# Natural Compounds in the Battle against Microorganisms--Linalool
## 1 Introduction
In the case of _Pantoea anantatis_, the solubility of the same (_3S_)-(+)-linalool synthase was improved by the N-terminal fusion of the halophilic \(\beta\)-lactamase from _Chromolobacter_ spp. 560 with hexahistidine [23]. Since linalool is cytotoxic to microorganisms, the instability of the DNA pathway constructs and the maintenance of a fully functioning metabolic pathway are major problems. For this reason, it is imperative to minimize genetic recombination that leads to loss of enzyme(s)/pathway. One can also try to increase the host microbial tolerance to linalool using adaptive laboratory evolution tools to limit the selection of mutant strains that do not have a fully functional pathway during fermentation [4]. Linalool exhibits a number of other biological activities in addition to its antimicrobial activity, which will be discussed in detail in this publication. Thanks to its anti \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Plant** & **Plant Part** & **Percentage [\%]** & **Ref.** \\ \hline _Antiba roseadeora_ Ducke & Wood & 100 & [7] \\ _Cinnamoun camphora_ Nees \& Eberm & Leaf & 95 & [8] \\ var. _linaloolifera_ & & & 94 & [9] \\ _Cinnamoun camphora_ ct. & Leaf & 94 & [10] \\ _Cinnamoun camphora_ Nees \& Eberm & Wood & 90 & [11] \\ var. _linaloolifera_ & & & 83 & [12] \\ _Coriandrum sativum_ L. & Seeds & & 82 & [13] \\ _Orthodon linalooliferum_ Fujita & Aerial parts & & 82 & [13] \\ _Coriandrum sativum_ L. & Mercarp & 79 & [14] \\ _Zanthoxylum alatum_ Roxb & Seeds & 71 & [15] \\ _Coriandrum sativum_ L. & Seeds & 66 & [16] \\ _Lavandula angusifolia_ & Whole plant & 54 & [17] \\ _Lippia alb_ & Leaves & 53 & [18] \\ _Hysopus officinalis_ & Aerial parts & 51 & [19] \\ _Lavandula latifolia_ & Whole plant & 51 & [14] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Plant resources of linalool. inflammatory [24; 25] and antioxidant [26] properties, administration of linalool to mice protected them against peripheral inflammation caused by exposure to the endotoxin _Salmonella_ Typhimurium [27]. Linalool also increased anti-inflammatory and antioxidant markers and restored kidney integrity in a rat model of streptozotocin-induced diabetic nephropathy [28]. Linalool also inhibits LDL oxidation and enhances cholesterol uptake by macrophage scavenger receptors. Linalool significantly lowered the levels of plasma triglycerides, total cholesterol and HMG-CoA, demonstrating antiatherosclerotic activity in vivo [29]. (3\(R\))-(\(-\))-Linalool can interact with nitric oxide synthase (NOS) to inhibit nitric oxide production without reducing enzyme synthesis. NO regulates inflammatory and immune responses, contributing to the formation of edema, vasodilation, and the recruitment of immune cells at the site of infection [30]. It is presumed that the anti-inflammatory activity of linalool is responsible for its neuroprotective effects in rats with hemiparkinsonism. It significantly prevented the downregulation of tyrosine hydroxylase and dopamine transporter in a rat model of Parkinson's disease [31]. Linalool also reduced TNF-\(\alpha\)-induced inflammation in brain-derived endothelial cells [32]. It also inhibited the pro-inflammatory pathways induced by LPS and the production of cytokines (e.g., nitric oxide, NF-\(\kappa\)B, TNF-\(\alpha\), IL-6 and IL-1\(\beta\)) in murine microglia (BV2) cells [33; 34]. In the triple transgenic model of Alzheimer's disease (3 xTg-AD) mice, 21-24 months of age, the influence of linalool (25 mg/kg) on the development of this disease was investigated. The 3 xTg-AD mice administered linalool showed better learning and spatial memory, and better risk assessment behavior during an elevated plus maze. In addition, a significant reduction in extracellular \(\beta\)-amyloidosis, tauopathy, astrogliosis and microgliosis in the hippocampus and amygdala was found, as well as a significant reduction in the level of pro-inflammatory markers p38 MAPK, NOS2, COX2 and IL-1\(\beta\).