Phytochemical and biological assessment of secondary metabolites isolated from a rhizosphere strain, Sphingomonas sanguinis DM of Datura metel

• Published in: BMC complementary and alternative medicine 2024-05, Vol.24 (1), p.205-12, Article 205
• Main Authors: Awad, Mohamed A, Hammad, Sherif F, El-Mashtoly, Samir F, El-Deeb, Bahig, Soliman, Hesham S M
• Format: Article
• Language: English
• Subjects: Acetic acid; Alternaria; Anti-Bacterial Agents - pharmacology; Antibiotics; Antimicrobial; Antimicrobial activity; Antimicrobial agents; Bacteria; Biological activity; Biological effects; Cell culture; Chromatography; Culture media; Cytotoxicity; Datura metel; Datura metel - chemistry; Ecosystems; Ethyl acetate; Ethylenediaminetetraacetic acid; Fermentation; Fusarium oxysporum; Gram-positive bacteria; Humans; Klebsiella; Metabolites; Microbial activity; Microbial Sensitivity Tests; Microorganisms; Minimum inhibitory concentration; Natural products; NMR; Nuclear magnetic resonance; Organic compounds; Organic soils; Pathogens; Phthalic acid; Phylogenetics; Phytochemicals; Phytochemicals - chemistry; Phytochemicals - pharmacology; Phytopathogenic fungi; Plant metabolites; Plant roots; Plant Roots - microbiology; Polyamines; Rhizosphere; Rhizosphere bacteria; RNA; Roots; rRNA 16S; Secondary Metabolism; Secondary metabolites; Skin cancer; Sphingomonas; Sphingomonas sanguinis DM; Taxonomy; Tumor cell lines
• ISSN: 2662-7671; 2662-7671; 1472-6882
• DOI: 10.1186/s12906-024-04482-6

The plant roots excrete a large number of organic compounds into the soil. The rhizosphere, a thin soil zone around the roots, is a hotspot for microbial activity, making it a crucial component of the soil ecosystem. Secondary metabolites produced by rhizospheric Sphingomonas sanguinis DM have sparked significant curiosity in investigating their possible biological impacts. A bacterial strain has been isolated from the rhizosphere of Datura metel. The bacterium's identification, fermentation, and working up have been outlined. The ethyl acetate fraction of the propagated culture media of Sphingomonas sanguinis DM was fractioned and purified using various chromatographic techniques. The characterization of the isolated compounds was accomplished through the utilization of various spectroscopic techniques, such as UV, MS, 1D, and 2D-NMR. Furthermore, the evaluation of their antimicrobial activity was conducted using the agar well diffusion method, while cytotoxicity was assessed using the MTT test. The extract from Sphingomonas sanguinis DM provided two distinct compounds: n-dibutyl phthalic acid (1) and Bis (2-methyl heptyl) phthalate (2) within its ethyl acetate fraction. Furthermore, the 16S rRNA gene sequence of Sphingomonas sanguinis DM has been registered under the NCBI GenBank database with the accession number PP422198. The bacterial extract exhibited its effect against gram-positive bacteria, inhibiting Streptococcus mutans (12.6 ± 0.6 mm) and Staphylococcus aureus (10.6 ± 0.6 mm) compared to standard antibiotics. Conversely, compound 1 showed a considerable effect against phytopathogenic fungi such as Alternaria alternate (56.3 ± 10.6 mm) and Fusarium oxysporum (21.3 ± 1.5 mm) with a MIC value of 17.5 µg/mL. However, it was slightly active against Klebsiella pneumonia (11.0 ± 1.0 mm). Furthermore, compound 2 was the most active metabolite, having a significant antimicrobial efficacy against Rhizoctonia solani (63.6 ± 1.1 mm), Pseudomonas aeruginosa (16.7 ± 0.6 mm), and Alternaria alternate (20.3 ± 0.6 mm) with MIC value at 15 µg/mL. In addition, compound 2 exhibited the most potency against hepatocellular (HepG-2) and skin (A-431) carcinoma cell lines with IC values of 107.16 µg/mL and 111.36 µg/mL, respectively. Sphingomonas sanguinis DM, a rhizosphere bacterium of Datura metel, was studied for its phytochemical and biological characteristics, resulting in the identification of two compounds with moderate antimicrobial and cytotoxic activities.