Osteoprotective Effect of Radix Scutellariae in Female Hindlimb-Suspended Sprague-Dawley Rats and the Osteogenic Differentiation Effect of Its Major Constituent

Targeting Wnt signaling pathway with small-molecule therapeutics for treating osteoporosis

Small molecules are emerging as potential candidates for treating osteoporosis by activating canonical Wnt signaling. These candidates work either by inhibiting DKK-1, sclerostin, SFRP-1, NOTUM, and S1P lyase or by preventing β-catenin degradation through inhibition of GSK-3β, or by targeting Dvl-CXXC5 and axin/β-catenin interactions. While many of these anti-osteoporotic small molecules are in preclinical development, the paucity of FDA-approved small molecules, or promising candidates, that have progressed to clinical trials for treating bone disorders through this mechanism poses a challenge. Despite advancements in computer-aided drug design, it is rarely employed for designing Wnt signaling activators to treat osteoporosis, and high-throughput screen (HTS) remains the primary method for discovering initial hits. Acknowledging the promising therapeutic potential of these compounds in addressing bone diseases, this review underscores the need for further mechanistic elucidation to enhance our understanding of their applications. Additionally, caution must be exercised in the design of small molecule-based Wnt activators due to their association with oncological risks.

The Effect of the Extraction Conditions on the Antioxidant Activity and Bioactive Compounds Content in Ethanolic Extracts of Scutellaria baicalensis Root

Ethanolic extracts of Baikal skullcap (Scutellaria baicalensis) root were obtained using various techniques, such as maceration, maceration with shaking, ultrasound-assisted extraction, reflux extraction, and Soxhlet extraction. The influence of the type and time of isolation technique on the extraction process was studied, and the quality of the obtained extracts was determined by spectrophotometric and chromatographic methods to find the optimal extraction conditions. Radical scavenging activity of the extracts was analyzed using DPPH assay, while total phenolic content (TPC) was analyzed by the method with the Folin-Ciocalteu reagent. Application of gas chromatography with mass selective detector (GC-MS) enabled the identification of some bioactive substances and a comparison of the composition of the particular extracts. The Baikal skullcap root extracts characterized by both the highest antioxidant activity and content of phenolic compounds were obtained in 2 h of reflux and Soxhlet extraction. The main biologically active compounds identified in extracts by the GC-MS method were wogonin and oroxylin A, known for their broad spectrum of biological effects, including antioxidant, anti-inflammatory, antiviral, anticancer, and others.

Insight of Chinese Herbal Medicine in Treating Osteoporosis: Achievements from 2013 to 2023

Osteoporosis is the most common bone metabolic disease, and it is becoming increasingly common as the global population ages. Osteoporosis and its complications, such as fractures and pain, negatively affect patient quality of life and easily lead to disability, placing enormous burdens on society. Although several anti-osteoporosis drugs are currently available, many adverse reactions have been observed during the long-term application of these drugs. Therefore, safer and more useful medications are urgently needed to replace those currently available. Chinese herbal medicine has been extensively used to treat osteoporosis, and the current literature confirms that such medicines have anti-osteoporosis effects, are safe, and have minimal side effects. Thus, Chinese herbal medicines are natural alternatives to pharmaceutical approaches to treating osteoporosis, and these medicines must be further developed and utilized. In this article, we review the mechanisms underlying the anti-osteoporosis effects of single herbal extracts and traditional Chinese medicine (TCM) formulas that have been elucidated since 2013, providing key evidence and support for future research on the anti-osteoporosis effects of Chinese herbal medicines. In addition, due to the complexity of the ingredients in Chinese herbal medicine, more thorough investigations are needed to determine the specific ingredients that are effective in osteoporosis treatment. Therefore, identifying the effective ingredients of Chinese herbal medicines will be a necessary focus in laboratory research and clinical application.

