Seco-labdane diterpenoids from the leaves of Callicarpa nudiflora showing nitric oxide inhibitory activity

Anti-inflammatory labdane diterpenoids from the aerial parts of Leonurus sibiricus

Eleven undescribed labdane diterpenoids, sibiricusins K-U, and seven known analogues were obtained from the MeOH extract of the aerial parts of Leonurus sibiricus. The structures of the compounds were established by detailed spectroscopic data analysis, single-crystal X-ray diffraction analysis and ECD calculations. Among them, sibiricusins L-N featured a rare α, β-unsaturated-γ-lactam moiety. Fourteen of the isolates were evaluated for their anti-inflammatory effect on the production of NO in LPS-induced RAW264.7 cells through Griess assay. Sibiricusin O displayed the strongest activity with an IC50 value of 9.0 ± 1.7 μM.

Isolation and identification of 3,4-seco-labdane diterpenoids from Callicarpa nudiflora and investigation of their cytotoxicity against HepG2 cells

Twenty-one previously undescribed compounds, including nineteen 3,4-seco-labdanes (nudiflopenes P-W, Y, A_I-J_I), one 3,4-seco-pimarane (nudiflopene X), and one labdane (nudiflopene Z), along with nine known compounds (one 3,4-seco-pimarane and eight 3,4-seco-labdanes) were isolated from the leaves of Callicarpa nudiflora Hook. Et Arn. The structures of these compounds were elucidated by high-resolution electrospray ionization mass spectrometry and one- and two-dimensional nuclear magnetic resonance spectroscopy. In addition, configurations of the isolated compounds were determined by electronic circular dichroism, DP4+ probability analysis, and single-crystal X-ray diffraction experiments. All undescribed compounds were evaluated for their cytotoxicity against HepG2 cells in vitro, among which compound 12 exhibited a moderate activity with an IC₅₀ value of 27.8 μM.

Nudifloids A-N, structurally diverse 3,4-seco-labdane diterpenoids from Callicarpa nudiflora with inflammatory inhibitory activity

Fourteen undescribed seco-type diterpenoids, named nudifloids A-N, together with ten known analogs, were isolated from the leaves of Callicarpa nudiflora. Nudifloids A-N had a characteristic 3,4-seco-labdane-type diterpenoid skeleton, whereas nudifloids A-C and K-N were 3,4-seco-norditerpenoids. Nudifloid A was the first example of a 3,4-seco-12,13,14,15,16-quartnor-labdane diterpenoid, with a seven-membered lactone ring formed through esterification between C-3 and C-11. Nudifloids B and C were a pair of highly modified 3,4-seco-labdane nor-diterpenoid epimers, of which C-2 and C-18 were cyclized together to form a cyclohexene fragment. The structures of these undescribed diterpenoids were established by spectroscopic analysis and reference data. The anti-inflammatory activity of diterpenoids in rich yield was evaluated by analyzing the inhibition of lipopolysaccharide plus nigericin-induced pyroptosis in J774A.1 cells. Nudifloids D and E exhibited prominent anti-NLRP3 inflammasome activity, with IC₅₀ values of 1.80 and 1.59 μM, respectively. Cell permeability assays revealed that nudifloid D inhibited pyroptosis, which could ameliorate inflammation by blocking the activation of the NLRP3 inflammasome.

Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXV. Structurally diverse triterpenoids and diterpenoids from two endangered Pinaceae plants endemic to the Chinese Qinling Mountains and their bioactivities

