Polymer fractions from a biological matrix have been well-characterized by vibrational spectroscopy, XPS, CP/MAS 13C NMR, MALDI-TOF mass spectrometry, thermal analysis, and SEM, and all the results had corroborated for the chemical extraction of β-glucan polymers grafted amino groups by peptide bonds (namely NH2- β-glucan) as well as a cyclic oligosaccharide. Our primary purpose was to explore the polysaccharide extraction parameters in the sample of Usnea lichen, mainly in terms of extraction time and concentration of the extractive alkaline solution, to investigate the chemical characterization of the polysaccharide fractions. The low-cost methodology adopted in this work was able to extract the materials of interest with the expected efficiency without the significant impact of chemicals on the environment. The chemical extraction of an NH2- bonded biopolymer can be a very interesting material for many applications since chemical functionalization is crucial to introducing specific properties for developing new materials. In this regard, the cyclic β-glucan described as a very porous material is highly desirable for various applications in the biomedical, biotechnological, and environmental areas. Keywords: β-Glucan · Amino acids · Lichens · Spectroscopic characterization.