List of Contributors ........................................... xi
Introduction ................................................. xiii
1 Membranes as Targets of Antimicrobial Lipids ................. 1
Peter J. Quinn
1.1 Introduction ............................................ 2
1.2 Oil and Water Don't Mix! ................................ 2
1.3 Polar Lipids ............................................ 3
1.3.1 The Amphiphilic Character of Polar Lipids ........ 3
1.3.2 Hydrophobic Constituents of Lipids ............... 4
1.3.3 Polar Groups of Complex Lipids ................... 5
1.4 Properties of Surfactants ............................... 7
1.4.1 Critical Micelle Concentration ................... 7
1.4.2 Aggregation of Surface-Active Molecules .......... 8
1.4.3 The Influence of Solvent ......................... 9
1.5 Cell Membranes ......................................... 11
1.5.1 Membrane Lipids ................................. 11
1.5.2 Lipid Domains in Membranes ...................... 13
1.5.3 Membrane Proteins ............................... 15
1.5.4 Membrane Stability .............................. 15
1.5.4.1 Membrane Lipid Phase Behaviour ......... 17
1.5.4.2 Membrane Lipid Homeostasis in
Homoiothermic Organisms ................ 18
1.5.4.3 Membrane Lipid Adaption in
Poikilothermic Organisms ............... 19
1.6 The Action of Antimicrobial Lipids on Cell Membranes ... 20
1.7 Conclusions ............................................ 21
Acknowledgements ............................................ 21
References .................................................. 22
2 Antibacterial Effects of Lipids: Historical Review (1881
to 1960) .................................................... 25
Halldor Thormar
2.1 Introduction ........................................... 25
2.2 Antibacterial Activity of Soaps ........................ 26
2.2.1 Antibacterial Action of Fatty Acids and Their
Derivatives ..................................... 29
2.3 Inhibition of Lipids and Serum Albumin against the
Antibacterial Action of Soaps .......................... 33
2.4 Diverse Actions of Fatty Acids and Their Salts on
Bacteria ............................................... 34
2.5 The Nature of the Bactericidal Action of Fatty Acids ... 36
2.6 A Possible Role of Soaps and Fatty Acids in Host
Defence against Bacteria ............................... 38
2.7 Studies of Prophylactic and Therapeutic Applications
of Soaps and Fatty Acids ............................... 40
2.8 Conclusions ............................................ 43
References .................................................. 43
3 Antibacterial, Antiviral and Antifungal Activities of
Lipids ...................................................... 47
Gudmundur Bergsson, Hilmar Hilmarsson and Halldor Thormar
3.1 Introduction ........................................... 48
3.2 Antibacterial Activities of Fatty Acids and
Monoglycerides ......................................... 48
3.2.1 Activities against Gram-Positive Bacteria In
Vitro ........................................... 48
3.2.2 Activities against Gram-Negative Bacteria In
Vitro ........................................... 51
3.2.3 Antibacterial Mechanism ......................... 53
3.2.4 A Possible Role of Antimicrobial Lipids in
Host Defence against Bacteria ................... 57
3.3 Antiviral Activities of Fatty Alcohols, Fatty Acids
and Monoglycerides ..................................... 58
3.3.1 Early Studies of Antiviral Lipids ............... 58
3.3.2 Antiviral Activities of Milk Lipids ............. 60
3.3.3 Antiviral Activities of Lipids and Fatty
Alcohols ........................................ 61
3.3.4 Antiviral Mechanism of Lipids ................... 65
3.4 Antifungal Activities of Fatty Acids and
Monoglycerides ......................................... 67
3.4.1 In Vitro Studies ................................ 67
3.4.2 In Vivo Studies ................................. 71
3.5 Conclusions ............................................ 74
References .................................................. 75
4 Antimicrobial Lipids in Milk ................................ 81
Charles E. Isaacs
4.1 Introduction ........................................... 82
4.2 Occurrence ............................................. 83
