Similarly, several components of the H. citrina Baroni extracts were described to affect the serotonergic system: (1) Rutin, a quercetin glucoside derivative, increased serotonin in the hippocampus of a rat model of diabetes; (2) chlorogenic acid, a hydroxycinnamic acid, promoted serotonin release through enhancing synapsin I expression; (3) quercetin has been suggested to bind to 5-HT1AR, inhibiting the binding of serotonin; and (4) kaempferol, which is often acylated with hydroxycinnamic acid, inhibited the 5-HT3AR [27,28,29,30]. This evidence concerns the gene SYN1 and diabetes mellitus.