3, 4-seco-Labdane diterpenoids from the leaves of Callicarpa nudiflora and their inhibitory effects on nitric oxide production

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.

Holistic quality evaluation of Callicarpae Formosanae Folium by multi-chromatography-based qualitative and quantitative analysis of polysaccharides and small molecules

Callicarpae Formosanae Folium (CFF), derived from the leaves of Callicarpa formosana Rolfe, is a common Chinese medicinal herb used for the treatment of hematemesis. Phytochemical studies found that phenylpropanoids, flavonoids, terpenoids and polysaccharides were the main ingredients of CFF. However, there is limited scientific information concerning holistic quality method and quality consistency evaluation of CFF. In this study, a strategy integrating HPGPC-ELSD, HPLC-PDA, UV-VIS and UPLC-QTOF-MS/MS was firstly developed to simultaneously qualify and quantify polysaccharides, as well as representative small molecules in CFF. HPGPC-ELSD was applied to characterize the molecular weight distribution of polysaccharides, HPLC-PDA was developed to qualitatively and quantitatively determine monosaccharides. UV-VIS was used to determine the total polysaccharides content, and UPLC-QTOF-MS/MS was established to characterize the small molecules. The quality consistency of commercial CFF (CM-CFF) was also evaluated. It was shown that the relative molecular weights, the compositional monosaccharides and small molecules composition in CM-CFF and self-collected CFF (SC-CFF) samples were similar. A total of 32 small molecules including 6 phenylpropanoids, 7 flavonoids and 19 terpenoids were characterized in CFF. However, the variation was observed in the content of polysaccharides, luteolin, ursolic acid, as well as total contents of terponoids in CM-CFF samples, which implied that the holistic quality of CM-CFF was inconsistent. The results suggested that the proposed evaluation strategy could be applied as a potential approach for the quality control of CFF. And the quality of CM-CFF should be improved by Good Agriculture Practice (GAP) base and standard processing method.

Callicarpanes A-L, Twelve New Clerodane Diterpenoids with NLRP3 Inflammasome Inhibitory Activity from Callicarpa integerrima

Twelve new clerodane diterpenoids named callicarpanes A-L (1-12), together with eight known compounds (13-20), were isolated from Callicarpa integerrima. Their structures were determined by comprehensive spectroscopic data. The calculated chemical shifts were used to identify relative configurations using DP4+ analysis. The absolute configurations (AC) were assigned based on quantum chemical calculations and X-ray single-crystal diffraction methods. Compounds 1, 3, 5, 9, 10, 12, 15, 16, and 19 showed significant inhibitory activity for NLRP3 inflammasome activation, with the IC₅₀ against lactate dehydrogenase (LDH) release ranging from 0.08 to 4.78 μM. Further study revealed that compound 10 repressed IL-1β secretion and caspase-1 maturation in J774A.1 cell as well as blocked macrophage pyroptosis.

Callintegers A and B, Unusual Tricyclo[4.4.0.09,10]tetradecane Clerodane Diterpenoids from Callicarpa integerrima with Inhibitory Effects on NLRP3 Inflammasome Activation

Callintegers A (1) and B (2), unprecedented clerodane norditerpenoids based on a novel carbon skeleton, were isolated from Callicarpa integerrima. Compounds 1 and 2 possess a novel 6/6/6-fused tricyclic ring system. Their structures and absolute configurations were determined by quantum chemical calculations, spectroscopic analysis, and single-crystal X-ray diffraction methods. Biological evaluation showed that compound 2 inhibited IL-1β secretion in a dose-dependent manner with an IC₅₀ value of 5.5 ± 3.2 μM. Caspase-1 maturation and IL-1β secretion were also reduced, indicating that compound 2 impaired NLRP3 inflammasome activation.

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.

Study on The Anti-Inflammatory Effects of Callicarpa nudiflora Based on The Spectrum-Effect Relationship

