Design, synthesis and anti-inflammatory activity of diterpenoid alkaloids and non-steroidal anti-inflammatory drug hybrids based on molecular hybridization strategy.

Molecular hybridization is a widely employed approach in pharmaceutical chemistry for modifying drugs with the aim of improving pharmacological efficacy and reducing adverse effects. A prime example of this is the case of benorylate, which was created by combining aspirin and acetaminophen, two non-steroidal anti-inflammatory drugs (NSAIDs). Diterpenoid alkaloids, which exhibit potent anti-inflammatory activity, have limitations in their application due to their toxicity and side effects. Thus, we aimed to design new anti-inflammatory lead compounds through the molecular hybridization of the anti-inflammatory active skeletons (lappaconitine, aconorine, and bulleyaconitine A) of diterpenoid alkaloids with classical NSAIDs. In this study, we synthesized 25 diterpenoid alkaloid derivatives with NSAIDs, organized into four series. Among these derivatives, lappaconitine derivative 1e demonstrated the strongest inhibition of lipopolysaccharide (LPS)-induced NO production in RAW 264.7 cells with minimal cytotoxicity. Additionally, 1e effectively suppressed the inflammatory response induced by carrageenan in vivo, with a swelling rate of only 1%. This anti-inflammatory potency was found to be significantly superior to that of naproxen. The molecular docking analysis revealed that the binding affinity of 1e was scored as -10.3 kcal/mol, suggesting that it forms a stable complex with cyclooxygenase-2 (COX-2). Therefore, compound 1e holds potential as a lead anti-inflammatory compound that could be further developed.

Metabolite Profiling of Talatisamine in Heart Tissue After Oral Administration and Analysis of Cardiac Bioactivities.

The lateral roots of the Aconitum carmichaelii ("Fuzi") have been used for centuries as a cardiotonic in China. The diterpenoid alkaloid talatisamine (TA) is a major bioactive component of Fuzi, but the identity and bioactivities of the TA metabolites have not been examined in detail. In this study, metabolite profiling of TA was performed in rat heart by UPLC-MS following oral administration. Metabolites were identified by comparing protonated molecules, fragmentation patterns, and chromatographic behaviors with those of standard compounds. Metabolites of TA were then prepared and tested for cardiotonic activity on isolated frog hearts. The metabolite cammaconine, a C19 diterpenoid alkaloid with a hydroxyl group at C-18, exhibited substantial cardiotonic activity during frog heart perfusion. To further investigate the structure-cardiac effect relationships, a series of C19-diterpenoid alkaloids with 18-OH were prepared. Eight tested compounds (5: -12: ) demonstrated measurable cardioactivity, of which compound 5: with an N-methyl group and compound 7: with a methoxy at C-16 showed stronger effects on ventricular contraction than the other compounds. Thus, 18-OH is a critical structural feature determining cardiotonic activity, and efficacy is improved by the presence of N-methyl or methoxy at C-16. Preliminary mechanistic studies suggested that the cardiotonic effect of compound 5: is mediated by enhanced cellular calcium influx. Metabolites of TA with these structural features may be useful therapeutics to prevent heart failure.

Two new dammarane triterpenoid saponins from the leaves of Cyclocarya paliurus.

Two undescribed dammarane triterpenoid saponins, cypaliurusides O and P (1 and 2), were isolated from the ethanol extracts of the leaves of Cyclocarya paliurus. Bioactivity assay results showed that compound 1 has potential cytotoxic activities against selected human cancer cell lines in vitro, with IC50 values ranging from 14.55 ± 0.55 to 22.75 ± 1.54 µM. Compound 1 showed better antitumor activity against HepG2 cells with IC50 of 14.55 ± 0.55 µM. In addition, compound 2 showed no obvious antitumor activity.

[Diterpenoid alkaloids from roots of Aconitum kongboense].

