Chemical Constituents from the Stems of Tinospora sinensis and Their Bioactivity

Indian herb Tinospora cordifolia and Tinospora species: Phytochemical and therapeutic application

Clinical investigations are increasingly focusing on natural materials with medical benefits because, in contrast to medicines, they have extremely few adverse effects. Tinospora species of the Menispermaceae family has many bioactive principles for plant nutraceuticals. A thorough assessment of the existing literature revealed that Indian Tinospora species are an important group of medicinal herbs used for a variety of pharmacological activities. While, Tinospora cordifolia is widely recognized as a significant herb in the Indian System of Medicines (ISM) due to its bioactive components and has been used in the treatment of diabetes, cancer, urinary problems, fever, jaundice, helminthiasis, leprosy, dysentery, skin diseases, and many more. Using the search phrases "phytochemistry," "traditional uses," and "pharmacological evaluation of Indian Tinospora species," appropriate articles were carefully extracted from the MEDLINE/PubMed, Scopus, and WOS databases. Around 180 articles, related to the India Tinospora species, were selected from a pool of 200 papers published between 1991 and 2023. T. cordifolia has received a lot of scientific attention because of its diverse therapeutic characteristics in treating various diseases. Our present study in this review encompasses 1.) Phytochemistry, traditional uses and pharmacological potential of T. cordifolia as well as other Indian Tinospora species. 2.) Safety and toxicity study and available marketed formulation of T. cordifolia for the treatment of various diseases. The chemical constitution and pharmacological characteristics of other Tinospora species must also be investigated, indicating a need for further scientific research.

Exploration of the main active metabolites from Tinospora crispa (L.) Hook. f. & Thomson stem as insulin sensitizer in L6.C11 skeletal muscle cell by integrating in vitro, metabolomics, and molecular docking

ETHNOPHARMACOLOGICAL RELEVANCE

Tinospora crispa (L.) Hook. f. & Thomson stem (TCS) has long been used as folk medicine for the treatment of diabetes mellitus. Previous study revealed that TCS possesses multi-ingredients and multi-targets characteristic potential as insulin sensitizer activity. However, its mechanisms of action and molecular targets are still obscure.

AIM OF THE STUDY

In the present study, we investigated the effects of TCS against insulin resistance in muscle cells through integrating in vitro experiment and identifying its active biomarker using metabolomics and in molecular docking validation.

MATERIALS AND METHODS

We used centrifugal partition chromatography (CPC) to isolate 33 fractions from methanolic extract of TCS, and then used UHPLC-Orbitrap-HRMS to identify the detectable metabolites in each fraction. We assessed the insulin sensitization activity of each fraction using enzyme-linked immunosorbent assay (ELISA), and then used confocal immunocytochemistry microscopy to measure the translocation of glucose transporter 4 (GLUT4) to the cell membrane. The identified active metabolites were further simulated for its molecular docking interaction using Autodock Tools.

RESULTS

The polar fractions of TCS significantly increased insulin sensitivity, as measured by the inhibition of phosphorylated insulin receptor substrate-1 (pIRS1) at serine-312 residue (ser312) also the increasing number of translocated GLUT4 and glycogen content. We identified 58 metabolites of TCS, including glycosides, flavonoids, alkaloids, coumarins, and nucleotides groups. The metabolomics and molecular docking simulations showed the presence of minor metabolites consisting of tinoscorside D, higenamine, and tinoscorside A as the active compounds.

CONCLUSIONS

Our findings suggest that TCS is a promising new treatment for insulin resistance and the identification of the active metabolites in TCS could lead to the development of new drugs therapies for diabetes that target these pathways.

In Vitro and In Silico Studies for the Identification of Potent Metabolites of Some High-Altitude Medicinal Plants from Nepal Inhibiting SARS-CoV-2 Spike Protein

Despite ongoing vaccination programs against COVID-19 around the world, cases of infection are still rising with new variants. This infers that an effective antiviral drug against COVID-19 is crucial along with vaccinations to decrease cases. A potential target of such antivirals could be the membrane components of the causative pathogen, SARS-CoV-2, for instance spike (S) protein. In our research, we have deployed in vitro screening of crude extracts of seven ethnomedicinal plants against the spike receptor-binding domain (S1-RBD) of SARS-CoV-2 using an enzyme-linked immunosorbent assay (ELISA). Following encouraging in vitro results for Tinospora cordifolia, in silico studies were conducted for the 14 reported antiviral secondary metabolites isolated from T. cordifolia-a species widely cultivated and used as an antiviral drug in the Himalayan country of Nepal-using Genetic Optimization for Ligand Docking (GOLD), Molecular Operating Environment (MOE), and BIOVIA Discovery Studio. The molecular docking and binding energy study revealed that cordifolioside-A had a higher binding affinity and was the most effective in binding to the competitive site of the spike protein. Molecular dynamics (MD) simulation studies using GROMACS 5.4.1 further assayed the interaction between the potent compound and binding sites of the spike protein. It revealed that cordifolioside-A demonstrated better binding affinity and stability, and resulted in a conformational change in S1-RBD, hence hindering the activities of the protein. In addition, ADMET analysis of the secondary metabolites from T. cordifolia revealed promising pharmacokinetic properties. Our study thus recommends that certain secondary metabolites of T. cordifolia are possible medicinal candidates against SARS-CoV-2.

