Sessein and isosessein with anti-inflammatory, antibacterial and antioxidant activity isolated from Salvia sessei...

Salvia sessei Benth, popularly known as "pipilolxochitl" or "sabanito", is a plant utilized in Mexico in traditional medicine for the treatment of erysipela. To date, only one report, to our knowledge, has been found in which a royleanone-type diterpene of the aerial parts of the species was isolated but, again to our knowledge, studies have not been conducted on the pharmacological activity of extracts and compounds isolated from this plant.

The objective of the study was to evaluate the anti-inflammatory, antibacterial and antioxidant activity of the organic extracts of the aerial parts of Salvia sessei Benth and sessein and isosessein isomers isolated from this.

Anti-inflammatory activity was evaluated in a model of edema in mouse ear at 1 mg/ear of the isolated extracts and compounds (1 and 2), a dose-response curve was performed on these latter and one-half of the effective dose (ED₅₀) was determined; antibacterial activity was determined through minimal inhibitory concentration (MIC) by microdilution at 100, 50, 25, and 12.5 µg/mL, and antioxidant capacity, by means of DPPH, ABTS, and FRAP assays where, for the first two assays noted, the inhibitory concentration 50% (IC₅₀) was calculated for the extracts as well as for the compounds isolated.

The hexanic extracts (40.55 ± 0.5%), dichloromethanic (56.01 ± 1.1%) and methanolic (66.05 ± 0.3%), as well as isolated compounds 1 (79.85 ± 3.5%) and 2 (54.36 ± 1.7%), demonstrated anti-inflammatory activity; the methanolic extract presented the greatest percentage of inhibition, while isolated compounds 1 and 2 did not present a difference in their ED₅₀; additionally, compound 1 exerted a similar effect to that of the drug-of-reference at the same dose (75.24 ± 2.4%). The antibacterial activity of the extracts and compounds was principally against Gram-positive bacteria: the hexanic extract presented activity against Staphylococcus hominis and the methanolic and dichloromethanic extracts, and compound 1 exhibited activity against Staphylococcus haemolyticus, S. hominis, E. faecalis, in addition to that Escherichia coli was sensitive to compound 1, while isomer 2 showed activity against Staphylococcus aureus, Staphylococcus haemolyticus, Staphylococcus epidermis and Streptococcus pyogenes bacteria related to erysipela. In the three assays, the extract demonstrating greatest antioxidant capacity was the methanolic extract, while that of the isolated compounds was compound 1.

The results show that the three extracts evaluated in the three models presented activity and the chromatographic separation of the dichloromethanic extract permitted the isolation of compounds 1 and 2 royleanone-type isomers, which also presented significant activities such as anti-inflammatory, antibacterial and antioxidant, thus validate the use of this species in traditional medicine.