Apocarotenoids from the fresh roots of Rehmannia glutinosa and their anti-pulmonary fibrosis activity.

Six undescribed compounds (1-6) and twenty-three known analogues (7-29) were isolated from the fresh roots of Rehmannia glutinosa. The structures of the compounds (1-29) were established through the application of spectroscopic analysis. Compounds 3, 4, 6, 8, 13, 18, 21, 22, 25, and 28 exhibited excellent anti-pulmonary fibrosis activity. The potential mechanistic pathway of 3 was also investigated, whose results indicate that compound 3 ameliorate TGF-ß1 induced BEAS-2B cell injury via PI3K/AKT/NF-κB signaling pathway.

Genome-Wide Identification of the Rehmannia glutinosa miRNA Family and Exploration of Their Expression Characteristics Caused by the Replant Disease Formation-Related Principal Factor.

Background/Objectives: Rehmannia glutinosa, a highly valuable medicinal plant in China, is encountering severe replant disease. Replant disease represents a complex stress driven by multiple principal factors (RDFs), including allelochemicals, microbes, and their interactions. miRNAs are recognized as key regulators of plant response to stresses; however, their specific roles within RDFs are not entirely clear. Methods: This study builds six RDF treatments, comprising R. glutinosa continuously planted (SP), normally planted (NP), and NP treated with ferulic acid (FA), Fusarium oxysporum (FO), and a combination of FA with FO (FAFO). sRNA-seq technology was used to identify crucial miRNAs in response to diverse RDFs. Results: In total, 30 sRNA datasets were generated from the SP, NP, FA, FO, and FAFO samples. A total of 160 known and 41 novel miRNAs (RgmiRNAs) were identified in the R. glutinosa genome based on the sRNA database. Abundance analysis revealed that RgmiRNAs in SP exhibited a distinct expression profile in comparison with others. Of these, 124, 86, 86, and 90 RgmiRNAs were differentially expressed in SP, FA, FO, and FAFO compared with NP. Target analysis indicated that RgmiRNAs downregulated in both SP and RDFs impede the organism growth of R. glutinosa. RgmiRNAs upregulated in SP can disrupt root formation and nutrient metabolism, in which, two RgmiR398 were uniquely expressed in SP. It was confirmed to target RgCSD genes. The expression patterns of RgmiR398 and RgCSD indicated that replant disease induces the oxidative damage of R. glutinosa through RgmiR398. Conclusions:RgmiRNA profiling under RDFs provides a theoretical basis for the further clarification of RgmiRNA function in replant disease.

Effects of polysaccharide from hot-compressed steamed Rehmannia glutinosa on the immune system and gut microbiota in an immunosuppressed mice model.

In this study, the immunomodulatory effects of polysaccharide obtained by hot-compressed steaming of Rehmannia glutinosa Libosch (HRP) were investigated using both in vitro and in vivo methods. It was found that HRP activated the TLR4/NF-κB signaling pathway, up-regulated the intracellular expression of TNF-α, IL-6 and IL-1ß, and induced of innate immune memory in macrophages. We then investigated the effect of HRP on immunosuppressed mice induced by cyclophosphamide (CTX). Surprisingly, HRP improved CTX-induced weight loss and increased the splenic index, alleviated intestinal mucosal damage and hematopoietic insufficiency caused by CTX, as demonstrated by H&E staining. In addition, HRP promoted the expression of key proteins in the TLR4/NF-κB and autophagy pathways in intestinal tissues, thereby enhancing intestinal immune function. Bacterial 16S rRNA gene sequences of colon contents suggested that HRP may alleviate gut microbiota disruption by increasing the populations of Lachnospiraceae and Erysipelotrichaceae while inhibiting Lactobacillaceae. The results of this study show the potential use of HRP as an immunomodulator in functional foods or pharmaceuticals.

[Effect of 2-phenylethyl-beta-glucopyranoside isolated from Huaizhong No. 1 Rehmannia glutinosa on hypoxic pulmonary hypertension by regulating PI3K/Akt/m TOR/HIF-1α pathway].

