Characterization of the 2ODD genes of DOXC subfamily and its members involved in flavonoids biosynthesis in Scutellaria baicalensis.

BACKGROUND: 2-oxoglutarate-dependent dioxygenase (2ODD) superfamily is the second largest enzyme family in the plant genome and plays diverse roles in secondary metabolic pathways. The medicinal plant Scutellaria baicalensis Georgi contains various flavonoids, which have the potential to treat coronavirus disease 2019 (COVID-19), such as baicalein and myricetin. Flavone synthase I (FNSI) and flavanone 3-hydroxylase (F3H) from the 2ODDs of DOXC subfamily have been reported to participate in flavonoids biosynthesis. It is certainly interesting to study the 2ODD members involved in the biosynthesis of flavonoids in S. baicalensis. RESULTS: We provided a genome-wide analysis of the 2ODDs of DOXC subfamily in S. baicalensis, a total of 88 2ODD genes were identified, 82 of which were grouped into 25 distinct clades based on phylogenetic analysis of At2ODDs. We then performed a functional analysis of Sb2ODDs involved in the biosynthesis of flavones and dihydroflavonols. Sb2ODD1 and Sb2ODD2 from DOXC38 clade exhibit the activity of FNSI (Flavone synthase I), which exclusively converts pinocembrin to chrysin. Sb2ODD1 has significantly higher transcription levels in the root. While Sb2ODD7 from DOXC28 clade exhibits high expression in flowers, it encodes a F3H (flavanone 3-hydroxylase). This enzyme is responsible for catalyzing the conversion of both naringenin and pinocembrin into dihydrokaempferol and pinobanksin, kinetic analysis showed that Sb2ODD7 exhibited high catalytic efficiency towards naringenin. CONCLUSIONS: Our experiment suggests that Sb2ODD1 may serve as a supplementary factor to SbFNSII-2 and play a role in flavone biosynthesis specifically in the roots of S. baicalensis. Sb2ODD7 is mainly responsible for dihydrokaempferol biosynthesis in flowers, which can be further directed into the metabolic pathways of flavonols and anthocyanins.

Effects of light qualities on growth and physiological-biochemical traits of Scutellaria baicalensis.

Canopy spectral composition significantly affects growth and functional traits of understory plants. In this study, we explored the optimal light condition suitable for enhancing Scutellaria baicalensis's yield and quality, aiming to provide scientific reference for the exploitation and utilization of medicinal plant resources in the understory of forests. We measured the responses of growth, morphology, biomass allocation, physiological traits, and secon-dary metabolites of S. baicalensis to different light qualities. S. baicalensis was cultured under five LED-light treatments including full spectrum light (control), ultraviolet-A (UV-A) radiation, blue, green, and red light. Results showed that UV-A significantly reduced plant height, base diameter, leaf thickness, leaf area ratio, and biomass of each organ. Red light significantly reduced base diameter, biomass, effective quantum yield of photosystem Ⅱ (ФPSⅡ), and total flavonoid concentration. Under blue light, root length and total biomass of S. baicalensis significantly increased by 48.0% and 10.8%, respectively, while leaf number and chlorophyll content significantly decreased by 20.0% and 31.6%, respectively. The other physiological and biochemical traits were consistent with their responses in control. Our results suggested that blue light promoted photosynthesis, biomass accumulation, and secondary metabolite synthesis of S. baicalensis, while red light and UV-A radiation negatively affected physiological and biochemical metabolic processes. Therefore, the ratio of blue light could be appropriately increased to improve the yield and quality of S. baicalensis.

Programmable Biosynthesis of Plant-Derived 4'-Deoxyflavone Glycosides by an Unconventional Yeast Consortium.

