants Pa–c and Ma–c at
25 ꢀC. It is clear from Figure 1 that the surface tension
values were decreasing gradually by increasing the alkyl
chain length (hydrophobic chains). This could be due to
increasing the interaction forces between these chains
and the polar medium (H2O), which directs the surfac-
tant molecules towards the air/water interface.11 Hence,
the surface tension values decrease gradually. Due to
increasing the repulsion forces between the various
piperidine derivatives and the water molecules, their
ability for micellization increases at lower concentra-
tions as represented in Table 2. The gradual increase
of alkyl chain lengths in the surfactant molecules is char-
acterized by decreasing their critical micelle concentra-
tions (CMC), Table 2. That effect was observed in
several studies of surfactants.12–14 On the contrary, mor-
The interfacial tension values of piperidine and mor-
pholine cationic surfactants between their solutions
and paraffin oil generally decrease by increasing the
hydrophobic chain length, which may be due to the

5924
N. A. Negm et al. / Bioorg. Med. Chem. 13 (2005) 5921–5926
Table 2. HLB, critical micelle concentration (CMC), interfacial tension (cIT), emulsion stability, foaming power and adsorption free energy of the
synthesized cationics
Compound
CMC,
M/L
Interfacial tension
(mN/m)
E.B,a
Sec.
Foaming power
(mL)
pcmc
Pc20
Pmax · 10ꢀ9
Amin
Nm2
DGads, kJ/mole
Pa
Pb
0.00100
0.00050
0.00025
0.00025
0.00100
0.00160
12.5
3.0
6.5
3.0
2.5
2.0
165
35
—
30
40
—
—
—
43
46
48
45
43
40
5.53
5.51
5.94
4.45
3.04
3.12
5.253
5.231
5.639
4.225
2.886
2.962
3.16
ꢀ9.33
ꢀ8.55
ꢀ8.45
ꢀ10.42
ꢀ11.45
ꢀ9.99
3.174
2.944
3.93
Pc
65
Ma
Mb
Mc
160
135
117
5.753
5.905
a E.B.: Emulsification power.
presence of surfactant molecules at the interfacial layer
between water and paraffin oil phases.16 The presence
of surfactant molecules at the interfaces may facilitate
their amphipathic structure, the presence of polar
groups (N+, OH) (hydrophile) and the nonpolar group
(alkyl chain) (hydrophobe). Hence, the total energy of
the system decreases as a result of solvation of polar
groups in the polar medium and the hydrophobes in
the nonpolar phase. Piperidine cationic derivatives Pa–c
showed higher interfacial tension values in H2O/paraffin
oil system than those of morpholine homologues. That
may be due to the effect of nonpolar phase on the inter-
facial tension values. Variation of the nonpolar phase
nature from paraffin oil to benzene decreases the interfa-
cial tension values of piperidine cationic surfactants to
extremely lower values (Table 2).
IThe surface pressure (slope of surface tension profile
at pre-CMC) determines the variation of surface ten-
sion by increasing the surfactant concentration at the
surface of its solution. This reflects the pumping of sur-
factant molecules from the bulk to surface of the solu-
tion. Table 2 shows the ability of Pa–c surfactant
molecules to be pumped towards the interface, which
is proved by higher surface pressure and extreme sur-
face concentration at the interface. Also, increasing
the alkyl chain length of the hydrophobe increases
the maximum surface excess values (Cmax) since hydro-
phobicity of the surfactant molecules increases with
increasing the number of methylene groups in the alkyl
chains.
In the case of morpholine cationic surfactants, Ma–c, the
trend of increasing the surface pressure (oc/ologC) and
Cmax was reversed. That may be due to the increase of
hydrophilicity of the surfactant molecules (Ma–c) due
to the presence of an oxygen atom within their skeleton.
In general, compounds Ma–c showed the lowest surface
concentration, which indicates their tendency towards
solvation in polar medium (H2O).
3.2.2. Effectiveness (pCMC), efficiency (Pc20), maximum
surface excess (Cmax) and minimum surface area (Amin).
The difference between surface tension value of the sur-
factant solution at its CMC and that of corresponded
distilled water is defined as effectiveness (pCMC).17 The
efficiency (Pc20) is the concentration of a surfactant solu-
tion, which is capable of suppressing the surface tension
of surfactant solution to 51.7 mN/m at 25 ꢀC.18 These
two variables determine the activity of surfactant mole-
cules at the air/water interface. Table 2 shows the effec-
tiveness and efficiency values of the synthesized
surfactants Pa–c and Ma–c in their solutions at 25 ꢀC.
Obviously, piperidine cationic derivatives showed an
increasing trend in both pCMC and Pc20 values by
increasing the hydrophobic chain length reaching the
maximum activity corresponding to the octadecyl pip-
ridinium derivative (Pc) at 25 ꢀC. This trend is reversed
in morpholine cationic derivatives, which may be due
to higher hydrophilicity of these molecules as a result
of the presence of an oxygen atom within them. The
lowest surface activity was noticed in octadecyl mor-
pholinium derivative (Mc).