Baicalin Nanocomplexes with an In Situ-Forming Biomimetic Gel Implant for Repair of Calvarial Bone Defects via Localized Sclerostin Inhibition

In situ-forming hydrogels are highly effective in covering complex and irregular tissue defects. Herein, a biomimetic gel implant (CS-GEL) consisting of methacrylated chondroitin sulfate and gelatin is obtained via visible light irradiation, which displays rapid gelation (∼30 s), suitable mechanical properties, and biological features to support osteoblast attachment and proliferation. Sclerostin is proven to be a viable target to promote osteogenesis. Hence, baicalin, a natural flavonoid with a high affinity to sclerostin, is selected as the therapeutic compound to achieve localized neutralization of sclerostin. To overcome its poor solubility and permeability, a baicalin nanocomplex (BNP) is synthesized using Solutol HS15, which is then dispersed in the CS-GEL to afford a nanocomposite delivery system, i.e., BNP-loaded gel (BNP@CS-GEL). In vitro, BNP significantly downregulated the level of sclerostin in MLO-Y4 osteocytes. In vivo, either CS-GEL or BNP@CS-GEL is proven to effectively promote osteogenesis and angiogenesis in a calvarial critical-sized bone defect rat model, with BNP@CS-GEL showing the best pro-healing effect. Specifically, the BNP@CS-GEL-treated group significantly downregulated the sclerostin level as compared to the sham group (p < 0.05). RANKL expression was also significantly suppressed by BNP in MLO-Y4 cells and BNP@CS-GEL in vivo. Collectively, our study offers a facile and viable gel platform in combination with nanoparticulated baicalin for the localized neutralization of sclerostin to promote bone regeneration and repair.

Skullcapflavone II, a novel NQO1 inhibitor, alleviates aristolochic acid I-induced liver and kidney injury in mice

Aristolochic acid I (AAI) is a well established nephrotoxin and human carcinogen. Cytosolic NAD(P)H quinone oxidoreductase 1 (NQO1) plays an important role in the nitro reduction of aristolochic acids, leading to production of aristoloactam and AA-DNA adduct. Application of a potent NQO1 inhibitor dicoumarol is limited by its life-threatening side effect as an anticoagulant and the subsequent hemorrhagic complications. As traditional medicines containing AAI remain available in the market, novel NQO1 inhibitors are urgently needed to attenuate the toxicity of AAI exposure. In this study, we employed comprehensive 2D NQO1 biochromatography to screen candidate compounds that could bind with NQO1 protein. Four compounds, i.e., skullcapflavone II (SFII), oroxylin A, wogonin and tectochrysin were screened out from Scutellaria baicalensis. Among them, SFII was the most promising NQO1 inhibitor with a binding affinity (K_D = 4.198 μmol/L) and inhibitory activity (IC₅₀ = 2.87 μmol/L). In human normal liver cell line (L02) and human renal proximal tubular epithelial cell line (HK-2), SFII significantly alleviated AAI-induced DNA damage and apoptosis. In adult mice, oral administration of SFII dose-dependently ameliorated AAI-induced renal fibrosis and dysfunction. In infant mice, oral administration of SFII suppressed AAI-induced hepatocellular carcinoma initiation. Moreover, administration of SFII did not affect the coagulation function in short term in adult mice. In conclusion, SFII has been identified as a novel NQO1 inhibitor that might impede the risk of AAI to kidney and liver without obvious side effect.

Effects of baicalin on the proliferation and expression of OPG and RANKL in human cementoblast-lineage cells

Background/purpose

Baicalin, a natural bioactive flavonoid extracted from Scutellaria baicalensis Georgi, mediates bone metabolism, and recent studies have revealed that it has cell signaling properties. However, its biological functions in cementoblasts still remain unclear. This study therefore aimed to investigate the effects of baicalin on bone resorption markers, including osteoprotegerin (OPG) and receptor activator of nuclear factor-κβ ligand (RANKL), in human cementoblast-lineage cells, as well as their proliferation ability.

