Diterpenoids from the stems of Tripterygium hypoglaucum (Celastraceae) and cytotoxic evaluation

Four new diterpenoids, 2α,16α-hydroxy-ent-kauran-19,20-olide (1), isopimara-8(14),15-diene-11β,19-diol (2), isopimara-8(14),15-diene-12α,19-diol (3), and 3-oxo-14,15-dihydroxyabieta-8,11,13-trien-19-ol (4), along with seven known compounds (5–11) were isolated from Tripterygium hypoglaucum. Their structures were established on the basis of extensive spectroscopic analysis. Triptolide (5) and 2-epitripdiolide (6) showed significant cytotoxicity against A549, DU145, KB, KBvin and MDA-MB-231 cell lines with IC₅₀ values of 0.0012–0.1306 μM in vitro.     

A potential anti-inflammation activity and depigmentation effect of Lespedeza bicolor extract and its fractions

Postinflammatory hyperpigmentation (PIH) is an acquire hypermelanosis after cutaneous inflammation and injury. The aim of the present study was to investigate a natural ingredient with the anti-inflammatory and depigmentation activities into possible applications of postinflammatory hyperpigmentation. Methanol extracts of Lespedeza bicolor and its various fractions inhibited LPS-induced NO production in RAW 264.7 macrophages in a concentration-dependent manner. In particular, the ethyl acetate fraction was shown to be inhibition of NO production (89%) and down-regulation of iNOS mRNA without causing cytotoxicity. In addition, ethyl acetate fraction significantly attenuated LPS-induced NF-κB activation (P < 0.05), indicating the anti-inflammatory activity due to NF-κB inhibition. Moreover, extracts, mainly ethyl acetate fraction, exhibited not only DPPH free radical scavenging activity (IC₅₀, 112.45 μg/mL) with 4 times lower activity than ascorbic acid, but also anti-tyrosinase activity (IC₅₀, 1 μg/mL) with a similar activity to arbutin showing a competitive inhibitor. Furthermore, vitexin and haginins A, B and C were identified through LC–MS analysis as potential compounds responsible for these effects. These results suggest that L. bicolor extract have anti-inflammatory, antioxidant activities and tyrosinase inhibitory effect and it might be used in the management of postinflammatory pigmentation through inhibition of pathogenic process involved in hyperpigmentation.     

Cytotoxic and anti-inflammatory effects of lignans and diterpenes from Cupressus macrocarpa

Cupressus macrocarpa is a windbreak tree and is reported to have various cytotoxic effects. A natural product study on the leaves of C. macrocarpa has yielded ten secondary metabolites, including three new diterpenoids (1–3), four known diterpenoids (4–7), and three known lignans (8–10). The structures of all isolated compounds were elucidated via the interpretation of spectroscopic methods, especially 2D NMR and mass analyses. In the cytotoxic assays, compounds 1–3 and 7–10 showed inhibition effect against HepG2, MDA-MB-231, and A549 cells with IC₅₀ values ranging from 0.004 to 19.9 μg/mL. Moreover, the anti-inflammatory assays revealed that (−)-matairesinol (8) had significant inhibitory activities on superoxide anion generation (IC₅₀ = 2.7 ± 0.3 μM) and elastase release (IC₅₀ = 6.6 ± 0.7 μM).     

Anti-inflammatory abietane diterpenoids from the seeds of Podocarpus nagi

In searching for naturally occurring anti-inflammatory agents, three new abietane-type diterpenoids, named 16-hydroxylambertic acid (1), 7-oxo-18-hydroxyferruginol (2), and 5α,12-dihydroxy-6-oxa-abieta-8,11,13-trien-7-one (3), were isolated from the seeds of Podocarpus nagi, together with three known compounds. The structures of the new compounds were elucidated by extensive analysis of NMR and HR-ESIMS data. All the new compounds were tested for nitric oxide (NO) inhibitory activities on lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Compound 1 significantly inhibited NO production with IC₅₀ value of 5.38 ± 0.17 μM, and suppressed inducible NO synthase (iNOS) expression in a dose-dependent manner, which were mediated through inhibiting the mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB) activation.     

