Nuwamanya Herbert, Lukubye Ben, Kagoro-Rugunda Grace, Ajayi Clement Olusoji, Wangalwa Raphael, Olet Eunice Apio
Department of Biology, Mbarara University of Science and Technology, P.O. Box 1410, Mbarara, Uganda.
Department of Pharmacy, Mbarara University of Science and Technology, P.O. Box 1410, Mbarara, Uganda.
BMC Complement Med Ther. 2025 Jul 12;25(1):262. doi: 10.1186/s12906-025-05003-9.
Ferns have potential antimicrobial compounds but are understudied compared to higher plants. This limits our knowledge of their phytochemical composition and antimicrobial properties, despite their traditional use to treat various ailments. Therefore, this study profiled the phytochemical composition and evaluated the antimicrobial activity of four fern species, namely; Menisorus pauciflorus (Hook.) Alston, Pteris catoptera (Kunze.), Conniogramme africana (Hieron.) and Antrophyum mannianum (Hook.).
Fern fronds were collected from Kalinzu Central Forest Reserve (KCFR), cleaned with distilled water, and dried under shade at room temperature for two weeks. Dry fronds were ground using an electric blender into a powder and extracted by means of infusion and cold maceration, using distilled water and 70% ethanol as extraction solvents, respectively. Preliminary qualitative screening and a UV-VIS-spectrophotometer were used for phytochemical profiling by recording the presence (+) or absence (-) and quantities of the selected phytochemical classes, respectively. The antimicrobial activity (zones of inhibition) was determined by Agar well diffusion assay while the minimum inhibitory concentrations were determined using micro-broth dilution in 96-well microplates. The minimum bactericidal concentrations and minimum fungicidal concentrations were determined by subculturing technique.
Fern extracts contain various phytochemical compounds, such as phenols, tannins, saponins, anthraquinones, terpenoids, and flavonoids, with phenols being the most abundant. The antimicrobial activity of both water and ethanol extracts was higher against Escherichia coli and Staphylococcus aureus and lower against Candida albicans. The antibacterial activity was generally greater against E. coli than against S. aureus. The ethanolic extract of A. mannianum had the lowest minimum inhibitory concentration (3.91 mg/mL) and minimum bactericidal concentration (7.81 mg/mL) against E. coli. The A. mannianum aqueous and ethanol extracts, and the M. pauciflorus ethanol extract had the lowest minimum fungicidal concentration (125 mg/mL) against C. albicans. The C. africana ethanol extract at various concentrations (1000, 500, 250, and 125 mg/mL), produced larger inhibition zones against S. aureus (up to 32.67 mm) than did ciprofloxacin (20.77 mm).
All the M. pauciflorus, P. catoptera, C. africana, and A. mannianum extracts presented variable secondary metabolite contents, but the concentration of phenols was greater than that of flavonoids and saponins. The extracts possess antimicrobial bioactive agents but weak activity against E. coli, S. aureus and C. albicans. We recommend more studies on the effect of these fern extracts on other bacterial and fungal strains to prove their antimicrobial potential on various pathogenic bacteria and fungi.
蕨类植物含有潜在的抗菌化合物，但与高等植物相比，对其研究较少。尽管蕨类植物在传统医学中用于治疗各种疾病，但这限制了我们对其植物化学成分和抗菌特性的了解。因此，本研究分析了四种蕨类植物的植物化学成分，并评估了它们的抗菌活性，这四种蕨类植物分别是少花新月蕨（Menisorus pauciflorus (Hook.) Alston）、翅柄凤尾蕨（Pteris catoptera (Kunze.)）、非洲金毛裸蕨（Conniogramme africana (Hieron.)）和曼氏拟蕨（Antrophyum mannianum (Hook.)）。
从卡林祖中央森林保护区（KCFR）采集蕨类植物的叶子，用蒸馏水清洗，在室温下阴凉处干燥两周。将干燥的叶子用电 blender 磨成粉末，分别用蒸馏水和 70%乙醇作为提取溶剂，通过浸泡和冷浸法进行提取。通过记录所选植物化学类别的存在（+）或不存在（-）以及数量，使用初步定性筛选和紫外可见分光光度计进行植物化学分析。通过琼脂孔扩散法测定抗菌活性（抑制圈），同时使用 96 孔微量滴定板中的微量肉汤稀释法测定最低抑菌浓度。通过传代培养技术测定最低杀菌浓度和最低杀真菌浓度。
蕨类植物提取物含有多种植物化学化合物，如酚类、单宁、皂苷、蒽醌、萜类和黄酮类，其中酚类含量最高。水提取物和乙醇提取物对大肠杆菌和金黄色葡萄球菌的抗菌活性较高，对白色念珠菌的抗菌活性较低。总体而言，对大肠杆菌的抗菌活性比对金黄色葡萄球菌的抗菌活性更强。曼氏拟蕨的乙醇提取物对大肠杆菌的最低抑菌浓度（3.91mg/mL）和最低杀菌浓度（7.81mg/mL）最低。曼氏拟蕨的水提取物和乙醇提取物以及少花新月蕨的乙醇提取物对白色念珠菌的最低杀真菌浓度（125mg/mL）最低。不同浓度（1000、500、250 和 125mg/mL）的非洲金毛裸蕨乙醇提取物对金黄色葡萄球菌产生的抑制圈（最大达 32.67mm）比环丙沙星（20.77mm）更大。
少花新月蕨、翅柄凤尾蕨、非洲金毛裸蕨和曼氏拟蕨的所有提取物均呈现出不同的次生代谢产物含量，但酚类的浓度高于黄酮类和皂苷类。这些提取物具有抗菌生物活性剂，但对大肠杆菌、金黄色葡萄球菌和白色念珠菌活性较弱。我们建议对这些蕨类植物提取物对其他细菌和真菌菌株的作用进行更多研究，以证明它们对各种病原菌和真菌的抗菌潜力。
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