Previous data established 4'-deoxyflavone glycosides (4'-DFGs) as important pharmaceutical components in the roots of rare medical plants like Scutellaria baicalensis Georgi. Extracting these compounds from plants involves land occupation and is environmentally unfriendly. Therefore, a modular ("plug-and-play") yeast-consortium platform is developed to synthesize diverse 4'-DFGs de novo. By codon-optimizing glycosyltransferase genes from different organisms for Pichia pastoris, six site-specific glycosylation chassis are generated to be capable of biosynthesizing 18 different 4'-DFGs. Cellular factories showed increased 4'-DFG production (up to 18.6-fold) due to strengthened synthesis of UDP-sugar precursors and blocked hydrolysis of endogenous glycosides. Co-culturing upstream flavone-synthesis-module cells with downstream glycoside-transformation-module cells alleviated the toxicity of 4'-deoxyflavones and enabled high-level de novo synthesis of 4'-DFGs. Baicalin is produced at the highest level (1290.0 mg L-1) in a bioreactor by controlling the consortium through carbon-source shifting. These results provide a valuable reference for biosynthesizing plant-derived 4'-DFGs and other glycosides with potential therapeutic applications.

Combination of Polygonatum Rhizoma and Scutellaria baicalensis triggers apoptosis through downregulation of PON3-induced mitochondrial damage and endoplasmic reticulum stress in A549 cells.

OBJECTIVE: Scutellaria baicalensis (SB) and Polygonatum Rhizoma (PR), two traditional Chinese medicines, are both known to suppress cancer. However, the mechanism and effect of combined treatment of them for lung cancer are rarely known. Investigating the combined effect of SB and PR (hereafter referred to as SP) in potential mechanism of lung cancer is required. This study was to evaluate the inhibitory effects of SP on A549 cell growth and to explore the underlying molecular mechanisms. METHODS: According to the theory of Chinese medicine and network pharmacology, in the in vivo experiment, a mouse model of carcinoma in situ was constructed, and lung carcinoma in situ tissues were collected for proteomics analysis, hematoxylin-eosin staining, and CK19 immunohistochemistry. In the in vitro experiment, lung cancer A549 cells at logarithmic growth stage were taken, and the inhibitory effect of SP on the proliferation of A549 cells was detected by CCK8 method. The expression of PON3 was detected by quantitative polymerase chain reaction and western blot. In addition, the effect of SP on the induction of apoptosis in A549 cells and the changes of membrane potential and reactive oxygen species (ROS) content were detected by flow cytometry. The changes of PON3 content in endoplasmic reticulum (ER) are observed by laser confocal microscopy, whereas the effects of SP on the expression of apoptosis-related proteins and ER stress-related proteins in A549 cells were examined by western blot. RESULT: By searching the Traditional Chinese Medicines of Systems Pharmacology (TCMSP) (https://www.tcmspe.com/index.php) database and SymMap database, the respective target genes of PR and SB were mapped into protein network interactions, and using Venn diagrams to show 38 genes in common between PR and SB and lung cancer, SP was found to play a role in the treatment of lung cancer. In vivo experiments showed that in a lung carcinoma in situ model, lung tumor tissue was significantly lower in the SP group compared with the control group, and PON3 was shown to be downregulated by lung tissue proteomics analysis. The combination of SP was able to inhibit the proliferation of A549 cells in a concentration-dependent manner (p < .0001). The expression levels of apoptosis-related proteins and ER stress proteins were significantly increased and the expression levels of PON3 and anti-apoptosis-related proteins were decreased in A549 cells. At the same time, knockdown of PON3 could inhibit tumor cell proliferation (p < .0001). The combination of different concentrations of SP significantly induced apoptosis in A549 cells (p < .05; p < .0001), increased ROS content (p < .01), and damaged mitochondrial membrane potential of A549 cells (p < .05; p < .0001), and significantly increased the expression levels of apoptosis-related proteins and ER stress proteins in lung cancer A549 cells. CONCLUSION: SP inhibits proliferation of lung cancer A549 cells by downregulating PON3-induced apoptosis in the mitochondrial and ER pathways.

Genome-wide identification, stress- and hormone-responsive expression characteristics, and regulatory pattern analysis of Scutellaria baicalensis SbSPLs.