A joint phytochemical investigation on the MeOH extracts of the twigs and needles of two endangered Pinaceae plants endemic to the Chinese Qinling Mountains, Picea neoveitchii (an evergreen spruce) and Larix potaninii var. chinensis (a deciduous larch), led to the isolation and characterization of 34 and 24 structurally diverse terpenoids, respectively. Among them, seven are previously undescribed, including a picane-type [i.e., 14(13 → 12)abeo-12αH-serratane] (neoveitchin A) and a serratane-type (neoveitchin B) triterpenoids, and an abietane-type (neoveitchin C) as well as four labdane-type (potalarxins A-D) diterpenoids. Their structures and absolute configurations were established by extensive spectroscopic methods and/or X-ray diffraction analyses. All isolates were evaluated for their inhibitory activities against the human protein tyrosine phosphatase 1B (PTP1B). Serrat-14-en-3α,21β-diol, betulinic acid, 3β-hydroxy-11-ursen-13(28)-olide, ursolic acid, and oleanolic acid were found to have considerable inhibitory effects against PTP1B, with IC₅₀ values ranging from 1.1 to 18.1 μM. The interactions of the bioactive triterpenoids with PTP1B were thereafter performed by employing molecular docking studies. In addition, 7-oxo-dehydroabietic acid (an abietane-type diterpenoid) and mangiferonic acid (a cycloartane-type triterpenoid) inhibited acetyl-coenzyme A carboxylase 1 (ACC1), with IC₅₀ values of 3.4 and 6.6 μM, respectively.

Integrating network pharmacology and an experimental validation strategy elucidates the protective effect and mechanism of callicarpa nudiflora against neuroinflammation

Abnormal activation of microglia promotes neuroinflammation (NI) in Alzheimer's disease (AD). Callicarpa nudiflora Hook et Arn. (CN) is a traditional Chinese herb with a wide range of clinical applications and definite anti-inflammatory effects. However, the anti-inflammatory action and mechanism of NI are not known. The purpose of this research was to survey whether CN could inhibit lipopolysaccharide (LPS)-induced inflammatory activation in BV-2 microglia. This study used a network pharmacology and pharmacophore model-based approach to explore the molecular mechanism of CN anti-NI by combining molecular docking and experimental validation. First, we screened the key active components and targets of CN anti-NI by network pharmacology. Then, the common structural features of these functional molecules in the treatment of neuroinflammation were predicted by 3D-QSAR pharmacodynamic modeling. Finally, the molecular mechanism of the active ingredient 5-hydroxy-3,7,4'-trimethoxyflavone (THF) against neuroinflammation was validated by molecular docking and in vitro experiments. In conclusion, this study established the structure-activity relationships of the active components of CN anti-NI and provided new insights into the pharmacological mechanisms of CN anti-NI at an integrative level.

Chemical profiling and quality evaluation of Callicarpa nudiflora from different regions in China by UPLC-QTOF-MS fingerprint

Callicarpa nudiflora, belonging to the family Verbenaceaae, is wildly used as a traditional Chinese herbal medicine (Luo-hua-zi-zhu) for hemostasis, antibiosis and antiphlogosis in clinlic. However, the underlying chemical basis of C. nudiflora for the significant effects remains obscure. Hence, an ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry method was established for the characterization of multi-constituents in C. nudiflora. As a result, 57 chemical compounds were identified based on their retention times, accurate masses and MS/MS data, and 20 of them were uncovered for the first time in C. nudiflora. In addition, an optimized UHPLC fingerprint analysis, combined with chemometrics including similarity analysis , principal component analysis and partial least squares-discriminant analysis was developed for quality assessment and origin discrimination of C. nudiflora. Multivariate data analysis revealed the resemblances and differences of C. nudiflora related to regions, while partial least squares-discriminant analysis screened nine characteristic markers including luteoloside, acteoside, luteolin-4'-O-β-D-glucopyranoside, pachypodol, isoquercitrin, nudifloside, 5,7,3',4'-tetrahydroxy-8-methoxy-6-C-β-D-glucopyranosyl flavone, 7α-acetoxysandaracopimaric acid and sandaracopimaric acid which contributed the most to the classification. This was the first report on the comprehensive profiling of chemical components in C. nudiflora, which helped to uncover the material basis of C. nudiflora and possess potential value for quality evaluation and clinical application purpose.