The minimum surface area occupied by each surfactant
molecule at the air/water interface (Amin) is calculated,
which is affected mainly by the presence of the polar
and/or charged groups. The polar groups are considered
as attachment points, which are anchored to the water
surface hence, Amin of the surfactants (Ma–c) were ob-
served to increase Amin values than those corresponding
to (Pa–c),19 which is due to the presence of an ethereal
bond (–O–) that increases Amin at the interface. The
maximum area at the air/water interface is correspond-
ing to Ma–c, which has the longest hydrophobic chain
length (17-CH2 group).
3.2.3. Emulsification power. Emulsification power of the
synthesized surfactants was tested against paraffin oil.
The results (Table 2) showed that increasing the hydro-
phobic chain lengths of the synthesized surfactants, gen-
erally, decreases their emulsification powers towards
paraffin oil. That could be rationalized to their HLB val-
ues, which decrease by increasing the hydrophobic
chain.20 The maximum emulsification tendency is signifi-
cantly observed for Pa/paraffin oil (0.1 aqueous solution).
The maximum surface excess is expressed as the concen-
tration of surfactant molecules at the interface per unit
area (Cmax). While, the minimum surface area is defined
as the area occupied by each molecule in nm2 at the
interface. Using the adsorption law of molecules at the
interfaces, Cmax values were calculated according to
the following equation:19
In general, cationic surfactants show the minimum
foamability relative to the other types of surfactants
(anionic, nonionic, zwitterionic or amphoteric). The
synthesized cationic surfactants Pa–c and Ma–c showed
Cmax ¼ ðoc=ologCÞT =2.303RT ;
where oc/ologC is the surface pressure, R, universal gas
constant and T, the absolute temperature.

N. A. Negm et al. / Bioorg. Med. Chem. 13 (2005) 5921–5926
5925
low foaming power only for Pb,c, while Pa and Ma–c
show no foaming power, Table 2.
tive bacterial cell wall a negative charge, which may be
important in determining the types of substances
attracted to the cell membrane.31
3.2.4. Adsorption free energy (DGads). The standard free
energies of adsorption for the synthesized cationic sur-
factants were calculated at 25 ꢀC, according to the meth-
odology of Rosen,21 Table 2. It is clear from the ꢀve
values of DGads and DGmic that the process of adsorp-
tion is spontaneous.22 However, the high negativity
DGads values showed that the process of adsorption is
the most predominant process. Obviously, the synthe-
sized cationic surfactants prefer adsorption at air/water
interface due to a higher interaction between the hydro-
phobic chains and the polar medium.23 Hence, the
adsorption is the most favourable situation, owing to
their low interaction, which is also stabilized by the
anchoring points (polar groups) at the interface.
The synthesized cationic Mannich bases (Pa–c, Ma–c
)
showed a higher biocidal activity towards Gram-positive
strains than the Gram-negative strains, Table 3. That
higher biological activity may be due to several reasons,
which are as follows:
1. The ionization of the molecules under investigation
in the aqueous medium produces different ions32
CBr ¼¼¼¼¼¼ Cþ þ Brꢀ
The produced cations C+ are attracted to the negatively
charged cell membrane and neutralize its charges, on ac-
count of which its selective permeability is distorted.
The behaviour of surfactant molecules towards their
medium decides their fields of applications. Adsorbed
molecules play an important role in the interfacial appli-
cations including corrosion inhibition,24 emulsification25
and metal flotation.26 Also, micellized molecules had an
applicable role in detergency, solubilization27 and phase
transfer catalyst.28
2. The halogen ions penetrate into the cytoplasm of the
cell, which inactivates the essential metabolic com-
pounds, such as proteins and enzymes. The inactivation
action proceeded via oxidation of these proteins result-
ing in the bacterial cell death.33
The obtained biological activity of the target compounds
showed a lower extent towards Gram-negative bacteria.
This activity may be due to the halogen anions (Brꢀ),
which play a minor role in penetration through the cell
membrane, which is characterized by a more fragile
structure than the Gram-positive strain. As a result,
the Gram-negative bacteria showed some resistance to-
wards the synthesized cationic Mannich bases.
3.2.5. Evaluation of the synthesized surfactants as anti-
bacterial, antifungal and antiyeast agents
3.2.5.1. Antibacterial activity. The combined proper-
ties of quaternary ammonium compounds including ger-
micidal activity, detergent action, low toxicity, high
solubility, stability and noncorrosiveness facilitate their
application as disinfectants and sanitizing agents.29,30
Hence, the prepared cationic surfactants were evaluated
as biocides for Gram-positive bacteria, Gram-negative
bacteria, fungi and yeast using different doses (1, 2.5
and 5 mg/mL). The data of biological activity of Pa–c
and Ma–c cationic compounds are given in Table 3.