The study investigated the protective effect and mechanism of 2-phenylethyl-beta-glucopyranoside(Phe) from Huaizhong No.1 Rehmannia glutinosa on hypoxic pulmonary hypertension(PH), aiming to provide a theoretical basis for clinical treatment of PAH. Male C57BL/6N mice were randomly divided into normal group, model group, positive drug(bosentan, 100 mg·kg~(-1)) group, and low-and high-dose Phe groups(20 and 40 mg·kg~(-1)). Except for the normal group, all other groups were continuously subjected to model induction in a 10% hypoxic environment for 5 weeks, with oral administration for 14 days starting from the 3rd week. The cardiopulmonary function, right ventricular pressure, cough and asthma index, lung injury, cell apoptosis, oxidative stress-related indicators, immune cells, and phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)/mammalian target of rapamycin(mTOR)/hypoxic inducible factor 1α(HIF-1α) pathway-related proteins or mRNA levels were examined. Furthermore, hypoxia-induced pulmonary arterial smooth muscle cell(PASMC) were used to further explore the mechanism of Phe intervention in PH combined with PI3K ago-nist(740Y-P). The results showed that Phe significantly improved the cardiopulmonary function of mice with PH, decreased right ventricular pressure, cough and asthma index, and lung injury, reduced cell apoptosis, oxidative stress-related indicators, and nuclear levels of phosphorylated Akt(p-Akt) and phosphorylated mTOR(p-mTOR), inhibited the expression levels of HIF-1α and PI3K mRNA and proteins, and maintained the immune cell homeostasis in mice. Further mechanistic studies revealed that Phe significantly reduced the viability and migration ability of hypoxia-induced PASMC, decreased the expression of HIF-1α and PI3K proteins and nuc-lear levels of p-Akt and p-mTOR, and this effect was blocked by 740Y-P. Therefore, it is inferred that Phe may exert anti-PH effects by alleviating the imbalance of oxidative stress and apoptosis in lung tissues and regulating immune levels, and its mechanism may be related to the regulation of the PI3K/Akt/mTOR/HIF-1α pathway. This study is expected to provide drug references and research ideas for the treatment of PH.

Exploring the potential mechanisms of Rehmannia glutinosa in treating sepsis based on network pharmacology.

The present study utilized network pharmacology to identify therapeutic targets and mechanisms of Rehmannia glutinosa in sepsis treatment. RNA-sequencing was conducted on peripheral blood samples collected from 23 sepsis patients and 10 healthy individuals. Subsequently, the RNA sequence data were analyzed for differential expression. Identification of active components and their putative targets was achieved through the HERB and SwissTarget Prediction databases, respectively. Functional enrichment analysis was performed using GO and KEGG pathways. Additionally, protein-protein interaction networks were constructed and survival analysis of key targets was conducted. Single-cell RNA sequencing provided cellular localization data, while molecular docking explored interactions with central targets. Results indicated significant involvement of identified targets in inflammation and Th17 cell differentiation. Survival analysis linked several targets with mortality rates, while molecular docking highlighted potential interactions between active components and specific targets, such as rehmaionoside a with ADAM17 and rehmapicrogenin with CD81. Molecular dynamics simulations confirmed the stability of these interactions, suggesting Rehmannia glutinosa's role in modulating immune functions in sepsis.

Genomic Analysis of a Novel Torradovirus "Rehmannia Torradovirus Virus": Two Distinct Variants Infecting Rehmannia glutinosa.

