# Lemongrass Essential Oil Components with Antimicrobial and Anticancer Activities
## 3 LEO Therapeutics
### Anticancer Activity  
According to the World Health Organization (WHO), cancer caused an approximated 10 million deaths, or one in six deaths, in 2020. This situation is not going to be relieved, as there is estimated to be an increase of 45% in cancer mortality rate between 2008-2030. Among cancers, the most common types are breast cancer, lung cancer, colorectal cancer, prostate cancer, skin, and stomach cancer. The ongoing conventional chemotherapies, radiotherapy treatment, and surgeries have shown a large number of involuntary side effects due to insufficient knowledge of treatment specificity, and are not recommended for long-term usage [105,106]. Medicinal plants emerge as potential candidates in the cancer world and raise hopes for the scientific community. Scientists are constantly looking for natural sources to uncover the potential plant-based therapeutic agents having immense anticancer properties [20]. In this sense, the essential oil of lemongrass counts among such plants for its cytotoxicityon human cancer cells (Table 4). Its active ingredients, including geraniol, geranyl acetate, \(\alpha\)-bisabolol, and iso-intermedeol have individually been found to impart cytotoxic effects on cancer cells [107]. Lemongrass EO has exhibited inhibition of human mouth epidermal carcinoma (KB) and murine leukemia cell lines (P388) [108]. Among LEO terpenes, citral, the major component of lemongrass oil, plays a potential role as antiproliferative against several types of cancer cells, such as the two human prostate cancer cell lines, LNCaPP and PC-3 [107], HL60, U937 ovarian cancer cells [108; 109; 110], cervical cancer cell lines [111], and the breast cancer cell line, MCF-7 [112]. Interestingly, citral does not exert cytotoxicity to normal epithelial cells but exhibits toxic effects against human breast cancer cell lines, confirming its cancer-specific efficacy [113]. Although a large number of studies evinced the anticancer activity of lemongrass, scarce data are available on its mode of action. Studies based on different cancer cell types substantiated citral efficacy via activated procosparse-3, induction of apoptosis, and cell cycle arrest in the G2/M phase [114; 115]. Citral consists of a double bond in conjugation with an aldehyde (\(\alpha\), \(\beta\)-unsaturated) group in its core structure, which serves as a potent caspase 3 activator, responsible for pro-apoptotic activity [114]. Moreover, citral-induced apoptotic activity was associated with DNA fragmentation and induced caspase 3 activity against hematopoietic cancer cell lines and ovarian cancer cell lines. Among the relationship between LEO constituents and intracellular signalling, several studies reported significant upregulation of antiapoptotic proteins. The Src-tyrosine kinase is expressed in small cell lung cancer and can phosphorylate transcription factor Stat3(Y705) [114], which sequentially enhances the expression of downstream genes engaged in the antiapoptotic activity, i.e., Bcl-xL and Mcl-1 [116]. An experimental study showed the inhibitory effects of LEO and citral on phosphorylation of Src(Y416) blocking its activation, resulting in reduced phosphorylation of Stat3 (Y705). Non-phosphorylated Stat3 disrupts cell growth and the signal pathways that upregulate the expression of Bcl-xL and Mcl-1 [117]. Citral-dependent apoptosis induction has also been observed against prostate cancer cell lines. Citral induced gene activation initiates AMPK (an enzyme necessary in the fatty acid metabolism) phosphorylation resulting in the activation of BAX and the downregulation of Bcl-2, which initiates an apoptosis cascade in prostate cancer cell lines [118]. Citral-mediated breast tumour growth inhibition via the inhibition of ALDHA3 was reported [119]. The up-regulation of retinoic acid (RA)