Constituents of Tinospora sinensis and their nitric oxide inhibitory activities

One new phenylpropanoid glycoside, tinosinen A (1) and 13 known compounds, tinosinen (2), citrusin B (3), picraquassioside C (4), erythro-guaiacylglycerol-β-O-4'-coniferyl alcohol (5), erythro-guaiacylglycerol-8-O-4'-(sinapyl alcohol) ether (6), erythro-syringylglycerol-8-O-4'-(sinapyl alcohol) ether (7), seco-isolariciresinol 9-O-D-β-glucopyranoside (8), tinosposide A (9), pinoresinol-4'-O-β-D-glucopyranoside (10), syringaresinol-4'-O-β-D-glucopyranoside (11), pinoresinol (12), syringaresinol (13), and lirioresino-β-dimethyl ether (14) were isolated from the stems of Tinospora sinensis (Lour.) Merr. Their structures were established by detailed spectroscopic studies and comparisons with those reported in the literature. Compound 13 showed significant inhibitory NO production (IC₅₀ value of 38.53 ± 1.90 μM) in RAW264.7 macrophages, LPS-stimulated. Compounds 3-7, 11, 12, and 14 inhibited NO production with IC₅₀ values ranging from 38.53 to 99.07 μM.

Clerodane furanoditerpenoids from the stems of Tinospora sinensis

One new clerodane-type furanoditerpenoid tinosinoid A (1) and nine new nor-clerodane analogs tinosinoids B-J (2-10) have been isolated from the stems of Tinospora sinensis. The structures of the new compounds with absolute configurations have been elucidated by spectroscopic means, including MS, NMR and ECD techniques, as well as chemical correlation. Compound 1 is a rare sulfur-containing clerodane diterpenoid incorporating a 2-mercaptoethanol unit via a thioether bond, while compounds 4/5 and 9 represent two pairs of unusual equilibrium regioisomers through an interesting intramolecular transesterification. Our bioassays established that 1 and 8 displayed moderate antiproliferative effects against two human tumor cell lines, and 9 and 10 showed significant α-glucosidase inhibitory activities. A kinetics study revealed that compound 10 was a noncompetitive α-glucosidase inhibitor, and its possible binding mode to the enzyme was further probed by molecular docking experiments.

Meso-Dihydroguaiaretic Acid Ameliorates Acute Respiratory Distress Syndrome through Inhibiting Neutrophilic Inflammation and Scavenging Free Radical

The pathogenesis of acute respiratory distress syndrome (ARDS) is very complex. Patients with ARDS still suffer high mortality rates. Infiltration and activation of neutrophils in lungs are critical pathogenic factors in ARDS. In this study, we demonstrate that meso-dihydroguaiaretic acid (MDGA), a natural lignan, inhibits inflammatory responses in human neutrophils and ameliorates ARDS in mice. MDGA inhibited superoxide anion generation and elastase release in various G-protein coupled receptor agonists-induced human neutrophils. However, MDGA did not alter superoxide anion generation and elastase activity in cell-free systems. These results suggest that the anti-inflammatory effects of MDGA are mediated by regulating cellular signals in human neutrophils. In consistent with this, MDGA suppressed phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase in activated human neutrophils. Moreover, MDGA inhibited CD11b expression and adhesion in activated human neutrophils. Interestingly, MDGA reduced reactive oxygen species (ROS) generation but not superoxide anion generation in protein kinase C (PKC) activator-induced human neutrophils, suggesting that MDGA may also have ROS scavenging ability. Indeed, MDGA showed strong free radical scavenging activity in cell-free assays. Significantly, MDGA suppressed PKC-induced neutrophil extracellular trap formation. Additionally, treatment of MDGA attenuated neutrophil infiltration and lung damage on lipopolysaccharide-induced ARDS in mice. In conclusion, our results demonstrate that MDGA has anti-neutrophilic inflammatory effects and free-radical scavenging activity. We also suggest that MDGA has potential to serve as a lead for developing new therapeutics to treat ARDS.

Lignans with NO inhibitory activity from Tinospora sinensis

Two new lignan glucosides, tinsinlignans A and B (1 and 2), two new oxyneolignans, tinsinlignans C and D (3 and 4), along with one known analogue (5), were isolated from the stems of Tinospora sinensis. The structures of the new compounds were elucidated based on analysis of spectroscopic data, and the absolute configuration of 1 was determined through electronic circular dichroism (ECD) calculation based on the time-dependent density functional theory (TD-DFT). Compounds 1-4 were evaluated for their inhibitory effects on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in murine RAW264.7 macrophage cells and compounds 1 and 2 exhibited moderate inhibitory activities with IC₅₀ values of 18.5 ± 2.0 and 28.8 ± 1.2 μmol·L^-1, respectively.

