{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,11]],"date-time":"2026-10-11T13:45:16Z","timestamp":1791726316015,"version":"4.3.4"},"reference-count":39,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,2,1]],"date-time":"2026-02-01T00:00:00Z","timestamp":1769904000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Grand Challenges Africa\u20142nd Drug Discovery Round10 Seed Grant","award":["GCA\/DD2\/Round10\/087\/008"],"award-info":[{"award-number":["GCA\/DD2\/Round10\/087\/008"]}]},{"name":"South African Medical Research Council Centre for Tuberculosis Research"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background\/Objectives: The increase in incidences of multidrug resistance exacerbates tuberculosis-related global health challenges and underscores a call for more efforts for development of new antitubercular drugs, including the use of medicinal plants, especially those that have been used for generations by traditional healers. Despite reports of antimicrobial activity and chemical profiling of Kirkia wilmsii (K. wilmsii) extracts, chemical structures of the bioactive agents have not been elucidated. Here, we used a combination of bioactivity-guided fractionation, mass spectrometry, and nuclear magnetic resonance to purify and elucidate the chemical structure of antimycobacterial agents contained in leaf and twig extracts for K. wilmsii. Results: After overnight extraction with acetone and 90 g of dry twigs and leaves produced 5.38 g (6%) and 4.56 g (5%) of product, which displayed moderate antimycobacterial activity of 0.5 and 1 mg\/mL, respectively. The antimycobacterial activity was increased six- and three-fold, respectively, after the crude extracts were subjected to solvent\u2013solvent partitioning. Due to many bioactive fractions being obtained after silica gel chromatography purification, fraction 5 of twig extract was prioritized for further purification due to its low minimum inhibitory concentration (MIC) (0.25 mg\/mL) and cytotoxicity (20%, in THP-1 cells). Sequential purification of the fraction 5 (twig extract) extracts through the C18 cartridge and high-performance liquid chromatography (HPLC) produced four fractions, which were subjected to structural elucidation. The high-resolution mass spectrometric analyses revealed that the first two eluting peaks had the same mass ion of 441.0822 m\/z (M \u2212 H\u2212), which corresponded to catechin monogallate, and so were the last two eluting peaks, which had a mass ion of 539.0932 m\/z (M \u2212 H\u2212), corresponding to catechin digallate. Further analyses by 1H, 13C, and 2D NMR confirmed the chemical structures of compounds eluting in the first two peaks on HPLC as structural isomers of catechin 3\u2032-monogallate and catechin 4\u2032-monogallate (MIC not determined). Similarly, compounds eluting in the last two peaks were identified as structural isomers catechin 3\u2032-digallate and catechin 4\u2032-digallate, with an MIC of 250 \u00b5g\/mL against Mycobacterium smegmatis and Mycobacterium tuberculosis H37Rv and an MBC of 500 \u03bcg\/mL against M. smegmatis. Conclusions: To the best of our knowledge, this study is the first to report the structure of catechin 3\u2032- and 4\u2032-digallate, their antimycobacterial activity, and the existence of acyl migration involving galloyl 3\u2032 and 4\u2032-hydroxyl groups of catechin ring B.<\/jats:p>","DOI":"10.3390\/antibiotics15020141","type":"journal-article","created":{"date-parts":[[2026,2,2]],"date-time":"2026-02-02T09:00:33Z","timestamp":1770022833000},"page":"141","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Discovery of Novel Derivatives of Catechin Gallate with Antimycobacterial Activity from Kirkia wilmsii Engl. Extracts"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9776-6779","authenticated-orcid":false,"given":"Nenekazi","family":"Masikantsi","sequence":"first","affiliation":[{"name":"SAMRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Stellenbosch University, Francie van Zijl Drive, Tygerberg, Cape Town 7505, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3507-5857","authenticated-orcid":false,"given":"Rendani","family":"Mbau","sequence":"additional","affiliation":[{"name":"SAMRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Stellenbosch University, Francie van Zijl Drive, Tygerberg, Cape