Rehmannia glutinosa, a crucial medicinal plant native to China, is extensively cultivated across East Asia. We used high-throughput sequencing to identify viruses infecting R. glutinosa with mosaic, leaf yellowing, and necrotic symptoms. A novel Torradovirus, which we tentatively named "Rehmannia torradovirus virus" (ReTV), was identified. The complete sequences were obtained through reverse-transcription polymerase chain reaction (RT-PCR), 5' and 3' rapid amplification of cDNA ends, and Sanger sequencing. The amino acid sequence alignment between the ReTV-52 isolate and known Torradovirus species in the Pro-Pol and coat protein regions were 51.3-73.3% and 37.1-68.1%, respectively. Meanwhile, the amino acid sequence alignment between the ReTV-8 isolate and known Torradovirus species in the Pro-Pol and coat protein regions were 52.7-72.8% and 36.8-67.5%, respectively. The sequence analysis classified ten ReTV strains into two variants. The ReTV-52 genome has two RNA segments of 6939 and 4569 nucleotides, while that of ReTV-8 consists of two RNA segments containing 6889 and 4662 nucleotides. Sequence comparisons and phylogenetic analysis showed ReTV strains clustered within the Torradovirus, exhibiting the closet relation to the squash chlorotic leaf spot virus. The RT-PCR results showed a 100% ReTV detection rate in all 60 R. glutinosa samples. Therefore, ReTV should be classified as a novel Torradovirus species. ReTV is potentially dangerous to R. glutinosa, and necessitating monitoring this virus in the field.

[Gene cloning and functional analysis of an iridoid oxidase gene in Rehmannia glutinosa].

Rehmannia glutinosa is one of the commonly used Chinese herbal medicines, which has activities of heat-clearing,blood-cooling, Yin-nourishing, and body fluid-promoting. Iridoid glycosides are the main bioactive in R. glutinosa. Iridoid oxidase is a key rate-limiting enzyme in the biosynthetic pathway of iridoid glycosides. In this study, an iridoid oxidase gene Rg IO was screened based on the transcriptome data, followed by bioinformatics analysis, expression characteristic detection, and subcellular localization analysis. The results show that the coding region of Rg IO is 1 536 bp, with 511 amino acids encoded, and the molecular weight is about 58 258. 01. The protein sequence of Rg IO contains the conserved domains and motifs of cytochrome P450 oxidases. Rg IO has the highest sequence identities with its ortholog proteins in Striga asiatica, Striga hermonthica, and Centranthera grandiflora and has good sequence identities(77. 28%) with Catharanthus roseus Cr IO. Rg IO shows specific expression in the leaf of R. glutinosa. In response to MeJA induction, the expression of MeJA in leaves and roots after treatment increases by 3. 15 and 1. 3 times at 3 h and 6 h,respectively. The result of subcellular localization shows that Rg IO is distributed in the endoplasmic reticulum. Agrobacterium-mediated transient expression of Rg IO gene in leaves of R. glutinosa makes the content of catalpol increase by 0. 82 times compared with the transient expression of the empty vector. This study provides a key target gene for the molecular regulation and biosynthesis of catalpol in R. glutinosa and lays a foundation for revealing the complete biosynthetic pathway of catalpol.

Alleviated diabetic osteoporosis and peripheral neuropathic pain by Rehmannia glutinosa Libosch polysaccharide via increasing regulatory T cells.

Diabetic peripheral neuropathy (DPN) and diabetic osteoporosis (DOP) are conditions that significantly impact the quality of life of patients worldwide. Rehmanniae Radix Preparata, a component of traditional Chinese medicine with a history spanning thousands of years, has been utilized in the treatment of osteoporosis and diabetes. Specifically, Rehmannia glutinosa Libosch polysaccharide (RGP), a key bioactive compound of Rehmanniae Radix Preparata, has demonstrated immune-modulating properties and beneficial effects on hyperglycemia, hyperlipidemia, and vascular inflammation in diabetic mice. Despite these known actions, the precise mechanisms of RGP in addressing DOP and DPN remain unclear. Our study aimed to explore the impact of RGP on osteoporosis and peripheral neuropathic pain in diabetic mice induced by streptozotocin (STZ). The findings revealed that RGP not only improved hyperglycemia and osteoporosis in STZ-induced diabetic mice but also enhanced osteogenesis, insulin production, and nerve health. Specifically, RGP alleviated distal pain, improved nerve conduction velocity, nerve fiber integrity, and immune cell balance in the spleen. Mechanistically, RGP was found to upregulate HDAC6 mRNA expression in regulatory T cells, potentially shedding light on novel pathways for preventing DOP and DPN. These results offer promising insights for the development of new therapeutic approaches for diabetic complications.

