Enhancing secondary metabolites accumulation in Coleus blumei through LED light application

Coleus blumei is a medicinal plant often chosen for in vitro extraction of organic molecules. This study aims to investigate the potential accumulation of specific secondary metabolites in the leaves and roots of Coleus, with a focus on its response to LED treatments. The plants were cultivated in a growth chamber and exposed to four different light spectra: full spectrum white as control, monochromatic blue, monochromatic red, and RB 6:1. The light intensity was consistently set at 150 µmol m-2 s-1, with a photoperiod of 12:12 h L:D (8:00-20:00). The dry weight of leaves and roots, along with the concentrations and yield of rosmarinic acid and flavonoids, at 14 and 21 days of treatment, were analysed. The results revealed a positive correlation between the duration of exposure and the final compounds yield. Both B and RB light significantly influenced the accumulation of rosmarinic acid, quercetin, apigenin in leaves, with considerable results especially for rosmarinic acid and quercetin extraction. Conversely, in the case of roots, the RB treatment achieved the highest values for rosmarinic acid and quercetin yields, while the highest apigenin content was recorded under red light. Luteolin concentration remained below the limit of detection. In conclusion, the interplay between the duration of exposure and light spectra had a notable impact on the biochemical composition of Coleus organs.