SQUAMOSA PROMOTER BINDING PROTEIN-LIKEs (SPLs) encode plant-specific transcription factors that regulate plant growth and development, stress response, and metabolite accumulation. However, there is limited information on Scutellaria baicalensis SPLs. In this study, 14 SbSPLs were identified and divided into 8 groups based on phylogenetic relationships. SbSPLs in the same group had similar structures. Abscisic acid-responsive (ABRE) and MYB binding site (MBS) cis-acting elements were found in the promoters of 8 and 6 SbSPLs. Segmental duplications and transposable duplications were the main causes of SbSPL expansion. Expression analysis based on transcriptional profiling showed that SbSPL1, SbSPL10, and SbSPL13 were highly expressed in roots, stems, and flowers, respectively. Expression analysis based on quantitative real-time polymerase chain reaction (RT‒qPCR) showed that most SbSPLs responded to low temperature, drought, abscisic acid (ABA) and salicylic acid (SA), among which the expression levels of SbSPL7/9/10/12 were significantly upregulated in response to abiotic stress. These results indicate that SbSPLs are involved in the growth, development and stress response of S. baicalensis. In addition, 8 Sba-miR156/157 s were identified, and SbSPL1-5 was a potential target of Sba-miR156/157 s. The results of target gene prediction and coexpression analysis together indicated that SbSPLs may be involved in the regulation of L-phenylalanine (L-Phe), lignin and jasmonic acid (JA) biosynthesis. In summary, the identification and characterization of the SbSPL gene family lays the foundation for functional research and provides a reference for improved breeding of S. baicalensis stress resistance and quality traits.

Huangqin Decoction Delays Progress of Colitis-Associated Carcinogenesis by Regulating Nrf2/HO-1 Antioxidant Signal Pathway in Mice.

OBJECTIVE: To investigate the effect of Huangqin Decoction (HQD) on nuclear factor erythroid 2 related-factor 2 (Nrf2)/heme oxygenase (HO-1) signaling pathway by inducing the colitis-associated carcinogenesis (CAC) model mice with azoxymethane (AOM)/dextran sodium sulfate (DSS). METHODS: The chemical components of HQD were analyzed by liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-Q-TOF-MS/MS) to determine the molecular constituents of HQD. Totally 48 C57BL/6J mice were randomly divided into 6 groups by a random number table, including control, model (AOM/DSS), mesalazine (MS), low-, medium-, and high-dose HQD (HQD-L, HQD-M, and HQD-H) groups, 8 mice in each group. Except for the control group, the mice in the other groups were intraperitoneally injected with AOM (10 mg/kg) and administrated with 2.5% DSS orally for 1 week every two weeks (totally 3 rounds of DSS) to construct a colitis-associated carcinogenesis mouse model. The mice in the HQD-L, HQD-M and HQD-H groups were given HQD by gavage at doses of 2.925, 5.85, and 11.7 g/kg, respectively; the mice in the MS group was given a suspension of MS at a dose of 0.043 g/kg (totally 11 weeks). The serum levels of malondialdehyde (MDA) and superoxide dismutase (SOD) were measured by enzyme-linked immunosorbent assay. The mRNA and protein expression levels of Nrf2, HO-1, and inhibitory KELCH like ECH-related protein 1 (Keap1) in colon tissue were detected by quantitative real-time PCR, immunohistochemistry, and Western blot, respectively. RESULTS: LC-Q-TOF-MS/MS analysis revealed that the chemical constituents of HQD include baicalin, paeoniflorin, and glycyrrhizic acid. Compared to the control group, significantly higher MDA levels and lower SOD levels were observed in the model group (P<0.05), whereas the expressions of Nrf2 and HO-1 were significantly decreased, and the expression of Keap1 increased (P<0.01). Compared with the model group, serum MDA level was decreased and SOD level was increased in the HQD-M, HQD-H and MS groups (P<0.05). Higher expressions of Nrf2 and HO-1 were observed in the HQD groups. CONCLUSION: HQD may regulate the expression of Nrf2 and HO-1 in colon tissue, reduce the expression of MDA and increase the expression of SOD in serum, thus delaying the progress of CAC in AOM/DSS mice.

