[A new sesquiterpene from Syringa oblata].

In this study, the chemical components of ethanol extract from the aromatic parts of Syringa oblata were systematically separated and purified by silica gel column chromatography, thin layer plate preparation and liquid phase preparation. Combined with ultraviolet analyzer(UV), infrared analyzer(IR), nuclear magnetic resonance analyzer(NMR), high resolution mass spectrometer(HR-ESI-MS), X-ray diffraction and other spectrum technology as well as literature physicochemical data comparison methods for structural identification, a total of 10 compounds were identified. They were identified as oblatanoid D(1),(-)-T-muurolol(2), oblatanoid E-G(3-5), 14-noreudesma-3-hydroxy-3-en-2,9-dione(6), 1-isopropyl-2,7-dimethylnaphthalene(7), isocoradiol(8), α-calacorene(9), cadin-4-en-1-ß-ol(10). Compound 1 is a new sesquiterpene compound that has not been reported, and the other 9 compounds are isolated from S. oblata for the first time. The compound 1 has a significant protective effect on the LPS-induced inflammatory injury model of RAW264.7 cells.

Dimeric eremophilane-type sesquiterpenoids from the peeled stems of Syringa pinnatifolia.

A continued phytochemical investigation guided by 1H NMR and LC-MS data on the ethanol extract from the peeled stems of Syringa pinnatifolia Hemsl. led to the isolation of 16 undescribed dimeric eremophilane sesquiterpenoids, namely syringenes R-Z (1-9) and A1-G1 (10-16). These structures were elucidated by extensive analysis of spectroscopic data, including HRESIMS, NMR, quantum-mechanics-based computational analysis of NMR chemical shifts, and single-crystal X-ray diffraction analyses, and a concise rule for determination of relative configuration of angular methyl was proposed. The results of the cardioprotective assay demonstrated that 3 exhibits a protective effect against hypoxia-induced injuries in H9c2 cells. This effect was observed at a concentration of 10 µM, with a protective rate of 28.43 ± 11.80%.

9,9'-epoxylignans from Syringa pinnatifolia: A typical case of stereochemical assignment by a quantum chemical calculation with MAEΔΔδ parameter.

In the current study, twenty-two stereochemical 9,9'-epoxylignans including 19 undescribed ones were isolated from the ethanol extract of Syringa pinnatifolia in our continuing effort to understand the overall chemical spectrum of this species. These isolates were structurally elucidated by extensive spectroscopic data analysis, X-ray diffraction, modified Mosher's method, and quantum chemical calculations. Meanwhile, the utilization of 13C NMR calculation and the MAEΔΔδ parameter facilitated the stereochemical assignment of groups of lignan stereoisomers. The 13C NMR data were corrected by the averaged errors at each corresponding carbon position in groups of lignan stereoisomers, which improved the theoretic 13C NMR calculation. The finding of the stereochemical structures of 9,9'-epoxylignans is significant. It is helpful to determine the absolute configurations of molecules with the similar core. In addition, these lignans exhibited potential cardioprotective activities on H9c2 cardiomyocytes in vitro and presented significant antioxidant effect.

Alashanines A-C, Three Quinone-Terpenoid Alkaloids from Syringa pinnatifolia with Cytotoxic Potential by Activation of ERK.

Three quinone-terpenoid alkaloids, alashanines A-C (1-3), possessing an unprecedented 6/6/6 tricyclic conjugated backbone and quinone-quinoline-fused characteristic, were isolated from the peeled stems of Syringa pinnatifolia. Their structures were elucidated by analysis of extensive spectroscopic data and quantum chemical calculations. A hypothesis of biosynthesis pathways for 1-3 was proposed on the basis of the potential precursor iridoid and benzoquinone. Compound 1 exhibited antibacterial activities against Bacillus subtilis and cytotoxicity against HepG2 and MCF-7 human cancer cell lines. The results of the cytotoxic mechanism revealed that compound 1 induced apoptosis of HepG2 cells through activation of ERK.

