‘Phytonutrients’ is a collective noun for various, very diverse, classes of plant components. They are mainly involved in determining colour (flavonoids, carotenoids) and taste (terpenoids) of fruits, vegetables, and seeds, and not so much in determining their structure and caloric content (like carbohydrates, proteins and triacylglycerides).
Description of theme
Furthermore, phytonutrients are often associated with health benefits of plant-derived foods, i.e. antioxidant activity (vitamin C, carotenoids, tocopherols, etc.), cholesterol-lowering capacity (phytosterols and –stanols), transcriptional regulation of human gene expression (phytoestrogens, including isoflavones and lignans). Therefore, phytonutrients are of interest for use as food ingredients and in food supplements.
The aim of our research is to (i) characterize phytonutrients from various plant materials; (ii) monitor changes in phytonutrient levels and composition during plant growth, processing, storage, and passage through the gastrointestinal tract; (iii) convert phytonutrients, enzymically or microbially, in order to increase their bioavailability and bioactivity, and (iv) improve the processibility of plant materials.
Our current research deals with the following classes of components:
- Lignans from flax- and sesame seed.
- Proanthocyanidins from grape seeds and other sources.
- Saponins from soybean and pea.
- Glycoalkaloids from tomato.
The molecules of interest are first extracted from the plant material. The various compounds in the extracts obtained are separated chromatographically, and annotated by mass spectroscopic techniques. To allow more detailed structural characterization, compounds are purified by preparative-scale chromatography. Series of structurally-related, purified compounds are often used for determining structure-function relationships, i.e. interaction with proteins (proanthocyanidins), bitterness (saponins), critical micel concentration (saponin), and affinity for the estrogen receptor (lignans).
Modification of phytonutrients is performed using enzymes or microbial fermentations. Examples of modifications include deglycosylation (to improve bioavailability), glycosylation (enhance water-solubility, slow-release applications), acylation (enhance solubility in oil), and influencing hydroxylation/methylation patterns (to modulate bioactivity).