Saponins, classification and occurrence in the plant kingdom

Molecular activities, biosynthesis and evolution of triterpenoid saponins.

Saponins are natural glycosides which possess a wide range of pharmacological properties including cytotoxic activity. In this review, the recent studies (2005–2009) concerning the cytotoxic activity of saponins have been summarized. The correlations between the structure and the cytotoxicity of both steroid and triterpenoid saponins have been described as well as the most common mechanisms of action.

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Saponins as cytotoxic agents: a review

The triterpenes are one of the most numerous and diverse groups of plant natural products. They are complex molecules that are, for the most part, beyond the reach of chemical synthesis. Simple triterpenes are components of surface waxes and specialized membranes and may potentially act as signaling molecules, whereas complex glycosylated triterpenes (saponins) provide protection against pathogens and pests. Simple and conjugated triterpenes have a wide range of applications in the food, health, and industrial biotechnology sectors. Here, we review recent developments in the field of triterpene biosynthesis, give an overview of the genes and enzymes that have been identified to date, and discuss strategies for discovering new triterpene biosynthetic pathways.

Triterpene Biosynthesis in Plants

Advances in saponin-based adjuvants.

The bitterness of a saponin mixture (containing saponin B and DDMP (2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one) saponin in a ratio of 1:4) and saponin B obtained from dry peas were established by a trained panel using line scaling. Both saponins were found to be bitter. However, the saponin mixture, and hence DDMP saponin, was found to be significantly more bitter than saponin B. The bitterness perceived correlated with the saponin concentration. In addition to saponin bitterness, the saponin content and composition of 16 dry pea varieties were also investigated. In two varieties, DDMP saponin was the only saponin present whereas, in the rest of the varieties, DDMP saponin was more abundant than saponin B. The pea varieties investigated differed significantly in saponin content. The amounts of DDMP saponin ranged from 0.7 to 1.5 g kg-1 (dry matter), whereas those of saponin B ranged from 0 to 0.4 g kg-1. As saponins are bitter, pea varieties with lower saponin contents would be preferred for use in food production

Bitterness of saponins and their content in dry peas

Saponins, Classification and Occurrence in the Plant Kingdom

Proteins are known to interact with relatively small molecules such as flavour compounds and saponins, and may thus influence the taste perception of food. In this study, the interactions of flavour volatiles with pea proteins, and the effects of heat on these interactions were investigated. The presence of saponins, which are non-volatile flavour compounds, was also explored. Saponins are known to contribute to the bitterness in pea and were found to interact with proteins. Pea proteins, legumin (11S) and vicilin (7S), were used for interaction studies with aldehydes and ketones using static headspace-gas chromatography (SH–GC). The binding of various flavour compounds as a function of concentration was studied at pH 7.6 and pH 3.8. Vicilin binds both aldehydes and ketones at pH 7.6 and pH 3.8. Legumin only showed binding to aldehydes at pH 7.6 and no binding to aldehydes or ketones at pH 3.8. The effect of heat on vicilin-flavour interactions was studied at pH 7.6. Heating of vicilin seemed to lead to a decrease in the binding of aldehydes and ketones to the protein. In addition, the presence of saponins in hulled pea flour was identified by high performance liquid chromatography and mass spectrometry (HPLC–MS) and three groups of saponins, A, B and DDMP saponins were found to be present, with group B saponins dominating.

Protein–flavour interactions in relation to development of novel protein foods

Abstract Proteins are known to interact with relatively small molecules such as flavour compounds and saponins, and may thus influence the taste perception of food. In this study, the interactions of flavour volatiles with pea proteins, and the effects of heat on these interactions were investigated. The presence of saponins, which are non-volatile flavour compounds, was also explored. Saponins are known to contribute to the bitterness in pea and were found to interact with proteins. Pea proteins, legumin (11S) and vicilin (7S), were used for interaction studies with aldehydes and ketones using static headspace-gas chromatography (SH–GC). The binding of various flavour compounds as a function of concentration was studied at pH 7.6 and pH 3.8. Vicilin binds both aldehydes and ketones at pH 7.6 and pH 3.8. Legumin only showed binding to aldehydes at pH 7.6 and no binding to aldehydes or ketones at pH 3.8. The effect of heat on vicilin-flavour interactions was studied at pH 7.6. Heating of vicilin seemed to lead to a decrease in the binding of aldehydes and ketones to the protein. In addition, the presence of saponins in hulled pea flour was identified by high performance liquid chromatography and mass spectrometry (HPLC–MS) and three groups of saponins, A, B and DDMP saponins were found to be present, with group B saponins dominating.

L. Heng

Papers

Saponins, classification and occurrence in the plant kingdom

Bitterness of saponins and their content in dry peas

Saponins, Classification and Occurrence in the Plant Kingdom

Protein–flavour interactions in relation to development of novel protein foods

Protein-flavour interactions in relation to development of novel protein foods.