Integrated metabolome and transcriptome analyses of anthocyanin biosynthesis reveal key candidate genes involved in colour variation of Scutellaria baicalensis flowers.

BACKGROUND: Bright flower colour assists plants attract insects to complete pollination and provides distinct ornamental values. In some medicinal plants, diverse flower colour variations usually imply differences in active ingredients. Compared to the common bluish purple of Scutellaria baicalensis flower (SB), the natural variants present rose red (SR) and white (SW) flowers were screened out under the same growing conditions in the genuine producing area Shandong Province, China. However, the mechanism of flower colour variation in S. baicalensis was remain unclear. In the present study, we conducted integrated transcriptome and metabolome analyses to uncover the metabolic difference and regulation mechanism in three S. baicalensis flowers. RESULTS: The results showed that 9 anthocyanins were identified. Among which, 4 delphinidin-based anthocyanins were only detected in SB, 4 cyanidin-based anthocyanins (without cyanidin-3-O-glucoside) mainly accumulated in SR, and no anthocyanin but high level of flavanone, naringenin, was detected in SW. The gene expression profile indicated that the key structural genes in the flavonoid and anthocyanin biosynthesis pathway differentially expressed in flowers with different colours. Compared to SB, the down-regulated expression of F3'5'H, ANS, and 3GT gene in SR might influence the anthocyanin composition. Especially the InDel site with deletion of 7 nucleotides (AATAGAG) in F3'5'H in SR might be the determinant for lack of delphinidin-based anthocyanins in rose red flowers. In SW, the lower expression levels of DFR and two F3H genes might reduce the anthocyanin accumulation. Notably the SNP site of G > A mutation in the splicing site of DFR in SW might block anthocyanin biosynthesis from flavanones and thus cause white flowers. In addition, several key transcription factors, including MYB, bHLH, and NAC, which highly correlated with structural gene expression and anthocyanin contents were also identified. CONCLUSIONS: These results provide clues to uncover the molecular regulatory mechanism of flower colour variation in S. baicalensis and promote novel insights into understanding the anthocyanin biosynthesis and regulation.

The transcription factors SbMYB45 and SbMYB86.1 regulate flavone biosynthesis in Scutellaria baicalensis.

Scutellaria baicalensis Georgi is an important Chinese medicinal plant that is rich in the flavones baicalin, wogonoside, and wogonin, providing it with anti-cancer, anti-inflammatory, and antibacterial properties. However, although the biosynthetic pathways of baicalin and its derivates have been elucidated, the regulation of flavone biosynthesis in S. baicalensis is poorly understood. Here, we found that the contents of baicalin and its derivates increased and that baicalin biosynthetic pathway genes were induced in response to light, and baicalin and baicalein are not exclusively produced in the roots of S. baicalensis. Based on the fact that MYB transcription factors are known to play important roles in flavone biosynthesis, we identified SbMYB45 and SbMYB86.1 in S. baicalensis and determined that they bind to the promoter of the flavone biosynthesis gene SbCHI to enhance its transcription. Moreover, overexpressing SbMYB45 and SbMYB86.1 enhanced the accumulation of baicalin in S. baicalensis leaves. We demonstrate that SbMYB45 and SbMYB86.1 bind to the cis-acting element MBSII in the promoter of CHI to redundantly induce its expression upon light exposure. These findings indicate that SbMYB45 and SbMYB86.1 transcriptionally activate SbCHI in response to light and enhance flavone contents in S. baicalensis.

Integrated metabolomics and proteomics analysis to study the changes in Scutellaria baicalensis at different growth stages.