Town 7505, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1171-8707","authenticated-orcid":false,"given":"Nuhu","family":"Tukur","sequence":"additional","affiliation":[{"name":"SAMRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Stellenbosch University, Francie van Zijl Drive, Tygerberg, Cape Town 7505, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8076-083X","authenticated-orcid":false,"given":"Peter","family":"Masoko","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, Microbiology and Biotechnology, Faculty of Science and Agriculture, University of Limpopo, Private Bag X1106, Sovenga 0727, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7455-4493","authenticated-orcid":false,"given":"Gabriel","family":"Mashabela","sequence":"additional","affiliation":[{"name":"SAMRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Stellenbosch University, Francie van Zijl Drive, Tygerberg, Cape Town 7505, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,1]]},"reference":[{"key":"ref_1","unstructured":"WHO (2023). Global Tuberculosis Report, 2023."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"617","DOI":"10.1038\/s41579-024-01025-1","article-title":"Drug-resistant tuberculosis: A persistent global health concern","volume":"22","author":"Farhat","year":"2024","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1016\/j.sajb.2022.05.028","article-title":"Natural bioactive products as promising therapeutics: A review of natural product-based drug development","volume":"151","author":"Aware","year":"2022","journal-title":"S. Afr. J. Bot."},{"key":"ref_4","unstructured":"WHO (2000). General Guidelines for Methodologies on Research and Evaluation of Traditional Medicine, Report No: WHO\/EDM\/TRM\/2000.1."},{"key":"ref_5","unstructured":"WHO (2019). Global Report on Traditional and Complementary Medicine."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2507","DOI":"10.4314\/tjpr.v15i11.28","article-title":"Ethnomedicinal uses, phytochemistry and pharmacological properties of the genus, Kirkia","volume":"15","author":"Maroyi","year":"2016","journal-title":"Trop. J. Pharm. Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"br1","DOI":"10.4081\/pb.2012.br1","article-title":"Field Guide to Trees of Southern Africa","volume":"3","author":"Palgrav","year":"2012","journal-title":"Int. J. Plant Biol."},{"key":"ref_8","first-page":"109","article-title":"Ethnobotanical survey of plants used by Bapedi traditional healers to treat hypertension in the Polokwane Munucipality, Limpopo province, South Africa","volume":"17","author":"Silas","year":"2018","journal-title":"Indilinga Afr. J. Indig. Knowl. Syst."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1016\/j.sajb.2018.10.010","article-title":"Ethnobotanical survey of plants used by Bapedi traditional healers to treat tuberculosis and its opportunistic infections in the Limpopo Province, South Africa","volume":"122","author":"Semenya","year":"2019","journal-title":"S. Afr. J. Bot."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/j.jep.2004.02.011","article-title":"In vitro antiplasmodial activity of medicinal plants native to or naturalised in South Africa","volume":"92","author":"Clarkson","year":"2004","journal-title":"J. Ethnopharmacol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.sajb.2018.04.013","article-title":"Phytochemical screening and pharmacological evaluation of herbal concoctions sold at Ga Maja Limpopo Province","volume":"117","author":"Matotoka","year":"2018","journal-title":"S. Afr. J. Bot."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"e02668","DOI":"10.1016\/j.heliyon.2019.e02668","article-title":"Antifungal and anti-mycotoxigenic activity of selected South African medicinal plants species","volume":"5","author":"Dikhoba","year":"2019","journal-title":"Heliyon"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"805","DOI":"10.1177\/2156587217727112","article-title":"Evaluation of Herbal Concoctions Sold at Ga Maja (Limpopo Province) in South Africa and In Vitro Pharmacological Evaluation of Plants Used to Manufacture the Concoctions","volume":"22","author":"Matotoka","year":"2017","journal-title":"J. Evid.-Based Complement. Altern. Med."