Lignans and clerodane diterpenoids from Tinospora sinensis

Sixteen lignans with diverse carbon skeletons, including tetrahydrofuran lignans (1, 13-18), 7,9'-dinorlignan (2), dibenzylbutane lignans (9-10), aryl tetrahydronaphthalene lignans (11-12), dihydrobenzofuran neolignans (19-20), 8-O-4' neolignans (21-22), and six clerodane diterpenoid glucosides (3-8) were isolated from the 70% ethanolic extract of the stems of Tinospora sinensis (Lour.) Merr. Their structures were established by spectroscopic analyses and chemical methods. Among all these isolates, compounds 1-2 and 3-4 were determined as previously undescribed lignans and clerodane diterpenoids respectively, and compounds 9-13 and 17-22 were discovered from T. sinensis for the first time. In addition, it was the first time to report three types of lignans including 7,9'-dinorlignan, dihydrobenzofuran neolignan and 8-O-4' neolignan from T. sinensis. The biological activities of all isolated compounds were assessed in terms of their nitric oxide production inhibitory activity in LPS stimulated RAW264.7 cells. The results showed that compound 20 exhibited a mild NO production inhibitory effect with an IC50 value of 17.43 ± 2.06 μM.

Undescribed phenylpropanoid and a dimeric sesquiterpenoid possessing a rare cyclobutane ring from Tinospora sinensis

A rare dimeric sesquiterpenoid (tinosposinoside, 1) and a phenylpropanoid (cordifolioside C, 2), two undescribed metabolites, were isolated from the methanolic extract of the stems of Tinospora sinensis together with thirteen known compounds. This is the second example of a sesquiterpene dimer where two monomers linked together through a cyclobutane ring, possibly generated through [2 + 2] cycloaddition. The structures of 1 and 2 were elucidated by NMR and mass techniques.

Development of a chemical fingerprint as a tool to distinguish closely related Tinospora species and quantitation of marker compounds

Tinospora species are morphologically similar. Several cases of human toxicity have been reported in association with T. crispa. A chemical fingerprint was developed to differentiate T. crispa from its closely related species and to quantitate its major furanoditerpenes namely as borapetosides B, C and F. The rapid, sensitive and repeatable method was established using ultra-high performance liquid chromatography coupled with photodiode array and single quadrupole electrospray mass spectrometry detectors using a flavonoid, two alkaloids, an amide and six diterpenoids. Qualitative and quantitative determination was performed by UHPLC-UV and confirmed by MS. The intra-day RSD for replicates was between 0.9 and 6.8% and inter-day RSD was between 1.2 and 9.1%. Recovery was 97-103 %. The method is useful to achieve decisiveness in not only identifying but also differentiating T. crispa from T. sinensis and other closely related Tinospora species. Seventeen Tinospora plant samples and seventeen dietary supplements claiming T. crispa, T. sinensis and T. cordifolia were analyzed. The newly developed and validated method successfully resulted in the conclusive identification of two dietary supplements to be mislabeled.

A new dimeric protoberberine alkaloid and other compounds from the tubers of Tinospora dentata

A new dimeric quaternary protoberberine alkaloid, bispalmatrubine (1), and thirteen known compounds (2-14) were purified from the tubers of Tinospora dentata. Their structures were determined by spectroscopic and spectrometric analytical methods. Among the isolates, eight compounds were examined for their in vitro anti-inflammatory potential and several tested alkaloids displayed moderate inhibitory effects of N-formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLP/CB)-induced superoxide anion generation and elastase release.

Metabolic engineering Escherichia coli for efficient production of icariside D2

BACKGROUND

Icariside D2 is a plant-derived natural glycoside with pharmacological activities of inhibiting angiotensin-converting enzyme and killing leukemia cancer cells. Production of icariside D2 by plant extraction and chemical synthesis is inefficient and environmentally unfriendly. Microbial cell factory offers an attractive route for economical production of icariside D2 from renewable and sustainable bioresources.

RESULTS

We metabolically constructed the biosynthetic pathway of icariside D2 in engineered Escherichia coli. We screened the uridine diphosphate glycosyltransferases (UGTs) and obtained an active RrUGT3 that regio-specifically glycosylated tyrosol at phenolic position to exclusively synthesize icariside D2. We put heterologous genes in E. coli cell for the de novo biosynthesis of icariside D2. By fine-tuning promoter and copy number as well as balancing gene expression pattern to decrease metabolic burden, the BMD10 monoculture was constructed. Parallelly, for balancing pathway strength, we established the BMT23-BMD12 coculture by distributing the icariside D2 biosynthetic genes to two E. coli strains BMT23 and BMD12, responsible for biosynthesis of tyrosol from preferential xylose and icariside D2 from glucose, respectively. Under the optimal conditions in fed-batch shake-flask fermentation, the BMD10 monoculture produced 3.80 g/L of icariside D2 using glucose as sole carbon source, and the BMT23-BMD12 coculture produced 2.92 g/L of icariside D2 using glucose-xylose mixture.

CONCLUSIONS

We for the first time reported the engineered E. coli for the de novo efficient production of icariside D2 with gram titer. It would be potent and sustainable approach for microbial production of icariside D2 from renewable carbon sources. E. coli-E. coli coculture approach is not limited to glycoside production, but could also be applied to other bioproducts.