Isolation, purification, structural elucidation, and antitumor activity in vitro of lentinan LNT2 / 中草药

ABSTRACT

Objective: To purify the lentinan from sporophore of Lentinus edodes and to study the structure and antitumor activity in vitro of lentinan. Methods: A refined lentinan, named LNT2, was isolated from the sporophore of L. edodes by alkali extraction and alcohol precipitation, and further purified by hydrogen peroxide decoloration and ultrafiltration. The molecular weight and sugar content of LNT2 were measured by HPLC and phenol-sulfuric acid method, respectively. UV was used to detect the protein and nucleic acid in LNT2, and specific rotation was detected. The chemical structure of LNT2 was determined by acid hydrolysis, periodate oxidation, methylation analysis, Fourier infrared spectrum, and NMR experiments. The chain conformation of LNT2 was evaluated by Congo-red test. The inhibitory effect of LNT2 on H22 tumor cells growth was evaluated using MTT assay. Results: The molecular weight, sugar content, and [α]D20 value of LNT2 were estimated to be 185 200, 94.99%, and +8.03°, respectively. UV spectrum showed that there were no peaks at 280 and 260 nm. Chemical and spectroscopic analyses illustrated that LNT2 had a backbone chain of β-(1→3)-linked glucopyranosyl residues and had branches of single glucosyl stubs at C-6 of terminal glucose sugar residues. Congo-red test revealed that LNT2 exhibited a triple helix comformation in low concentration of NaOH solution. Results of the antitumor activity in vitro demonstrated that LNT2 could exhibit the strong effect against the growth of H22 tumor cells and showed a dose-dependent manner. Conclusion: LNT2 is composed of β-(1→3)-linked glucan and has a triple helix comformation. Moreover, LNT2 could present the certain antitumor activities in vitro. Our study lays a solid foundation for the development and utilization of LNT2.