Materials and methods

Human cementoblast cell line (HCEM) cells were cultured and treated with 0, 0.01, 0.1, or 1 μM of baicalin. The proliferative capacity of cultured HCEM cells was analyzed using bromodeoxyuridine immunoassay and cell counting. The baicalin effect on OPG and RANKL expression was determined using quantitative polymerase chain reaction (qPCR) and western blotting. Furthermore, OPG expression was measured in 1 μM baicalin-treated HCEM cells in the presence or absence of the Wnt signaling pathway inhibitor, Dickkopf (Dkk)-1, using qPCR and western blotting.

Results

The addition of 0.01, 0.1, and 1 μM of baicalin did not significantly change the proliferative capacity of cultured HCEM cells. Compared with the non-supplemented group, baicalin increased and suppressed OPG and RANKL gene and protein expression, respectively, in a concentration-dependent manner. OPG mRNA and protein expression levels were increased by 1 μM baicalin, which was suppressed by Dkk-1 addition.

Conclusion

Baicalin enhanced OPG expression in HCEM cells through the Wnt/beta-catenin signaling pathway, which could contribute to periodontal tissue regeneration.

Comparative two-dimensional GPC3 overexpressing SK-Hep1 cell membrane chromatography /C18/ time-of-flight mass spectrometry for screening selective GPC3 inhibitor components from Scutellariae Radix

Screening active components targeting membrane proteins is important for drug discovery from traditional Chinese medicine. Cell membrane chromatography (CMC) has achieved a wide application in screening active components on pathological cells due to its high sensitivity and effectiveness. However, it is hard to clarify the specific target protein through simply using pathological and normal cells. In this study, a novel comparative two-dimensional (2D) cell membrane chromatography system was established. Based on the construction of hepatocellular carcinoma cell line SK-Hep1-GPC3 with high expression of protein Glypican-3 (GPC3), SK-Hep1-GPC3/CMC column was loaded to screen selective antitumor components from Scutellariae Radix according to the retention behaviors on column. Viscidulin I was retained on SK-Hep1-GPC3/CMC column, and showed 4.33 μM affinity to GPC3 according to surface plasmon resonance (SPR). The IC₅₀ of viscidulin I on SK-Hep1-GPC3 cells was 18.01 μM in cell proliferation assay. Thus, this method can be applied to screen complex herbal medicines for ligands bound to specific target protein receptor related to hepatic carcinoma.

Development of 3-mercaptopropyltrimethoxysilane (MPTS)-modified bone marrow mononuclear cell membrane chromatography for screening anti-osteoporosis components from Scutellariae Radix

Osteoporosis is a bone metabolic disease caused by the imbalance between osteoblasts and osteoclasts due to excess osteoclastogenesis, manifesting in the decrease of bone density and bone strength. Scutellariae Radix shows good anti-osteoporosis activity, but the effective component is still unclear. Cell membrane chromatography (CMC) is a biological affinity chromatography with membrane immobilized on a silica carrier as the stationary phase. It can realize a dynamical simulation of interactions between drugs and receptors on cell membrane, which is suitable for screening active compounds from complex systems. In this study, the components of Scutellariae Radix with potential anti-osteoporosis activity through inhibiting the differentiation from bone marrow mononuclear cells (BMMCs) to osteoclast were screened by a BMMC/CMC analytical system. Firstly, a new 3-mercaptopropyltrimethoxysilane (MPTS)-modified BMMC/CMC stationary phase was developed to realize covalent binding with cell membrane fractions. By investigating the retention time (t_R) of the positive drug, the life span of the MPTS-modified CMC columns was significantly improved from 3 to 12 days. Secondly, 6 components of Scutellariae Radix were screened to show affinity to membrane receptors on BMMCs by a two-dimensional BMMC/CMC–TOFMS analytical system. Among them, tectochrysin demonstrated the best anti-osteoporosis effect in vitro, which has never been reported. We found that tectochrysin could inhibit the differentiation of BMMCs into osteoclasts induced by receptor activator of nuclear factor-κΒ ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) in a concentration-dependent manner in vitro. In vivo, it significantly reduced the loss of bone trabeculae in ovariectomized mice, and decreased the level of C-terminal cross-linking telopeptides of type 1 collagen (CTX-1), tartrate-resistant acid phosphatase 5b (TRAP-5b), interleukin 6 (IL-6) in serum. In conclusion, tectochrysin serves as a potential candidate in the treatment of osteoporosis. The proposed two-dimensional MPTS-modified BMMC/CMC-TOFMS analytical system shows the advantages of long-life span and fast recognition ability, which is very suitable for infrequent cell lines.