The chemical constituents from the roots of Aconitum kongboense were studied. Twenty-five diterpenoid alkaloids were isolated from the 95% methanol extract of the roots of A. kongboense by silica gel, reverse-phase silica gel and basic alumina column chromatography. They included a new aconitine-type diterpenoid alkaloid, named as kongboensenine(1), and twenty-four known ones(2-25), i.e., acotarine F(2), acotarine G(3), 14-acetyltalatisamine(4), talatisamine(5), indaconitine(6), yunaconitine(7), chasmanine(8), 6-epi-foresticine(9), homochasmanine(10), 8-deacetyl-yunaconitine(11), chasmaconitine(12), ajaconine(13), franchetine(14), ezochasmanine(15), crassicautine(16), 14-O-deacylcrassicausine(17), genicunine A(18), falconeridine(19), sachaconitine(20), liljestrandisine(21), 8-methyl-14-acetyltalatisamine(22), kongboendine(23), 14-benzoylchasmanine(24) and pseudaconine(25). Their structures were elucidated by common spectroscopic methods including high-resolution electrospray ionization mass spectrometry(HR-ESI-MS) and nuclear magnetic resonance(NMR) techniques. Compounds 2-4, 10, 13, 15-19 and 21-22 were isolated from this plant for the first time. Experimental results showed that all compounds did not have a significant inhibitory activity against acetylcholinesterase(AChE).

Three New C19-Diterpenoid Alkaloids from Aconitum novoluridum.

Three new aconitine-type C19-diterpenoid alkaloid namely novolunines A (1), B (2), and C (3), along with fifteen known diterpenoid alkaloids were isolated from the roots of Aconitum novoluridum, whose phytochemical investigations have never been reported before. The structures of three new alkaloids were established on the basis of spectra data (high-resolution electrospray ionization (HR-ESI)-MS, IR, one dimensional (1D)- and 2D-NMR). Noteworthily, novolunines A (1) and B (2) are two diterpenoid alkaloids bearing conformational isomerism. In addition, the diterpenoid alkaloids 1-3 did not show any anti-acetylcholinesterase (AChE) or anti-inflammatory activities.

Phloroglucinol derivatives rhotomensones A-G from Rhodomyrtus tomentosa.

Undescribed phloroglucinol derivatives, rhotomensones A-G, and a known derivative rhodomyrtosone B, were isolated from the leaves of Rhodomyrtus tomentosa. Rhotomensones A-D and G have unreported structural characteristics, in which rhotomensone A substitutes a benzene ring, rhotomensones B-D are bonded with a 2-methylbutanoyl group, and rhotomensone G has two fewer carbons. The structures of these compounds were determined by NMR spectroscopy, circular dichroism (CD) spectroscopy and X-ray crystallography. The inhibitory activities against α-glucosidase of rhotomensones E and F were evaluated in vitro, with IC50 values of 0.50 ± 0.14 mg/mL and 0.07 ± 0.02 mg/mL. Moreover, rhodomyrtosone B showed significant antibacterial activity against some bacteria, with MIC values ranging from 0.50 to 16.00 µg/mL.

Anti-hepatitis B virus activity and hepatoprotective effect of des(rhamnosyl) verbascoside from Lindernia ruellioides in vitro.

Although clinically approved hepatitis B virus (HBV) polymerase inhibitors (lamivudine-3TC, entecavir, etc.) serve as effective therapeutics, the virus can easily generate resistance to them. Therefore, the treatment of HBV infection remains a public health problem. Numerous studies have shown that natural products have prospective anti-HBV activity. The purpose of this study was to isolate and extract des(rhamnosyl) verbascoside from Lindernia ruellioides (Colsm.) Pennell and explore its anti-HBV and hepatoprotective effects. Anti-HBV activity was evaluated in HepG2.2.15 cells, a human hepatocellular carcinoma cell line with HBV-stable infection, and its protective effect was evaluated in HL-7702 cells, a normal human liver cell line. HepG2.2.15 cells maintained normal growth morphology within the selected concentration range of des(rhamnosyl) verbascoside. It also inhibited the expression of HBV antigens and HBV DNA in a dose- and time-dependent manner in vitro. Further, western blot experiments showed that it could downregulate HBV X protein (HBx) expression in a dose-dependent manner. In the H2 O2 -induced hepatocyte injury model, the cell-survival rate of the HL-7702 cells with the highest drug dose reached 85.25%, which was significantly improved compared with that of the model group. Most of the cells returned to normal morphology, showing polygonal or fusiform structures. Thus, it may be stated that des(rhamnosyl) verbascoside exhibits anti-HBV activity and hepatoprotective effects in vitro and may exert an anti-HBV effect via antigen inhibition, HBV DNA secretion, and HBx protein expression.