Synthesis and anti-inflammatory evaluations of β-lapachone derivatives

β-Lapachone (β-LAPA), a natural product from the lapacho tree in South America, is a potential chemotherapeutic agent that exhibit a wide variety of pharmacological effects such as anti-virus, anti-parasitic, anti-cancer, and anti-inflammatory activities. In order to discover novel anti-inflammatory agents, we have synthesized a series of β-LAPA derivatives for evaluation. Among them, 4-(4-methoxyphenoxy)naphthalene-1,2-dione (6b) was found to be able to inhibit NO and TNF-α released in LPS-induced Raw 264.7 cells. Inhibition of iNOS and COX-2 was also observed in compound 6b treated cells. Mechanism studies indicated that 6b exhibited anti-inflammatory properties by suppressing the release of pro-inflammatory factors through down-regulating NF-κB activation. In addition, it suppressed NF-κB translocation by inhibiting the phosphorylation of p38 kinase. Our results also indicate that the inhibitory effect of 6b on LPS-stimulated inflammatory mediator production in Raw 264.7 cell is associated with the suppression of the NF-κB and MAPK signaling pathways. A low cytotoxicity (IC₅₀ = 31.70 μM) and the potent anti-inflammatory activity exhibited by compound 6b make this compound a potential lead for developing new anti-inflammatory agents. Further structural optimization of compound 6b is on-going.     

Diterpenoids and triterpenoids with potential anti-inflammatory activity from the leaves of Aglaia odorata

Chemical investigation of the leaves of the oriental medicinal plant Aglaia odorata resulted in the isolation of five compounds: two dolabellane diterpenoids, two dammarane triterpenoids and a protostane triterpenoid, along with twenty known compounds. Their structures were elucidated on the basis of extensive spectroscopic analysis and by comparison of their NMR spectroscopic data with those reported in the literature. The anti-inflammatory activities of all compounds were evaluated as inhibitory activities against lipopolysaccharide (LPS) induced nitric oxide (NO) production in RAW264.7 cell lines. Eleven compounds possessed potent nitric oxide inhibitory activity with IC₅₀ values ranging from 2.1 to 14.2 μM, these being better than that of the positive control, indomethacin (IC₅₀ = 14.5 μM). In addition, three compounds exhibited significant activity against PGE₂ release with IC₅₀ values of 2.6, 16.1 and 23.0 μM.     

Synthesis and biological evaluation of parthenolide derivatives with reduced toxicity as potential inhibitors of the NLRP3 inflammasome

Parthenolide (PTL) can target NLRP3 inflammasome to treat inflammation and its related disease, but its cytotoxicity limits further development as an anti-inflammatory drug. A series of PTL analogs and their Michael-type adducts were designed and synthesized, and most of them showed high activities against the NLRP3 inflammasome pathway. The most potent compound 8b inhibited the release of IL-1β with IC₅₀ values of 0.3 μM in J774A.1 cell and 1.0 μM in primary glial cells, respectively. Moreover, 8b showed low toxicity against J774A.1 cell (IC₅₀ = 24.1 μM) and HEK-293T (IC₅₀ = 69.8 μM) with a ~8 folds increase of therapeutic index compared to its parent PTL. The preliminary mechanism study revealed that 8b mediated anti-inflammation is associated with the NLRP3 inflammasome signal pathway. Based on these investigations, we propose that 8b might be a potential drug candidate for ultimate development of the anti-inflammation drug.     

