Metabolite profiling of Bacillus velezensis DM extract linked to the rhizosphere of Datura metel L. and dermatoprotective potential of an isolated glycoglycerolipid

Abstract

Abstract Background Rhizosphere bacterial metabolites play a pivotal role in drug discovery by producing diverse bioactive compounds with cosmeceuticals and pharmaceuticals applications, offering eco-friendly and potent alternatives for skin care, wound healing, and therapeutic formulations. This study outlines the procedures for fermenting and processing Bacillus velezensis DM, derived from the rhizosphere of Datura metel L., to isolate secondary metabolites. Chemical profiling was performed to analyze and identify the bacterial metabolites using HR-LC-MS. The EtOAc extract obtained from the cultured strain underwent fractionation and purification using a range of chromatographic techniques. The isolated compound was then structurally characterized through 1D, 2D-NMR and HR/MS. Bacterial extract and its pure compound were assessed for their anti-phototoxicity using MTT assay. Furthermore, the anti-melanogenesis and anti-allergic activities of the isolated compound were evaluated using melanin content inhibition assays in B16-F10 melanoma cells and β-hexosaminidase release assays in RBL-2H3 cells, respectively. Results Chemical profiling of the crude extract of Bacillus velezensis DM indicated the presence of 46 compounds. The main metabolites present in bacterial extract were nitrogenous compounds, dipeptides and lipid derivatives. A microbial glycoglycerolipid derivative, (2 S)-1-O-(9Z,12Z-octadecadienoyl)-3-O-β-D-galactopyranosylglycerol, was successfully isolated from the strain. The crude bacterial extract exhibited high cytotoxicity toward NHDF cells, reducing viability to 56.3% even at the lowest tested concentration. It also showed no photoprotective activity, as cell viability following UVB exposure remained below that of the UVB-only control (39.9%). In contrast, the purified glycoglycerolipid compound was non-cytotoxic and even appeared to promote HaCaT keratinocyte viability. However, it did not confer protection against UVB-induced damage. The compound exhibited a dose-dependent reduction in melanin levels, with a maximum inhibition of 27% observed at 5 µM. However, the melanin suppression trend closely mirrored a decrease in cell viability. Although the glycoglycerolipid compound improved RBL-2H3 cell viability, it did not significantly inhibit β-hexosaminidase release, suggesting no effective anti-allergic activity. Conclusion These findings demonstrate the potential of Bacillus velezensis DM as a microbial source of bioactive glycoglycerolipids. Further structural optimization and mechanistic investigation are required to enhance its functional specificity for safe and effective dermatological or cosmeceutical applications.