Scutellaria baicalensis is a functional food that has the potential to treat various diseases. Scutellaria baicalensis can be divided into two types: Ziqin (strip types) and (rotten xylem). Ziqin is used to clear lower energizer large intestine heat syndrome, while Kuqin is used for the treatment of upper energizer lung heat syndrome. At present, the substance basis of the differences between Ziqin and Kuqin is not clear. The changes in metabolite accumulation and protein expression between them were analyzed by the non-targeted metabolomic technique in combination with the label-free proteomics approach. The results showed that the differentially accumulated metabolites and abundant proteins were mainly enriched in the pathways of phenylalanine, tyrosine and tryptophan biosynthesis, phenylpropanoid biosynthesis, flavonoid biosynthesis, flavone and flavonol biosynthesis, isoflavonoid biosynthesis, and anthocyanin biosynthesis. Collectively, these results reveal the changes of Scutellaria baicalensis in different growth years and provide a reference for selecting the appropriate harvest period.

Inhibition of UV-B stress in lettuce through enzyme-like Scutellaria baicalensis carbon dots.

Oxidative stress in plants caused by UV-B stress has always been a great challenge to the yield of agricultural products. Carbon dots (CDs) with enzyme-like activity have been developed, and inhibiting oxidative stress in animals has been achieved, but little is known about abiotic stress resistance in plants, especially UV-B stress. In this study, CDs were synthesized from Scutellaria baicalensis via a hydrothermal method. The ability of CDs to scavenge reactive oxygen species (ROS) in vivo and in vitro and to enhance antioxidant resistance in vivo was evaluated. The results show that CDs promoted the nutrient assimilation ability of lettuce seedlings and protected the plants from UV-B stress by increasing the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX). Moreover, the antioxidant metabolism of plants can be activated by CDs and the expression levels of aquaporin (AQP) genes PIP1 and PIP2 are also up-regulated. These results facilitate the design and fabrication of CDs to meet the challenge of abiotic stress in food production.

The leaves of Scutellaria baicalensis Georgi attenuate brain aging in D-galactose-induced rats via regulating glutamate metabolism and Nrf2 signaling pathway.

The present study aimed to evaluate the anti-aging effect of the leaves of Scutellaria baicalensis Georgi (LSBG) and investigate its mechanisms. For this purpose, SD rats were received D-galactose (D-gal) subcutaneously (0.3 g/kg) and LSBG intragastrically (0.4 g/kg or 0.8 g/kg) for 7 weeks. Behavior tests were conducted to evaluate the cognitive function of all rats. Results showed that memory impairment was reversed by LSBG. Then, metabolomics of the cortex and hippocampus were used to investigate the potential mechanisms. 21 metabolites in the cortex and 22 metabolites in the hippocampus of aging rats were altered, respectively. Additionally, results showed that the content of key metabolites and activities of enzymes in glutamate metabolism and its downstream metabolism (glutathione metabolism) could be regulated by the LSBG. Additionally, proteins in the Nrf2 signaling pathway were analyzed by western blot. And the protein expression levels of Nrf2, GCLC, HO-1, NQO-1 were significantly regulated by the LSBG in the cortex and hippocampus. Above all, the anti-aging effects of the LSBG were involved in regulating the glutamate metabolism and Nrf2 signaling pathway.

Wogonin, a Compound in Scutellaria baicalensis, Activates ATF4-FGF21 Signaling in Mouse Hepatocyte AML12 Cells.

Fibroblast growth factor 21 (FGF21), which is mainly synthesized and secreted by the liver, plays a crucial role in systemic glucose and lipid metabolism, ameliorating metabolic diseases. In this study, we screened the WAKANYAKU library derived from medicinal herbs to identify compounds that can activate Fgf21 expression in mouse hepatocyte AML12 cells. We identified Scutellaria baicalensis root extract and one of its components, wogonin, as an activator of Fgf21 expression. Wogonin also enhanced the expression of activating transcription factor 4 (ATF4) by a mechanism other than ER stress. Knockdown of ATF4 by siRNA suppressed wogonin-induced Fgf21 expression, highlighting its essential role in wogonin's mode of action. Thus, our results indicate that wogonin would be a strong candidate for a therapeutic to improve metabolic diseases by enhancing hepatic FGF21 production.

Therapeutic efficacy of Scutellaria baicalensis Georgi against psoriasis-like lesions via regulating the responses of keratinocyte and macrophage.

