Lack of Antibacterial Activity of Commercial Supplies of Buchu Leaf and Pygeum Bark Against a Panel of Bacterial Pathogens


  • Chantelle Florenca
  • Matthew Cheesman
  • Ian Cock
  • Gary Grant



antibacterial, activity, pathogens, Buchu, Pygeum, resistance, toxicity


Background: Agathosma betulina (Buchu) and Pygeum africana (Pygeum) are native Southern African plants with numerous traditional medicinal uses. However, studies on their antibacterial effects are limited. The discovery of new antibacterial treatment options has become important given the growing prevalence of bacterial resistance to common antibiotics.

Aims: To investigate the antibacterial effects of water, methanolic and ethyl acetate extracts prepared from different commercial plant materials against antibiotic-sensitive and antibiotic-resistant pathogens, and to determine their phytochemical and toxicity profiles.

Methods: Agar disc diffusion and liquid microdilution assays were used to determine the inhibitory effects of the Buchu and Pygeum extracts against common bacteria, including Staphylococcus aureus, MRSA, Escherichia coli, ESBL E. coli, Klebsiella pneumoniae and ESBL K. pneumoniae. Five different conventional antibiotics were also tested against the six bacterial species using these assays, serving as reference antibiotics. Qualitative phytochemical assays were used to identify phytochemical classes within each extract. Artemia nauplii assays were used to assess toxicities.

Results: All Buchu and Pygeum extracts prepared from the powdered commercial product, as well as the commercially supplied plant segments, were inactive in agar and liquid broth assays. All extracts were deemed to be non-toxic in Artemia.

Conclusion: Commercial supplies of Buchu and Pygeum were ineffective against all bacterial pathogens tested. While toxicity studies suggest they are safe to use in Artemia, the use of these products is brought into question due to their lack of antimicrobial activity. It is possible that extracts prepared from the fresh plant, compared to pre-processed plant material, may yield antimicrobial activities.


Antimicrobial resistance (2023 Nov 21; cited 2023 Jan 4) Website, available from: sheets/detail/antibiotic-resistance

Elder FCT, et al. (2020). The role of stereochemistry of antibiotic agents in the development of antibiotic resistance in the environment. Environment International, 139, 105681. https://doi. org/10.1016/j.envint.2020.105681

Rice LB. Federal funding for the study of antimicrobial resistance in nosocomial pathogens: No ESKAPE. (2008 Apr 15). The Journal of Infectious Diseases, 197 (8), 1079-81. Doi 10.1086/533452

Nandhini P, et al. (2022 April 29). Recent developments in Methicillin-Resistant Staphylococcus aureus (MRSA) treatment: A review. Antibiotics, 11 (5), 606. Doi 10.3390/antibiotics11050606

Russo A, et al. (2021 Feb 17). Recent molecules in the treatment of severe infections caused by ESBL-producing bacteria. Expert Review of Anti-infective Therapy, 19 (8), 983-91. Doi 10.1080/14787210.2021.1874918

Blair JMA, et al. (2014 Dec 1). Molecular mechanisms of antibiotic resistance. Nature Reviews Microbiology, 13 (1), 42-51. Doi 10.1038/nrmicro3380

Mickymaray S. (2019 Dec 9). Efficacy and mechanism of traditional medicinal plants and bioactive compounds against clinically important pathogens. Antibiotics, 8 (4), 257. Doi 10.3390/ antibiotics8040257

Moolla A, et al. (2008 Oct 28). 'Buchu' - Agathosma betulina and Agathosma crenulata (Rutaceae): A review. Journal of Ethnopharmacology, 119 (3), 413-19. Doi 10.1016/j.jep.2008.07.036

Huisamen B. (1st ed.) (2019). Medicinal effects of Agathosma (Buchu) extracts. 1, AOSIS. Doi 10.4102/aosis.2019.BK84

Moolla A, et al. (2007 Nov). Biological activity and toxicity profile of 17 Agathosma (Rutaceae) species. South African Journal of Botany, 73 (4), 588-92. Doi 10.1016/j.sajb.2007.05.007

Brendler T, et al. (2022 Feb 7). Buchu (Agathosma betulina and A. crenulata): Rightfully forgotten or underutilized? Frontiers in Pharmacology, 13, 813142. Doi: 10.3389/fphar.2022.813142

Viljoen AM, et al. (2006 Jan). The biological activity and essential oil composition of 17 Agathosma (Rutaceae) species. Journal of Essential Oil Research, 18 (sup1), 2-16. Doi 10.1080/10412905.2006.12067112

Papaioannou M, et al. (2009 Sept 23). NBBS isolated from Pygeum africanum bark exhibits androgen antagonistic activity, inhibits AR nuclear translocation and prostate cancer cell growth. Investigational New Drugs, 28 (6), 729-43. Doi: 10.1007/s10637- 009-9304-y

Madivoli ES, et al. (2018 June 27). In vitro antioxidant and antimicrobial activity of Prunus africana (Hook. f.) Kalkman (bark extracts) and Harrisonia abyssinica Oliv. extracts (bark extracts): A comparative study. Journal of Medicinal Plants for Economic Development, 2 (1), 1-9. Doi 10.4102/jomped.v2i1.39

Mwitari PG, et al. (2013 June 13) Antimicrobial activity and probable mechanisms of action of medicinal plants of Kenya: Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus. PLoS One, 8 (6), e65619. Doi 10.1371/journal. pone.0065619

Ang JY, et al. (2023 Nov 3). Risk-taking in consumers’ online purchases of health supplements and natural products: A grounded theory approach. Journal of Pharmaceutical Policy and Practice, 16 (1), 134. Doi 10.1186/s40545-023-00645-x

Therapeutic Goods (Permissible Ingredients) Determination (No. 4) 2023. (2023 Oct 4; cited 2024 Jan 4). Website, available from: latest/text.

