Evaluation of immunological adjuvant activities of saponin rich fraction from the fruits of Asparagus adscendens Roxb. with less adverse reactions

Abstract

The hemolytic activity, in vitro as well as in vivo toxicity, and immunomodulatory potential of saponins-rich fraction of Asparagus adscendens Roxb. fruit (AA-SRF) have been assessed in this study in order to explore AA-SRF as an alternative safer adjuvant to standard Quil-A saponin. The AA-SRF showed lower hemolytic activity (HD₅₀ = 301.01 ± 1.63 µg/ml) than Quil-A (HD₅₀ = 17.15 ± 2.12 µg/ml). The sulforhodamine B assay also revealed that AA-SRF was less toxic to VERO cells (IC₅₀≥200 ± 4.32 µg/ml) than Quil-A (IC₅₀ = 60 ± 2.78 µg/ml). The AA-SRF did not lead to mortality in mice up to 1.6 mg and was much safer than Quil-A for in vivo use. Conversely, mice were subcutaneously immunized with OVA 100 μg alone or along with Alum (200 μg) or Quil-A (10 μg) or AA-SRF (50 μg/100 μg/200 μg) on days 0 and 14. The AA-SRF at 100 μg dose best supported the LPS/Con A primed splenocyte proliferation activity, elevated the serum OVA-specific total IgG antibody, IL-12, CD4 titer and upsurged CD3/CD19 expression in spleen as well as lymph node sections which in turn advocated its adjuvant potential. Thus, AA-SRF can be further studied for use as a safe alternative adjuvant in vaccines.

Keywords:

• Asparagus adscendens saponins
• immune response
• in vitro assays
• mice
• ovalbumin
• vaccine adjuvant

Acknowledgements

The authors gratefully acknowledge the Director, ICAR-IVRI, Izatnagar, Bareilly, Uttar Pradesh, India for providing necessary facilities for the study. We extend our sincere gratitude to the CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh for providing facilities for UPLC-ESI-Q-TOF-MS/MS work and its analysis, ELISA work and photomicrography.

Ethical approval

All the experimental procedures on animals were carried out according to the recommendations and approval of the Indian Council of Agricultural Research-Indian Veterinary Research Institute Regional Station, Palampur, Institute Animal Ethics Committee (PLP-IAEC-16) as per the guidelines set forth by the Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA).

Author contributions

Ri.S. designed and supervised this study, reviewed and analyzed the data, and critically edited the manuscript. Ra.S. performed all the experiments, generated the data, wrote the manuscript, and engaged in all necessary research activities. R.V and M.G. helped in data curation, formal analysis, investigation, writing and editing of manuscript. G.M. and B.S. provided technical counseling in the laboratory experiments. All the authors reviewed the manuscript.

Disclosure statement

The authors have no relevant financial or non-financial competing interests.

Data availability statement

The data will be made available on request.

Additional information

Funding

This work was supported by the research fund of Indian Council of Agricultural Research-Indian Veterinary Research Institute, Izatnagar, India (Project Code: IVRI/PALAM/17-19/013).