The Ethanol Extract of Syringa oblata Heartwood, a Mongolian Folk Medicine Containing Major Lignans, Exerts Analgesic and Sedative Effects on Mice.

The heartwood of Syringa oblata Lindl. (SO) is one of Mongolian folk medicines to treat insomnia and pain, while its pharmacological evaluation and underlying mechanism remain unclear. In this study, the sedative effect of ethanol extract of SO (ESO) was evaluated with the locomotor activity test and the threshold dose of pentobarbital sodium-induced sleep test in mice, and the hot plate test, acetic acid-induced writhing test, and formalin test in mice were used to evaluate its analgesic effect. The underlying mechanism of ESO analgesia was explored by RT-PCR and western blot analysis, which is associated with the regulation of the NF-κB signaling pathway. Besides, the main constituents of ESO were characterized by LC/MS data analysis and comparison with isolated pure compounds. The current findings brought evidence for clinical application and further pharmacological and phytochemical studies on SO.

Diverse lignans with protective effect against hypoxia/oxidative injuries to H9c2 cells from Syringa pinnatifolia Hemsl.

A bioactivity-guided fractionation on the phenolic fractions from the peeled stems of Syringa pinnatifolia Hemsl., one of representative Mongolian folk medicine in China, led to the isolation and structural determination of 11 undescribed lignans and 12 known ones. These lignans cover diverse types, among them syringanones A and B represent an unprecedented carbon skeleton (proposed syringanane) and alashanenol A possesses a rare bicyclo [3.3.1]nonadienemethanol core. Their structures were established by extensive spectroscopic data analysis, X-ray diffraction, and quantum chemical calculations. All isolates were evaluated for their cardioprotective activities on H9c2 cardiomyocytes in vitro. The results showed that five lignans exhibited the protective effects against hypoxia-induced injury at the concentrations of 1.2-40 µM and six lignans exhibited anti-oxidative stress injury at 10-40 µM. These findings account to some extend for the traditional therapeutic effects of S. pinnatifolia for the treatment of ischemic heart diseases in clinic.

Zerumbone, a major sesquiterpene from Syringa pinnatifolia Hemsl., exerts the sedative effect by regulating GABAergic nervous system.

ETHNOPHARMACOLOGICAL RELEVANCE: Zerumbone (ZER) is a humulane sesquiterpenoid isolated from Syringa pinnatifolia Hemsl. (SP), its content accounts for 64.7% of volatile oil and 0.86% of total ethanol extract (TEE), representing one of characteristic ingredient of SP. As a representative Mongolian medicine with anti-"Khii", anti-asthma, and clearing-heat effects, SP has been used for the treatment of cardiovascular diseases, upset, insomnia, and other symptoms. AIM OF STUDY: Previous results showed that TEE has sedative effect, but the pharmacological substances and its sedative mechanism remains unclear. This study aims to determine whether ZER, as one of major and characteristic sesquiterpenoids of SP, contributes to the sedative effect of SP and its underlying mechanism. MATERIALS AND METHODS: Locomotor activity and threshold dose of pentobarbital sodium sleep experiments were used to evaluate the sedative effects in mice. ELISA assay was used to examine the level of GABA/Glu ratio in rats hippocampus, cortex and hypothalamus tissue. The binding ability of ZER with glutamic acid decarboxylase 67 (GAD67) and Gephyrin protein were predicted by molecular docking. Western blot and Immunohistochemistry assay were used to determine the expression of GABAergic nerve system related proteins (GAD67, Gephyrin) in rat's hypothalamus. ZER was co-administrated with flumazenil and bicuculline (GABAA antagonist) to determine whether it acts on GABAA receptor. Furthermore, MQAE assay was used to test the effect of ZER on the chloride ion concentration in cerebellar granule cells. RESULTS: Current data demonstrated that ZER dose-dependently (5-20 mg/kg) reduces the locomotor activity and sleep latency of mice, and extend sleeping time of mice. The results of ELISA showed that ZER increases the level of GABA/Glu in rats brain tissue, in particular in hypothalamus. Molecular docking results revealed that ZER has a strong affinity to GAD67 and Gephyrin protein. The Western blot and Immunohistochemistry data indicated that ZER up-regulates the expression of GAD67 and Gephyrin protein in rat's hypothalamus. Antagonism test results demonstrated that flumazenil and bicuculline reverse the effect of ZER on threshold dose of pentobarbital sodium sleep experiments. In addition, ZER also could dose-dependently (5-20 µM) increase the chloride ion concentration in cerebellar granule cell, suggesting that ZER induces the opening of chloride channel, exerts central inhibitory effect. CONCLUSION: ZER has a significant sedative effect in mice and rat, and the effect is associated with GABAergic nervous system. The present results suggest that ZER, as one of the major bioactive ingredients of SP, contributes to the sedative effect and provide substantial evidence for its traditional use of anti-"Khii" in clinic of Syringa pinnatifolia.

