A mango () leaf extract (Zynamite), rich in the polyphenol mangiferin, has been demonstrated to modulate brain activity, boost cognitive function, and reduce mental fatigue. Research evidence supports that improving the solubility of this extract could significantly enhance its efficacy as an active ingredient. This study examined the effects of a soluble version of Zynamite, Zynamite S (Zyn-S), on cognitive function and mood in young adults at low doses. A total of 119 university students were enrolled in the study. Participants were randomly assigned to receive either 100 mg, 150 mg, or placebo in a double-blind crossover design. Short- and long-term memory were evaluated using the Rey Auditory Verbal Learning Test (RAVLT), executive functions with the Trail Making Test (TMT), processing speed with the Digit Symbol Substitution Test (DSST), and selective attention with the Stroop Color and Word Test. Additionally, mood was assessed using the Spanish short version of the Profile of Mood States (POMS). All these assessments were conducted before taking the product and at 30 min, 3 h, and 5 h post-intake. The results demonstrated that participants who received Zynamite S experienced significant improvements in reduced tension, depression, and confusion, suggesting an enhancement in mental clarity and overall emotional well-being. Both interventions also improved processing speed and cognitive flexibility. However, no significant differences were observed in short- and long-term verbal memory. In summary, these findings support Zynamite S as a natural nootropic capable of acutely improving key cognitive functions and emotional balance at low doses in young adults, with sustained efficacy for at least five hours.