Small molecules for mesenchymal stem cell fate determination

Mesenchymal stem cells (MSCs) are adult stem cells harboring self-renewal and multilineage differentiation potential that are capable of differentiating into osteoblasts, adipocytes, or chondrocytes in vitro, and regulating the bone marrow microenvironment and adipose tissue remodeling in vivo. The process of fate determination is initiated by signaling molecules that drive MSCs into a specific lineage. Impairment of MSC fate determination leads to different bone and adipose tissue-related diseases, including aging, osteoporosis, and insulin resistance. Much progress has been made in recent years in discovering small molecules and their underlying mechanisms control the cell fate of MSCs both in vitro and in vivo. In this review, we summarize recent findings in applying small molecules to the trilineage commitment of MSCs, for instance, genistein, medicarpin, and icariin for the osteogenic cell fate commitment; isorhamnetin, risedronate, and arctigenin for pro-adipogenesis; and atractylenolides and dihydroartemisinin for chondrogenic fate determination. We highlight the underlying mechanisms, including direct regulation, epigenetic modification, and post-translational modification of signaling molecules in the AMPK, MAPK, Notch, PI3K/AKT, Hedgehog signaling pathways etc. and discuss the small molecules that are currently being studied in clinical trials. The target-based manipulation of lineage-specific commitment by small molecules offers substantial insights into bone marrow microenvironment regulation, adipose tissue homeostasis, and therapeutic strategies for MSC-related diseases.

Simultaneous quantification of six indicator compounds in Wen-Qing-Yin by high-performance liquid chromatography-diode array detection

A simple gradient high-performance liquid chromatography with diode array detection (HPLC-DAD) method was used to simultaneously to analyze characteristics of six indicator compounds in the traditional Chinese medicine (TCM) formulation Wen-Qing-Yin (WQY). Separate optimization was performed using a Cosmosil C18 column gradient method with 0.1% formic acid in both mobile phases of aqueous and acetonitrile (ACN), at a flow rate, detection wavelength, and sample volume of 1.8 mL/min, 268 nm, and 10 μL, respectively. The linear regression of six active compounds berberine (BER), baicalin (BAI), ferulic acid (FER), geniposide (GEN), hydorxymethoxylfurfural (HMF), and paeoniflorin (PAE) was produced at the concentration range of 10–2000 μg/mL. The method validation revealed an acceptable precision (intra- and inter-day precision < 3.39% and 4.11%, respectively) and recovery (85.60–110.45% and 86.58–110.90%), a recovery range of 86.61–109.42%, and sensitivity (limit of detection [LOD] and limit of quantification [LOQ] values were in the range of 0.03–3.13, and 0.08–9.38 μg/mL, respectively) while the calibration curves were linear with a correlation coefficient (R²) ranging from 0.9966 to 0.9989. The qualitative and quantitative analyses were performed by direct comparison of the peaks of the WCY extract to retention times of reference standards. Additionally, principal component analysis (PCA) successfully discriminated four purchased commercial samples of all six indicator constituents, and the present results indicate their comprehensive potential usefulness for qualitative and quantitative analyses of the WQY decoction and its commercial products.

