Metabolomic analysis and antioxidant activity of wild type and mutant chia (Salvia hispanica L.) stem and flower grown under different irrigation regimes

Abstract

Background: Chia (Salvia hispanica L.) is a functional food from Central America. Interest in it is growing rapidly due to the many health benefits from the seed. However, when chia is grown at high latitudes, seed yield may be low whereas a high stem biomass and immature inflorescences are produced. Little is known about the chemical composition and the properties of stems and flowers. In this work, the metabolite profile, the antioxidant activity, and the total polyphenol content of stems and inflorescences were evaluated in a factorial experiment with different chia populations (commercial black chia and long-day flowering mutants G3, G8, and G17) and irrigation (100% and 50% of evapotranspiration).

Results: The results show the influence of irrigation and seed source on the antioxidant activity and total polyphenol content of chia flower and stem. Inflorescences exhibit higher antioxidant activity, suggesting their potential use as natural antioxidant. The mutants G3 and G8, at 50% irrigation, contained the highest amounts of compounds with nutraceutical value, especially within the flower. The mutant G17 showed lower antioxidant activity and polyphenol content compared to other seed sources but exhibited high omega 3 content in flowers but low in stems. This indicates that chia varieties should be chosen according to the objective of cultivation.

Conclusion: These findings, indicating a close relation of metabolite content with irrigation and seed source, may provide the basis for the use of chia flower and stem for their nutraceutical value in the food, feed, and supplement industries. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Keywords: arbutin; danshensu; early flowering genotypes; myo-inositol; polyunsaturated fatty acids; total polyphenolic content.

Figure 1

Total ion chromatograms (TIC) of chia flower (a) and stem (b) polar extracts where peaks correspond to numbering of compounds in Table 1. The TICs of chia flower (c) and stem (d) non‐polar extracts where peaks correspond to numbering of compounds in Table 2. Chromatograms of Mexico (50% irrigation) are taken as representative examples.

Figure 2

Effect of mutation and irrigation on some polar compounds identified in chia flower (a) and stem (b) polar extracts. Polar compounds were detected as trimethylsilyl and methyloxime derivatives by GC–MS. Different letters on the bars show significant differences between samples (P < 0.05) with the post‐hoc Tukey's test.

Figure 3

Effect of irrigation on chia fatty acids composition: (a) flower at 50% irrigation, (b) flower at 100% irrigation, (c) stem at 50% irrigation, and (d) stem at 100% irrigation. Fatty acids were detected in non‐polar extracts as methyl esters by GC–MS. Different letters on the bars show significant differences between samples (P < 0.05) with the post‐hoc Tukey's test.

Figure 4

Antioxidant activity and TPC of chia flower (a and c, respectively) and stem (b and d, respectively) at different irrigation regimes (50% irrigation and 100% irrigation) shown as Trolox equivalent. Different letters on the bars indicate significant differences (P < 0.05) with the post‐hoc Tukey's test.