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Ultraviolet‐B (UV‐B) radiation is one of the abiotic stresses that can significantly affect the secondary metabolite accumulation in in vitro tissue cultures of medicinal plants. The present study investigated the effects of UV‐B radiation on the secondary metabolites and antioxidant activities of Scutellaria baicalensis in vitro shoots grown at different concentrations of 6‐benzyl aminopurine (6‐BA), which is the cytokinin most widely used in plant tissue culture. The UV‐B radiation caused significant increases in lipid peroxidation, total phenolic, and flavonoid contents, and antioxidant activities in the in vitro shoots grown at lower 6‐BA concentrations (0 and 1 mg L−1), while it did not cause any significant changes in those grown at higher 6‐BA concentrations (2 and 3 mg L−1). However, the UV‐B radiation significantly altered the contents of main individual flavonoids at both lower and higher 6‐BA concentrations. Upon UV‐B radiation, aglycones (including baicalein, wogonin, and scutellarein) increased, while glucuronides such as baicalin and wogonoside decreased; this was more evident at higher 6‐BA concentrations. This study demonstrated that the effects of UV‐B radiation on the secondary metabolites of S. baicalensis in vitro shoots highly depended on the 6‐BA concentration in the culture medium. [ABSTRACT FROM AUTHOR]

Scutellaria baicalensis is a medicinal plant possessing abundant bioactive polysaccharides. This study aimed to optimize the ultrasound-assisted enzymatic extraction of S. baicalensis root polysaccharide (SRP) and investigate its hypoglycemic and immunomodulatory activities. The optimal extraction conditions found in this study were as follows: cellulase concentration 165.6 U/mL, temperature 57.3 °C, liquid-solid ratio 44.8 mL/g, time 50 min, and ultrasonic power 225 W; with the yield reached up to 12.27 %. The ion exchange and gel filtration chromatographies were used to obtain a purified SRP. The carbohydrate content of SRP was 85.09 %, with a relatively high content of uronic acids (11.27 %). The SRP had a molecular weight of 89.7 kDa and was composed of eight monosaccharides. The inhibitory activity of SRP against α-amylase and α-glucosidase was determined. It was revealed that SRP could effectively inhibit these two enzymes with IC 50 values of 1.23 and 0.63 mg/mL, respectively. Finally, the immunomodulatory effect of SRP on the dendritic cell activation was investigated, and the expressions of MHC II, CD80, CD86, and CD40 increased by 1.56, 1.96, 1.75, and 1.70 times, respectively, by the SRP treatment. This work will provide a foundation for SRP's efficient extraction and utilization for diabetes and immune therapy. [Display omitted] • SRP was extracted by the optimized ultrasound-assisted enzymatic method. • The maximum extraction yield of SRP reached up to 12.27 %. • SRP (molecular weight 89.7 kDa) was composed of eight monosaccharides. • SRP has strong inhibitory activities against α-amylase and α-glucosidase. • SRP has a potent immunomodulatory activity on dendritic cell maturation. [ABSTRACT FROM AUTHOR]

Ultraviolet-A (UV-A) can affect plant secondary metabolism, but the flavonoid synthesis in Scutellaria baicalensis Georgi aerial parts in response to UV-A radiation was not clear. Therefore, the effects of UV-A radiation on flavonoid synthesis in S. baicalensis aerial parts were investigated in this study. The results showed that the total flavonoid content in aerial parts of S. baicalensis reached the maximum value (41.86 mg g−1) after 7 d of UV-A radiation. Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) analysis showed that the composition of flavonoids was not changed, but the contents of different components were changed according to High-Performance Liquid Chromatography (HPLC) analysis. Compared with the control treatment, the contents of scutellarin, baicalin and wogonoside were increased by 2.70-fold, 2.22-fold and 2.31-fold, respectively. However, scutellarein and baicalein decreased by 1.80-fold and 1.91-fold respectively. Meanwhile, UV-A radiation significantly increased the contents of nitric oxide (NO) and hydrogen peroxide (H 2 O 2), and enhanced the activities of Phenylalanine ammonia lyase (PAL), Cinnamic acid 4-hydroxylase (C4H), and 4-coumarate CoA ligase (4CL). In addition, the antioxidant activity of S. baicalensis aerial part extracts after UV-A radiation was stronger than that of the control treatment. Further correlation analysis showed that there was a significant correlation between total flavonoid content and NO, H 2 O 2 , PAL, C4H, and 4CL. The enhancement of the antioxidant activity of S. baicalensis aerial part extracts was significantly correlated with total flavonoid, baicalin, wogonin and scutellarin content. This study shows that UV-A radiation can be used as an effective and economic way to increase the flavonoid contents in S. baicalensis aerial parts and promote the antioxidant activity of its extracts. [Display omitted] • The composition of flavonoids did not change after UV-A radiation. • The content of flavonoids was significantly affected by UV-A radiation. • Signal molecules and key enzyme activities were increased by UV-A radiation. • The antioxidant activity was enhanced by UV-A radiation. • The increase in bioactivity was correlated with the flavonoid profile change. [ABSTRACT FROM AUTHOR]

