## 4 Biological Activities of _Passiflora caerulea_ L.
### Neuromodulatory Activity  
Neurogenerative diseases are becoming more and more prevalent nowadays. One of the most studied properties of _Passiflora_ species is their effect on the nervous system. Different studies have been carried out to investigate the acetylcholinesteraseic activity and the anticonvulsant, anxiolytic and neuromodulatory activity of _Passiflora caerulea_ extracts [9; 16; 19; 48].  
The research conducted by [PERSON] et al. has explored the acetylcholinesteraseic inhibiterase inhibitory potential of _P. caerulea_, which is important in the context of neurodegenerative diseases such as Alzheimer's disease [19]. Acetylcholinesteraseterase is an enzyme in the brain that breaks the neurotransmitter acetylcholine, which plays a key role in cognitive function. The inhibition of this enzyme enhances the production of more acetylcholine, thus influencing memory and cognition problems [49]. Phytochemical studies have revealed that a number of the components found in _Passiflora caerulea_, including flavonoids, alkaloids and phenolic compounds, exhibit an AChE inhibitory effect [19; 50]. In the research by [PERSON] et al., decreased levels of AChE (0.35 \(\pm\) 0.86 umol/min/mg protein) were observed in the hippocampi of pilocarpine-induced mice treated with _Passiflora_ extract as compared to the control [19]. The same authors have shown the anticonvulsant activity of _P. caerulea_ extract, which also influences cognitive function and contributes to oxidative damage reduction. These results are in good agreement with [9]. In their study, they reported that ethanol leaf extract (100 mg/kg b. wt) showed the highest anticonvulsant activity (63% potency relative to carbamazepine). It has been shown that different bioactive compounds, such as C-glycosyl flavones and hydroxycinnamic acid derivatives, contribute to its anticonvulsant effects.  
The anxiolytic (anxiety-reducing) activity of _Passiflora caerulea_ has been extensively studied [47; 51; 52]. A possible mechanism responsible for the anxiolytic effects of _P. caerulea_ could be through the modulation of the GABAergic system. Gamma-aminobutyric acid (GABA) is a neurotransmitter that plays a crucial role in inhibiting excessive neuronal activity, leading to relaxation and reducing anxiety. It has been demonstrated that different compounds in _P. caerulea_ could enhance GABAergic transmission by using similar mechanisms of action as benzodiazepines but with fewer side effects [53]. For example, the flavonoid chrysin has been found to bind to GABA receptors, promoting anxiolytic activity [54]. The alkaloids harmane and harmane are able to modulate neurotransmitter systems and thus express calming effects [55]. [PERSON] et al. confirmed the anxiolytic effects of chrysin, isolated from the aerial parts of _P. caerulea_, through in vitro assays [48]. Additionally, [PERSON] et al. showed, through experiments with mice, that chrysin enhanced both the number of entries and the duration spent in the elevated plus-maze test for anxiety, aligning with anxiolytic effects, similar to the commercial medication diazepam [56]. This finding was of high significance because the chrysin influenced the reduction of anxiety without depressing the central nervous system, as is the case of commercial benzodiazepines. [PERSON] et al. have shown the aphrodisiac potential of _P. caerulea_. An underlying factor might be the aromatase inhibition that is responsible for the conversion of androgens to estrogens [38].