First Report of Aspergillus westerdijkiae Causing Leaf Blight on Rehmannia glutinosa in China.

Rehmannia glutinosa (also known as Chinese foxglove) is a perennial dicotyledonous herb, which plays an important role in traditional Chinese medicine. Its active ingredients have a wide range of pharmacological effects on the blood system, endocrine system, immune system, cardiovascular system, and nervous system (Zhang et al. 2008). In May 2022, leaf blight was observed on 45-day-old R. glutinosa in a seedling nursery in Jiaozuo City (35°01'44.20″N, 113°05'30.63″E), Henan Province, China with an approximate disease incidence up to 54% (~1,300 plants). Irregular brown lesion initially appeared on the tips of basal leaves, then progressed to the entire leaf causing leaf drying out (Supple. Fig. 1-A, B, C). The same symptoms appeared successively in the leaves from the base to the top of the plant, which eventually caused the whole plant to die. To identify the pathogen, eight symptomatic leaves were randomly collected from eight individual plants, and cut into small pieces (5 × 5 mm) at the border of lesions. The pieces were surface disinfected in 75% ethanol for 15 s, followed by 1% NaClO for 1 min, rinsed in sterile water three times, and placed on potato dextrose agar (PDA) medium in the dark for 3 days at 25℃. Finally, 12 purified isolates (DHY1-DHY12) were obtained by using single spore method. Leaves of R. glutinosa seedlings were inoculated with conidial suspension (106 conidia/ml), three plants were inoculated per isolate. Controls were treated with sterilized water. All inoculated and control plants were incubated in a greenhouse at 25℃ under 80 ± 10% humidity and a 8-h/16-h dark/light cycle. This experiment was repeated three times. After 5 days, similar symptoms to those of diseased leaves in the seedling nursery appeared on leaves inoculated with DHY4-DHY10, while plants inoculated with DHY1-DHY3, DHY11-DHY12, and the controls remained asymptomatic (Supple. Fig.1-D, E). The same fungi were re-isolated from diseased leaves, fulfilling Koch's postulates. The causal agents DHY4 to DHY10, showed similar morphology, which were morphologically identified as Aspergillus sp. (Visagie et al. 2014). Isolate DHY5 was selected for further study. On PDA plates, the colonies were covered with white velutinous mycelia (Supple. Fig.1-F). Conidia were ochre yellow and outwards concentric circles. Vesicles were globose, and about 20.1-26.6 µm in diameter (Supple. Fig.1-G). Conidiophore stipes were smooth walled and hyaline, with conidial heads radiating. The conidia were light yellow to orange, exudate clear to orange droplets. The conidia were (2.53-3.25) µm × (2.58-3.47) µm in diameter (n=50) (Supple. Fig.1-H). For further molecular identification, the ITS and TUB gene sequences were amplified with primer pairs ITS1/ITS4 and BT2a/BT2b (Glass and Donaldson. 1995), respectively. BLASTn searches of the ITS (PP355445) and TUB (PP382788) sequences showed 100% and 98.42% similarity to those of A. westerdijkiae (OP237108 and OP700424), respectively. Phylogenetic analysis based on the concatenated sequences of ITS and TUB confirmed that the fungus was A. westerdijkiae, (Supple. Fig.2). A. westerdijkiae was mainly reported on its secondary metabolite ochratoxin A contamination of agricultural products, fruits, and various food products, such as coffee beans (Alvindia et al 2016), grapes (Díaz et al. 2009), oranges and fruit juice (Marino et al. 2009), etc. To our knowledge, this is the first report of A. westerdijkiae causing leaf blight on R. glutinosa in China.

