Identification of Anti-Nutritional Factors and Trypsin Inhibitory Activity of Three Spontaneous Plants: Malva sylvestris L, Cynara cardunculus L, and Spinacia oleracea L

Malva sylvestris L., Cynara cardunculus L., and Spinacia oleracea L. are spontaneous plants often consumed by humans and animals. Although, these plants possess nutritional and therapeutic value, they may also contain anti-nutritional factors in their carbohydrate fraction and trypsin inhibitors that interfere with protein digestion. This study aims to identify the antinutritional factors, and determine the trypsin inhibitory activity of Malva sylvestris L., Cynara cardunculus L., and Spinacia oleracea L. The sugar contents of the plants’ ethanol extracts were determined using the Anthrone and Ortho-Toluidine colorimetric methods. Specific monosaccharides and oligosaccharides were identified by thin layer chromatography (TLC). The polysaccharides (starch and cellulose) contents were also assessed. The trypsin inhibitory activity was evaluated according to standard procedures. The results showed that the sugar contents of the plants ranged from 0.14 to 0.34 g/100 g dw. TLC analysis revealed the presence of sucrose in all the three plant extracts, while two oligosaccharides; raffinose and stachyose were identified in M. sylvestris and S. oleracea. The extracts exhibited significant trypsin inhibitory activity with C. cardunculus demonstrating the highest inhibitory effect with IC50 value of 4.92 mg/mL, while the IC50 values for M. sylvestris and S. oleracea where 9.26 mg/mL and 12.24 mg/mL, respectively. The presence of these anti-nutritional factors may interfere with digestion in both humans and animals, hence the need for caution in the use of these plants for medicinal purposes.