An unexpected Lewis acid-mediated structural conversion of a Euphorbia Diterpene: From a Lathyrane skeleton to diterpene pseudo-alkaloids.

Three types of new Euphorbia diterpene pseudo-alkaloids possessing 5/6/7/3 (1), 5/6/6/4 (2-5), and 5/7/7/4 (6-7) fused ring skeletons were obtained through an unexpected BF3·Et2O/CH3CN-mediated structural conversion and amination of lathyrane diterpene (Euphorbia factor L1), in which the solution acetonitrile had been introduced into the Euphorbia diterpene as a nitrogen source and tandem amination/oxirane-opening (cyclopropane-opening)/oxa-Michael addition reaction was involved in the conversion. The structures of new Euphorbia diterpene pseudo-alkaloids were elucidated by a combination of spectroscopic data and single crystal X-ray diffraction analysis. The basic skeletons of Euphorbia diterpene pseudo-alkaloids 1 and 2-5 could fall into the structural types of euphoractine B and euphoractine A diterpenes, respectively, suggesting the possible biogenetic pathway relationship between lathyrane diterpene with euphoractines A and B types diterpenes. Pseudo-alkaloids 1-7 did not show any potential cytotoxicity against several tumor cell lines.

Kusnezosines A-C, three C19-diterpenoid alkaloids with a new skeleton from Aconitum kusnezoffii Reichb. var. gibbiferum.

Kusnezosines A-C (1-3), three C19-diterpenoid alkaloids with a new skeleton which featured an undescribed lactone type D-ring, were isolated from the roots of Aconitum kusnezoffii Reichb. var. gibbiferum. Kusnezosines A-C are the first naturally occurred C19-diterpenoid alkaloids which possessing an unprecedented lactone D ring, this structure was formed by the cleavage of bond between C-15 and C-16 and a successive lactonization. Their structures were established on the basis of comprehensive spectroscopic data analysis. Besides, another 12 known ones were isolated from this plant, analgesic activity tests on the isolated alkaloids were also carried out.

Antitumor activity of nervosine VII, and the crosstalk between apoptosis and autophagy in HCT116 human colorectal cancer cells.

Nervosine VII is one of the known saturated pyrrolizidine alkaloids isolated from the plant of Liparis nervosa. This is first study to investigate the antitumor activity of nervosine VII in vitro, and the results indicated that nervosine VII induced autophagy and apoptosis in HCT116 human colorectal cancer cells. Mechanistic studies showed that nervosine VII-induced apoptosis was associated with the intrinsic pathway by the activation of caspase-9, -3 and -7. Autophagy induced by nervosine VII was characteristic with the regulation of autophagic markers including the increase of LC3-II and beclin 1 proteins, and the decrease of p62 protein. Nervosine VII simultaneously induced autophagy and apoptosis by activated MAPKs signaling pathway including JNK, ERK1/2 and p38, suppressing the p53 signaling pathway.

Fifteen new diterpenoid alkaloids from the roots of Aconitum kirinense Nakai.

Extensive phytochemical investigation from the roots of Aconitum kirinense Nakai led to the identification of fifteen new compounds, including four ranaconitine type C18-diterpenoid alkaloids (kirisines A-D, 1-4), one lappaconitine type C18-diterpenoid alkaloid (kirisine E, 5), seven denudatine type C20-diterpenoid alkaloids (kirisines F-L, 6-12), and three napelline type C20-diterpenoid alkaloids (kirisines M-O, 13-15), together with 25 known ones. Their structures were elucidated by extensive spectroscopic analyses. Among them, compounds 1 and 2 are rare diterpenoid alkaloid with 9,14-methylenedioxy group, and the latter also has a rare chloro-substituent. The diterpenoid alkaloids isolated were C18, C19 and C20-category, which might provide further clues for understanding the chemotaxonomic significance of this plant. The isolated compounds were tested for neuroprotective activity and acetylcholinesterase inhibitory activity. Compounds 7, 18, 30 and 40 which exhibited moderate activity at 80 µM against acetylcholinesterase.