4.2.1 Biosynthesis .................................... 83
4.2.2 Quantitative Assays ............................. 83
4.2.2.1 Measurement of Antibacterial
Activity ............................... 83
4.2.2.2 Measurement of Antiviral Activity ...... 84
4.3 Molecular Properties ................................... 84
4.3.1 Lipids in Milk and Plant Oils ................... 84
4.3.2 Dependence of Antimicrobial Activity on Chain
Length, Saturation and pH ....................... 85
4.4 Antimicrobial Activity ................................. 85
4.4.1 Mechanism of Action ............................. 85
4.4.2 Synergy between Antimicrobial Lipids and
Antimicrobial Peptides .......................... 87
4.4.2.1 Antimicrobial Peptides and Proteins .... 87
4.4.2.2 Potential Synergism between
Antimicrobial Milk Lipids and
Peptides ............................... 88
4.4.3 Influencing Factors ............................. 88
4.4.4 Spectrum ........................................ 89
4.5 Applications ........................................... 89
4.5.1 Additive Advantage to Foods and Biological
Products ........................................ 89
4.5.2 Physiological Advantage ......................... 90
4.5.3 Sexually Transmitted Pathogens and Topical
Activity ........................................ 91
4.6 Safety, Tolerance and Efficacy ......................... 91
4.7 Conclusions ............................................ 92
References .................................................. 92
5 Antimicrobial Lipids of the Skin and Tear Film .............. 99
Carol L. Bratt, Phil Wertz, David Drake, Deborah V.
Dawson and Kim A. Brogden
5.1 Introduction .......................................... 100
5.2 Innate Immune Mechanisms in Skin ...................... 101
5.2.1 The Extensive Cutaneous Microbial Burden ....... 101
5.2.2 Cutaneous Innate Immune Mechanisms ............. 104
5.3 Types and Locations of Lipids of the Skin and Tear
Film .................................................. 106
5.3.1 Hypodermal and Dermal Lipids ................... 107
5.3.2 Epidermal Lipids ............................... 107
5.3.3 Secreted Lipids ................................ 109
5.3.4 Tear-Film Lipids ............................... 109
5.4 Functions of Lipids ................................... 111
5.4.1 Cutaneous Lipids as Permeability Barriers ...... 111
5.4.2 Cutaneous Lipids as Innate Immune Mechanisms ... 111
5.5 Antimicrobial Activity of Lipids and Their
Mechanisms of Killing ................................. 111
5.5.1 Lipid Deficiencies ............................. 112
5.5.2 Lipid Antimicrobial Activity and Mechanism of
Action ......................................... 112
5.5.2.1 Sphingolipids ......................... 113
5.5.2.2 Fatty acids ........................... 114
5.6 Synergy of Cutaneous Lipids and Other Innate Immune
Molecules ............................................. 114
5.7 Lipids as Therapeutic Agents .......................... 115
5.8 Conclusions ........................................... 115
Acknowledgements ........................................... 116
References ................................................. 116
6 Antimicrobial Lipids and Innate Immunity ................... 123
Halldor Thormar
6.1 Introduction .......................................... 124
6.2 The Role of Human Milk Lipids in Innate Immunity ...... 126
6.2.1 Breast-Feeding Protects Infants against
Infection ...................................... 126
6.2.2 Factors in Human Milk which Protect against
Infection ...................................... 127
6.2.3 Antimicrobial Lipids in Human Milk and Their
Possible Protective Function ................... 129
6.3 Antimicrobial Lipids in the Pulmonary Mucosa .......... 134
6.3.1 The Innate Immune System of the Respiratory
Tract .......................................... 134
6.3.2 Antimicrobial Fatty Acids in the Alveoli of
Animal and Human Lungs ......................... 135
6.4 Antimicrobial Skin Lipids ............................. 137
6.4.1 The Self-Disinfecting Power of the Human
Skin ........................................... 137
6.4.2 The Role of Skin Lipids in the Self-
Disinfection of Human Skin ..................... 137
6.4.3 Sebum Lipids as a Source of Antimicrobial
Fatty Acids in the Skin ........................ 139
6.4.4 Stratum Corneum as a Source of Antimicrobial
