Lentinan molecular weight analysis made easy with BeSEC

Lentinan is a bioactive polysaccharide extracted from shiitake mushrooms and renowned for its immunomodulatory effects. It is often used as an adjuvant in cancer therapy to ease potential complications following chemo- and radiotherapy.

Beyond oncology, lentinan has shown antioxidant and antiviral activity and is commonly incorporated in health supplements to slow aging and enhance immunity. In food applications, it can improve stability and texture and add nutritional benefits.

Molecular weight is an essential component of lentinan’s functionality. Higher-molecular-weight molecules often bind more effectively to immune cell receptors and adopt more ordered structures, yielding more potent immunomodulatory effects.

Lower-molecular-weight molecules dissolve and absorb more easily, but their biological activity is sometimes shorter-lived. Using the best molecular weight is crucial for optimizing performance in specific applications.

Experimental section

This study employed a Size Exclusion Chromatography (SEC) system that was equipped with refractive index (RI) and light-scattering (LS) detectors.

The light-scattering detector used was the BeSEC LS2 from Bettersize Instruments, with detection angles at 90 ° and 7 °.

The BeSEC workstation uses light scattering, along with UV or RI signals, to calculate molecular-weight averages (Mn, Mw, and Mz) and distributions.

System configuration:

• Detectors: Refractive Index (RI) and Light Scattering (LS)
• Column: Shodex Ohpak LB-806M
• Mobile phase: 0.05 M NaNO₃ aqueous solution
• Flow rate: 0.7 mL/min
• Injection volume: 100 μL
• Column temperature: 40 ℃
• dn/dc: 0.129 mL/g

Sample preparation:

Five different lentinan samples were analyzed. Each powder was accurately weighed and dispersed in 0.05 M sodium nitrate (NaNO₃) and stirred until clear (1 to 3 mg/mL). Following stirring, the samples were filtered through a 0.22 μm PES syringe filter, transferred to vials, and placed in the autosampler for measurement.

Results and discussion

Figure 1. Elution profiles of the multi-detector signals (top) and molecular weight distribution (bottom) for Sample A. Image Credit: Bettersize Instruments 

Figure 2. Elution profiles of the multi-detector signals (top) and molecular weight distribution (bottom) for Sample B. Image Credit: Bettersize Instruments 

Figure 3. Elution profiles of the multi-detector signals (top) and molecular weight distribution (bottom) for Sample C. Image Credit: Bettersize Instruments 

Figure 4. Elution profiles of the multi-detector signals (top) and molecular weight distribution (bottom) for Sample D. Image Credit: Bettersize Instruments 

Figure 5. Elution profiles of the multi-detector signals (top) and molecular weight distribution (bottom) for Sample E. Image Credit: Bettersize Instruments 

Figures 1 to 5 show chromatograms of the five samples. The right-angle light scattering (RALS) signal is shown in green, the low-angle light scattering (LALS) signal in red, and the refractive index (RI) signal in blue.

The purple line indicates the molecular weight distribution, which represents molecular weight as a function of elution time.

Across all samples, the signals are clean, with minimal noise, high signal-to-noise ratios, and flat baselines.

In Figure 1, the molecular weight profile steadily decreases with increasing elution volume, consistent with SEC principles: larger species elute first, followed by smaller ones.

Scattering peaks exhibit no tailing, and the molecular weight curve stays stable at the end, suggesting effective size-based separation.

Table 1. Molecular weight results of lentinan samples. Source: Bettersize Instruments 

The molecular weight results for all five samples are summarized in Table 1. Substantial differences in molecular weight can be seen, which directly affect viscosity, formulation behavior, solubility, and biological activity.

Accordingly, each sample may be more suited to different applications.

Conclusion

This study demonstrated the use of the BeSEC LS2 with light scattering detection to characterize the molecular weights of lentinan samples.

The results revealed significant variation in the molecular weights of the five samples, providing crucial information for selecting the appropriate grade for pharmaceutical, nutraceutical, or food applications.

Acknowledgments

Produced using materials originally created by Zhibin Guo, from Bettersize Instruments 

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With over 29 years of experience, Bettersize Instruments has established itself as a leading global manufacturer of analytical instruments for particle analysis. Quality is core to our business - we carry out 95 % in-house production for strict quality control.

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