Bis(4-hydroxy-2H-chromen-2-one): Synthesis and effects on leukemic cell lines proliferation and NF-κB regulation

Synthesis of the bis-4-hydroxycoumarin-type compound, 3,3′-[3-(2-hydroxyphenyl)-3-oxopropane-1,1-diyl]bis(4-hydroxy-2H-chromen-2-one), was performed by two alternative pathways, either involving a basic organocatalyzed 1,4-conjugate addition tandem reaction of 4-hydroxycoumarin on chromone-3-carboxylic acid, or a double condensation of 4-hydroxycoumarin on ω-formyl-2′-hydroxyacetophenone. The anti-proliferative effects of the bis-4-hydroxycoumarin-type compound on human K-562 (chronic myeloid leukaemia) and JURKAT (acute T-cell leukaemia) cell lines using trypan blue staining, as well as its involvement in nuclear factor-kappa B (NF-κB) regulation analyzed by luciferase reporter gene assay, gene expression analysis and western blots were analysed. This compound inhibited TNFα-induced NF-κB activation in K-562 (IC₅₀ 17.5 μM) and JURKAT (IC₅₀ 19.0 μM) cell lines, after 8 h of incubation. Interestingly, it exerted mainly cytostatic effects at low doses on both cell lines tested, whereas it decreased JURKAT cell viability starting at 50 μM from 24 h of treatment. Importantly, it did not affect the viability of peripheral blood mononuclear cells (PBMCs) from healthy donors, even at concentrations above 100 μM.     

Discovery of novel antitumor dibenzocyclooctatetraene derivatives and related biphenyls as potent inhibitors of NF-κB signaling pathway

Several dibenzocyclooctatetraene derivatives (5–7) and related biphenyls (8–11) were designed, synthesized, and evaluated for inhibition of cancer cell growth and the NF-κB signaling pathway. Compound 5a, a dibenzocyclooctatetraene succinimide, was discovered as a potent inhibitor of the NF-κB signaling pathway with significant antitumor activity against several human tumor cell lines (GI₅₀ 1.38–1.45 μM) and was more potent than paclitaxel against the drug-resistant KBvin cell line. Compound 5a also inhibited LPS-induced NF-κB activation in RAW264.7 cells with an IC₅₀ value of 0.52 μM, prevented IκB-α degradation and p65 nuclear translocation, and suppressed LPS-induced NO production in a dose-dependent manner. The antitumor data in cellular assays indicated that relative positions and types of substituents on the dibenzocyclooctatetraene or acyclic biphenyl as well as torsional angles between the two phenyls are of primary importance to antitumor activity.     

20-Nor-abietane and rearranged abietane diterpenoids from the root of Salvia argentea

From the root of Salvia argentea three new abietane diterpenoids, 1R-hydroxymiltirone, arucadiol and 1-keto-aethiopinone, have been isolated, together with the previously known diterpenes isopimara-8(9),15-diene, salvipisone, ferruginol and aethiopinone. The structures of the new compounds were established by spectroscopic means.     

Synthesis and characterization of norbelladine,a precursor of Amaryllidaceae alkaloid,as an anti-inflammatory/anti-COX compound

Rising ROS and systemic inflammation is often a serious concern in many disease conditions including obesity. Therefore, compounds with both anti-oxidant and anti-inflammatory activities are considered beneficial in preventing/treating several human chronic diseases. Norbelladine is an amine compound, a precursor for Amaryllidaceae alkaloids (e.g., belladine, crinamine, lycorine, and galanthamine) found in plants traditionally used for treating a variety of human diseases. However, little information is available about its potential health effects. Therefore, the amine was first synthesized, and its anti-oxidant and anti-inflammatory activities were investigated in this study. Also, the potential effects of the amine on NF-κB activation were investigated due to the critical involvement of ROS in the activation. Norbelladine was synthesized with more than 60% yield, analyzed by a HPLC method, and verified using NMR spectroscopic method. Then, its radical scavenging activity was investigated using DPPH- and superoxide radical assays. At the concentration of 10 μM, norbelladine was a compound able to quench DPPH-radical by 31% (P < 0.05) and reduce superoxide radicals from xanthine oxidase by 33% (P < 0.05). At the concentration of 0.25 μM, the amine also inhibited both COX-1 and COX-2 enzymes by 51% and 25% (P < 0.05), respectively. Furthermore, at the concentration of 10 μM, norbelladine inhibited NF-κB activation by 23% (P < 0.05). In summary, the data suggests that norbelladine may be a compound to quench radicals, inhibit COX enzymes as well as suppress NF-κB activation at relatively lower concentrations.     