Five new eremophilane-type sesquiterpenes from the fresh roots of Rehmannia glutinosa.

Five undescribed eremophilane-type sesquiterpenes, remophilanetriols E-I (1-5), along with seven known compounds (6-12) were isolated from the fresh roots of Rehmannia glutinosa. Their structures were characterized by extensive spectroscopic data analysis and their absolute configurations were determined by comparing their calculated electronic circular dichroism (ECD) spectra and experimental ECD spectra. The anti-pulmonary fibrosis activities of all compounds were evaluated in vitro by MTT methods, and compounds 2, 8, 10, and 12 exhibited excellent anti-pulmonary fibrosis activities. In addition, compound 2 can reduce the levels of ROS and apoptosis in TGF-ß1-induced BEAS-2B cells.

The Active Ingredient Catalpol in Rehmannia glutinosa Reduces Blood Glucose in Diabetic Rats via the AMPK Pathway.

Background: Type 2 diabetes mellitus (T2DM) poses a huge threat to population health globally, and more drugs need to be explored for treatment. In this study, we investigated the mechanism of active ingredient catalpol in Rehmannia glutinosa on reduces blood glucose in diabetic. Methods: The T2DM model was constructed by intraperitoneal injection of streptozotocin into Sprague-Dawley (SD) rats, which were randomly grouped into diabetes model group, pioglitazone group, Rehmannia glutinosa group, catalpol high-dose group, catalpol low-dose group and normal control group.The intervention was continued for 28 d, and changes in body weight, fasting blood glucose, insulin and lipid levels were observed. Results: Of all the drugs, pioglitazone had the most pronounced hypoglycemic effect, which began to decline after 2 weeks of treatment in the low-dose catalpol group and had no hypoglycemic effect in the high-dose catalpol group. Among them, Rehmannia glutinosa was able to increase serum triglyceride level, and pioglitazone effectively reduced total cholesterol level in rats. The low dose of catalpol decreased the concentration of low-density lipoprotein cholesterol (LDL), while the high dose of catalpol increased the concentration of LDL. Conclusion: As an active ingredient in Rehmannia glutinosa, catalpol has the potential to lower blood glucose and improve blood lipids in diabetes treatment, and its action may be achieved by regulating the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway, which provides a new idea for the development of new diabetes therapeutic approaches.

Assessment of the Effect of Rehmannia glutinosa Leaf Extract in Maintaining Skin Health: A Proof-of-Concept, Double-Blind, Randomized, Placebo-Controlled Clinical Trial.

Purpose: A double-blind, placebo-controlled, randomized, proof-of-concept trial aimed to evaluate the efficacy and safety of VerbasnolTM [Rehmannia glutinosa Libosch leaf-based extract (RGLE)] in females, with moderate to severe acne vulgaris. Participants and Methods: Twenty-two females aged 18 to 35 years having moderate to severe acne with Global Acne Grading System (GAGS) scores of 19 to 38 were included in the study and were randomized in a 1:1 ratio to receive either one capsule (100 mg/day) of RGLE or placebo orally after breakfast for 56 days. The primary outcome was a change in acne severity measured by the GAGS compared to the placebo on day 56. The secondary outcomes were changes in the number of inflammatory acne lesions, facial sebum secretion, quality of life, local pain and itching, skin wrinkle severity, and other skin characteristics, including radiance, luminosity, smoothness, texture, firmness, and hydration. Additionally, the percentage of responders and global tolerability and efficacy were evaluated. Results: The mean GAGS score was reduced by 21.72% and 14.20% on day 28 in RGLE (n=10) and placebo groups (n=12), respectively, which further reduced in both groups on day 56. The RGLE group reported better improvement in other skin characteristics on day 56. No safety or tolerability concerns were reported for the extract. RGLE reduced acne and improved the skin quality in females compared to placebo as early as 28 days of supplementation. Conclusion: RGLE supplementation at a dose of 100 mg/day has provided a clinically relevant decrease in acne severity and improved the skin hydration and quality of life of the participants with acne after 56 days of dose administration.

