Pharmacognostic study and evaluation of the antioxidant capacity of the fruit of two varieties of Nephelium lappaceum L. (Sapindaceae), (rambutan)

Context: Nephelium lappaceum (achotillo or rambutam), is a fruit native to Malaysia and Indonesia introduced in Ecuador for consumption purposes. Aims: To identify the bioactive metabolites present in the peels and seeds of the sweet and bitter varieties of rambutan fruits and their antioxidant capacity. Methods: It was performed through a pharmacognostic analysis of the peels of the fruits, based on the evaluation of the physicochemical parameters, the phytochemical analysis, the quantification of the phenols and flavonoids, the determination of the antioxidant capacity and the identification of the fatty compounds present in the seeds by gas chromatography coupled to mass spectrometry. Results: The results showed that both the peels and the seeds of the two varieties differ in the content of phyto-constituents and antioxidant properties. Conclusions: The bitter fruit presented a higher concentration of phenols and flavonoids in the peels and a higher concentration of fatty compounds in the seeds, with marked differences between the fractions of the non-saponifiable compounds. For the fatty acid fraction, a greater qualitative similarity was evidenced, with quantitative differences. Although the peels extract of both fruits have antioxidant capacity, it was significantly higher in bitter fruits.