Anti-Hepatitis B Virus Activity of Esculetin from Microsorium fortunei In Vitro and In Vivo.

Coumarins are widely present in a variety of plants and have a variety of pharmacological activities. In this study, we isolated a coumarin compound from Microsorium fortunei (Moore) Ching; the compound was identified as esculetin by hydrogen and carbon spectroscopy. Its anti-hepatitis B virus (HBV) activity was investigated in vitro and in vivo. In the human hepatocellular liver carcinoma 2.2.15 cell line (HepG2.2.15) transfected with HBV, esculetin effecting inhibited the expression of the HBV antigens and HBV DNA in vitro. Esculetin inhibited the expression of Hepatitis B virus X (HBx) protein in a dose-dependent manner. In the ducklings infected with duck hepatitis B virus (DHBV), the levels of DHBV DNA, duck hepatitis B surface antigen (DHBsAg), duck hepatitis B e-antigen (DHBeAg), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) decreased significantly after esculetin treatment. Summing up the above, the results suggest that esculetin efficiently inhibits HBV replication both in vitro and in vivo, which provides an opportunity for further development of esculetin as antiviral drug.

Semi-synthesis and structural elucidation of brevicanines A-D, four new C19-diterpenoid alkaloids with rotameric phenomenon from Aconitum brevicalcaratum.

Four new C19-diterpenoid alkaloids brevicanines A-D (1-4) with rotameric phenomenon were isolated from Aconitum brevicalcaratum. They all possessed an unusual axial chiral phenyl-quinazoline side chain and their structures were elucidated by extensive spectroscopic analysis and chemical methods. Meanwhile, brevicanines A and B were semi-synthesized from their parent compound scaconine to further confirm their structures. Variable-temperature NMR spectroscopy was also used to investigate the atropisomers of brevicanine A, in which two sets of signals in 1H NMR spectra were observed at room temperature and coalesced over 140 °C. It's the first time to determine the atropisomeric preference of diterpenoid alkaloids.

Lewis acid-mediated skeleton transformation of Euphorbia diterpenes: From lathyrane to euphoractane and myrsinane.

Natural euphoractane and myrsinane diterpene skeletons, together with an unnatural 5/7/7/4 fused-ring diterpene skeleton were furnished via BF3·Et2O-mediated transformation of lathyrane-type diterpene, Euphorbia factor L1. The skeleton transformation process was mainly involved in the cascade oxirane-opening (cyclopropane-opening)/oxe-Micheal addition reaction. The structures of three diterpenes were confirmed by comprehensive spectra analysis and single crystals X-ray diffraction. Current results proved the biogenesis pathway between lathyrane with euphoractane and myrsinane by chemical transformation for the first time.

Four new C20-diterpenoid alkaloids from Aconitum rotundifolium.

Four new C20-diterpenoid alkaloids, rotundifosines D-G (1-4), along with eight known ones (5-12) were isolated from the whole plant of Aconitum rotundifolium Kar. & Kir. The structures of the compounds were elucidated on the basis of spectroscopic analyses, including HR-ESI-MS and 1D, 2D NMR. Rotundifosine F (3) is a rare C20-diterpenoid alkaloid with quaternary ammonium salt. Alkaloids 1-4, 5, 6, 9, and 12 were evaluated for cytotoxicity against MCF-7, HCT-116 and HepG2 human cancer cell lines.

Four New Diterpenoid Alkaloids from the Roots of Aconitum carmichaelii.