Effects of various antimicrobial agents on multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells

Antimicrobial drugs of several classes play an important role in the treatment of bone and joint infections. In addition to fighting pathogenic microorganisms, the effects of drugs on local tissues and cells are also related to the course and prognosis of bone and joint infections. The multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) is essential for tissue repair after local injury, which is directly related to the recovery of bone, cartilage, and medullary adipose tissue. Our previous studies and the literature indicate that certain antimicrobial agents can regulate the differentiation potential of bone marrow-derived MSCs. Here, in order to systematically analyze the effects of various antimicrobial drugs on local tissue regeneration, we comprehensively review the studies on the effects of these drugs on MSC differentiation, and classify them according to the three differentiation directions (osteogenesis, chondrogenesis, and adipogenesis). Our review demonstrates the specific effects of different antimicrobial agents on bone marrow-derived MSCs and the range of concentrations at which they work, and provides a basis for drug selection at different sites of infection.

A comprehensive review on phytochemistry, pharmacology, and flavonoid biosynthesis of Scutellaria baicalensis

CONTEXT

Scutellaria baicalensis Georgi (Lamiaceae) is a popular medicinal plant. Its roots are used as the famous traditional Chinese medicine Huang-Qin, which is recorded in Chinese Pharmacopoeia, European Pharmacopoeia, and British Pharmacopoeia.

OBJECTIVE

This review comprehensively summarizes research progress in phytochemistry, pharmacology, and flavonoid biosynthesis of S. baicalensis.

METHODS

English and Chinese literature from 1973 to March 2018 was collected from databases including Web of Science, SciFinder, PubMed, Elsevier, Baidu Scholar (Chinese), and CNKI (Chinese). Scutellaria baicalensis, chemical constituents, phytochemistry, biological activities, and biosynthesis were used as the key words.

RESULTS

A total of 126 small molecules (1-126) and 6 polysaccharides have been isolated from S. baicalensis. The small molecules can be classified into four structural types, namely, free flavonoids, flavonoid glycosides, phenylethanoid glycosides, and other small molecules. Extracts of S. baicalensis and its major chemical constituents have been reported to possess anti-viral, anti-tumor, anti-bacterial, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective activities. Key steps in the biosynthetic pathways of Scutellaria flavonoids have also been summarized.

CONCLUSIONS

This article could be helpful for researchers who are interested in the chemical constituents, bioactivities, biosynthesis, and clinical applications of S. baicalensis.

Comparative two-dimensional HepG2 and L02/ cell membrane chromatography/ C18/ time-of-flight mass spectrometry for screening selective anti-hepatoma components from Scutellariae Radix

Screening active components from Chinese traditional medicine is an effective approach to discover new drugs or active structures. Cell membrane chromatography (CMC), developed rapidly because of its high sensitivity and effectiveness, has achieved a wide application in screening active components on pathological cells or tissues. However, it is hard to clarify the selectivity between pathological and normal tissues through simply using pathological cells. In this study, a novel comparative two-dimensional (2D) cell membrane chromatography system was established. Briefly, hepatic carcinoma HepG2 CMC columns and normal hepatic L02 CMC columns were simultaneously loaded to screen potential selective antitumor components from Scutellariae Radix by comparing the retention behaviors on two kinds of cells. Totally 13 components in Scutellariae Radix retained on both HepG2/ CMC and L02/ CMC columns. Among them, three components, oroxylin A, wogonin and chrysin, were screened out to perform stronger affinity on HepG2 columns, and in further cell proliferation assay, IC₅₀ of these three compounds of HepG2 cells were 9.66 μM, 66.77 μM and 36.26 μM respectively, while of L02 cells, IC₅₀ of chrysin was 59.10 μM and over 200 μM of the other two components. On the whole, the toxity of these three compounds to hepatoma cells was stronger than to normal cells. It can be supposed that oroxylin A, wogonin, and chrysin own the potential to be developed as selective anti-hepatoma active components, which expects further research to validate.