ISOLATION, AMINO ACID COMPOSITION, AND HYPOGLYCEMIC ACTIVITY OF PROTEIN COMPONENTS FROM Arundo donax L.
Abstract
Total protein components were isolated from the aerial parts of Arundo donax L. by alkaline extraction followed by precipitation with ammonium sulfate, dialysis, and freeze-drying. Total protein content was determined by the Nessler method after mineralization using the Kjeldahl protein conversion factor. Amino acid composition was analyzed by high-performance liquid chromatography (HPLC) following acid hydrolysis. Structural characterization was performed using Fourier-transform infrared spectroscopy (FTIR) and SDS-PAGE electrophoresis. Hypoglycemic activity was evaluated in Wistar rats with glucose-induced hyperglycemia after intraperitoneal administration of the protein preparation at 50 and 100 mg/kg, using Glucare capsules as the reference; acute toxicity was assessed according to standard preclinical guidelines. The aerial parts of Arundo donax contained 20.40% total protein. The developed isolation procedure yielded a stable lyophilized protein preparation with good water solubility. HPLC analysis demonstrated a complete profile of essential and non-essential amino acids with a total amino acid content of 826.56 mg/g. Arginine, leucine, cysteine, histidine, valine, glutamic acid, and aspartic acid were among the predominant amino acids. FTIR spectra confirmed the protein nature of the preparation through characteristic amide I and II absorption bands, whereas SDS-PAGE revealed two major protein fractions with molecular masses of approximately 16 and 30 kDa, indicating a relatively high degree of purification. In vivo studies demonstrated pronounced dose-dependent hypoglycemic activity. Following a single administration, blood glucose levels decreased by 30.4% at 50 mg/kg and 38.4% at 100 mg/kg, exceeding the effect of the reference preparation Glucare (27.5%). Repeated administration further enhanced the pharmacological response, reaching 41.9% reduction in blood glucose by day 7. Acute toxicity studies revealed no mortality or clinical signs of intoxication, and the LD₅₀ exceeded 5000 mg/kg, indicating very low toxicity of the protein preparation. The developed isolation technology provides a stable protein preparation from Arundo donax L. with a well-characterized amino acid composition, confirmed protein structure, and favorable molecular profile. The preparation demonstrated significant hypoglycemic activity superior to the reference drug under experimental conditions while exhibiting a high safety profile. These findings indicate that protein components of Arundo donax represent a promising natural source for the development of novel protein-based hypoglycemic pharmaceuticals and justify further preclinical and mechanistic investigations.
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