Design,synthesis and activity of benzothiazole-based inhibitors of NO production in LPS-activated macrophages

Series of benzothiazoles were synthesized and evaluated their inhibitory activities for NO production in lipopolysaccharide-activated macrophages. The most potent compound was the indole-containing benzothiazole 3c with 4.18 μM of IC₅₀. The mechanistic study suggested that benzothiazoles inhibited NO production by the suppression of iNOS protein and mRNA expression. They also suppressed the expression of COX-2 through the NF-κB inactivation.     

Synthesis and biological activity of 4-substituted benzoxazolone derivatives as a new class of sEH inhibitors with high anti-inflammatory activity in vivo

A series of novel 4-substituted benzoxazolone derivatives was synthesized, characterized and evaluated as human soluble epoxide hydrolase (sEH) inhibitors and anti-inflammatory agents. Some compounds showed moderate sEH inhibitory activities in vitro, and two novel compounds, 3g and 4j, exhibited the highest activities with IC₅₀ values of 1.72 and 1.07 μM, respectively. Structure–activity relationships (SARs) revealed that introduction of a lipophilic amino acid resulted in an obvious increase in the sEH inhibitory activity, especially for derivatives containing a phenyl (3d, IC₅₀ = 2.67 μM), pyrrolidine (3g, IC₅₀ = 1.72 μM), or sulfhydryl group (3e, IC₅₀ = 3.02 μM). Several compounds (3a–3g) were tested in vivo using a xylene-induced ear edema mouse model. Three compounds (3d, 3f, and 3g) showed strong anti-inflammatory activities in vivo which were higher than that of Chlorzoxazone, a reference drug widely used in the clinic. Our investigation provided a novel type of sEH inhibitor and anti-inflammatory agent that may lead to the discovery of a potential candidate for clinical use.     

Bioactive cassane diterpenoids from the seeds of Caesalpinia sappan

Three new cassane-type diterpenoids named caesalppans G-I (1–3) together with three known ones (4–6), were isolated from the methanol extract of Caesalpinia sappan seeds. Their structures were determined based on spectroscopic data. Among the isolated compounds, compound 2 displayed a moderate antimalarial activity with an IC₅₀ value of 2.4 μM, and compound 4 showed mild anti-inflammatory activity with an IC₅₀ value of 28.65 μM.     

Cytotoxic terpenoids from the stem bark of Taxus wallichiana

Chemical study of the stem bark of Taxus wallichiana Zucc. afforded the isolation of two new cyclopenta[b]naphthalene terpenoids, wallichianones A (1) and B (2) and 13 taxane diterpenoids, baccatin III (3), 10-deacetylbaccatin III (4), baccatin IV (5), 1-dehydroxybaccatin IV (6), 1-deoxybaccatin VI (7), taxol (8), 10-deacetyltaxol (9), 7-epi-10-deacetyltaxol (10), taxol-7-xyloside (11), 7-xylosyl-10-deacetyltaxol C (12), cephalomannine (13), 10-deacetylcaphalomannine (14), and 7-epi-10-deacetylcephalomannine (15). Their structures were identified by comprehensive analyses of the spectroscopic methods, including NMR and mass spectra. The absolute configurations of 1 and 2 were clarified by time-dependent density functional theory (TD-DFT) electronic circular dichroism (ECD) spectroscopic analyses. Compounds 3 and 7–15 showed cytotoxicity against all five human cancer cell lines, including lung (SK-LU-1), liver (HepG2), breast (MCF7), skin (SK-Mel-2), and prostate (LNCaP), with IC₅₀ values ranging from 1.4 ± 0.2 to 88.1 ± 5.8 μM. Compounds 9–11, 14, and 15 were additionally cytotoxic against human embryonic kidney (HEK-293A) cell line (IC₅₀ = 14.5 ± 1.0–48.4 ± 1.0 μM), however, 13 was noncytotoxic toward this cell line. The positive control, ellipticine showed cytotoxicity against all the cell lines, with IC₅₀ values in a range of 1.5 ± 0.1–2.0 ± 0.3 μM. Preliminary analysis of the structural and cytotoxicity relationship of compounds 3–15 suggested that the phenylalanine substituent at C-13 may contribute an important role for the cytotoxicity of the taxane diterpenoids.     