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1037","DOI":"10.1016\/j.apjtb.2016.10.004","article-title":"Phytochemical and antioxidant properties of different solvent extracts of Kirkia wilmsii tubers","volume":"6","author":"Chigayo","year":"2016","journal-title":"Asian Pac. J. Trop. Biomed."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"563","DOI":"10.5897\/JMPR2018.6688","article-title":"Phytochemical analysis, antioxidant, antibacterial and combinational effects of medicinal plants used by Bapedi traditional healers to prepare herbal mixtures","volume":"12","author":"Matotoka","year":"2018","journal-title":"J. Med. Plants Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"275","DOI":"10.4314\/ajtcam.v11i3.38","article-title":"The Preliminary Assessment of Anti-Microbial Activity of Hplc Separated Components of Kirkia Wilmsii","volume":"11","author":"Chigayo","year":"2014","journal-title":"Afr. J. Tradit. Complement. Altern. Med."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Lee, J.E., Jayakody, J.T.M., Kim, J.I., Jeong, J.W., Choi, K.M., Kim, T.S., Seo, C., Azimi, I., Hyun, J., and Ryu, B. (2024). The Influence of Solvent Choice on the Extraction of Bioactive Compounds from Asteraceae: A Comparative Review. Foods, 13.","DOI":"10.3390\/foods13193151"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1016\/j.fitote.2010.09.013","article-title":"Isolation of a novel catechin from Bergenia rhizomes that has pronounced lipase-inhibiting and antioxidative properties","volume":"82","author":"Ivanov","year":"2011","journal-title":"Fitoterapia"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.fitote.2008.10.003","article-title":"A new epicatechin gallate and calpain inhibitory activity from Orostachys japonicus","volume":"80","author":"Kim","year":"2009","journal-title":"Fitoterapia"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/S0021-9673(01)96734-2","article-title":"Analysis of gallic, digallic and trigallic acids in tannic acids by high-performance liquid chromatography","volume":"265","author":"Delahaye","year":"1983","journal-title":"J. Chromatogr. A"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"846","DOI":"10.1021\/ja01680a036","article-title":"Gallotannin. XIII. The Identity of Digallic Acid from Gallotannin with Synthetic Meta-Digallic Acid","volume":"47","author":"Nierenstein","year":"1925","journal-title":"J. Am. Chem. Soc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"796","DOI":"10.1016\/j.phytochem.2011.02.020","article-title":"ent-Eudesmane sesquiterpenoids, galloyl esters of the oak lactone precursor, and a 3-O-methylellagic acid glycoside from the wood of Platycarya strobilacea","volume":"72","author":"Maeda","year":"2011","journal-title":"Phytochemistry"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"6329","DOI":"10.1007\/s00216-019-01931-x","article-title":"Comprehensive analysis of tara tannins by reversed-phase and hydrophilic interaction chromatography coupled to ion mobility and high-resolution mass spectrometry","volume":"411","author":"Venter","year":"2019","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Miklasi\u0144ska, M., K\u0119pa, M., Wojtyczka, R.D., Idzik, D., Dziedzic, A., and W\u0105sik, T.J. (2016). Catechin Hydrate Augments the Antibacterial Action of Selected Antibiotics against Staphylococcus aureus Clinical Strains. Molecules, 21.","DOI":"10.3390\/molecules21020244"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1439","DOI":"10.1292\/jvms.16-0198","article-title":"Antimicrobial activity of tea catechin against canine oral bacteria and the functional mechanisms","volume":"78","author":"Bai","year":"2016","journal-title":"J. Vet. Med. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Makarewicz, M., Dro\u017cd\u017c, I., Tarko, T., and Duda-Chodak, A. (2021). The Interactions between Polyphenols and Microorganisms, Especially Gut Microbiota. Antioxidants, 10.","DOI":"10.3390\/antiox10020188"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2039","DOI":"10.1016\/S0006-2952(03)00585-9","article-title":"The galloyl moiety of green tea catechins is the critical structural feature to inhibit fatty-acid synthase","volume":"66","author":"Wang","year":"2003","journal-title":"Biochem. Pharmacol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1039\/D0FO02689A","article-title":"The galloyl moiety enhances the inhibitory activity of catechins and theaflavins against \u03b1-glucosidase by increasing the polyphenol-enzyme binding interactions","volume":"12","author":"Sun","year":"2021","journal-title":"Food Funct."