Callnudoids A-H: Highly modified labdane diterpenoids with anti-inflammation from the leaves of Callicarpa nudiflora

Eight undescribed 3,4-seco-norlabdane diterpenoids, callnudoids A-H, as well as two known analogues were isolated from the leaves of Callicarpa nudiflora. The structures were elucidated using spectroscopic methods and were compared with published NMR spectroscopic data. The absolute configurations of callnudoids D and E were defined based on ECD data or single-crystal X-ray diffraction. Callnudoids A-C are the highly modified labdane diterpenoids featuring rearranged 3,4-seco-ring and the formation of an undescribed cyclohexene moiety via C2-C18 cyclization. They only contain 15 carbon atoms on the carbon skeleton. Callnudoid D represents the unusual 3,4-seco-15,16-norlabdane diterpenoid with C13-C17 cyclization, and a putative biosynthesis pathway for callnudoids A, B, D, and E was proposed. All compounds were evaluated for their anti-inflammatory activities by inhibiting the lipopolysaccharide (LPS)-induced nitric oxide (NO) released in RAW264.7 cells; callnudoids A-E and H, and methylcallicarpate obviously inhibited pro-inflammatory cytokines TNF-α and IL-1β in a dose-dependent manner.

Two New Seco-Labdane Diterpenoids from the Leaves of Callicarpa nudiflora

Two new seco-labdane diterpenoids, nudiflopene N (1) and nudiflopene O (2), and four known compounds were isolated from the leaves of Callicarpa nudiflora. The structures of the new compounds were established by 1D-, 2D-NMR, and HR-ESI-MS spectral analyses. Compounds 1–3 showed inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 cells, and new compounds 1–2 exhibited more potent inhibitory activity than compound 3. The cytotoxicity of compounds 1–3 against human hepatocellular carcinoma HepG2 cells and human gastric carcinoma SGC-7901 cells were evaluated, while all of them exhibited no cytotoxicity.

Five new seco-labdane-type diterpenoids from Caesalpinia latisiliqua

Five new seco-labdane-type diterpenoids, caesalatisics A-E (1-5), were isolated from the leaves of Caesalpinia latisiliqua (Cav.) Hattink. Their chemical structures were determined using 1D and 2D NMR, mass spectra, and circular dichroism spectroscopies.

Further terpenoids from the Chloranthaceae plant Chloranthus multistachys and their anti-neuroinflammatory activities

Three labdane-type [multisins A-C (1-3)], two guaiane-type [multisins D (4) and E (5)], and one eudesmane-type [multisin F (6)] previously undescribed terpenoids, together with 14 mono- (7-20) and seven dimeric- (21-27) known terpenoids, were isolated from the 90% MeOH extract of the whole plant of Chloranthus multistachys. Their structures and absolute configurations were determined by extensive spectroscopic methods and electronic circular dichroism (ECD) calculations. Compounds 4 and 5 are rare trinor-sesquiterpenes with a de-isopropyl guaiane skeleton, whereas compound 6 is a rearranged dinor-eudesmene featuring an uncommon octahydro-1H-indene ring system. Among the isolates, the dimeric lindenane sesquiterpenoid shizukaol C (25) exhibited the most potent (IC₅₀ = 8.04 μM) anti-neuroinflammatory activity by inhibiting the nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated murine BV-2 microglial cells.

3, 4-seco-Isopimarane and 3, 4-seco-pimarane diterpenoids from Callicarpa nudiflora

A phytochemical investigation was carried out on the extract of a medicinal plant Callicarpa nudiflora, resulting in the characterization of five new 3, 4-seco-isopimarane (1-5) and one new 3, 4-seco-pimarane diterpenoid (6), together with four known compounds. The structures of the new compounds were fully elucidated by extensive analysis of MS, 1D and 2D NMR spectroscopic data, and time-dependent density functional theory (TDDFT) calculation of electronic circular dichroism (ECD) spectra, and DFT calculations for NMR chemical shifts and optical rotations.

seco-Labdanes: A Study of Terpenoid Structural Diversity Resulting from Biosynthetic C-C Bond Cleavage

The cleavage of a C-C bond is a complexity generating process, which complements oxidation and cyclisation events in the biosynthesis of terpenoids. This process leads to increased structural diversity in a cluster of related secondary metabolites by modification of the parent carbocyclic core. In this review, we highlight the diversifying effect of C-C bond cleavage by examining the literature related to seco-labdanes-a class of diterpenoids arising from such C-C bond cleavage events.