Establishment of fingerprint and mechanism of anti-myocardial ischemic effect of Syringa pinnatifolia.

This study established the fingerprint of Syringa pinnatifolia Hemsl. (SP), analyzed the SP ingredients absorbed into the rats blood, and evaluated its anti-myocardial ischemic effect to provide a scientific basis for the follow-up development and research of SP and lay a foundation for its clinical application using ultra-performance liquid chromatography-Q Exactive-mass spectrometry and GC-MS. Myocardial infarction was induced in rat by ligating the left anterior descending branch of the rat coronary artery, and SP alcohol extract was administered to evaluate its anti-myocardial ischemic effect. We analyzed the SP ingredients absorbed into the rats blood, screened the active compounds, established a database of SP anti-myocardial ischemic targets, and explored the possible mechanism of SP in treating myocardial infarction using bioinformatics. The rats were examined using echocardiography, serum biomarkers were determined, and pathological changes were observed by histopathological examination. TUNEL staining was performed to detect the apoptotic level of cells, and Western blot and quantitative real-time polymerase chain reaction were performed to detect the expression levels of Bcl-2, Bax, and Caspase-3 in heart tissues. In the fingerprint of SP, 24 common peaks were established, and the similarity evaluation results of 10 batches of SP were all >0.9. Ultra-performance liquid chromatography-Q Exactive-mass spectrometry and GC-MS detected 17 active ingredients in the drug-containing serum, including terpenoids, flavonoids, phenols, phenylpropanoids, and phenolic acids, the most abundant of which was resveratrol. Enrichment analysis of SP targets against myocardial ischemia revealed that key candidate targets of SP were significantly enriched in multiple pathways associated with apoptosis. Resveratrol was administered to the successfully modeled rats, and the results showed that the resveratrol group significantly decreased left ventricular end-diastolic diameter and left ventricular end-systolic diameter and significantly increased ejection fraction and fractional shortening in all groups compared with the model group. Resveratrol significantly decreased the levels of creatine kinase isoenzyme and lactate dehydrogenase in serum compared to the model group (P < 0.001). Hematoxylin-eosin staining of rat myocardial tissue showed that all lesions were reduced under microscopic observation in the resveratrol group compared with the model group. Real-time polymerase chain reaction and Western blot results showed that the resveratrol group downregulated the expression of the proapoptotic factor Bax, upregulated the expression of the antiapoptotic factor Bcl-2, and decreased the expression of Caspase-3. The established fingerprints are accurate, reliable, and reproducible and can be used as an effective method for quality control of the herbs. The anti-myocardial ischemia effect of SP is that resveratrol improves cardiac function and inhibits cardiomyocyte apoptosis to protect cardiomyocytes. The present study provides ample evidence for the clinical use of SP, suggesting that this drug has great potential in the treatment of ischemic heart disease.

Syringenes M - Q, Eremophilane Sesquiterpenoid Dimers from the Peeled Stems of Syringa pinnatifolia.

