Red Jambo Flower (Syzygium malaccense L.) as a Potential Bioactive Compound to Obtain Edible Extract: Optimization of Extraction, Toxicity, Antioxidant, and Antimicrobial Potential

This paper aimed to demonstrate the production of edible extracts from red jambo flowers, cultivated in northeastern Brazil, and investigate their bioactive properties. For this purpose, a multivariate optimization of the extraction process was performed, by solid–liquid extraction, where it was observed that the presence of ethanol, acetone, and polysorbate in the extracting solution had the most significant influence on the extraction process, as opposed to temperature, time, volume of extracting solution, and the use of ultrasound. After the mixture system optimization, the best extraction condition was achieved when the extracting solution was composed of 25% ethanol, 25% acetone, and 50% polysorbate 0.25% in water, resulting in an extract containing 27.11 mg of anthocyanins, 457.69 mg of total carotenoids, and 198.09 mg of, total flavonoids, per 100 g of dried flower. The reducing capacity was 466.8 mg GAE per 100 g of dried flower, and the antioxidant activity was 17.25% against the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical. Through chromatographic analysis, it was possible to identify 10 compounds with bioactive properties (ferulic acid dihexoside, pedunculagin, methyl-dihydroquercetin dihexoside, dimethyl-dihydromyricetin diglucoside, kaempferol-3-O-hexosyl-rutinoside-7-O-rhamnoside, quercetin-O-hexoside-O-hexoside, ellagic acid, quercetin-O-hexoside, hesperetin-O-rutinoside, and diosmetin-O-rhamnoside), with a high prevalence of flavonoids. The extract showed no toxicity in an in vivo model of Galleria mellonella when administered at up to 1.6 g kg⁻¹ of body mass. The extract exhibited inhibition of Staphylococcus aureus (23 mm), Salmonella Typhimurium (12 mm), and Escherichia coli (12 mm), with inhibition zones close to that of gentamicin for the latter two. This study highlights the promising potential of red jambo flower extract as a valuable source of bioactive compounds with significant antioxidant, antimicrobial, and non-toxic properties. The optimized extraction process yielded extracts rich in bioactive compounds, demonstrating its suitability for various applications in the food industry. Further research is warranted to explore the full range of applications and potential health benefits of this natural extract.