Synthesis and cytotoxic activity of nitric oxide-releasing isosteviol derivatives

Fifteen novel hybrids containing diterpene skeleton and nitric oxide (NO) donor were prepared from isosteviol. All the compounds were tested on preliminary cytotoxicity, and the results showed that six target compounds (8c, 10b, 14a, 14c, 18c, and 18d) exhibited anti-proliferation activity on HepG2 cells, with 8c (IC₅₀ = 4.24 μM) and 18d (IC₅₀ = 2.75 μM) superior to the positive control CDDO-Me (2-cyano-3,12-dioxooleana-1,9(11)-dien-28-acid methyl ester, IC₅₀ = 4.99 μM); eleven target compounds (8a–c, 9a–c, 10a–b, 14a, 14c, 18d) exhibited anti-proliferation activities on B16F10 cells at different levels, among them, seven compounds were more potent than comptothecin (IC₅₀ = 2.78 μM) and CDDO-Me (IC₅₀ = 5.85 μM), particularly, 10b (IC₅₀ = 0.02 μM) presented the strongest effect, which was selected as a candidate for further study.     

In vitro inhibitory effects of ethanol extract of Danshen (Salvia miltiorrhiza) and its components on the catalytic activity of soluble epoxide hydrolase

Background: Soluble epoxide hydrolase (sEH) has been demonstrated to be a key enzyme involved in the pathologic development of several cardiovascular diseases and inflammation, and inhibition of sEH is therefore very helpful or crucial for the treatment of ischemia-reperfusion injury, cardiac hypertrophy, hypertension and inflammation. Danshen, the dried root of Salvia miltiorrhiza (Fam. Labiatae), has been used for the treatment of cardiovascular and cerebrovascular diseases in China and other countries for hundreds of years. Recent studies indicated that Danshen and its preparations also have potential for the management of inflammation. However, little information is available about the possibility of Danshen and its components on sEH inhibition.Purpose and methods: Danshen extracts and its constituents were tested for sEH inhibition using its physiological substrate, 8,9-EET, based on a LC–MS/MS assay in this study.Results: Among the tested 15 compounds, tanshinone IIA and cryptotanshinone were found to be the potent (K_i = 0.87 μM) and medium (K_i = 6.7 μM) mixed-type inhibitors of sEH, respectively. Salvianolic acid C (K_i = 8.6 μM) was proved to be a moderate noncompetitive sEH inhibitor. In consistent with the inhibition results of the pure compounds, the 75% ethanol extract of Danshen (EE, IC₅₀ = 86.5 μg/ml) which contained more tanshinone IIA and cryptotanshinone exhibited more potent inhibition on sEH than the water extract (WE, IC₅₀ > 200 μg/ml) or 1 M NaHCO₃ (BE, IC₅₀ > 200 μg/ml) extract.Conclusion: These data indicated that using the ethanol fraction of Danshen and increasing the amounts of tanshinone IIA, cryptotanshinone and salvianolic acid C, especially the contents of tanshinone IIA in Danshen extract or preparations to enhance the inhibitory effects on sEH might be efficient ways to improve its cardiovascular protective and anti-inflammatory effects, and that herbal medicines could be an untapped reservoir for sEH-inhibition agents and developing sEH inhibitors from the cardiovascular protective and anti-inflammatory herbs is a promising approach.