The term “grapefruit” generates great confusion. Indeed, the term grapefruit defines 2 trees and 2 fruits of different species (Citrus maxima and its hybrid Citrus x paradisi) of the Citrus genus of the Rutaceae family. Depending on the times, world regions and languages, the term “pomelo” or “grapefruit” is used to describe the same fruit. To avoid misunderstandings and amalgams between the 2, we use the latin names. Citrus maxima is native to South East Asia, its peel is very thick, greenish, yellow or pink. Its texture is crunchy and slightly juicy. Citrus x paradisi is an American hybrid between C.maxima and C. sinensis. Its peel is thin yellow or pink. This fruit grows in clusters, hence its English name “grapefuit” and its texture is very juicy.
Citrus x paradisi is used in traditional medicine in many countries as an antibacterial, antifungal, anti-inflammatory, antimicrobial, antioxidant, antiviral, astringent agent and preservative. It is also used for cancer prevention, cell regeneration, cholesterol reduction, detoxification, maintenance of heart health, lupus nephritis, rheumatoid arthritis and weight loss (GUPTA & al., 2012).
In phytotherapy, one frequently uses peel essential oil, which is rich in monoterpenes such as limonene, sabinene and myrcene, as well as in β-caryophyllene (HATA & al., 2003 ; DE CASTRO & al., 2006 DENG & al., 2020). Citrus x paradisi is rich in flavonoids (flavonones, flavones, flavonols and anthocyanins). Interestingly, citrus flavonoids have been shown in several studies to have a protective effect against cardiovascular diseases and certain types of cancer (BENAVENTE-GARCÍA & CASTILLO, 2008).
Additionally, some citrus flavonoids have beneficial effects on lipid metabolism in obesity, diabetes, hypertension and metabolic syndrome (ALAM & al., 2014 ; RAZAVI & HOSSEINZADEH, 2019). The abundance of the different compounds depends on the variety, the geographical location, the time of harvest and the method of processing the fruit (DE CASTRO & al., 2006).
Citrus x paradisi juice and its essential oil obtained from the peel administered orally exhibit anxiolytic and antidepressant effects in rats in various behavioral tests. They increase the locomotor activity and exploratory abilities of animals in the elevated maze test similarly to diazepam. In addition, they decrease the duration of immobility and increase the duration of climbing during the forced swim test (MALLICK & KHAN, 2016 ; GUPTA & al., 2009 ; 2010 ; 2011 ; 2014).
This anxiolytic effect of Citrus x paradisi seems to be linked to the presence of flavonoids (rutin, quercetin, kaempferol and myricetin) which exhibit significant tranquilizing activity in different animal models (GUPTA & al., 2018).
It has been shown that the essential oil of Citrus x paradisi shows good antioxidant activity estimated by the DPPH (2,2-diphenyl 1-picrylhydrazyl) and ABTS (2,2′-azino-bis3-ethylbenzothiazoline-acid assays. 6-sulphonic) (DENG & al., 2020).
In addition, the flavonoids it contains, such as naringin and naringenin, exhibit strong anti-inflammatory and antioxidant activities (BENAVENTE-GARCÍA & CASTILLO, 2008 ; ALAM & al., 2014).
Citrus x paradisi peel essential oil exhibits in vitro antimicrobial effect against different clinical bacterial isolates (Bacillus cereus, Enterococcus faecalis, Escherichia coli, E. coli ATCC 25292, Klebsellia pneumonia, Pseudococcus sp., Salmonella typhmurium, Shigella flexneri, Staphylococcus aureus and Staphylococus aureus ATCC 29213) and fungal isolates (Aspergillus niger, Candida albicans and Penicillium chrysogenum) (OKUNOWO & al., 2013 ; DENG & al., 2020). This antifungal effect has also been demonstrated on strains of Candida albicans isolated from mucosal swabs taken from patients diagnosed with prosthetic stomatitis (CHURATA-OROYA & al., 2016).
Furthermore, ethereal extracts of Citrus x paradisi paradisi peel have an insecticidal effect against the fly species Anastrepha fraterculus and Ceratitis capitata, both on eggs and larvae (RUIZ & al., 2014).
Citrus x paradisi peel essential oil has anticancer activity as determined by the Cell Counting Kit-8 (CCK-8) test. Indeed, it inhibits the proliferation of HepG2 liver cancer cells and HCT116 colon cancer cells in vitro (DENG & al., 2020). It induces apoptosis of HL-60 leukemia cells in vitro. This pro-apoptotic activity is partly related to the content of limonene, decanal, octanal and citral, all compounds that exhibit strong apoptotic activity (HATA & al., 2003).