Callicarpa nudiflora (C. nudiflora) is widely used to treat inflammation-related diseases in China. C. nudiflora mainly contains phenylethanol glycosides, flavonoids, triterpenes, diterpenes, iridoid glycosides, volatile oils, and other small molecules. Therefore, it is necessary to screen out anti-inflammatory active substances from C. nudiflora. In this paper, high-performance liquid chromatography was used to establish the fingerprint of C. nudiflora extracts. The anti-inflammation of C. nudiflora extracts were evaluated by the experiment of toes swelling in inflammatory rats. Then, the spectrum–effect relationship between the fingerprints and anti-inflammatory activities was researched by Pearson analysis and orthogonal partial least squares analysis to identify a group of anti-inflammatory compounds of C. nudiflora extracts. The differences of extracts are illustrated by principal component analysis and cluster analysis in pharmacological effects. Finally, 12 compounds, including catalpol (P1), caffeic acid (P2), protocatechuic acid (P9), 3,4-dihydroxybenzaldehyde (P10), forsythiaside E (P12), protocatechualdehyde isomers (P14), forsythiaside B (P15), rutin (P16), alyssonoside (P21), verbascoside (P22), 2′-acetyl forsythoside B (P24), and isorhamnetin (P32) by HPLC-DAD and UPLC-Q-TOF MS/MS, were determined as potential compounds for anti-inflammatory activity in C. nudiflora. In particular, six compounds were identified as active substances with the greatest anti-inflammatory potential. Moreover, all compounds were tested for anti-inflammatory experiments or anti-inflammatory literature retrieval. In this study, a method for rapid screening of potential anti-inflammatory active ingredients of C. nudiflora was established, which can provide a reference for the future study of active compounds of C. nudiflora.

Active Substances from Callicarpa nudiflora Exert Anti-Cervicitis Effects and Regulate NLRP3-Associated Inflammation

Luohuazizhu suppository is a Traditional Chinese Medicine used in clinic to treat cervicitis, which is prepared from Callicarpa nudiflora Hook. et Arn (C. nudiflora), an herbal Chinese medicine named Luohuazizhu. This study aimed to figure out the active constituents of C. nudiflora and the potential mechanism for its anti-cervicitis effect. The ethanol extract in C. nudiflora (CNE) and the different fractions of CNE extracted by petroleum ether (CNE-p), dichloromethane (CNE-d), and n-butanol (CNE-b) were tested in vivo for their anti-cervicitis effects. Then the isolated compounds from the CNE-p were tested in vitro for their anti-inflammatory activities. The results displayed that CNE-p, CNE-d, and CNE-b exhibited adequate anti-cervicitis effects, with CNE-p showing the highest efficacy. Further experiment demonstrated that CNE-p could significantly inhibit the expression of NLRP3 in vitro. Six diterpenoids obtained from the CNE-p showed the ability to regulate inflammatory factor levels in vitro. Among these compounds, compounds 1 (callicarpic acid A) and 2 (syn-3,4-seco-12S-hydroxy-15,16-epoxy-4(18),8(17),3(16),14(15)-labdatetraen-3-oic acid) were the most effective agents, and they also inhibited the expression level of NLRP3 in vitro. The results confirmed that C. nudiflora has significant anti-cervicitis effects and the diterpenoids were most likely to be its active components. These data provide scientific support for the clinic usage of Luohuazizhu suppository and the development of new agents in treating cervicitis.

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.

Callicarpa nudiflora Hook. & Arn.: A comprehensive review of its phytochemistry and pharmacology

ETHNOPHARMALOGICAL RELEVANCE

Callicarpa nudiflora Hook. & Arn. is a perennial evergreen shrub or low arbor in the Genus Callicarpa. Its dried aerial parts are used as traditional Chinese herbal medicine, Luo-hua-zi-zhu (Callicarpa nudiflora), which has been widely used in anti-bacteria and anti-ulcer in China (Commission, 2015; Development, 1994; Ming-Sheng, 2008).

AIM OF THE STUDY

The present paper reviewed findings in phytochemistry and pharmacology of Callicarpa nudiflora.

METHODS

Chinese and English studies on Callicarpa nudiflora were collected from databases including Web of Science, SciFinder, PubMed, Elsevier, and CNKI (Chinese), and the phytochemical and pharmacological studies of Callicarpa nudiflora were reviewed.

RESULTS

A total of 300 small molecules, 173 of which are volatile oils, have been isolated from Callicarpa nudiflora. These small molecules could be divided into seven structural types - phenylpropanoids, flavonoids, triterpenes, diterpenes, iridoid glycosides, volatile oils, and other small molecules. Different types of compounds in Callicarpa nudiflora were summarized as follow: a) diterpenoid compounds can inhibit the generation of nitric oxide (NO) for exerting the function of anti-inflammation; b) triterpene compounds can play a role of anti-thrombus via inhibiting platelet aggregation and oleanane type and arbutane type pentacyclic triterpenes have the hepatoprotective activities; c) iridoid glycosides have cytotoxicity to tumor cells, and phenylpropanoids compounds have an antioxidant effect and could improve the function of memory. Our group further studied the antiviral activities of Callicarpa nudiflora finding that it has significant effects on RSV, EV71, COXB5, and HSV-1.