Lipids in the Skin ............................. 142
6.4.5 Antimicrobial Lipids as a Part of the Innate
Immune Defence ................................. 144
6.5 Conclusions ........................................... 144
References ................................................. 144
7 Lipids as Active Ingredients in Pharmaceuticals,
Cosmetics and Health Foods ................................. 151
Thordis Kristmundsdóttir and Skúli Skúlason
7.1 Introduction .......................................... 152
7.2 Antimicrobial Effects of Lipids ....................... 152
7.2.1 Antibacterial Activity ......................... 152
7.2.2 Antiviral Activity ............................. 153
7.2.3 Antifungal Activity ............................ 154
7.3 Lipids in Pharmaceuticals ............................. 155
7.3.1 Lipids in Pharmacopeias ........................ 155
7.3.2 Microbicidal Lipids for Treatment of Mucosal
and Skin Infections ............................ 155
7.3.3 Lipids as Penetration Enhancers in
Pharmaceutical Dosage Forms .................... 159
7.4 Microbicidal Lipids in Agriculture and Aquaculture .... 160
7.5 Lipids in Therapy ..................................... 163
7.5.1 Effect of Lipids on Infectious and
Inflammatory Diseases .......................... 163
7.5.2 Effect of Lipids on Psoriasis .................. 165
7.5.3 Effect of Lipids on Cardiovascular Diseases .... 165
7.5.4 Effect of Lipids on Cognitive Function ......... 166
7.6 Lipids in Cosmetics ................................... 167
7.6.1 Sources of Lipids Used in Cosmetics ............ 167
7.6.2 Antimicrobial Activity of Lipids in
Cosmetics ...................................... 168
7.6.3 Other Activities of Lipids in Cosmetics ........ 169
7.7 Lipids in Health Food ................................. 169
7.8 Conclusions ........................................... 171
References ................................................. 171
8 Antimicrobial Lipids as Disinfectants, Antiseptics and
Sanitizers ................................................. 179
Halldor Thormar and Hilmar Hilmarsson
8.1 Introduction .......................................... 179
8.2 Soaps as Disinfectants and Antiseptics ................ 182
8.3 Use of Bactericidal Lipids to Reduce Microbial
Contamination of Food Products ........................ 184
8.4 Killing of Foodborne Bacteria by Glycerol
Monocaprate (Monocaprin) Emulsions .................... 186
8.4.1 Reduction of Viable Campylobacter in Drinking
Water and Feed of Chickens by Addition of
Monocaprin Emulsions ........................... 187
8.4.2 Reduction of Viable Campylobacter on Poultry
Carcasses ...................................... 188
8.4.3 Reduction of Psychrotrophic Spoilage Bacteria
on Chicken Carcasses ........................... 191
8.4.4 Sanitation of Kitchen Surfaces by Washing
with Monocaprin Emulsions ...................... 194
8.5 Conclusions ........................................... 197
References ................................................. 197
9 Chemistry and Bioactivity of Essential Oils ................ 203
Christine F. Carson and Katherine A. Hammer
9.1 Introduction .......................................... 204
9.2 Chemistry of Essential Oils ........................... 205
9.2.1 Terpenes ....................................... 205
9.2.1.1 Biosynthesis of Terpenes .............. 206
9.2.1.2 Monoterpenes .......................... 206
9.2.1.3 Sesquiterpenes ........................ 208
9.2.1.4 Diterpenes ............................ 208
9.2.1.5 Norterpenes ........................... 209
9.2.2 Phenylpropanoids ............................... 209
9.2.2.1 Biosynthesis of Phenylpropanoids ...... 209
9.2.2.2 Phenylpropanoids in Essential Oils .... 210
9.2.3 Sulfur and Nitrogen Compounds of Essential
Oils ........................................... 210
9.3 Biological Activity of Essential Oils ................. 211
9.3.1 General Overview ............................... 211
9.3.2 Antimicrobial Activity ......................... 212
9.3.2.1 Antibacterial Activity ................ 212
9.3.2.2 Antifungal Activity ................... 215
9.3.2.3 Mechanisms of Antibacterial and
Antifungal Action .................... 216
9.3.2.4 Antiviral Activity .................... 216
9.3.2.5 Antiprotozoal Activity ................ 218