Tiwana G, et al. (2020 Oct 5). Use of specific combinations of the triphala plant component extracts to potentiate the inhibition of gastrointestinal bacterial growth. Journal of Ethnopharmacology, 260, 112937. Doi 10.1016/j.jep.2020.112937 19. Eloff JN. (1998 Feb). Which extractant should be used for the screening and isolation of antimicrobial components from plants? Journal of Ethnopharmacology, 60 (1), 1-8. Doi 10.1016/ s0378-8741(97)00123-2

Clinical and Laboratory Standards Institute CLSI Document M100. Performance Standards for Antimicrobial Susceptibility Testing. (2019 Jan). 29th ed., Clinical and Laboratory Standards Institute.

Ilanko A, et al. (2019 March). The interactive antimicrobial activity of conventional antibiotics and Petalostigma spp. extracts against bacterial triggers of some autoimmune inflammatory diseases. Pharmacognosy Journal, 11 (2), 292-309. Doi 10.5530/ pj.2019.11.45

Eloff JN. (2019 May 22). Avoiding pitfalls in determining antimicrobial activity of plant extracts and publishing the results. BMC Complementary and Alternative Medicine, 19 (1), 1-8. Doi 10.1186/s12906-019-2519-3

Vesoul J, et al. (2011 Oct 1). An examination of the medicinal potential of Pittosporum phylliraeoides: Toxicity, antibacterial and antifungal activities. Pharmacognosy Communications, 1 (2), 8-17. Doi 10.5530/pc.2011.2.3

Shalom J, et al. (2018 Apr 11). Terminalia ferdinandiana Exell. fruit and leaf extracts inhibit proliferation and induce apoptosis in selected human cancer cell lines. Nutrition and Cancer, 70 (4), 579-93. Doi 10.1080/01635581.2018.1460680

Akiyama H, et al. (2001 Oct 1). Antibacterial action of several tannins against Staphylococcus aureus. Journal of Antimicrobial Chemotherapy, 48 (4), 487-91. Doi 10.1093/ jac/48.4.487

Rempe CS, et al. (2017 Mar 16). The potential of systems biology to discover antibacterial mechanisms of plant phenolics. Frontiers in Microbiology, 8, 422. Doi 10.3389/fmicb.2017.00422 27. Tan Z, et al. (2022 Mar 7). The antibacterial activity of natural-derived flavonoids. Current Topics in Medicinal Chemistry, 22 (12), 1009-19. Doi 10.2174/1568026622666220221110506

Khan MI, et al. (2018 Nov 26). Green tea seed isolated saponins exerts antibacterial effects against various strains of gram positive and gram negative bacteria, a comprehensive study in vitro and in vivo. Evidence-Based Complementary and Alternative Medicine, 2018, 1-12. Doi 10.1155/2018/3486106

Wronska N, et al. (2022 Jan 27). The synergistic effect of triterpenoids and flavonoids - new approaches for treating bacterial infections? Molecules, 27 (3), 847. Doi 10.3390/molecules27030847 30. Raghuveer D, et al. (2023 Feb 7). Exploring anthraquinones as antibacterial and antifungal agents. ChemistrySelect, 8 (6). Doi 10.1002/slct.202204537

Lis-Balchin M, et al. (2001 Apr). Buchu (Agathosma betulina and A. crenulata, Rutaceae) essential oils: Their pharmacological action on guinea-pig ileum and antimicrobial activity on microorganisms. Journal of Pharmacy and Pharmacology, 53 (4), 579-82. Doi 10.1211/0022357011775703

Drews RC. (1977 Jun) Acetone sterilization in ophthalmic surgery. Annals of Ophthalmology. 9 (6), 781-4.

Steenkamp V, et al. (2006 Jan 3). Studies on antibacterial, anti-inflammatory and antioxidant activity of herbal remedies used in the treatment of benign prostatic hyperplasia and prostatitis Journal of Ethnopharmacology, 103 (1), 71-5. Doi 10.1016/j. jep.2005.07.007

Bii C, et al. (2010 June 4). The potential use of Prunus africana for the control, treatment and management of common fungal and bacterial infections. Journal of Medicinal Plants Research, 4 (11), 995-8. Doi 10.5897/JMPR09.227

Ngule MC, et al. (2014). Chemical constituents screening and in vitro antibacterial assessment of Prunus africana bark hydromethanolic extract. Journal of Natural Sciences Research, 4 (16), 85-90.

Deresa DA, et al. (2022 May). Chemical constituents of the stem bark of Prunus africana and evaluation of their antibacterial activity. Journal of the Turkish Chemical Society Section A: Chemistry, 9 (2), 395-414. Doi 10.18596/jotcsa.1029564

Wadhwani T, et al. (2009 Jan). Effect of various solvents on bacterial growth in context of determining MIC of various antimicrobials. The Internet Journal of Microbiology, 7 (1), 1-8. Doi: 10.7717/peerj.16444