As a part of systematic studies on Syringa pinnatifolia, a continued phytochemical investigation guided by 1 H-NMR and LC/MS data on the ethanol extract afforded five new dimeric eremophilane sesquiterpenoids, namely syringenes M-Q (1-5). These structures were elucidated by extensive analysis of spectroscopic data, including infrared (IR), high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), nuclear magnetic resonance (NMR), quantum-mechanics-based computational analysis of NMR chemical shifts, and single-crystal X-ray diffraction. Compounds 4 and 5 showed inhibitory activities against NO production induced by lipopolysaccharide in RAW264.7 macrophage cells, with IC50 values of 5.1 and 9.3 µM, compared to positive control indomethacin (IC50 33.6 µM). These dimeric eremophilane sesquiterpenoids may be potential markers for discriminating this species from the genus Syringa and the Oleaceae family.

Syringenes A-L: Bioactive dimeric eremophilane sesquiterpenoids from Syringa pinnatifolia.

A phytochemical investigation guided by 1H NMR and LC-MS data on the ethanol extract of Syringa pinnatifolia stems led to the isolation of 11 new dimeric eremophilane sesquiterpenoids, namely, syringenes A-K (1-11) and one known analog (12, syringene L). These structures were elucidated by extensive analysis of spectroscopic data, single-crystal X-ray diffraction, and computational methods. Biological assays revealed that 1-12 exhibited different degrees of anti-inflammatory effects, and 5 and 6 showed significant cytotoxicity against human hepatoma HepG2 cells with IC50 values of 12.3 and 12.9 µM, respectively. Furthermore, flow cytometry assays and western blot analysis revealed that 5 and 6 promoted the apoptosis of HepG2 cells by activating ERK. Finally, the molecular docking analysis implied that the carbonyl and hydroxy groups at the C-11/C-6' of 5 and 6 had a good binding affinity with ERK.

Eremophilane and Cadinene Sesquiterpenes from Syringa oblata and Their Protective Effects against Hypoxia-Induced Injury on H9c2 Cells.

Seven sesquiterpenes including four eremophilanes (1-4) and three cadinenes (5-7), were isolated from the heartwood of Syringa oblata Lindl. Among them, three new eremophilane-type sesquiterpenes were identified and named oblatanoids A-C (1-3), respectively. Their structures were established by extensive analyses of spectroscopic methods, and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. All these new compounds were evaluated for protective effects against hypoxia-induced injury on H9c2 cells, and 1-3 exhibited significantly protective activities toward H9c2 cells in vitro.

A pair of enantiomeric dimers with an unprecedented skeleton from stem barks of Syringa pinnatifolia.

A pair of enantiomers with a rearranged dimeric phenylethanol skeleton, namely (±)-disyringol A (1a and 1b), were isolated from the stem barks of Syringa pinnatifolia. The structures were established using IR, UV, MS, and NMR data, and their absolute configurations were resolved by experimental and calculated ECD data analysis. Their biosynthetic pathway was speculated on the basis of a phenylethanoid precursor and was proved by a total synthesis. Compounds 1a and 1b showed the inhibition against NO production in LPS-induced RAW264.7 cells with their IC50 values of 27.28 and 24.64 µM, respectively, however no protective effect was observed against the hypoxia-induced injuries to H9c2 cells.

A comparative study of echinacoside, oleuropein content and antioxidant properties of different solvent extracts from Syringa pubescens Turcz.

Syringa pubescens Turcz is commonly used folk medicinal herb in west of Henan Province of China. In this work, water and various concentration of methanol, ethanol and acetone in water were used as solvent to extract echinacoside and oleuropein from S. pubescens. The antioxidant properties of different extracts were evaluated using various in vitro assays. The highest yields of echinacoside and oleuropein were obtained by using the 60% aqueous methanol and 80% aqueous ethanol, respectively. The extracts of water, aqueous ethanol or methanol showed strong antioxidant abilities. Furthermore, the high correlation between echinacoside content and antioxidant properties was found. The contribution of oleuropein content was not significant to antioxidant abilities. These findings indicate that S. pubescens can be used as a new natural antioxidant resource.

Six new secoiridoid glycosides from the stem barks of Syringa Reticulata (Bl.) Hara.