Ultraviolet A (UV-A) radiation is the main component of solar radiation and can elicit a wide range of biochemical responses in plants. In this study, the effects of UV-A radiation on the flavonoid content, composition, and bioactivity in postharvest Scutellaria baicalensis roots were investigated. The total flavonoid content in S. baicalensis roots under postharvest UV-A radiation increased in a time-dependent manner and reached its maximum value (183.64 g kg−1) on the fifth day. Compared with the control group, the contents of four main flavonoids—baicalin, baicalein, wogonoside, and wogonin increased by 1.68 times, 3.00 times, 2.07 times, and 1.57 times, respectively; and new chemicals including pectolinarigenin, puerarin, isokaempferide, and jaceosidin were detected after 5 d of UV-A radiation. In addition, extracts of S. baicalensis roots exposed to postharvest UV-A radiation showed stronger antioxidant and antibacterial activities than control root extracts. Further correlation analysis revealed that baicalin and baicalein contents in the roots of S. baicalensis after postharvest UV-A radiation were positively correlated with antioxidant activity, while the main flavonoids showed different correlations with various bacteria. These results suggest that the appropriate duration of postharvest UV-A radiation is an effective way to enhance bioactive compound contents and their bioactivities in S. baicalensis roots. • UPLC-MS/MS showed that 4 flavonoid compounds newly appeared after UV-A radiation. • The content of flavonoids was significantly increased by UV-A radiation. • The antioxidant and antimicrobial activities were enhanced by UV-A radiation. • The increase of bioactivity was correlated to the flavonoid profile change. [ABSTRACT FROM AUTHOR]

• S. baicalensis was pre-treated with ultrasound and enzyme to promote hydrolysis. • Factors affecting ultrasound-assisted enzymatic transformation were investigated. • The pretreatment conditions were optimized by response surface methodology. • Ultrasound irradiation nearly doubled the enzyme-assisted transformation rate. • The method highly improves the extraction efficiency of baicalein and wogonin. It is of great theoretical interest and industrial significance to improve the extraction efficiency of baicalein and wogonin from Scutellaria baicalensis roots because of their high pharmacological activities. The present study was aimed to establish the optimized ultrasound-assisted enzymatic pretreatment (UAEP) process by which ultrasound irradiation and the exogenous enzyme were simultaneously applied to efficiently transform baicalin and wogonoside into baicalein and wogonin, enhancing their extraction efficiency. Single-factor experiment and Box-Behnken design were used to optimize the main UAEP conditions to maximize the total extraction yield of baicalein and wogonin. The optimized UAEP conditions were cellulase concentration of 1.1%, pH of 5.5, UAEP temperature of 56.5 °C, UAEP time of 39.4 min, and ultrasonic power of 200 W with the total extraction yield of 82.51 ± 0.85 mg/g DW. The comparison of the established technique with the reference method based on the enzymatic pretreatment revealed that the productive efficiency was significantly improved with the transformation rates nearly doubled. These results suggest that the optimized UAEP process has the potential to be applied for the green, simple, and efficient extraction of baicalein and wogonin in the pharmaceutical and food industry. [ABSTRACT FROM AUTHOR]