The hairy roots (HRs) of Scutellaria baicalensis are widely used and consumed worldwide as a medicine, especially in Asian countries, due to their biological and pharmacological activities. The HRs of this plant are rich in secondary metabolites. However, the optimal method and solvents for the extraction of secondary metabolites from S. baicalensis HRs have not been well studied. Therefore, in this study, S. baicalensis HRs were extracted with different solvents, including water (WE), 99.9% pure methanol (PM), 70% aqueous methanol (AM), 99.9% pure ethanol (PE), and 70% aqueous ethanol (AE). The phenolic and flavonoid compounds and various antioxidant activities of each extract were measured. The AE extract (16.85 ± 0.15%) had a higher yield, which led to the highest accumulation of total phenolic content (TPC) and total flavonoid content (TFC), and antioxidant activity. The TPC and TFC were highest in AE (66.03 ± 0.44 mg GAE/g and 40.11 ± 1.31 mg QE/g, respectively), whereas WE, PM, and PE showed lower values in all assays. In addition, the highest antioxidant activities, such as DPPH, ABTS, and SOD-like scavenging activities and reducing power, were achieved in the AE extract compared to the other solvent extracts. Based on these results, the AE extract showed the highest phenolic and flavonoid accumulation and antioxidant activities, highlighting its potential use in the manufacture of useful materials from S. baicalensis HRs and its novel applications.

Pakchoi (Brassica rapa subsp. chinensis) is one of the most widely consumed vegetables in Asian countries, and it is high in secondary metabolites. The availability, quantity, and quality of light play a critical role in the growth and development of plants. In this study, we investigated the effect of LEDs (light-emitting diodes; white, blue, red, and red + blue) on anthocyanin, glucosinolates, and phenolic levels in red pakchoi baby leaves. On the 24th day after sowing (DAS), red baby pakchoi leaves were harvested, and shoot length, root length, and fresh weight were measured. Among the different LED treatments, there was no significant difference in shoot length, whereas the highest root length was achieved in the red + blue LED treatment (23.8 cm). The fresh weight also showed a significant difference among the different LED treatments. In total, 12 phenolic and 7 glucosinolate individual compounds were identified using high-performance liquid chromatography (HPLC) analysis. The highest total glucosinolate (2937 μg/g dry wt) and phenolic (1589 μg/g dry wt) contents were achieved in baby leaves exposed to red + blue light. Similarly, the highest contents of total anthocyanins (1726 μg/g dry wt), flavonoids (4920 μg/g dry wt), and phenolics (5900 μg/g dry wt) were achieved in the red + blue treatment. Plants exposed to red + blue LED light showed the highest accumulation of anthocyanin, glucosinolates, and phenolic compounds. For antioxidant activity, DPPH (2,2-diphenyl-1-picrylhydrazylradical) free radical scavenging, ABTS (2,2-azinobis (3-ethylbenzothiazoline)-6-sulfonic acid) radical scavenging, and reducing power assays were performed, and the antioxidant activity of red pakchoi baby leaves grown under red + blue LED light was found to be the best. The metabolic profiling of the identified metabolites revealed distinct separation based on the secondary metabolites. This research will be helpful for farmers to choose the best LED light combination to increase the secondary metabolic content in pakchoi plants.

Magnolia kobus belongs to the Magnoliaceae family and the genus Magnolia. The flowers are widely used in herbal tea and dietary supplements. It is effectively used in traditional medicines and its chemical constituents have various biological activities, such as anti-obesity, antioxidant, anticancer, anti-inflammatory, and anti-hyperlipidaemic activities. The flower developmental process of M. kobus involves a complex regulatory network and is intensively related to the quality and relative composition of primary and secondary metabolites of the flower. Hence, the identification of metabolic changes during different developmental stages of the flower was important for enhancing organoleptic and nutritional characteristics. To our knowledge, to date, none of the studies has investigated the relationship between metabolic changes (primary and secondary metabolites) during different developmental stages of the M. kobus flower. This study investigated metabolic changes in 47 hydrophilic and 13 lipophilic compounds and biological activities in Magnolia kobus flowers during four developmental stages. Metabolites were identified using HPLC, GC–qMS, and GC–TOFMS. Throughout flower development, metabolite accumulation showed significant differences based on metabolomics approaches. The dynamic changes of 21 differential metabolites occurred between the young and mature stages. Flower buds exhibited high levels of phenylpropanoids and phytosterols. The total phenolic and flavonoid contents were most abundant in the buds and decreased from the bud to the old stages. Flower bud extracts showed the most powerful effects in three antioxidant assays and antibacterial effects against 10 pathogenic bacterial strains. These findings emphasise the value of M. kobus flower buds as an edible natural source and provide valuable insight into the metabolic changes that occur in M. kobus flowers during development.

Agastache rugosa is also known as Korean mint, and it has numerous health benefits due to its rich source of phenolic compounds. The main objective of this study was to produce a ZmLC-overexpressing transgenic hairy root line via Agrobacterium rhizogenes-mediated transformation. The overexpressing transgenic lines were screened using qRT-PCR after exposure to light conditions. The best hairy root line was selected, and the expression levels of phenylpropanoid biosynthetic pathway genes and phenylpropanoid compound accumulation were analysed using qRT-PCR and HPLC, respectively. In addition, antioxidant activities (RPA, ABTS, and DPPH), total phenolic content, and total flavonoid content were analysed. The ZmLC-overexpressing transgenic line upregulated all the phenylpropanoid pathway genes, which led to the higher accumulation of phenylpropanoid compounds in the transgenic line than in the control line. In addition, the total phenolic and flavonoid content was significantly higher in the transgenic line. The antioxidant activity assay showed that the transgenic hairy root line had significantly higher activity than that of the control lines. Thus, ZmLC positively enhances the phenylpropanoid biosynthetic pathway and antioxidant activities in A. rugosa. The results show that ZmLC can be used to enhance phenylpropanoid compounds and antioxidant activities in transgenic A. rugosa hairy root lines via the genetic engineering approach.