Six new secoiridoids, syrretosides E-J (1-6) and four known secoiridoids (7-10), were isolated from the stem barks of Syringa reticulata. Their structures were established by the 1D and 2D NMR spectra, HR-ESI-MS, and comparison with the literature. The cytotoxicity of the isolated monomeric compounds against RAW264.7 cells was investigated by the CCK8 assay, and the results showed that the individual compounds were not cytotoxic to RAW264.7. The anti-inflammatory activity of these compounds was evaluated using the LPS-induced RAW264.7 inflammatory cell model and the results showed that compounds 3-7 and 9 showed varying degrees of anti-inflammatory activity.

Four new secoiridoids from the stem barks of Syringa reticulata (Bl.) Hara.

Four new secoiridoids, syrretoside A (1), syrretoside B (2), 5ß, 8ß-syrretaglucone C(3), 5ß, 8α-syrretaglucone C (4), together with eight known secoiridoids (5-12), were isolated from the stem barks of Syringa reticulata (Bl.) Hara. The structures of isolated compounds were established based on the physical and chemical means, NMR spectroscopy, high-resolution mass spectrometry (HR-ESI-MS), and circular dichroism spectrum (CD), as well as in comparison with the literature. The cytotoxicity of isolated compounds was investigated using CCK8 assay, which showed that these compounds had different degrees of inhibitory effect on two human tumor (MGC803, LN229) cell lines.

Alashanoids O-S, seco-Humulane and Eremophilane Sesquiterpenoids from Syringa pinnatifolia.

Five new sesquiterpenoids, alashanoids O-S (1-5), along with three known analogs (6-8) were isolated from the peeled stems of Syringa pinnatifolia. Their structures were elucidated by analysis of extensive spectroscopic data including ESI-MS, 1D, 2D NMR. The absolute configurations were determined by comparing its experimental and calculated electronic circular dichroism, calculated OR, calculated NMR, and single crystal X-ray diffraction data analysis. Compounds 1 and 2 belong to the seco-humulane type and possess a rare 13-membered oxygen heterocycle framework, and 3-5 belong to eremophilane-type. Compounds 1, 2, and 5 showed inhibitory effects against NO production in LPS-induced RAW264.7 macrophage cells with its IC50 values of 11.86±2.34, 72.08±7.72, and 69.22±15.29 µM, respectively, compared with the positive control indomethacin (IC50 =31.52 µM).

Synthesis and Olfactory Properties of Seco-Analogues of Lilac Aldehydes.

Lilac aldehydes are considered as principal olfactory molecules of lilac flowers. We have designed, prepared, and evaluated a set of racemic seco-analogues of such natural products. The synthesis employs commercially available α-chloroketones as substrates that are transformed in four steps to target compounds. Their qualitative olfactory analysis revealed that the opening of the tetrahydrofuran ring leads to a vanishing of original flowery scent with the emergence of spicy aroma accompanied by green notes, and/or fruity aspects of novel seco-analogues. These results suggest the important osmophoric role of THF moiety for the generation of the typical flowery aroma associated with lilac aldehydes.

Chemical Profile, Cytotoxic Activity and Oxidative Stress Reduction of Different Syringa vulgaris L. Extracts.

Syringa vulgaris L. (common lilac) is one of the most popular ornamental species, but also a promising not comprehensively studied source of bioactive compounds with important therapeutic potential. Our study was designed to characterize the chemical composition and to assess the antioxidant and cytotoxic properties of ethanolic extracts obtained from S. vulgaris L. flowers, leaves, bark, and fruit. The chemical profile of the ethanolic extracts was investigated using chromatographic (HPLC-DAD-ESI+, GC-MS) and spectral (UV-Vis, FT-IR) methods, while the protective effect against free radicals was evaluated in vitro by different chemical assays (DPPH, FRAP, CUPRAC). The cytotoxic activity was tested on two tumoral cell lines, HeLa, B16F10, using the MTT assay. Significant amounts of free or glycosylated chemical components belonging to various therapeutically important structural classes, such as phenyl-propanoids (syringin, acteoside, echinacoside), flavonoids (quercetin, kaempferol derivatives) and secoiridoids (secologanoside, oleuropein, 10-hydroxy oleuropein, demethyloleuropein, syringalactone A, nuzhenide, lingstroside) were obtained for the flowers, leaves and bark extracts, respectively. Furthermore, MTT tests pointed out a significant cytotoxic potential expressed in a non-dose-dependent manner toward the tumoral lines. The performed methods underlined that S. vulgaris extracts, in particular belonging to flowers and leaves, represent valuable sources of compounds with antioxidant and antitumoral potential.

