The Potential of Selected South African Plants with Anti-Klebsiella Activity for the Treatment and Prevention of Ankylosing Spondylitis

Abstract

Introduction: Ankylosing spondylitis (AS) is a form of chronic inflammatory arthritis which mainly affects the spinal joints and large synovial joints such as the cacroiliac joint in the pelvis. AS afflicts up to 0.9 % of the world’s population, with a greater proportion of males up to 30 years afflicted than any other demographic. Methods: Thirty four extracts from 13 South African plant species with a history of ethnobotanical usage in the treatment of inflammation were investigated for their ability to control the microbial trigger for AS (K. pneumoniae). Results: Twenty six of the extracts (76.5 %) inhibited the growth of K. pneumoniae. Methanol and water extracts of Ballota africana, Carpobrotus edulis leaves, Kigellia africana, Lippia javanica, Pelargonium viridflorum, Syzygium cordatum leaf and bark, Terminalia pruinoides, Terminalia sericea, Tulbaghia violaceae roots and leaves and Warburgia salutaris bark were effective K. pneumoniae inhibitors, with MIC values < 1000 µg/ml. The most potent extracts were examined by RP-HPLC and UV-Vis spectroscopy for the presence of resveratrol. Methanolic extracts of B. africana, C. edulis leaves, L. javanica, T. pruinoides and T. sericea, as well as aqueous B. africana, T. pruinoides and T. sericea extracts, displayed peaks with retention times and UV-Vis spectra consistent with authentic resveratrol. When present, resveratrol was generally a minor component, indicating that resveratrol was not solely responsible for the K. pneumoniae growth inhibitory properties reported here. All extracts with K. pneumoniae inhibitory activity were either non-toxic, or of low toxicity in the Artemia nauplii bioassay. Conclusions: The low toxicity of these extracts and their inhibitory bioactivity against K. pneumoniae indicate their potential for preventing the onset of ankylosing spondylitis and for minimising its symptoms and the associated tissue damage once the disease is established.