Characterization of soluble dietary fiber from Moringa oleifera seeds and its immunomodulatory effects

• Moringa seed soluble fiber is protease resistant protein and termed as moringa seed resistant protein (MSRP).
• MSRP is a homodimer (18 kDa) with pI 10.8 and identified as a glycoprotein.
• MSRP is a potent mitogen.
• Moringa seeds are a potential nutritional source to improve immune system of the host.

Moringa oleifera (moringa or drumstick) seeds are a potential source of dietary fiber with 6.5% w/w soluble dietary fiber. Biochemical characterization of moringa seed soluble fiber revealed that it is a glycoprotein with 5% neutral sugars. Arabinose and xylose are the major neutral sugars identified by gas liquid chromatography (GLC). Moringa seed soluble fiber was identified as protease resistant—glycoprotein and termed as moringa seed resistant protein (MSRP). MSRP was found to be a homodimer (18 kDa) containing two 9 kDa monomeric units as revealed by SDS-PAGE analysis with pI 10.8. Immunostimulating activity of MSRP was assessed by murine splenocyte proliferation and production of NO from macrophages. MSRP at low concentration (0.01 μg/well) strongly increased proliferation of splenocytes, while MSRP at high concentration weakly responded. MSRP induced 6-fold increase in NO production when compared to the control which indicates the activation of macrophages. MSRP isolated from defatted moringa seed flour is a potent mitogen, enhancing the proliferation of lymphocytes and inducing NO from macrophages. This study concludes that moringa seed is a potential nutritional source to promote the immune system of the host.