Phytochemical composition, antioxidant and antimicrobial activities of Plecospermum spinosum Trecul

Abstract In the present investigation, antioxidant potential of the methanolic leaf extract was assessed using in vitro free radical scavenging and phosphomolybdenum assays. The (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) (ABTS•+) assay exhibited potent free radical scavenging capacity at 100 µg/mL (86.48 ± 0.8%). Antimicrobial activity of the methanolic leaf extract greatly inhibited the growth of Pseudomonas aeruginosa (9 ± 0.7 mm) and Echinodontium tinctorium (12 ± 0.9 mm) when compared to the other tested pathogens. The hemolysis (%) was calculated for anti-inflammatory activity and the results showed dose dependent effects. The lowest inhibition (53.08 ± 1.5%) was obtained for 800 μg/mL extract when compared with control aspirin (90.41 ± 1.3%) at the same concentration. Qualitative phytochemical tests confirmed the presence of triterpenoids, flavonoids, saponins, tannins, sterols, sugars and free aminoacids. Totally, 35 different phytochemical compounds were found using gas chromatography-mass spectrometry (GC-MS). Furthermore, the phenolics (70.34 ± 2.1 mg/g), flavonoids (164.28 ± 1.1 mg/g) and other metabolites were estimated quantitatively. These results demonstrated that the methanolic leaf extract of Plecospermum spinosum Trecul exhibited considerable antioxidant, and antimicrobial activities due to the presence of bioactive phytochemicals. P. spinosum may be employed for the separation of novel bioactive metabolites with potential pharmaceutical activities.