Chemical profiling of Callicarpa nudiflora and its effective compounds identification by compound-target network analysis

Callicarpa nudiflora, belonging to the family Verbenaceae, is widely used to treat inflammation caused by bacterial infection.However, the underlying active substances of C. nudiflora against inflammation remains obscure. In this work, an ultra high-performance liquid chromatography (UHPLC) coupled with quadrupole time-of-flight mass spectrometry method was developed to characterize the ingredients in C. nudiflora, and a validated UHPLC coupled with triple quadrupole tandem mass spectrometry method was applied to quantify major components. As a result, a total of 96 chemical compounds were identified in C. nudiflora, and 26 compounds of them were further quantified in 34 batches of C. nudiflora. Based on the identified components from C. nudiflora, a compound-target network for the anti-inflammation effect was constructed by reverse docking target prediction, disease associated genes screening in DisGeNET and the protein-protein interaction from STRING. The compound-target network showed that C. nudiflora might exert anti-inflammation effect on the target of complement 3 and 5 in the pathway of cells and molecules involved in local acute inflammatory response, and 16 effective candidate compounds were found such as catalpol, acteoside, rutin, etc. This study provided an opportunity to deepen the understanding of the chemical composition and the potential anti-inflammatory mechanism of C. nudiflora.

Phytochemical and biological studies on rare and endangered plants endemic to China. Part XV. Structurally diverse diterpenoids and sesquiterpenoids from the vulnerable conifer Pseudotsuga sinensis

An extensive phytochemical investigation on the chemical constituents from the needles and twigs of the vulnerable conifer Pseudotsuga sinensis yielded 19 diterpenoids and 21 sesquiterpenoids with various carbocyclic skeletons. Among them, 13 (named pseudosinins A-M, resp.) were undescribed compounds. Their structures with absolute configurations were characterized by a combination of spectroscopic methods, calculated and experimental electronic circular dichroism (ECD) data, quantum chemical calculations of the chemical shifts, and single crystal X-ray diffraction analyses. In particular, an array of labdane-derived norditerpenoids with C₁₉-, C₁₈-, and C₁₆-skeletons, and related drimane-type sesquitepenoids with C₁₅- and C₁₃-skeletons were found in the title plant. The possible biogenetic relationships of these degraded terpenoids were briefly discussed. Among the isolates, pseudosinin D, cis-communic acid, and 4β,15-dihydroxy-19-norabieta-8,11,13-trien-7-one showed moderate inhibitory activities against the enzyme ATP-citrate lyase (ACL), a potential drug target for the treatment of hyperlipidemia and hypercholesterolemia.

3, 4-seco-Labdane diterpenoids from the leaves of Callicarpa nudiflora with anti-inflammatory effects

Four new 3, 4-seco-labdane diterpenoids, nudiflopenes J-M, were isolated from the leaves of Callicarpa nudiflora along with six known compounds. The structures of these diterpenoids were determined by comprehensive spectroscopic analysis. All the isolated compounds were evaluated for their inhibitory effects on NO production in LPS-stimulated RPMs and RAW264.7 cells. The results suggest that nudiflopenes J-M and other four known compounds showed significant inhibitory effects against NO production comparable to the positive control dexamethasone.

Bioactive Diterpenoids from the Stems of Euphorbia antiquorum

A total of 18 diterpenoids, including 10 new analogues (1-10), were isolated from Euphorbia antiquorum. The structures were characterized by spectroscopic techniques, and circular dichroism data analysis was adopted to confirm the absolute configurations of 1-10. Compounds 1-9 were classified as ent-atisane diterpenoids, and 10 was assigned as an ent-kaurane diterpenoid. The biological evaluation of nitric oxide (NO) production inhibition was conducted, and all of these isolates showed the property of inhibiting NO generation in lipopolysaccharide-induced BV-2 cells. Further research on molecular docking disclosed the affinities between the diterpenoids obtained and inducible nitric oxide synthase.