The behaviours of the synthesized cationic surfactants
at the interface play a vital role in their antibacterial
activity. The surface and thermodynamic properties
of these surfactants showed
a tendency towards
adsorption at the interfaces, which facilitate their role
of adsorption at the bacterial cell membrane.
The biocidal activity of Pa–c and Ma–c towards microor-
ganisms is found to be dependent on the nature of the
target organisms.
Increasing DGads enhances the higher adsorptivity of
Ma–c derivatives, which show maximum biological activ-
ity towards Gram-positive and Gram-negative bacteria
(ꢀ10.42, ꢀ11.45 and ꢀ9.99 kJ molꢀ1).
Gram-positive and Gram negative bacteria were affected
extremely by the synthesized cationics (Pa–c, Ma–c). The
Gram-positive bacterial cell wall is composed of a pep-
tidoglycan chain of polysaccharide, teichonic acid and
phosphated sugar. Teichonic acids gave the Gram-posi-
3.2.5.2. Antifungal activity. Several investigators have
studied the fungicidal activity of different varieties of
surface active agents towards fungus. The obtained
Table 3. Antibacterial activity of the synthesized surfactants at 1, 2.5 and 5 mg/mL
Bacteria
Gram +ve
Gram ꢀve
Bacillus
2.5
Staph. Cocu.
Salmonella
E. coli
2.5
Dose (mg/mL)
Blank
1
5
1
2.5
++
5
1
2.5
++
5
1
5
+
++
+++
+
+++
+
+++
+
++
+++
Ma
Mb
Mc
+
++
+++
+++
+++
+
+
+
++
++
++
+++
+++
++
+
+
+
++
++
++
+++
+++
+++
++
++
++
+++
+++
++
+++
+++
+++
++
+
+++
++
Pa
Pb
Pc
+
+
+
++
+
++
++
++
+
+
+
++
++
++
+++
+++
++
+
+
+
++
++
++
+++
++
+
+
+
++
+
+++
++
++
+++
++
++

5926
N. A. Negm et al. / Bioorg. Med. Chem. 13 (2005) 5921–5926
Table 4. Antifungi and antiyeast activity of the synthesized surfactants at 1, 2.5 and 5 mg/mL
Organism
Fungi
Yeast
Candida
2.5
A. terrus.
2.5
A. flav.
2.5
Dose (mg/mL)
Blank
1
5
1
5
1
5
++
++
+++
++
++
+++
++
++
+++
Ma
Mb
Mc
+
++
+++
+++
+++
+
++
++
++
+++
+++
+++
++
++
++
+++
+++
+++
+++
+++
+++
++
+
+++
++
++
++
Pa
Pb
Pc
++
++
++
++
+++
++++
+++
++
++
++
++
+++
+++
+++
++
+++
+++
+++
+++
+++
+++
+++
++
+++
++
+++
+++
11. Kern, F.; Lequeux, F.; Zana, R.; Candau, J. Langmuir
1994, 10, 1714.
results showed minor effects; however, a limited range of
these compounds showed significant results.
12. Negm, N. A. Egypt. J. Chem. 2002, 45, 483.
13. Oda, R.; Huc, I.; Candau, S. J. Chem. Commun. 1997, 21,
6382.
14. Rosen, M. J.. Surface and Interfacial Phenomena, 2nd ed.;
John Wiely & Sons: New York, 1989.
15. Jonsson, B.; Lindman, B.; Holmberg, K.; Kronberg, B. In
Surfactants and Polymers in Aqueous Solutions; John
Wiley & Sons: New York, 1998; Vol. 92.
16. Rosen, M. J.; Zhu, B. Y. Structure Performance Rela-
tionships in Surfactants. ACS Symposium Series 253;
American Chemical Society: Washington, DC, 1983.
17. Negm, N. A. Egypt. J. Petrol. 2005, 14, 1.
18. Negm, N. A.; Mahmoud, S. A. Egypt. J. Petrol. 2003, 12, 11.
19. Gad, E. A. M.; El-Sukkary, M. M. A.; Ismail, D. A. J.
Am. Oil Chem. Soc. 1997, 74, 1.
The synthesized pipridinium and morpholinium bro-
mide derivatives (Pa–c, Ma–c) were evaluated for their
fungicidal activity against A. terrus. and A. flav. at differ-
ent doses (1, 2.5 and 5 mg/mL). The obtained results
(Table 4) showed a higher fungicidal activity of pipridi-
nium derivatives (Pa–c) and the morpholinium deriva-
tives (Ma–c). The highest fungicidal activity was
observed in the synthesized cetyl morpholinium bromide
derivative (Mb). The cetyl pipridinium derivative (Pb)
was the most active in the piperidine series (Mb, Pb;
DGads: ꢀ11.45 and ꢀ8.55 kJ molꢀ1, respectively). Iden-
tically, the synthesized cationic surfactants showed effec-
tive biological activity towards yeast (Candida), Table 4.
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The biological activity of the synthesized cationic surfac-
tants against the tested microorganisms was observed to
increase by increasing their doses. The highest activity
was observed at 5 mg/mL.
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