## 3 Antimicrobial Activities of p-C
### Biosynthesis and Antibacterial Effects from Plants
In a study evaluating the antimicrobial and antioxidant activities of thyme (_Thymus vulgaris_) essential oil, naturally derived p-C was found to have potent antimicrobial effects and higher antioxidant activity than oreganum (_Origanum vulgare_), ginger (_Zinger officinal_), and fennel (_Foeniculum vulgare_) [73]. In oreganum (_Origanum vulare_ L.), p-C is the main component that imparts the typical oregano odor and has been found to present antimicrobial activity against _E. coli_, _S. aureus_, _Bacillus cereus_, and _S. typhimurium_[74]. Essential oils are highly concentrated natural extracts obtained from plants and are reported to be very rich in bioactive components with antimicrobial properties [75]. Mint (_Mentha_ spp.) and thyme (_Thymus_ spp.) are also aromatic herbal plants that contain the antimicrobial effects of p-C. They are members of the tribe Mentheae, part of the mint family (_Lamiaceae_), and have been used as potential antimicrobial drug preparations [76]. The p-C obtained from essential oils is also used as an insecticide due to its antimicrobial properties [77; 78]. p-C has significant toxic activity against pests and demonstrates great potential as a safe, plant-derived insecticide in insecticidal activity tests against red flour beetle (_Tribolium castaneum_), tobacco beetle (_Lacidorma sericorneum_), and buzzards (_Liposcelis bstricophila_) [79]. The antimicrobial activity of thyme, thymol, and carvacrol, the main components of which are p-C, has been shown by essential oils, especially by _Shigella_ sp., and has also been implicated in organoleptic properties, such as browning and strong odor [80]. Experimental studies have also shown that p-C has antioxidant potential for the brain and may act as a neuroprotective agent. This demonstrates the potential of p-C as a therapeutic development agent for important pathophysiological diseases through p-C-induced oxidative stress [81; 82]. The antimicrobial activity of p-C from the essential oils of these plants was also significant in the antimicrobial activity test of thyme, which showed greater antimicrobial activity than majoram, which contains limonene, linalool, terpinene-4-ol, \(\alpha\)-terpineol, and linalyl acetate [83]. The evaluation of antioxidant activity from plant extracts includes a variety of organic chemicals, including the main volatile compound p-C, and the high antioxidant capacity of thyme and savory can be attributed to thymol and carvacrol. This indicates that the antioxidant power of oregano, sage, and hyssop may be influenced by non-phenolic components, such as terpin, o-cymene, terpinolene, and terpin-4-ol [84]. These are shown in Table 1. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Plant Species**} & \multicolumn{2}{c}{**Antimicrobial Component**} & \multirow{2}{*}{**Experimental Design**} & \multirow{2}{*}{**Results**} & \multirow{2}{*}{**References**} \\ \cline{2-2} \cline{4-5}  & p-C (29.52\%), thymol & & & Essential oil shows high antibacterial activity against _E. coli_ \\  & (22.8\%), linalool (4.73\%) & & & TVEO induces cervical \\ \hline \multirow{4}{*}{TSEO} & p-C (19.04\%), geraniol & & & adenocarcinoma HeLa cell apoptosis \\  & (11.09\%), linalool & & antimicrobial, cytotoxicity, apoptosis, oxidative stress & \\  & (9.16\%), geranyl acetate & & & \\  & (6.49\%), borneol & & & reduction, tumor suppressor \\ \cline{1-1}  & (5.24\%) & & & gene expression \\ \hline \multirow{4}{*}{Candida} & nisin, thymol, carvacrol, & Adding different concentrations of antimicrobial ingredients at & p-C completely inhibits yeast growth \\  & lusitaniae & p-C & 25 \({}^{\circ}\)C & & above 1 mm \\ \cline{1-1}  & & Observation of yeast growth & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Antibacterial effects of p-C from natural plants. \begin{table}
\begin{tabular}{c c c c c} \hline \hline