Aconitum carmichaelii Debeaux is a widely used traditional Chinese medicine and an important source of clinical drugs, of which the parent and lateral roots are known as 'Chuanwu' and 'Fuzi', respectively. Four new C19 -diterpenoid alkaloids, carmichasines A - D (1 - 4), were isolated from the roots of Aconitum carmichaelii, together with twelve known compounds (5 - 16). Their structures were elucidated via spectroscopic analyses, including HR-ESI-MS, IR, and NMR. Carmichasine A (1) is the first natural C19 -diterpenoid alkaloid possessing a cyano group. Most of the diterpenoid alkaloids isolated were C19 -category, which might provide further clues for understanding the chemotaxonomic significance of this plant. The cytotoxicity of the new compounds was also investigated against several human cancer cell lines, including MCF-7, HCT116, A549, and 786-0, and none of them showed considerable cytotoxic activity.

Cytotoxic Lathyrane-Type Diterpenes from Seeds of Euphorbia lathyris.

We isolated two new lathyrane-type diterpenes L27 (1) and L28 (2) along with seven known compounds (3-9) from the seeds of Euphorbia lathyris. These compounds were identified by NMR, high-resolution electrospray ionisation (HR-ESI)-MS as well as IR spectroscopy. Compounds 1 and 2 were assigned NMR spectrums with 1H-NMR, 13C-NMR, distortionless enhancement by polarization (DEPT), correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser effect spectroscopy (NOESY). Stereo configuration of 1 and 2 were confirmed by comprehensive interpretation of their nuclear Overhauser effect (NOE) relationship and showed they were first natural lathyrane-type diterpenes possessing α-configuration substitutes at C-3. Cytotoxicity assay of isolated compounds were evaluated against breast cancer cell lines MCF-7 or MDA-MB-231, 786-0 and liver cancer cell lines HepG2. As a result, Euphorbia factor L28 (2) showed strongly cytotoxicity to the 786-0 and HepG2 cell lines, with an IC50 value of 9.43 and 13.22 µM, respectively, which preliminarily suggested that the configuration of lathyrane-type diterpene at C-3 has a significant effect on its bioactivity.

The caffeoyl phenylethanoid glycosides from Lindernia ruellioides and their anti-HBV effects.

Five caffeoyl phenylethanoid glycosides, including two new ones linderruelliosides A (1) and B (2), were isolated from the leaves and stems of Lindernia ruellioides. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR and MS spectra. In addition, all these compounds were tested for their anti-HBV activity. Compounds 1, 3, and 4 showed anti-HBV activities, with IC50 values of 54.87, 30.74, and 69.02 µM for HBsAg and 26.70, 5.17, and 7.08 µM for HBeAg, respectively.

Diterpenoid Alkaloids from Two Aconitum Species with Antifeedant Activity against Spodoptera exigua.

Twenty-five diterpenoid alkaloids were isolated from the roots of two Aconitum species. The structures of seven new C19-diterpenoid alkaloids, apetaldines A-G (1-7), and 10 known alkaloids (8-17) from Aconitum apetalum and eight known alkaloids (18-25) from Aconitum franchetii var. villosulum were elucidated via HRESIMS, IR, and NMR data. Alkaloids 1-10, 15, 16, and 18-25 were screened for their antifeedant activity. Among the compounds tested, chasmanthinine (19) showed highly potent antifeedant activity with an effective concentration for 50% feeding reduction (EC50) at 0.07 mg/cm2. The antifeedant structure-activity relationship of the diterpenoid alkaloids is also discussed.

Recent advances in design, synthesis and bioactivity of paclitaxel-mimics.

Taxane-type anticancer drugs, including paclitaxel and its semi-synthetic derivatives docetaxel and cabazitaxel, are widely applied to chemotherapy of malignancy like breast cancer, ovarian cancer, non-small cell lung cancer and prostate cancer. However, their clinical applications are generally limited by scarce natural resources, various side effects and multidrug resistance. Therefore, it is significant to develop paclitaxel-mimics with simplified structure, fewer side effects and improved pharmaceutical properties. Based on our investigation on chemistry of paclitaxel, the current review summarized the most recent advances in the design, synthesis and biological activities of paclitaxel-mimics, which could be appealing to researchers in the field of medicinal chemistry and oncology. Meanwhile, smart design, interesting synthesis and potential bioactivities of these novel compounds may also provide valuable reference for the wider scientific communities.