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Xue, M., Shi, H., Zhang, J., Liu, Q.-Q., Guan, J., Zhang, J.-Y., and Ma, Q. (2016). Stability and Degradation of Caffeoylquinic Acids under Different Storage Conditions Studied by High-Performance Liquid Chromatography with Photo Diode Array Detection and High-Performance Liquid Chromatography with Electrospray Ionization Collision-Induced Dissociation Tandem Mass Spectrometry. Molecules, 21.","DOI":"10.3390\/molecules21070948"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"2737","DOI":"10.1016\/0031-9422(91)85134-L","article-title":"Derivatives of (+)-catechin-5-gallate from the bark of Acacia nilotica","volume":"30","author":"Malan","year":"1991","journal-title":"Phytochemistry"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2049","DOI":"10.1016\/S0031-9422(00)81756-2","article-title":"(+)-catechin-galloyl esters from the bark of Acacia gerrardii","volume":"26","author":"Malan","year":"1987","journal-title":"Phytochemistry"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Wen, L., Wu, D., Tan, X., Zhong, M., Xing, J., Li, W., Li, D., and Cao, F. (2022). The Role of Catechins in Regulating Diabetes: An Update Review. Nutrients, 14.","DOI":"10.3390\/nu14214681"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Nazir, N., Zahoor, M., Ullah, R., Ezzeldin, E., and Mostafa, G.A.E. (2020). Curative Effect of Catechin Isolated from Elaeagnus Umbellata Thunb. Berries for Diabetes and Related Complications in Streptozotocin-Induced Diabetic Rats Model. Molecules, 26.","DOI":"10.3390\/molecules26010137"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"478","DOI":"10.1016\/j.freeradbiomed.2018.11.010","article-title":"(\u2212)-Epicatechin in the control of glucose homeostasis: Involvement of redox-regulated mechanisms","volume":"130","author":"Cremonini","year":"2019","journal-title":"Free Radic. Biol. Med."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"710","DOI":"10.1002\/iub.1185","article-title":"(\u2212)-Epicatechin reduces blood pressure and improves vasorelaxation in spontaneously hypertensive rats by NO-mediated mechanism","volume":"65","author":"Galleano","year":"2013","journal-title":"IUBMB Life"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"9483845","DOI":"10.1155\/2017\/9483845","article-title":"Corrigendum to \u2018(\u2212)-Epicatechin Prevents Blood Pressure Increase and Reduces Locomotor Hyperactivity in Young Spontaneously Hypertensive Rats\u2019","volume":"2017","author":"Kluknavsky","year":"2017","journal-title":"Oxid. Med. Cell. Longev."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"440","DOI":"10.1016\/j.jep.2012.03.008","article-title":"Ethnobotanical survey of medicinal plants used by Bapedi healers to treat diabetes mellitus in the Limpopo Province, South Africa","volume":"141","author":"Semenya","year":"2012","journal-title":"J. Ethnopharmacol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"133","DOI":"10.5005\/jp-journals-10005-1610","article-title":"Effect of Green Tea Extract Mouthwash on Salivary Streptococcus mutans Counts in a Group of Preschool Children: An In Vivo Study","volume":"12","author":"Salama","year":"2019","journal-title":"Int. J. Clin. Pediatr. Dent."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1488","DOI":"10.1016\/j.cmi.2020.07.036","article-title":"Antimicrobial susceptibility testing of Mycobacterium tuberculosis complex isolates\u2014The EUCAST broth microdilution reference method for MIC determination","volume":"26","author":"Werngren","year":"2020","journal-title":"Clin. Microbiol. Infect."}],"container-title":["Antibiotics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6382\/15\/2\/141\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,2]],"date-time":"2026-02-02T09:27:11Z","timestamp":1770024431000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6382\/15\/2\/141"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,1]]},"references-count":39,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["antibiotics15020141"],"URL":"https:\/\/doi.org\/10.3390\/antibiotics15020141","relation":{},"ISSN":["2079-6382"],"issn-type":[{"value":"2079-6382","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,1]]}}}