Methylobamine, a UVA-Absorbing Compound from the Plant-Associated Bacteria Methylobacterium sp

To survive in harsh environments, phyllosphere microorganisms have developed numerous adaptive strategies against stressors. One such strategy is the synthesis of compounds that absorb ultraviolet A radiation (UVA). The chemical structure of a UVA-absorbing compound from Methylobacterium sp. strain W-213 was elucidated by spectroscopic analyses. 1 H, 13 C, and two-dimensional nuclear magnetic resonance spectra indicated the presence of N -methyl-α-galactosamine. The entire structure was revealed by interpretation of INADEQUATE and high-resolution liquid chromatography/electrospray ionization mass spectra. The absolute configuration was established by X-ray analysis and the compound was identified as 2-{(4a R, 6 R, 7 R, 8 R, 8a R)-7,8-dihydroxy-6-hydroxymethyl-1,2-dimethyl-4a H, 6 H, 7 H, 8 H, 8a H -pyrano[2,3- b][1,4]oxazin-3-yl}-2-iminoacetic acid and named ‘methylobamine'. Methylobamine shows promise for pharmaceutical and cosmetic applications due to its high polarity, UVA absorption properties, and stability under UVA exposure.