Alkaloid derivative ION-31a inhibits breast cancer metastasis and angiogenesis by targeting HSP90α.

Breast cancer has become the number one killer of women. In our previous study, an active compound, ION-31a, with potential anti-metastasis activity against breast cancer was identified through the synthesis of ionone alkaloid derivatives. In the present study, we aimed to identify the therapeutic target of ION-31a. We used a fluorescence tag labeled probe, molecular docking simulation, and surface plasmon resonance (SPR) analysis to identify the target of ION-31a. The main target of ION-31a was identified as heat shock protein 90 (HSP90). Thus, ION-31a is a novel HSP90 inhibiter that could suppress the metastasis of breast cancer and angiogenesis significantly in vitro and in vivo. ION-31a acts via inhibiting the HSP90/hypoxia inducible factor 1 alpha (HIF-1α)/vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) pathway and downregulating downstream signal pathways, including protein kinase B (AKT)/mammalian target of rapamycin (mTOR), AKT2/protein kinase C epsilon (PKCζ), extracellular regulated kinase 1/2 (ERK1/2), focal adhesion kinase (FAK), and mitogen-activated protein kinase 14 (p38MAPK) pathways. ION-31a affects multiple effectors implicated in tumor metastasis and has the potential to be developed as an anti-metastatic agent to treat patients with breast cancer.

Asymmetric Total Synthesis and Biosynthetic Implications of Perovskones, Hydrangenone, and Hydrangenone B.

Perovskones and hydrangenones are a family of structurally complex triterpenoids that were mainly isolated from the genus Salvia medicinal plants. These isoprenoids exhibit a broad range of biological activities, such as antitumor and antiplasmodial activities. Here, we report the collective total synthesis of perovskone, perovskones C, D, F, hydrangenone, and hydrangenone B. The key strategies in this work include the following: (1) an asymmetric photoenolization/Diels-Alder reaction was developed to construct a tricyclic ring bearing three contiguous quaternary centers, which was used to build the core icetexane skeleton; (2) a bioinspired Diels-Alder reaction of perovskatone D with trans-α-ocimene was applied to stereospecifically generate perovskones; (3) late-stage oxidations and ring forming steps were developed to synthesize perovskones and hydrangenones. Our synthetic work suggests that (1) perovskatone D may serve as the precursor of the biosynthesis of perovskones and (2) the formation of hydrangenone and hydrangenone B, containing a five-membered D ring, may involve an oxidative ring cleavage and ring regeneration process.

Discovery of Antimetastatic Chiral Ionone Alkaloid Derivatives Targeting HIF-1α/VEGF/VEGFR2 Pathway.

Novel chiral ionone alkaloid derivatives were synthesized and their antimetastatic effects were evaluated in human breast cancer cells using chemotaxis assay. Compared with positive control LY294002, a PI3 K inhibitor, derivatives 10 a, 11 a, 11 c, 11 g, 11 j, 11 k and 11 w exhibited significant inhibitory effects against cancer cell migration. Especially, the IC50 for compound 11 g was as low as 0.035±0.004 µM. Further investigations on compound 11 g revealed that it could exert inhibitory effects on the adhesion, migration and invasion of MDA-MB-231 cells. The mechanisms for the antitumor metastatic effects of 11 g might be through the inhibition of HIF-1α/VEGF/VEGFR2/Akt pathway, which suppressed the downstream signaling molecules, including Akt1/mTOR/p70S6K and Akt2/PKCζ/integrin ß1 pathways. Taken together, chiral ionone alkaloid derivative 11 g has the potential to be developed into an antitumor metastatic agent for breast cancer.

Synthesis and biological evaluation of ß-ionone oriented proapoptosis agents by enhancing the ROS generation.

ß-ionone, a cyclic terpenoid compound present in many fruits, has been showed a broad spectrum of biological activities. In this paper, we synthesized a panel of ß-ionone derivatives and tested their anti-proliferation activity on cancer cell by the MTT assay. The results showed that most of the ß-ionone derivatives were more active than ß-ionone and curcumin. Particularly, the ß-ionone derivatives (1a, 1d and 1g) with ortho-substituents on the aromatic ring exhibited much stronger cytotoxicity than their corresponding meta- and para-substituted compounds. Importantly, the cytotoxicity of the ß-ionone derivatives (1a, 1d and 1g) were relationship with their reactive oxygen species (ROS)-generation abilities, which could lead to the redox imbalance, lipid peroxidation, the loss of mitochondrial membrane potential (MMP), the activation of Bax and Caspase 3, followed by cell apoptosis. This work suggest that the "ortho effect", the ROS-generation ability and drawing fluorine atom into drugs may play a potent role in enhancing the anticancer activity of ß-ionone derivatives.

