Magagula Mfundo, Motaung Thabiso E, Mbita Zukile, Dithebe Khumiso
Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Private Bag X1106, Sovenga, Polokwane, Limpopo, 0727, South Africa.
Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Private Bag X20, Hatfield, Pretoria, Gauteng, 0028, South Africa.
BMC Microbiol. 2025 May 30;25(1):343. doi: 10.1186/s12866-025-03964-y.
Fungal endophytes produce various structurally and chemically diverse bioactive secondary metabolites including those that are similar to their host plants. However, fungal endophytes from South African medicinal plants are relatively under-explored. The medicinal plant, Oliv., is on the decline in the natural environment due to overharvesting. This necessitates the search for novel alternatives to sustainably obtain the plant’s bioactive metabolites. Thus, fungal endophytes may serve as suitable candidates as they can produce host-similar bioactive compounds.
Eighteen morphologically distinct fungal endophytes were isolated from the surface-sterilised stems of Oliv. Sequencing of the internal transcribed spacer (ITS) region revealed that the isolates were distributed among three genera, namely , and . The broth micro-dilution assay showed that 17 of the 18 ethyl acetate crude extracts exhibited inhibitory activity with minimum inhibitory concentration (MIC) values ranging from 0.31 to 2.5 mg/mL and 1.25 to 2.5 mg/mL against bacterial pathogens and , respectively. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that most of the crude extracts had dose-dependent cytotoxicity against non-cancerous human embryonic kidney (HEK-293) cells, with the crude extracts of the . KaS-3, KaS-4, . KaS-5 and . KaS-6 isolates demonstrating safety against the non-cancerous cells. The alamarBlue assay revealed that the four non-cytotoxic crude extracts had moderate anticancer activity against cervical cancer ME-180 and melanoma A375 cancerous cell lines. Moreover, mycochemical analysis of the non-cytotoxic crude extracts using colourimetric quantification methods revealed that the observed cytotoxic effect could be attributed to the high total phenolic content in the crude extracts.
The study highlights that the fungal endophytes inhabiting the stems of Oliv. produce secondary metabolites that may serve as leads for novel antimicrobial and non-toxic anticancer agents.
The online version contains supplementary material available at 10.1186/s12866-025-03964-y.
真菌内生菌能产生各种结构和化学性质多样的生物活性次生代谢产物，包括与宿主植物相似的代谢产物。然而，来自南非药用植物的真菌内生菌相对较少被研究。药用植物Oliv.由于过度采收，在自然环境中数量正在减少。这就需要寻找新的替代方法来可持续地获取该植物的生物活性代谢产物。因此，真菌内生菌可能是合适的选择，因为它们可以产生与宿主相似的生物活性化合物。
从Oliv.表面消毒的茎中分离出18种形态不同的真菌内生菌。内部转录间隔区（ITS）区域测序显示，这些分离株分布在三个属中，即、和。肉汤微量稀释法表明，18种乙酸乙酯粗提物中的17种具有抑制活性，对细菌病原体和的最低抑菌浓度（MIC）值分别为0.31至2.5毫克/毫升和1.25至2.5毫克/毫升。3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）试验表明，大多数粗提物对非癌性人胚肾（HEK-293）细胞具有剂量依赖性细胞毒性，而KaS-3、KaS-4、KaS-5和KaS-6分离株的粗提物对非癌性细胞表现出安全性。alamarBlue试验表明，四种无细胞毒性的粗提物对宫颈癌ME-180和黑色素瘤A375癌细胞系具有中等抗癌活性。此外，使用比色定量方法对无细胞毒性粗提物进行的真菌化学分析表明，观察到的细胞毒性作用可能归因于粗提物中较高的总酚含量。
该研究强调，栖息在Oliv.茎中的真菌内生菌产生的次生代谢产物可能成为新型抗菌和无毒抗癌药物的先导。
在线版本包含可在10.1186/s12866-025-03964-y获取的补充材料。
