Macroporous resin-assisted enrichment, characterizations, antioxidant and anticandidal potential of phytochemicals from Trachyspermum ammi.

Abstract

Extract of de-oiled seeds of Trachyspermum ammi was purified using macroporous resins and the performance of three resins were evaluated to enrich major phytochemical component. A HPLC method has been developed to separate major phytochemical constituents in the crude (CTAE) and partially purified extracts (PTAE). Macroporous resin assisted enrichment and purification suggested XAD-16 as the most efficient (yield 29.8%) followed by XAD-7HP and Diaion HP-20. Concentrated PTAE was subjected to multiple preparative-TLC to afford three compounds, namely, rosmarinic acid-3-O-glucopyranoside (TA-1), kaempferol-(coumaroyl-glucosyl)-rhamnoside (TA-2) and quercetin-3-O-galactoside (TA-3). The structure of these compounds was elucidated from their corresponding spectroscopic characterizations in FT-IR, HR-MS, and partially by 1 H NMR. Total phenolic and flavonoid contents of the extracts were determined. Antioxidant activity by DPPH and ABTS radical scavenging, CUPRAC assays indicated the highest antioxidant potential of CTAE. Among the compounds, TA-1 exhibited the highest scavenging activity in ABTS (IC50 33.41µg/ml) and DPPH (IC50 69.23µg/ml), however, relatively lower than CTAE. In vitro anti-candidal activity against virulent strains of Candida spp. revealed C. albicans 4718 as the most susceptible (23.9µg/ml) to PTAE. PRACTICAL APPLICATIONS: Seeds of Trachyspermum ammi has been extensively investigated for volatile aromatic components of the essential oil. However, the de-oiled seeds have rarely been exploited for potential bioactive phenolics. The present investigation envisaged possible utilization of the de-oiled Trachyspermum seeds for its phenolic constituents, which could be used as natural antioxidant with additional benefits of anticandidal properties. Indeed, macroporous resin assisted enrichment and purification of extracts of T. ammi seeds generate valuable reference compounds, rosmarinic acid-3-O-glucopyranoside, kaempferol-(coumaroyl glucosyl)-rhamnoside, and quercetin-3-O-galactoside.