Veilchenduft, ectopic olfactory receptors and endogenous volatile compounds: Who was Paul Krüger (1859-1916)?

The pharmacist and chemist Ferdinand Tiemann (1848-1899) having succeeded in the synthesis of vanillin, is considered to be the father of Geschmackstoff-Chemie (flavor chemistry). Tiemann, together with Paul Krüger (1859-1916) and then with Friedrich-Wilhelm Semmler (1860-1931), developed a method to obtain with a good yield Veilchenduft (violet scent); they condensed citral with di-methyl-ketone (acetone) thus generating an intermediate which upon exposure to an acidic environment cyclizes to ionone. By doing so the fragrance chemistry was born. Ionone (the compound responsible for the violet scent) was produced on an industrial scale at the factory of Wilhelm Haarmann (1847-1931) in Holzminden, factory renamed 1876 Haarmann & Reimer, after Karl Reimer (1845-1881) joined the group of owners. While a number of chemists and pharmacists were involved in the synthesis of Ionone (Veilchenduft; violet scent) and irone (iris scent), with few exceptions, their biographies are pretty well documented. In contrast, very little transpired about Dr. Paul Krüger, who spent some seven years trying to iron out the difficulties of ionone synthesis. The purpose of this short contribution is to shed some light on the life and work of Paul Krüger while providing an overview on the status of ionone pharmacology and to highlight the historical significance of ionone synthesis.

The synthesis and anti-metastatic effects of optical isomers of ionone alkaloid 9-(N,N-dimethyl)-4,7-megastigmedien-3-one.

Ionone alkaloid 9-(N,N-dimethyl)-4,7-megastigmedien-3-one (compound 1) is a new anti-metastatic natural product. However, it was previously reported as optical isomers mixture. Herein, the optical isomers (6a-6d) of compound 1 were synthesized. The absolute configurations of 6a-6d were determined by ECD experiments and calculated spectra with time-dependent density functional theory (TDDFT). The anti-metastatic effects of the optical isomers were examined by transwell assay. These results revealed that compound 6a had potential anti-metastatic activity with an IC50 value of 0.512 ±â€¯0.093 µM.

Synthesis and anti-metastatic effects of novel chiral ionone alkaloid derivatives.

Novel chiral ionone alkaloid derivatives were synthesized and evaluated their anti-metastatic effects in human MDA-MB-231 breast cancer cells. The chiral center C-6 of derivatives exerted an important role in response to the anti-metastatic activity. Comparing with a positive control of LY294002, compounds 17b and 19a exhibited potent inhibitory effects on the EGF-induced invasion of MDA-MB-231 cells with IC50 values of 0.026 ± 0.003 and 0.016 ± 0.002 µM, respectively. Moreover, compounds 17b and 19a showed inhibitory effects on the expressions of p-PKCζ and p-integrin ß1 in MDA-MB-231 cells in a dose-dependent manner. Thus, compounds 17b and 19a offer potential to be developed as novel anti-metastasis agents.

Recent Advances in the Synthesis of Carotenoid-Derived Flavours and Fragrances.

Carotenoids are important isoprenoid compounds whose oxidative degradation produces a plethora of smaller derivatives, called apocarotenoids, which possess a range of different chemical structures and biological activities. Among these natural products, compounds having less than 15 carbon atoms in their frameworks are often relevant flavours or fragrances and their manufacturing represents an important economic resource for chemical companies. The strict correlation between stereochemical structure and odour has made the stereospecific synthesis of the latter biological active compounds increasingly important. In this review, the recent advances on the synthesis of the most relevant carotenoid-derived flavours and fragrances are discussed. In particular, the new synthetic methods that have given new and innovative perspectives from a scientific standpoint and the preparative approaches that might possess industrial importance are described thoroughly.

The Importance of the 5-Alkyl Substituent for the Violet Smell of Ionones: Synthesis of Racemic 5-Demethyl-α-ionone.

The synthesis and the odor tonalities of racemic 5-demethyl-α-ionone are described. This synthetic ionone derivative did not show the typical floral-woody violet smell of α-ionone, definitely proving the importance of a suitably sized and spatially oriented alkyl substituent at C(5) for stimulating olfactory receptors of ionones.