Optimized combination of Cervus nippon (Sika deer), Angelica (Dangui), and Rehmannia (Suk-jihwang) mitigates LPS-induced inflammation: exploring signaling pathways through plasma metabolomics.

This study aimed to determine the optimal combination of three anti-inflammatory materials [i.e., Cervus nippon Temminck (CT), Angelica gigas Nakai (AN), and Rehmannia glutinosa (RG)] for the strongest anti-inflammatory potential. Eighteen combinations of the three materials were tested in LPS-stimulated RAW264.7 cells via assessing nitric oxide (NO). The best combination from in vitro studies was administered to LPS-treated C57BL/6J mice for five days. Subsequently, plasma metabolites were profiled by bioinformatics analyses and validations. As results, 2, 20, and 50 µg/mL of CT, AN, and RG (TM) were the most effective combination suppressing inflammation. In mice, TM mitigated hepatic inflammatory markers. Similarly, the metabolomics indicated that TM may suppress NF-κB signaling pathway, thereby alleviating hepatic inflammation. TM also decreased systemic and hepatic pro-inflammatory cytokines. Collectively, we found the optimal combination of TM for mitigating inflammation; thus further studies on safety, mechanisms, and clinical models are warranted for human applications. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01476-x.

[Role of mitochondrial autophagy and the curative effect of rehmannia glutinosa leaves total glycoside capsules on nucleos(t)ide drug-induced renal injury].

Objective: To study the curative effect of rehmannia glutinosa leaves total glycoside capsules and the role of mitochondrial autophagy on nucleos(t)ide drug-induced renal injury. Methods: Adefovir dipivoxil (ADV) was used to construct a hepatitis B virus (HBV) transgenic mouse model for renal injury. Renal function was measured in each group at one and two weeks of modeling. Mitochondrial autophagy indicators were measured at two weeks of modeling in renal tissue. Transmission electron microscopy was used to detect mitochondrial autophagy phenomena in renal tissue. The model was established for two weeks. Mouse with renal injury were treated with rehmannia glutinosa leaves total glycoside capsules or isotonic saline for eight weeks by intragastric administration. Renal function was measured. Renal tissue morphology was observed. Mitochondrial autophagy indicators were detected in renal tissue. The protective effect of different concentrations of verbascoside (the main active ingredient of rehmannia glutinosa capsule) was observed on HK-2 cell damage induced by ADV. HK-2 cells were divided into control, ADV, and ADV plus verbascoside groups. The effects of verbascoside at different times and concentrations were observed on the HK-2 mitochondrial autophagy indicators. Fifty patients with chronic hepatitis B were collected who presented with renal injury after treatment with nucleos(t)ide analogs. The random number method was used to divide 29 cases into a control group that received conventional treatment. The treatment group of 21 cases was treated with rehmannia glutinosa leaves total glycoside capsules on the basis of the control group. Serum creatinine (Scr) and urinary protein were detected at eight weeks.The χ(2) test or t-test was used for statistical analysis. Results: Compared with the control group, two weeks of modeling in the ADV group induced renal function injury in HBV mice. The expression of autophagy indicators was higher in the renal tissue of the ADV group than that of the control group. Transmission electron microscopy had revealed mitochondrial autophagy in the renal tissue of the ADV group. Compared with the control group, the renal function of HBV mice treated with rehmannia glutinosa leaves total glycoside capsules improved for two months, and the expressions of autophagy indicators were down-regulated.Verbascoside promoted proliferation in ADV-damaged HK-2 cells, and the expression of autophagy indicators was down-regulated compared with the ADV alone group. In 50 patients with renal function injury, the urinary protein improvement was significantly superior in the treatment group than that in the control group, with eighteen and three cases being effective and ineffective in the treatment group and 12 and 17 cases being effective and ineffective in the control group, with a statistically significant difference (χ(2) = 9.975 0, P = 0.001 6). Serum creatinine was decreased in the treatment group compared with the control group, with 11 and 10 cases being effective and ineffective in the treatment group and 12 and 17 cases being effective and ineffective in the control group, with no statistically significant difference (χ(2) = 0.593 5, P = 0.441 1). Conclusion: Rehmannia glutinosa leaves total glycoside capsule can improve the nucleos(t)ide drug-induced renal function injury in chronic hepatitis B, possibly playing a role via inhibiting PINK1/Parkin-mediated mitochondrial autophagy.

