Litsea cubeba is part of the Lauraceae family. This tree comes mainly from the tropical and subtropical regions of India, Southeast Asia and southern China. Its fruits resemble those of pepper. In phytotherapy, the essential oil of different parts of the plant is used: fruits, leaves and flowers.
Litsea cubeba is traditionally used to cure various gastrointestinal conditions, diabetes, edema, colds, arthritis, asthma and traumatic injuries (KAMLE & al., 2019). It is rich in monoterpenes (limonene, alpha and beta-pinene, sabinene), phenols (geranial, neral, citronellal) and sesquiterpenes (beta-caryophyllene) (JIANG & al., 2009 ; SAIKIA et al., 2013). The chemical composition of the essential oil varies according to the different parts of the plant used (THIELMANN & MURANYI, 2019).
In a study carried out on fifteen healthy volunteers, it was shown that the inhalation of litsea fruit essential oil improves mood and reduces the level of salivary cortisol (CHAIYASUT & al., 2020). Its oral administration prolongs the sleep induced by pentobarbitone in mice in a dose-dependent manner. Additionally, it increases locomotor activity in mice in the elevated maze test, demonstrating anxiolytic activity. In addition, it exhibits potent analgesic activity in the tail prick test (C.-J. CHEN & al., 2012).
The essential oil extracted from the litsea fruit has in vitro cytotoxic effects on human lung, liver and oral cancer cell lines. These properties are associated with its citral composition. In this study, leaf essential oil did not induce this anticancer activity (HO & al., 2010). Litsea fruit essential oil also exhibits cytotoxic effect against human cancer cell lines HT-29 (colon cancer) and HeLa (cervical cancer) (PANTE & al., 2021).
Inhalation of litsea seed essential oil induces apoptosis and cell cycle arrest in A549 lung carcinoma cells in vitro (SEAL & al., 2012).
Neral and geranial, the two isomers of citral contained in Litsea, have an anti-inflammatory effect. They inhibit the secretion of tumor necrosis factor (TNF)-α and interleukin (IL)-6 by lipopolysaccharide (LPS)-stimulated macrophages (81.4 and 58.2% inhibition for neral versus 63. 6 and 46.8% for the geranial). Additionally, compared to geranial, neral inhibits the expression of the pro-inflammatory mediators IL-1β, inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), and the inflammasome NOD-like receptor family, pyrin domain containing 3 (NLRP-3) more effectively (LIAO & al., 2015).
Litsea fruit essential oil exhibits an immunomodulatory effect on mouse dendritic cells: it inhibits the activation of dendritic cells stimulated by LPS and reduces their production of the cytokines TNF-α and IL-12 in a dose-dependent manner . In addition, it inhibits 2,4-Dinitro-1-fluorobenzene-induced contact hypersensitivity on the ear and reduces T cell infiltration in this in vivo mouse model (H.-C. CHEN & al., 2016).
Constituents extracted from the roots and stems of litsea, such as cubebanone, exhibit anti-inflammatory effects in vitro by reducing nitrogen oxide production in a murine microglial cell line and in LPS-stimulated macrophages in vitro (GUO & al., 2015).
In another study, similar results were highlighted: the methanolic extract of Litsea bark inhibits the production of pro-inflammatory mediators such as nitrogen oxide and prostaglandin E2 in macrophages activated by LPS in vitro. In addition, it reduces the activity of the enzyme myeloperoxidase, thus limiting the production of reactive oxygen species (CHOI & HWANG, 2004).
Finally, Litsea fruit essential oil has potent antioxidant activity in the DPPH radical scavenging test and the peroxidase/guaiacol test. In addition, it inhibits lipid peroxidation by 89 to 90% (HWANG & al., 2005 ; PANTE & al., 2021).
Litsea fruit essential oil destroys the outer and inner membrane of Escherichia coli cells. These antibacterial effects are mainly attributed to the presence of aldehydes (LI & al., 2014). It also exhibits antifungal activity against Fusarium moniliforme, Fusarium solani, Alternaria alternata and Aspergillus niger in a concentration-dependent manner (GOGOI & al., 1997).