Psoriasis is a chronic and recurrent skin problem that affects 3% of the global population. Nowadays, most medicines may not promise a complete cure for patients with psoriasis because of the development of pharmacoresistance and the side effects of drugs due to the microenvironment impact in the context of skin imbalance. Herein, we attempt to explore the pharmaceutical efficacy of Scutellaria baicalensis (S. baicalensis) in modulating the microenvironment created by macrophages and keratinocytes in psoriasis. The results indicated that treatment of S. baicalensis extract significantly reduced the thickness of epidermis and attenuated psoriatic lesions. Moreover, S. baicalensis extract obviously inhibited the activation and infiltration of macrophages by alleviating inflammatory factors such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and cyclooxygenase-2 (COX-2). The administration of S. baicalensis extract also remarkably abolished oxidative damage upon DNA and proteins, which attributed to the activation of nuclear factor erythroid 2-related factor-2 (Nrf2) and heme oxygenase-1 (HO-1). The network analysis of redox proteomics and cytokine profiles suggested that S. baicalensis administration regulated the specific pathways associated with oxidative stress, inflammation and cytokine signaling cascades to ameliorate the macrophage-targeted responses and subsequently arrest proliferation of keratinocytes. Collectively, our findings highlighted the importance of S. baicalensis application in reprogramming microenvironment to provide an alternative and complementary intervention for long-term psoriatic therapy.

Systematic Analysis and Functional Characterization of R2R3-MYB Genes in Scutellaria baicalensis Georgi.

R2R3-MYB transcription factors participate in multiple critical biological processes, particularly as relates to the regulation of secondary metabolites. The dried root of Scutellaria baicalensis Georgi is a traditional Chinese medicine and possesses various bioactive attributes including anti-inflammation, anti-HIV, and anti-COVID-19 properties due to its flavonoids. In the current study, a total of 95 R2R3-MYB genes were identified in S. baicalensis and classified into 34 subgroups, as supported by similar exon-intron structures and conserved motifs. Among them, 93 R2R3-SbMYBs were mapped onto nine chromosomes. Collinear analysis revealed that segmental duplications were primarily responsible for driving the evolution and expansion of the R2R3-SbMYB gene family. Synteny analyses showed that the ortholog numbers of the R2R3-MYB genes between S. baicalensis and other dicotyledons had a higher proportion compared to that which is found from the monocotyledons. RNA-seq data indicated that the expression patterns of R2R3-SbMYBs in different tissues were different. Quantitative reverse transcriptase-PCR (qRT-PCR) analysis showed that 36 R2R3-SbMYBs from different subgroups exhibited specific expression profiles under various conditions, including hormone stimuli treatments (methyl jasmonate and abscisic acid) and abiotic stresses (drought and cold shock treatments). Further investigation revealed that SbMYB18/32/46/60/70/74 localized in the nucleus, and SbMYB18/32/60/70 possessed transcriptional activation activity, implying their potential roles in the regulatory mechanisms of various biological processes. This study provides a comprehensive understanding of the R2R3-SbMYBs gene family and lays the foundation for further investigation of their biological function.

Exploring native Scutellaria species provides insight into differential accumulation of flavones with medicinal properties.

Scutellaria baicalensis is a well-studied medicinal plant belonging to the Lamiaceae family, prized for the unique 4'-deoxyflavones produced in its roots. In this study, three native species to the Americas, S. lateriflora, S. arenicola, and S. integrifolia were identified by DNA barcoding, and phylogenetic relationships were established with other economically important Lamiaceae members. Furthermore, flavone profiles of native species were explored. 4'-deoxyflavones including baicalein, baicalin, wogonin, wogonoside, chrysin and 4'-hydroxyflavones, scutellarein, scutellarin, and apigenin, were quantified from leaves, stems, and roots. Qualitative, and quantitative differences were identified in their flavone profiles along with characteristic tissue-specific accumulation. 4'-deoxyflavones accumulated in relatively high concentrations in root tissues compared to aerial tissues in all species except S. lateriflora. Baicalin, the most abundant 4'-deoxyflavone detected, was localized in the roots of S. baicalensis and leaves of S. lateriflora, indicating differential accumulation patterns between the species. S. arenicola and S. integrifolia are phylogenetically closely related with similar flavone profiles and distribution patterns. Additionally, the S. arenicola leaf flavone profile was dominated by two major unknown peaks, identified using LC-MS/MS to most likely be luteolin-7-O-glucuronide and 5,7,2'-trihydroxy-6-methoxyflavone 7-O-glucuronide. Collectively, results presented in this study suggest an evolutionary divergence of flavonoid metabolic pathway in the Scutellaria genus of Lamiaceae.