Inhibitory Effect of LGS and ODE Isolated from the Twigs of Syringa oblata subsp. dilatata on RANKL-Induced Osteoclastogenesis in Macrophage Cells.

Osteoblasts and osteoclasts play a pivotal role in maintaining bone homeostasis, of which excessive bone resorption by osteoclasts can cause osteoporosis and various bone diseases. However, current osteoporosis treatments have many side effects, and research on new treatments that can replace these treatments is ongoing. Therefore, in this study, the roles of ligustroside (LGS) and oleoside dimethylester (ODE), a natural product-derived compound isolated from Syringa oblata subsp. dilatata as a novel, natural product-derived osteoporosis treatments were investigated. In the results of this study, LGS and ODE inhibited the differentiation of receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced RAW264.7 cells into osteoclasts without cytotoxicity, and down-regulated the activity of TRAP, a specific biomarker of osteoclasts. In addition, it inhibited bone resorption and actin ring formation, which are important functions and features of osteoclasts. Also, the effects of LGS and ODE on the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) and phosphoinositide 3-kinases (PI3K)/ protein kinase B (Akt)/mechanistic target of rapamycin (mTOR) signaling pathways that play important roles in osteoclast differentiation were evaluated. In the results, LGS and ODE downregulated the phosphorylation of RANKL-induced MAPK and PI3K/Akt/mTOR proteins in a concentration-dependent manner, translocation of NF-κB into the nucleus was inhibited. As a result, the compounds LGS and ODE isolated from S. oblate subsp. dilatata effectively regulated the differentiation of RANKL-induced osteoclasts and inhibited the phosphorylation of signaling pathways that play a pivotal role in osteoclast differentiation. Therefore, these results suggest the possibility of LGS and ODE as new natural product treatments for bone diseases caused by excessive osteoclasts.

Effect of Syringopicroside Extracted from Syringa oblata Lindl on the Biofilm Formation of Streptococcus suis.

Syringopicroside is a natural drug with antibacterial activity, which is the main ingredient of Syringa oblata Lindl (S. oblata). In order to further develop the application of S. oblata and evaluate the ability of syringopicroside against Streptococcus suis (S. suis), this investigation first applied an ultrasonic-assisted method to extract syringopicroside, and then response surface methodology (RSM) was performed to get the optimum condition. Based on RSM analysis, a second-order polynomial equation about the syringopicroside yield and four variables, including ultrasonic power, time, temperature, and liquid-to-solid ratio, was purposed. Through RSM prediction and model verification experiments, the optimum conditions were determined, as follows: ultrasonic time was 63 min, temperature was 60 °C, a liquid-to-solid ratio was set to 63 mL/g, and ultrasonic power was 835 W. Under this condition, a high syringopicroside yield was obtained (3.07 ± 0.13 mg/g), which was not significantly different with a predicated value. After separation and purification by HPD 500 microporous resin, then mass spectrum was applied to identify the main ingredient in aqueous extract. A minimal inhibitory concentration (MIC) assay revealed the value against S. suis of syringopicroside was 2.56 µg/µL and syringopicroside with sub-inhibitory concentrations that could effectively inhibit biofilm formation of S. suis. Besides, scanning electron microscopy analysis indicated syringopicroside could destroy the multi-layered aggregation structure of S. suis. Finally, molecular docking analysis confirmed that syringopicroside was combined with Orfy protein of S. suis through hydrogen bonds, hydrophobic interaction, and π-π stacking.