In vitro antioxidant, antihyperglycemic, anti-inflammatory, and antimicrobial activity of Satureja kitaibelii Wierzb. ex Heuff. subcritical water extract

As the main goal of this study was the verification of Satureja kitaibelii Wierzb. ex Heuff. in form of the crude extract obtained by subcritical water extraction (SWE) technique in terms of polyphenolic composition, in vitro antioxidant capacity, antihyperglycemic, and anti-inflammatory activities as well as an antimicrobial effect against 10 microorganisms. HPLC analysis showed the presence of ten compounds in a total concentration of 89.33 mg/g of the SWE extract, and demonstrated that subcritical water polarity was the most selective for extracting syringic and caffeic acid, as well as epicatechin (37.88 18.06, and 10.04 mg/g, respectively), while flavonoids like rutin, luteolin, and apigenin were present in low concentration (<2 mg/g). Results of antioxidant activity assays revealed that superoxide anion and ABTS center dot+ radical models expressed the highest scavenging abilities (437.35 and 412.09 mu mol TE/g, respectively), followed by lipid radicals (69.61 mu mol TE/g), and DPPH center dot (32.28 mu mol TE/g), while in the case of ferric ion reducing ability was noted a high value (118.19 mu mol TE/g). S. kitaibelii SWE was less efficient in the antihyperglycemic assay (AhgA = 30.72 %), but the high antiinflammatory activity of S. kitaibelii SWE was observed (30.35 %). The antimicrobial activity was demonstrated against Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Listeria monocytogenes as well as Saccharomyces cerevisiae, Candida albicans, and Aspergillus brasiliensis through antimicrobial screening, minimal inhibitory concentration, and pharmacodynamics study.

Automated summary

This study aimed to verify the polyphenolic composition, antioxidant capacity, antihyperglycemic and anti-inflammatory activities, as well as antimicrobial effect of Satureja kitaibelii extract obtained by subcritical water extraction (SWE) technique. The results showed that SWE extract contained mainly syringic and caffeic acid with low concentrations of flavonoids. Additionally, the extract exhibited high antioxidant activity in scavenging free radicals.