Transcriptome Analysis Provides Insights into Catalpol Biosynthesis in the Medicinal Plant Rehmannia glutinosa and the Functional Characterization of RgGES Genes.

Rehmannia glutinosa, a member of the Scrophulariaceae family, has been widely used in traditional Chinese medicine since ancient times. The main bioactive component of R. glutinosa is catalpol. However, the biogenesis of catalpol, especially its downstream pathway, remains unclear. To identify candidate genes involved in the biosynthesis of catalpol, transcriptomes were constructed from R. glutinosa using the young leaves of three cultivars, Beijing No. 3, Huaifeng, and Jin No. 9, as well as the tuberous roots and adventitious roots of the Jin No. 9 cultivar. As a result, 71,142 unigenes with functional annotations were generated. A comparative analysis of the R. glutinosa transcriptomes identified over 200 unigenes of 13 enzymes potentially involved in the downstream steps of catalpol formation, including 9 genes encoding UGTs, 13 for aldehyde dehydrogenases, 70 for oxidoreductases, 44 for CYP450s, 22 for dehydratases, 30 for decarboxylases, 19 for hydroxylases, and 10 for epoxidases. Moreover, two novel genes encoding geraniol synthase (RgGES), which is the first committed enzyme in catalpol production, were cloned from R. glutinosa. The purified recombinant proteins of RgGESs effectively converted GPP to geraniol. This study is the first to discover putative genes coding the tailoring enzymes mentioned above in catalpol biosynthesis, and functionally characterize the enzyme-coding gene in this pathway in R. glutinosa. The results enrich genetic resources for engineering the biosynthetic pathway of catalpol and iridoids.

Neuroprotective effects of Rehmannia glutinosa polysaccharide on chronic constant light (CCL)-induced oxidative stress and autophagic cell death via the AKT/mTOR pathway in mouse hippocampus and HT-22 cells.

Rehmannia glutinosa polysaccharide (RGP) has been reported to exhibit anti-anxiety effects, yet the underlying mechanism remains unclear. Chronic constant light (CCL) induced cognitive dysfunction associated with oxidative stress in mice has been reported. Here, the neuroprotective effect of RGP on hippocampal neuron damage in CCL-treated mice was investigated. In vivo study, mice were subjected to CCL for 4 weeks and/or oral administration of 100, 200 and 400 mg/kg RGP every other day. In vitro experiment, hippocampal neuron cells (HT-22) was exposed to LED light and/or supplemented with 62.5, 125 and 250 µg/mL RGP. Mice exposed to CCL showed impaired cognitive and depressive-like behavior in the hippocampus, which were reversed by RGP. Meanwhile, RGP reversed light-induced oxidative stress and autophagy both in mice and hippocampal neuron cells (HT-22). Furthermore, compared with Light-exposed group, RGP treatment activated the AKT/mTOR pathway. Importantly, the AKT inhibitor Perifosine significantly weakened the neuroprotective of RGP on Light-induced oxidative stress and autophagy in HT-22 cells by inhibiting AKT/mTOR pathway and increasing the content of autophagy-related protein. Our data demonstrated, for the first time, that oxidative stress and the AKT/mTOR pathway plays a critical role in Light-induced apoptosis and autophagic cell death in mice and HT-22 cells.

Four new iridoid glycosides from the roots of Rehmannia glutinosa.

