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Immunoaffinity Knockout of Saponin Glycosides from Asparagus racemosus to Assess Anti‐lipid Peroxidation

Onlom, Churanya, Phrompittayarat, Watoo, Putalun, Waraporn, Waranuch, Neti, Ingkaninan, Kornkanok
Phytochemical analysis 2017 v.28 no.4 pp. 316-323
Asparagus racemosus, Ayurvedic medicine, carcinogenesis, chemical constituents of plants, enzyme-linked immunosorbent assay, gels, humans, inhibitory concentration 50, lipid peroxidation, low density lipoprotein, monoclonal antibodies, oxidation, roots, saponins, synergism
INTRODUCTION: Asparagus racemosus Willd (Asparagaceae family), known as Shatavari, is important in Ayurveda and traditional Thai medicines. The saponin glycosides, shatavarin I and IV are major constituents in its roots and may be responsible for their actions including protection against lipid peroxidation and carcinogenesis. OBJECTIVE: To develop an immunoaffinity column for isolating compounds with structures related to shatavarin IV from crude extracts of A. racemosus root. METHODOLOGY: The monoclonal antibody recognising shatavarin IV (mAbShavIV) was coupled to an Affi‐Gel Hz gel to isolate compounds with structures related to shatavarin IV from the other components of crude extracts of A. racemosus root. The saponin glycosides in each fraction were analysed by mAbShavIV ELISA and LC–MS/MS. RESULTS: The pooled wash‐through fractions contained 3% of loaded mAbShavIV reactive saponin glycosides, while eluted fractions released ~ 90% of shatavarin saponin glycosides in a single step. Using thiobarbiturate (TBARs) to measure lipid‐peroxidation, the extract, and the pooled wash‐through fractions showed moderate protection against Cu⁺‐induced oxidation of human low density lipoprotein (LDL) (IC₅₀ 11.3 ± 1.4 and 12.6 ± 0.9 μg/mL, respectively). In contrast, the saponin glycosides eluted from the mAbShavIV‐column had weaker protectant (IC₅₀ 29.7 ± 1.8 μg/mL) suggesting that A. racemosus shatavarins do not inhibit carcinogenesis through preventing lipid peroxidation. CONCLUSION: The strategy described here demonstrates its utility for isolating a group of related compounds from the rest of the extract with selectivity and recovery rate. Pharmacological efficacy and synergistic effects of the components obtained can be further investigated. Copyright © 2017 John Wiley & Sons, Ltd.