Latest research progress on anticancer effect of baicalin and its aglycone baicalein.

Cancer, which is a leading cause of deaths around the world, is characterized by genetic mutations and epigenetic changes. Baicalin and its aglycone baicalein, the major bioactive flavones derived from the dried root of Scutellaria baicalensis Georigi, belong to flavonoid compounds. Many studies demonstrated that both of them exhibited remarkable promising anticancer activities. This study summarized potential anticancer mechanisms of baicalin and baicalein including induction of apoptosis, initiation of cell cycle arrest, suppression of metastasis, induction of autophagy, and regulation of immunity. Combination strategies involving baicalin or baicalein as chemotherapeutic adjuvants, clinical trial and safety were also discussed. In addition, we compared the difference in their anticancer effects. Interestingly, baicalein showed quicker and stronger inhibitory effects on multiple cancers than those of baicalin, probably due to its smaller size and high lipophilicity which contribute to fast absorption and improve ability to penetrate cells. Taken together, both baicalin and baicalein are effective in treating cancer with good tolerance. However, deglycosylation of baicalin to baicalein was found to have stronger anticancer potential.

Genome-Wide Identification and Characterization of the WRKY Gene Family in Scutellaria baicalensis Georgi under Diverse Abiotic Stress.

The WRKY gene family is an important inducible regulatory factor in plants, which has been extensively studied in many model plants. It has progressively become the focus of investigation for the secondary metabolites of medicinal plants. Currently, there is no systematic analysis of the WRKY gene family in Scutellaria baicalensis Georgi. For this study, a systematic and comprehensive bioinformatics analysis of the WRKY gene family was conducted based on the genomic data of S. baicalensis. A total of 77 WRKY members were identified and 75 were mapped onto nine chromosomes, respectively. Their encoded WRKY proteins could be classified into three subfamilies: Group I, Group II (II-a, II-b, II-c, II-d, II-e), and Group III, based on the characteristics of the amino acid sequences of the WRKY domain and genetic structure. Syntenic analysis revealed that there were 35 pairs of repetitive fragments. Furthermore, the transcriptome data of roots, stems, leaves, and flowers showed that the spatial expression profiles of WRKYs were different. qRT-PCR analysis revealed that 11 stress-related WRKYs exhibited specific expression patterns under diverse treatments. In addition, sub cellular localization analysis indicated that SbWRKY26 and SbWRKY41 were localized in nucleus. This study is the first to report the identification and characterization of the WRKY gene family in S. baicalensis, which is valuable for the further exploration of the biological function of SbWRKYs. It also provides valuable bioinformatics data for S. baicalensis and provides a reference for assessing the medicinal properties of the genus.

Rational engineering in Escherichia coli for high-titer production of baicalein based on genome-scale target identification.

Baicalein is a bioactive flavonoid isolated from the traditional Chinese medicinal plant, Scutellaria baicalensis Georgi. Microbial synthesis of flavonoids has been intensively developed owing to the eco-friendly nature of the process. However, the titer of the flavonoids obtained is still at a low level, and effective methods to enhance these titers are lacking. In this study, the synthetic performance of baicalein-producing engineered Escherichia coli was rationally evaluated to enhance the expression of key enzymes. Transcriptional analyses of baicalein-overproducing strain and a control strain enabled the identification of 13 beneficial genes, including eight genes that are seemingly irrelevant to baicalein metabolism. With the combination of the enzyme assembly and modularization strategy, the engineered DN-8 strain produced 367.8 mg/L baicalein in fed-batch fermentation, the maximum titer reported to date.

