Fatty acid and nutrient profiles, diosgenin and trigonelline contents, mineral composition, and antioxidant activity of the seed of some Iranian Trigonella L. species

Abstract

Background: Fenugreeks (Trigonella L. spp.), belonging to the legume family (Fabaceae), are well-known multipurpose crops that their materials are currently received much attention in the pharmaceutical and food industries for the production of healthy and functional foods all over the world. Iran is one of the main diversity origins of this valuable plant. Therefore, the aim of the present study was to explore vitamins, minerals, and fatty acids profile, proximate composition, content of diosgenin, trigonelline, phenolic acids, total carotenoids, saponins, phenols, flavonoids, and tannins, mucilage and bitterness value, and antioxidant activity of the seed of thirty populations belonging to the ten different Iranian Trigonella species.

Results: We accordingly identified notable differences in the nutrient and bioactive compounds of each population. The highest content (mg/100 g DW) of ascorbic acid (18.67 ± 0.85‒22.48 ± 0.60) and α-tocopherol (31.61 ± 0.15‒38.78 ± 0.67) were found in the populations of T. filipes and T. coerulescens, respectively. Maximum content of catechin was found in the populations of T. teheranica (52.67 ± 0.05‒63.50 ± 0.72 mg/l). Linoleic acid (> 39.11% ± 0.61%) and linolenic acid (> 48.78 ± 0.39%) were the main polyunsaturated fatty acids, with the majority in the populations of T. stellata (54.81 ± 1.39‒63.46 ± 1.21%). The populations of T. stellata were also rich in trigonelline (4.95 ± 0.03‒7.66 ± 0.16 mg/g DW) and diosgenin (9.06 ± 0.06‒11.03 ± 0.17 mg/g DW).

Conclusions: The obtained data provides baseline information to expand the inventory of wild and cultivated Iranian Trigonella species for further exploitation of rich chemotypes in the new foods and specific applications.

Keywords: Fatty acid; Mineral; Natural products; Phenol; Proximate composition.

Fig. 1

Distribution map of the thirty wild populations of ten Trigonella species collected across Iran. T. astroides1 (TAS1, Soltanabad), T. astroides2 (TAS2, Bavi), T. astroides3 (TAS3, Mehran), T. calliceras1 (TCL1, Astara), T. calliceras2 (TCL2, Bandar Anzali), T. calliceras3 (TCL3, Behshahr), T. coerulescens1 (TCO1, Meshginshahr), T. coerulescens2 (TCO2, Tabriz), T. coerulescens3 (TCO3, Khoy), T. elliptica1 (TEP1, Mianeh), T. elliptica2 (TEP2, Kermanshah), T. elliptica3 (TEP3, Mariwan), T. filipes1 (TFP1, Salehabad), T. filipes2 (TFP2, Qasr e Shirin), T. filipes3 (TFP3, Saravand), T. foenum-graecum1 (TFG1, Minab), T. foenum-graecum2 (TFG2, Ardestan), T. foenum-graecum3 (TFG3, Mashhad), T. spruneriana1 (TSP1, Pataveh), T. spruneriana2 (TSP2, Shiraz), T. spruneriana3 (TSP3, Tarom), T. stellata1 (TST1, Qasregand), T. stellata2 (TST2, Borazjan), T. stellata3 (TST3, Kahnuj), T. strangulata1 (TSG1, Khorramabad), T. strangulata2 (TSG2, Ghorveh), T. strangulata3 (TSG3, Urmia), T. teheranica1 (TTH1, Karaj), T. teheranica2 (TTH2, Chalus), and T. teheranica3 (TTH3, Oushan)

Fig. 2

Histogram of vitamin content for thirty populations of ten Trigonella species

Fig. 3

Histogram of proximate composition for thirty populations of ten Trigonella species

Fig. 4

Comparisons of the levels of elements among the studied Trigonella species and their populations

Fig. 5

Content of major phenolic compounds identified among the thirty populations of ten Trigonella species

Fig. 6

Linear correlation between total phenol and flavonoid content, and antioxidant properties (a‒f). Significant difference in 1% level

Fig. 7

Bi-plot graph for the first and second principal components based on the major nutritional and phytochemical compounds for thirty populations of ten Trigonella species