Comparative Analysis of Water-Soluble Polysaccharides from Dendrobium Second Love 'Tokimeki' and Dendrobium nobile in Structure, Antioxidant, and Anti-Tumor Activity In Vitro

With potential anti-tumor and antioxidant properties, the polysaccharide content of D. nobile is relatively lower than that of the other medicinal Dendrobium. To find high-content polysaccharide resources, the polysaccharide (DHPP-Is) was prepared from D. Second Love 'Tokimeki' (a D. nobile hybrid) and compared with DNPP-Is from D. nobile. DHPP-Is (Mn 31.09 kDa) and DNPP-Is (Mn 46.65 kDa) were found to be O-acetylated glucomannans (-Glcp-(1,4) and O-acetylated-D-Manp-(1,4) backbones), analogous to other Dendrobium polysaccharides. DHPP-Is had higher glucose content (31.1%) and a lower degree (0.16) of acetylation than DNPP-Is (15.8%, 0.28). Meanwhile, DHPP-Is and DNPP-Is had the same ability in the radical scavenging assay, which was milder than the control of Vc. Both DHPP-Is and DNPP-Is inhibited SPC-A-1 cell proliferation in vitro, with obvious differences in dose concentrations (0.5-2.0 mg/mL) and treatment times (24-72 h). Therefore, the antioxidant activity of DHPP-Is and DNPP-Is is not associated with distinction in anti-proliferative activity. As a glucomannan derived from non-medicinal Dendrobium, DHPP-Is has similar bioactivity to other medicinal Dendrobium, and this could serve as a starting point for studying the conformational-bioactivity relationship of Dendrobium polysaccharides.