## 5 The Biological Properties of Camphor  
### Antimicrobial Activity  
#### 5.1.1 Antibacterial and Antifungal Activities  
Plants have been a valuable source of natural products for maintaining human health and the use of plant compounds for their antimicrobial activity has gradually increased worldwide. Numerous investigations have shown various essential oils of several species containing camphor as the major components, exhibited antimicrobial activity [14, 32, 33, 34, 35]. The composition of essential oil from the aerial parts of sweet wormwood (_Artemisia annua_) includes camphor (44%), germacrene D (16%), _trans_-pinocarveol (11%), \(\beta\)-selinene (9%), \(\beta\)-caryophyllene (9%) and artemisia ketone (3%). Significant activity of the essential oil was noted against the Gram-positive bacteria, _Enterococcus hirae_, as well as against the fungi _Candida albicans_ and _Saccharomyces cerevisiae_ using the liquid diffusion method [10]. Some studies found camphor as a single compound only exhibited weak antimicrobial activity [36, 37]. Greek sage (_Salvia fruticosa_) essential oil, containing camphor as the main component, exhibited poor activity against all of the bacteria tested (_Escherichia coli_, _P. aeruginosa_, _Salmonella typhimurium_, _Staphylococcus aureus_, _Rhizobium leguminosarum_ and _Bacillus subtilis_) [38]. [PERSON] _et al._[39] investigated the antimicrobial activity of rosmary essential oil obtained via supercritical fluid extraction and molecules including camphor against _S. aureus_, _B. subtilis_, _E. coli_, _P. aeruginosa_, _C. albicans_ and _Aspergillus niger_ by the disc diffusion and broth dilution methods. The test samples were active against all the test organisms with the most susceptible organism being _S. aureus_ and the least susceptible _A. niger_. The standards exhibit activity against all the micro-organisms tested in the order of effectiveness: borneol \(>\) camphor \(>\) verbenone. In another study, a yarrow variety (_Achillea sintenisii_) was found to contain camphor (14.8%) as its major component. The essential oil was further fractionated and the antibacterial and antifungal activities determined against a variety of micro-organisms. Data analysis revealed camphor to be the more active compound together with 1,8-cineole, as notable activity against _C. albicans_ and _C. krusei_ was reported. The fractions showed the same or higher activity than the neat essential oil in the majority of cases [40]. [PERSON] _et al._[41] confirmed that elemol, 1,8-cineole, camphor and _p_-cymene can be considered as the principal antimicrobial components of tea bush (_Lippia chevalieri_) oil. The antimicrobial activity of rosmary (_Rosmarinus officinalis_) and several other oils against organisms implicated in meat spoilage was investigated by [PERSON] _et al._[42]. In a 1/100 dilution, rosmary (_Rosmarinus officinalis_) oil, containing mainly camphor, was one of the most efficient antibacterial oils having antibacterial activity against two Gram-negative (_Pseudomonas fluorescens_ and _Serratia liquefaciens_) and four Gram-positive (_Brochothrix thermosphacta_, _Carnobacterium piscicola_, _Lactobacillus curvatus_, and _Lactobacillus sake_) bacteria [42]. The essential oils of _Salvia macrochlamys_ and decorative sage (_S. recognita_), rich in camphor (11% and 42%, respectively), exhibited no antimicrobial activity against methicillin-resistant _S. aureus_, _Mycobacterium intracellular_, _Cryptococcus neoformans_ and _Aspergillus fumigatus,_ but moderate antifungal activity against _Colletotrichum acutatum_, _C. fragariae_, and _C. gloesoporoides_ was noted at a concentration of 200 \(\mu\)g/mL. However, in the same study,(\(-\))-camphor and (\(+\))-camphor tested singularly exhibited no activity against the test bacteria and fungi [43]. [PERSON] _et al_. [13] determined, using time-kill studies, that a synergistic antimicrobial effect occurs between 1,8-cineole and (\(-\))-camphor.