Characterization of UDP-glycosyltransferase family members reveals how major flavonoid glycoside accumulates in the roots of Scutellaria baicalensis.

BACKGROUND: Flavonoid glycosides extracted from roots of Scutellaria baicalensis exhibit strong pharmaceutical antitumor, antioxidative, anti-inflammatory, and antiviral activities. UDP glycosyltransferase (UGT) family members are responsible for the transfer of a glycosyl moiety from UDP sugars to a wide range of acceptor flavonoids. Baicalin is the major flavonoid glycoside found in S. baicalensis roots, and its aglycone baicalein is synthesized from a specially evolved pathway that has been elucidated. However, it is necessary to carry out a genome-wide study of genes involved in 7-O-glucuronidation, the final biosynthesis step of baicalin, which might elucidate the relationship between the enzymes and the metabolic accumulation patterns in this medicinal plant. RESULTS: We reported the phylogenetic analysis, tissue-specific expression, biochemical characterization and evolutionary analysis of glucosyltransferases (SbUGTs) and glucuronosyltransferases (SbUGATs) genes based on the recently released genome of S. baicalensis. A total of 124 UGTs were identified, and over one third of them were highly expressed in roots. In vitro enzyme assays showed that 6 SbUGTs could use UDP-glucose as a sugar donor and convert baicalein to oroxin A (baicalein 7-O-glucoside), while 4 SbUGATs used only UDP-glucuronic acid as the sugar donor and catalyzed baicalein to baicalin. SbUGAT4 and SbUGT2 are the most highly expressed SbUGAT and SbUGT genes in root tissues, respectively. Kinetic measurements revealed that SbUGAT4 had a lower Km value and higher Vmax/Km ratio to baicalein than those of SbUGT2. Furthermore, tandem duplication events were detected in SbUGTs and SbUGATs. CONCLUSIONS: This study demonstrated that glucosylation and glucuronidation are two major glycosylated decorations in the roots of S. baicalensis. Higher expression level and affinity to substrate of SbUGAT4, and expansion of this gene family contribute high accumulation of baicalin in the root of S. baicalensis.

Combined Phyllostachys pubescens and Scutellaria baicalensis Prevent High-Fat Diet-Induced Obesity via Upregulating Thermogenesis and Energy Expenditure by UCP1 in Male C57BL/6J Mice.

This study examined the anti-obesity effects of a Phyllostachys pubescens (leaf) and Scutellaria baicalensis root mixture (BS21), and its underlying mechanisms of action, in high-fat diet (HFD)-induced obese mice. Mice were fed a HFD with BS21 (100, 200, or 400 mg/kg) for 9 weeks. BS21 reduced body weight, white adipose tissue (WAT) and liver weights, liver lipid accumulation, and adipocyte size. Additionally, BS21 reduced serum concentrations of non-esterified fatty acid, triglyceride, glucose, lactate dehydrogenase, low-density lipoprotein cholesterol, total cholesterol, leptin, and insulin growth factor 1, but elevated the adiponectin concentrations. Furthermore, BS21 suppressed the mRNA levels of lipogenesis-related proteins, such as peroxisome proliferator-activated receptor (PPAR) γ, SREBP-1c, C/EBP-α, fatty acid synthase, and leptin, but increased the mRNA gene expression of lipolysis-related proteins, such as PPAR-α, uncoupling protein (UCP) 2, adiponectin, and CPT1b, in WAT. In addition, BS21 increased the cold-stimulated adaptive thermogenesis and UCP1 protein expression with AMPK activation in adipose tissue. Furthermore, BS21 increased the WAT and mRNA expression of energy metabolism-related proteins SIRT1, PGC-1α, and FNDC5/irisin in the quadriceps femoris muscle. These results suggest that BS21 exerts anti-obesity and antihyperlipidemic activities in HFD-induced obese mice by increasing the thermogenesis and energy expenditure, and regulating lipid metabolism. Therefore, BS21 could be useful for preventing and treating obesity and its related metabolic diseases.