9.3.3 Anticancer Activity ............................ 219
9.4 Uses of Essential Oils ................................ 221
9.4.1 Pharmaceutical Products ........................ 221
9.4.2 Foods and Beverages ............................ 222
9.5 Conclusions ........................................... 223
References ................................................. 223
10 Antiviral Effects of Plant-Derived Essential Oils and
Pure Oil Components ........................................ 239
Paul Schnitzler, Akram Astani and Jürgen Reichling
10.1 Introduction .......................................... 239
10.2 Characterization and Medicinal Use of Essential
Oils .................................................. 240
10.3 Cytotoxicity of Essential Oils ........................ 240
10.4 Antiviral Activities of Essential oils ................ 241
10.4.1 In Vitro and In Vivo Studies of
Antiherpesvirus Activity of Essential Oils ..... 241
10.4.2 In Vitro and In Vivo Studies of
Antiherpesvirus Activity of Pure Essential
Oil Components ................................. 247
10.4.3 In Vitro and In Vivo Studies of Antiviral
Effects of Essential Oils against Other
Viruses ........................................ 248
10.5 Mode of Antiviral Action of Essential Oils ............ 250
10.6 Conclusions ........................................... 251
References ................................................. 252
11 Antibacterial and Antifungal Activities of Essential
Oils ....................................................... 255
Katherine A. Hammer and Christine F. Carson
11.1 Introduction .......................................... 256
11.2 Methods for Quantifying Antimicrobial Activity ........ 257
11.3 Antibacterial and Antifungal Essential Oils by Plant
Family ................................................ 258
11.3.1 Apiaceae ....................................... 258
11.3.2 Lamiaceae ...................................... 258
11.3.3 Lauraceae ...................................... 263
11.3.4 Myrtaceae ...................................... 264
11.3.5 Poaceae ........................................ 265
11.3.6 Rutaceae ....................................... 266
11.3.7 Other .......................................... 266
11.3.8 Comparative Activities of Essential Oils ....... 266
11.4 Antimicrobial Essential-Oil Components ................ 267
11.4.1 Aldehydes ...................................... 267
11.4.2 Alcohols ....................................... 267
11.4.3 Phenols ........................................ 268
11.4.4 Ketones ........................................ 269
11.4.5 Esters ......................................... 269
11.4.6 Oxides and Epoxides ............................ 270
11.4.7 Methyl Ethers .................................. 270
11.4.8 Terpene Hydrocarbons ........................... 270
11.4.9 Generalizations about Component Activity ....... 271
11.5 Factors Influencing Activity .......................... 271
11.5.1 Microorganism-Related Factors .................. 271
11.5.2 Environmental Conditions ....................... 272
11.6 Mechanisms of Action .................................. 274
11.6.1 Membrane and Membrane-Related Actions .......... 274
11.6.2 Adaptation and Tolerance ....................... 276
11.6.2.1 Resistance ........................... 278
11.6.3 Other Antimicrobial Effects .................... 279
11.6.3.1 Toxins, Enzymes and Virulence
Factors ............................... 279
11.6.3.2 Biofilms and Quorum Sensing ........... 280
11.6.3.3 Synergy between Essential Oils or
with Other Compounds .................. 281
11.6.3.4 Other .................................. 282
11.7 Clinical Efficacy of Essential Oils and Components .... 282
11.7.1 Animal Studies ................................. 282
11.7.2 Human Studies .................................. 288
11.8 Toxicity of Essential Oils ............................ 288
11.8.1 In Vitro Toxicity Assays ....................... 288
11.8.2 Animal Studies ................................. 288
11.8.3 Toxic Effects in Humans ........................ 293
11.9 Conclusions ........................................... 293
References .................................................... 295
Index ......................................................... 307
|
