Investigation of five selected Salix species against Mycobacterium smegmatis, a model bacterium for tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis is one of the leading causes of mortality globally with emerging drug-resistance [ 1 ] [ 2 ]. Salix species which are used for cough, lung problem and fever [ 3 ] could be good sources of new antimycobacterial compounds to combat TB. In this study, methanol, cold water and hot water extracts of the twigs of five Salix spp. were screened against Mycobacterium smegmatis. Also, some commercial compounds present in Salix species were tested against M. smegmatis . Agar diffusion and microplate methods were used to evaluate the antimycobacterial activity of the extracts and compounds. Methanol and cold-water twig extracts of S. caprea were significantly active against M. smegmatis with growth inhibition zone diameters of 23.5 mm and 20.2 mm respectively. However, none of the twig extracts of S. aurita , S. x pendulina , S. phylicifolia , and S. starkeana showed activity against M. smegmatis . The commercial compounds tested were devoid of antimycobacterial activity at 1 mg/ml concentration. UPLC-PDA-QTOF/MS (ESI- mode) investigation of the S. caprea twig methanol extract revealed the presence of catechin (m/z 289.0709), procyanidin B1 (m/z 577.1344), salicin-7-sulfate (m/z 365.0538), naringenin (m/z 271,0599), luteolin (m/z 285.0391), salicortin (m/z 423.1288), taxifolin (m/z 303.0500) and salicin (m/z 285.0977) as the major compounds in the twig extracts of S. caprea . This study is the first report on the antimycobacterial activity of these selected Salix species. The results indicate that S. caprea could contain anti-TB agents to curb the increasingly drug resistant TB strains. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany