## 3 Biological Activities
### Antiparasitic  
Several studies have demonstrated the effect of citral against different stages of trypanosomatids (Figure 5). [PERSON], [PERSON] [8] observed that citral affected the growth of the epimastigotes and trypanastigotes of _T Trypanosoma cruzi_ with an IC\({}_{50}\) of 42 \(\mu\)g/mL and 142 \(\mu\)g/mL after 24 h of incubation, respectively. Furthermore, 50 \(\mu\)g/mL resulted in 100% lysis of trypanastigotes, while 30 \(\mu\)g/mL citral induced a rounded body, mitochondrial swelling, kDNA alterations, and cytoplasmic vacuoles in epimastigotes [8; 113; 114]. [PERSON], [PERSON] [115] also demonstrated that citral exhibited an inhibitory effect against _T. cruzi_, affecting growth in different stages such as epimastigotes (14 \(\mu\)g/mL), trypanastigotes (22 \(\mu\)g/mL), andastigotes (74 \(\mu\)g/mL). [PERSON], [PERSON] [116] determined citral's in vivo antiparasitic effect against _T. cruzi_ inoculated in mice. They observed that a dose of 300 mg/kg of citral decreased the proliferation of the parasite at 16, 18, 20, and 22 days post-infection. Furthermore, the same dose of the compound evaluated after 28 days post-infection decreased the amastigote nests in the heart (67.7%) and the infected animal's inflammatory response (51.7%).  
Likewise, [PERSON] and [PERSON] [113] evaluated the antiparasitic effect of citral on _Crihidia fasciculata_ trypanosomatids and demonstrated that citral has trypanocidal activity. Citral effectively reduced the proliferation of amastigotes and trypanastigotes (IC\({}_{50}\) and IC\({}_{90}\) of 76.3 \(\mu\)g/mL and 146 \(\mu\)g/mL, respectively) in this parasite. [PERSON], [PERSON] [117] obtained that citral and _C. citratus_ EO (citral major constituent 78%) showed antiparasitic effects against promastigotes (IC\({}_{50}\): 8 and 1.7 \(\mu\)g/mL) and amastigote (IC\({}_{50}\): 25 and 3.2 \(\mu\)g/mL) of _Leishman amazonensis_. Also, an effect on intracellular amastigotes was observed at citral and EO  
Figure 5: Antiparasitic effect of citral [116; 117; 118].  
concentrations of 5, 10, and 15 \(\upmu\)g/mL, reducing the survival index in 0.6 and 47.5% (5 \(\upmu\)g/mL), 58.3 and 74.8% (10 \(\upmu\)g/mL), and 69.6 and 89.2% (15 \(\upmu\)g/mL), respectively.  
Similarly, the modes of action of citral and EOs against _L. amazonensis_ demonstrated promastigote morphological changes, causing rounded, swollen appearance, flagella damage, mitochondrial swelling, vacuole formation, membrane bleb formation, cell agglomeration, and rupture on membrane plasma. [PERSON], [PERSON] [118] analyzed the antiparasitic potential of citral and _C. citratus_ essential oils against different _Leishman_ strains, observing that both treatments affected _L. infantum_ (IC\({}_{50}\): 42 and 25 \(\upmu\)g/mL, respectively), _L. tropica_ (IC\({}_{50}\): 34 and 52 \(\upmu\)g/mL, respectively), and _L. major_ (IC\({}_{50}\): 38 and 36 \(\upmu\)g/mL, respectively) growth. In addition, it was demonstrated that the antiparasitic effect against _L. infantum_ promastigotes nuclear membrane rupture and nuclear chromatin condensation. These treatments produced externalization of phosphatidylserine, loss of mitochondrial membrane potential, and cell cycle arrest in the phase G(0)/G(1), suggesting an effect via apoptosis.  
In general, the mechanism of action of citral is related to the induction of microtubule disruption, inhibition of endoplasmic reticulum stress, inhibition of the PIP3/AKT survival pathway, stimulation of oxidative stress, and apoptosis. Furthermore, it is associated with its ability to interact with the cell membranes of parasites, losing its functionality and interacting with membrane components such as flagella. It can also cross cell membranes and interact with intracellular components, causing irreparable damage that promotes proapoptosis and cell cycle arrest [113; 115; 117].