Clerodane Diterpenoids from Callicarpa hypoleucophylla and Their Anti-Inflammatory Activity

Plants of the genus Callicarpa are known to possess several medicinal effects. The constituents of the Taiwan endemic plant Callicarpa hypoleucophylla have never been studied. Therefore, C. hypoleucophylla was selected for our phytochemical investigation. Two new clerodane-type diterpenoids, named callihypolins A (1) and B (2), along with seven known compounds were isolated from the leaves and twigs of the Lamiaceae plant C. hypoleucophylla and then characterized. The structures of compounds 1 and 2 were elucidated by spectroscopic data analysis, specifically, two-dimension nuclear magnetic resonance (NMR). The anti-inflammatory activity of compounds 1-9 based on the suppression of superoxide anion generation and elastase release was evaluated. Among the isolates, compounds 2-4 showed anti-inflammatory activity (9.52-32.48% inhibition at the concentration 10 μm) by suppressing superoxide anion generation and elastase release. Our findings not only expand the description of the structural diversity of the compounds present in plants of the genus Callicarpa but also highlight the possibility of developing anti-inflammatory agents from Callicarpa endemic species.

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.

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.

The Wound Healing Effect of Callicarpa nudiflora in Scalded Rats

Callicarpa nudiflora has been widely used in Li nationality medicine and treated burns and scalds in China. Our objective was to preliminarily elucidate healing effect and action mechanism of Callicarpa nudiflora water extract (CNE) on the scald wounds using an experimental rat mode. The second-degree scald wounds were induced by hot water on dorsal surface of Sprague-Dawley (SD) rats, and then they were randomly divided into 5 groups as follows: control (CON), Vaseline, Silver sulfadiazine (SSD), and Vaseline supplemented with 10% and 20% CNE groups. These ointments were employed locally once daily for 21 days. The macroscopic analysis showed CNE significantly accelerated the wound healing process and lowered the wound areas on days 15, 18, and 21 especially in 20% CNE group compared to CON group. Histopathological evaluation showed the mildly hypertrophic epidermis and the intact dermis in the 20% CNE-treated group were obviously distinguished from CON group on day 21. The CNE-treated groups had no obvious effect for TNF-α and IL-10 expressions on the second day and 14th day, while TGF-β1 expression level was decreased on the 21th day and VEGF level was increased on the 7th day in the 20% CNE group. Furthermore, the expression level of Samd3 was strongly inhibited in 20% CNE group. These findings suggested that the CNE can enhance the wound healing and skin repair in deep second-degree scald rats and thus support its traditional use.

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

Nine previously undescribed seco-labdane diterpenoids, nudiflopenes A-I, were isolated from the leaves of Callicarpa nudiflora. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of these compounds were established by the modified Mosher's method and experimental and calculated electronic circular dichroism spectra. Nudiflopenes A-I belong to the class of seco-labdane diterpenoids. All of the isolates showed inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production in murine microglial BV-2 cells. The possible mechanism of NO inhibition of some bioactive compounds was also investigated using molecular docking, which revealed interactions of bioactive compounds with the inducible nitric oxide synthase (iNOS) protein.

Three New Abietane-Type Diterpenoids from Callicarpa macrophylla Vahl

Three new abietane-type diterpenoids, named callicapoic acid M3 (1), callicapoic acid M4 (2) and callicapoic acid M5 (3), were isolated from the Callicarpa macrophylla Vahl. Their structures were established by spectroscopic techniques (IR, UV, MS, 1D and 2D NMR). All the isolated three compounds were evaluated for inhibitory activity on NO production in LPS-activated RAW 264.7 macrophage cells by using MTT assays. Compounds 1, 2 and 3 showed potent inhibitory activity, with inhibition rates of 34.47–40.13%.

Lignan Glucosides from the Stem Barks of Illicium difengpi

In this study, four new lignan glucosides, named difengpiosides A–D (1–4), were isolated from the stem barks of Illicium difengpi, together with seven known compounds 5–11. Their structures were identified on the basis of spectroscopic analyses (1D and 2D NMR, HRESIMS, CD) and a comparison with literature data. All the compounds were evaluated for their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 cells.

Bioactive Diterpenoids from the Leaves of Callicarpa macrophylla

A phytochemical investigation of the leaves of Callicarpa macrophylla led to the isolation of five new diterpenoids (1-5), macrophypenes A-E, and nine known analogues (6-14). The structures of 1-5 were established on the basis of extensive analysis of NMR spectroscopic data, X-ray diffraction data, and experimental and calculated electronic circular dichroism spectra. Compound 1 is a spiroditerpenoid with a novel skeleton, and compound 5 is a rare ent-abietane diterpenoid possessing a peroxide bridge. Compounds 1, 5-7, and 11-14 stimulate nerve growth factor mediated neurite outgrowth from PC12 cells.