Background: This study sought to identify and characterize the diverse flavonoids and phytochemical compounds in Saudi and Palestinian Salvia officinalis (sage) leaf extracts, and to evaluate their ability to inhibit protease enzymes, and thus their potential for use in antiretroviral drug discovery and development. We also explored sage’s ability to scavenge radicals; antioxidants derived from Lamiaceae plants play an important role in natural medicine.
Methods: The crude extract of methanol and dichloromethane solvents from Saudi and Palestinian Salvia officinalis leaves (sage) were in vitro screened for inhibitory activity against HIV-1 protease. We examined antioxidant capacity against the synthetic radicals of 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), identified the chemical constituents of the extracts by gas chromatography–mass spectrometry, ultrahigh-pressure liquid chromatography and nuclear magnetic resonance, and determined the diversity of flavonoids by liquid chromatography.
Results: Regarding the antiviral results, both Saudi and Palestinian sage leaf extracts significantly inhibited HIV-1 PR activity when compared to the vehicle control which was approximately (25.1 ± 10.6) µg/mL. The investigation of antioxidant capability revealed significant scavenging of synthetic ABTS radicals by Palestinian Salvia officinalis (sage) leaf extracts compared to the Saudi sage leaf extracts. Chemical analyses revealed a wide variety of secondary and primary compounds and flavonoids which were compared.
Conclusion: In this study we have investigated and revealed a variety of biological compounds that contribute to the inhibition of oxidative stress and protease enzyme. The results provide promising and beneficial data for the discovery and development of novel drugs against oxidation and HIV/AIDS.