**Changes in Beneficial** *C***-glycosylflavones and Policosanol Content in Wheat and Barley Sprouts Subjected to Di**ff**erential LED Light Conditions**

**Muthusamy Muthusamy 1,**† **, Jong Hee Kim 1,2,**† **, Suk Hee Kim <sup>1</sup> , Joo Yeol Kim <sup>1</sup> , Jeong Wook Heo <sup>3</sup> , HanGyeol Lee <sup>4</sup> , Kwang-Sik Lee <sup>4</sup> , Woo Duck Seo <sup>4</sup> , Soyoung Park <sup>1</sup> , Jin A Kim <sup>1</sup> and Soo In Lee 1,\***


Received: 24 September 2020; Accepted: 4 November 2020; Published: 6 November 2020

**Abstract:** The spectral quality and intensity of light, photoperiodism, and other environmental factors have profound impacts on the metabolic composition of light-dependent higher plants. Hence, we investigate the effects of fluorescent light (96 µmol m−<sup>2</sup> s −1 ) and white (100 µmol m−<sup>2</sup> s −1 ), blue (100 µmol m−<sup>2</sup> s −1 ), and red (93 µmol m−<sup>2</sup> s −1 ) light-emitting diode (LED) light irradiation on the *C*-glycosylflavone and policosanol contents in young seedlings of wheat and barley. Ultra-high-performance liquid chromatography (UHPLC) analyses of *C*-glycosylflavone contents in barley reveal that the saponarin content is significantly enhanced under blue LED light irradiation. Under similar conditions, isoorientin and isoschaftoside contents are improved in wheat seedlings. The contents of these *C*-glycosylflavones differed along with the light quality and growth period. The highest accumulation was observed in sprouts after three days under blue LED light irradiation. GC/MS analyses of policosanol contents showed that 1-hexacosanol (C26:o–OH) in barley and 1-octacosanol (C28:o–OH) in wheat seedlings were reduced under LED light irradiation, compared to seedlings under fluorescent light conditions. Nonetheless, the policosanol contents gradually improved with the extension of growth times and treatments, irrespective of the light quality. Additionally, a positive correlation was observed between the expression pattern of biosynthesis-related genes and the respective metabolite content in barley. This study demonstrates that blue LED light irradiation is useful in maximizing the *C*-glycosylflavone content in barley and wheat sprouts.

**Keywords:** saponarin; isoorientin; hexacosanol; octacosanol; fatty acyl-coenzyme A reductase (FAR)