Four new iridoid glycosides (1-4), rehmaglutosides L-O, were isolated from the air-dried roots of Rehmannia glutinosa. Their structures were established from the spectroscopic data obtained and by chemical evidence. The known mellittoside (5) and ajugol (6) were also obtained in the current investigation, and the structure of mellittoside was unequivocally defined using X-ray diffraction data. Compounds 1-6 were tested for their cytotoxicity against five human tumor cell lines and proliferation effects on Lactobacillus Reuteri.

Seven new pentasaccharides from the roots of Rehmannia glutinosa.

Seven new pentasaccharides (1-7), rehmaglupentasaccharides A-G, were isolated from the air-dried roots of Rehmannia glutinosa. Their structures were established from the spectroscopic data obtained and by chemical evidence. The known verbascose (8) and stachyose (9) were also obtained in the current investigation, and the structure of stachyose was unequivocally defined using X-ray diffraction data. Compounds 1-9 were tested for their cytotoxicity against five human tumor cell lines, influence on dopamine receptor activation, and proliferation effects against Lactobacillus reuteri.

Progress of research into the pharmacological effect and clinical application of the traditional Chinese medicine Rehmanniae Radix.

The traditional Chinese medicine (TCM) Rehmanniae Radix (RR) refers to the fresh or dried root tuber of the plant Rehmannia glutinosa Libosch of the family Scrophulariaceae. As a traditional Chinese herbal medicine (CHM), it possesses multiple effects, including analgesia, sedation, anti-inflammation, antioxidation, anti-tumor, immunomodulation, cardiovascular and cerebrovascular regulation, and nerve damage repair, and it has been widely used in clinical practice. In recent years, scientists have extensively studied the active components and pharmacological effects of RR. Active ingredients mainly include iridoid glycosides (such as catalpol and aucuboside), phenylpropanoid glycosides (such as acteoside), other saccharides, and unsaturated fatty acids. In addition, the Chinese patent medicine (CPM) and Chinese decoction related to RR have also become major research subjects for TCM practitioners; one example is the Bolus of Six Drugs, which includes Rehmannia, Lily Bulb and Rehmannia Decoction, and Siwu Decoction. This article reviews recent literature on RR; summarizes the studies on its chemical constituents, pharmacological effects, and clinical applications; and analyzes the progress and limitations of current investigations to provide reference for further exploration and development of RR.

Anti-aging activities of Rehmannia glutinosa Libosch. crude polysaccharide in Caenorhabditis elegans based on gut microbiota and metabonomic analysis.

Aging is a degenerative progress, accompanied by oxidative damage, metabolic disorders and intestinal flora imbalance. Natural macromolecular polysaccharides have shown excellent anti-aging and antioxidant properties, while maintaining metabolic and intestinal homeostasis. The molecular weight, monosaccharide composition, infrared spectrum and other chemical structure information of four Rehmannia glutinosa polysaccharides (RG50, RG70, RG90, RGB) were determined, and their free radical scavenging ability was assessed. Molecular weight and monosaccharide composition analysis exhibited that RG50 (2-72 kDa), RG70 (3.2-37 kDa), RG70 (3-42 kDa), and RGB (3.1-180 kDa) were heteropolysaccharide with significant different monosaccharide species and molar ratios. We found that RG70 had the best antioxidant activity in vitro and RG70 could enhance the antioxidant enzyme system of Caenorhabditis elegans, diminished lipofuscin and reactive oxygen species levels, up-regulate the expression of daf-16, skn-1 and their downstream genes, and down-regulate the expression of age-1. Metabolomics results showed that RG70 mainly influenced glycine, serine and threonine metabolism and citric acid cycle. 16S rRNA sequencing showed that RG70 significantly up-regulated the abundance of Lachnospiraceae_NK4B4_group, which were positively correlated with amino acid metabolism and energy cycling. These results suggest that RG70 may delay aging by enhancing antioxidant effects, affecting probiotics and regulating key metabolic pathways.