In vitro comparison of pharmacological properties of Syzygium jambos, Syzygium malaccense and Syzygium samarangense species in Sri Lanka, extracted with different solvents

Abstract

Syzygium jambos (SJ), Syzygium malaccense (SM) and Syzygium samarangense (SS) are dicotyledonous species with a high distribution density in the wet zone of Sri Lanka. The leaves, barks and seeds are utilized in traditional medicine to treat different diseases. Despite their prevalence, few studies have been conducted in Sri Lanka to screen the bioactive ingredients. Therefore a comparative study was performed for the first time to investigate the antioxidant, anti-diabetic and antibacterial activities of leaves, fruits and seeds of the three species. Extraction was carried out with hexane, ethyl acetate, methanol and water at room temperature. DPPH free radical scavenging assay, alpha amylase inhibition assay and agar well diffusion method were used for analysis. Highest antioxidant activity was observed in SS methanol seed extract with a maximum percentage inhibition value of 92.07±0.77% at 34.0 (µg/mL) concentration. A noticeable alpha amylase inhibitory activity was seen in SS methanol leaf extract with a maximum percentage inhibition value of   83.10±1.22% at 2.30 (mg/mL) concentration. Hexane extract of SJ leaves depicted the highest inhibition zone, against Escherichia coli which was 21.5±2.5 mm whereas hexane seed extract of SS showed the highest inhibition zones against the bacterial strains Bacillus subtilis and Staphylococcus aureus which was 20±1 mm in diameter. Significant antibacterial activity of SS and SJ seeds were noted against the selected strains for the first time through this study. Due to the appreciable antioxidant, antibacterial and alpha amylase inhibitory activity, these species could be a principal source in nutraceutical and pharmaceutical products.