UHPLC-MS/MS based comprehensive phenolic profiling, antimicrobial and antioxidant activities of Indian Rhodomyrtus tomentosa fruits

Rhodomyrtus tomentosa fruits, endemic to the Western Ghats were analyzed for its free, bound and
esterified phenolics by Ultra High Performance Liquid Chromatography–Mass Spectrometry. Overall,
twenty-nine phenolic compounds were identified, amongst them 18 were detected in this fruit for the
first time. Gallic acid (80.44 ± 8.74 mg/100 g) and ellagic acid (107.47 ± 7.28 mg/100 g) were the most
prominent ones found in the bound phenolic fraction and gallic acid (103.76 ± 6.34 mg/100 g) in the
esterified phenolic fraction of the fruit, respectively. Total Phenolic content was found to be highest in
bound phenolics (7.09 ± 0.17 mg Gallic acid equivalent/g). The antioxidant and antimicrobial activities
of the three extracts namely free, bound and esterified phenolic fruit fractions have been analyzed.
Bound phenolics exhibited the highest antioxidant potential (DPPH-15.63 ± 0.86; ABTS-34.73 ± 0.07;
FRAP-17.89 ± 0.27 mg/g Ascorbic acid equivalent). The bound phenolics showed good antimicrobial
activity against Bacillus cereus, Staphylococcus aureus and Escherichia coli with a MIC of 0.156, 0.625
and 1.25 mg/mL respectively. The exploration of phenolic compounds in Indian variety of Rhodomyrtus
tomentosa fruits may provide useful insights on its utilization as a functional food ingredient.