Anti-inflammatory potential of selected medicinal plants used in the treatment of sexually transmitted infections and 1H NMR-based metabolomics of Lannea schweinfurthii

Abstract

Inflammation and pain are major clinical signs of sexually transmitted infections (STIs) such as gonorrhoea, chlamydia, trichomoniasis, bacterial vaginosis and more recently, Mycoplasma genitalium. Delayed treatment of underlying infections often results in genital inflammation, genital ulcers, reproductive complication and an increased risk of human immunodeficiency virus (HIV) acquisition. South Africa has one of the highest rates of STIs globally and the current challenges with treatment are the issues of new infections, re-infection and multidrug resistant pathogens. Non-steroidal anti-inflammatory drugs (NSAIDs) are prescribed as part of the treatment regimen for pain and inflammation associated with STIs but their prolonged use has several undesirable side effects. This has necessitated the continuous search for suitable alternatives to existing therapeutics. Twelve South African medicinal plants used by traditional folklores in the management of STIs were screened for their anti-inflammatory activity against some inflammatory markers and their role as free radical scavenger was also assessed. Noteworthy anti-inflammatory and anti-oxidant activity with no cytotoxic effect was observed in most of the extracts. An application of proton nuclear magnetic resonance (1H NMR) and gas chromatography-mass spectroscopy (GC-MS) based metabolomics approach was used to guide the fractionation and dereplication of anti-inflammatory constituents in Lannea schweinfurthii which was the most potent inhibitor of 15-lipoxygenase (15-LOX) activity. The active fractions of L. schweinfurthii contained several bioactive phenolic compounds with known inflammatory activities and other constituents which are reported for the first time from this plant. The findings from this study reveals the anti-inflammatory potential of active plants as new sources of compounds which can be further explored for the management of STI related inflammation. The metabolomic approach and dereplication techniques employed in this study facilitated the identification of bioactive compounds and prevented the re-isolation of already known compounds and thus, facilitates the speedy discovery of novel compounds from plants.