**2.6 Phytosterols**

Buckwheat is also significant for its phytosterol content. Phytosterols present in buckwheat, although in low concentrations, also show a positive effect in lowering blood cholesterol levels. In addition, phytosterol intake significantly reduces in vivo cholesterol absorption. Buckwheat phytosterols are present throughout the grain, but their content varies by grain parts [37]. The most abundant phytosterol in buckwheat flour is β-sitosterol (0.86 mg/g DM) and makes up about 70% of total sterols, followed by campesterol (0.11 mg/g DM) and stigmasterol (0.02 mg/g DM) [94].

*The Importance of Buckwheat as a Pseudocereal: Content and Stability of Its Main Bioactive… DOI: http://dx.doi.org/10.5772/intechopen.102570*

According to the research of Dziedzic et al. [95]. the sterols content in Tartary buckwheat whole grains was 15,398 mg/kg of lipids and the most prevalent was the β-sitosterol (10,944 mg/kg of lipids).

#### **2.7 Iminosugars**

D-fagomin is a minor component from the group of iminosugars detected in the dehulled grain of common buckwheat which shows a glucose-lowering effect [96, 97].

Similar to D-fagomin, other imino sugars such as 1-deoxynojirimycin (DNJ) are intestinal glucosidase inhibitors, associated with a reduced risk of developing insulin resistance, gaining weight, and suffering from excess potentially pathogenic bacteria [97, 98]. Anthraquinone emodin is present in buckwheat concentrations between 1.72 and 2.71 mg/kg DM [99]. Due to the wide range of biological activities that emodin exhibits, it can be considered an important bioactive factor in buckwheat [100].

#### **2.8 Other components**

Along with vitamins, other components were detected, such as glutathione (1.10 mmol/g DM in buckwheat groats), phytic acid (35–38 mg/g DM in bran), carotenoids (2.10 mg/g DM in grain), and melatonin (470 pg/g DM in groats). These components may contribute to the antioxidant activity of buckwheat [4, 47].

Both types of buckwheat, common and Tartary, have a high tannin content (1.76 and 1.54%). Tannins isolated from buckwheat showed a relatively high level of activity against *Listeria monocytogenes* [101].

It has also been found that γ-aminobutyric acid (GABA) and 2″-hydroxynicothianamine (2HN) serve as functional components in buckwheat. Grains and sprouts contain GABA, while 2HN was identified in flour. Literature states that these components lower blood pressure in humans and inhibit the activity of angiotensin I-converting enzyme (ACE) [102–104]. Suzuki et al. [105] quantified GABA and 2HN concentrations in common and Tartary buckwheat leaves 14, 28, and 42 days after sowing (DAS). The concentration of GABA reached a peak at 42 DAS, while the concentration of 2HN decreased with the age of the plant.