Enantioselective divergent synthesis of (-)-cis-α- and (-)-cis-γ-irone by using Wilkinson's catalyst.

A simple, efficient synthesis is reported for (-)-cis-α- and (-)-cis-γ-irone, two precious constituents of iris oils, in ≥99 % diastereomeric and enantioselective ratios. The two routes diverge from a common intermediate prepared from (-)-epoxygeraniol. Of general interest in this approach is the installation of the enone moiety of irones through a NHCAu(I) -catalyzed Meyer-Schuster-like rearrangement of a propargylic benzoate and the use of Wilkinson's catalyst for the stereoselective hydrogenation of a prostereogenic exocyclic double bond to secure the critical cis stereochemistry of the alkyl groups at C2 and C6 of the irones. The stereochemical aspects of this reaction are rationally supported by DFT calculation of the conformers of the substrates undergoing the hydrogenation and by a modeling study of the geometry of the rhodium η(2) complexes involved in the diastereodifferentiation of the double bond faces. Thus, computational investigation of the η(2) intermediates formed in the catalytic cycle of prostereogenic alkene hydrogenation by using Wilkinson's catalyst could be highly predictive of the stereochemistry of the products.

Synthesis and in vitro characterization of ionone-based compounds as dual inhibitors of the androgen receptor and NF-κB.

Current therapeutic strategy for advanced prostate cancer is to suppress the androgen receptor (AR) signaling. However, lethal castration-resistant prostate cancer (CRPC) arises due to AR reactivation via multiple mechanisms, including mutations in the AR and cross-talk with other pathways such as NF-κB. We have previously identified two ionone-based antiandrogens (SC97 and SC245), which are full antagonists of the wild type and the clinically-relevant T877A, W741C and H874Y mutated ARs. Here, we discovered SC97 and SC245 also inhibit NF-κB. By synthesizing a series of derivatives of these two compounds, we have discovered a novel compound 3b that potently inhibits both AR and NF-κB signalling, including the AR F876L mutant. Compound 3b showed low micromolar antiproliferative activites in C4-2B and 22Rv1 cells, which express mutated ARs and are androgen-independent, as well as DU-145 and PC-3 cells, which exhibit constitutively activated NF-κB signalling. Our studies indicate 3b is effective against the CRPC cells.

Highly selective and asymmetric reductive biotransformation of α-ionone by Epicoccum purpurascens.

The biotransformation of terpenoid C13 norisoprenoid (±)-α-ionone (1) using the plant pathogenic fungus Epicoccum purpurascens as a biocatalyst was investigated for the production of useful novel organic compounds. There are no reported biotransformations using E. purpurascens. The biotransformation of compound 1 via reduction of the C-9 ketone position yielded α-ionol (2) as the major metabolic product. Reduction of the racemic α-ionone [(-)-(6S)- and (+)-(6R)-] resulted in the exclusive formation of the two enantiomers (-)-(6S,9R)- and (+)-(6R,9S)-α-ionol (2). Thus, the enzymatic reduction of α-ionone by E. purpurascens proceeds with high asymmetry.

Synthesis of ß-ionone derived chalcones as potent antimicrobial agents.

A series of chalcones (3a-v) have been synthesized by condensation of ß-ionone (1) with a variety of aldehydes (2a-v). The synthesized compounds have been screened for their in vitro antimicrobial activity against five bacterial and five fungal strains, using disc diffusion assay. The evaluated compounds display a wide range of activities, from completely inactive to the highly active compounds. Some of the compounds are also active against methicillin resistant staphylococcus aureus (MRSA).

A practical chemo-enzymatic approach to highly enantio-enriched 10-ethyl-7,8-dihydro-γ-ionone isomers: a method for the synthesis of 4,5-didehydro-α-ionone.

An efficient and convenient strategy for the enantioselective synthesis of enantiomerically enriched 10-ethyl-7,8-dihydro-γ-ionone isomers (R)-(+)-7, and (S)-(-)-7 are described utilizing a lipase mediated resolution protocol, and reductive elimination of the secondary allylic alcohol as the key step. The enantioselective and diastereoselective lipase kinetic acetylation of 4-hydroxy-γ-ionone derivatives 6a afforded the 4-acetyl-γ-ionone derivatives (-)-8, and the 4-hydrox-γ-ionone derivatives (+)-6a, which are suitable precursors of the desired products. Stereospecific palladium-mediated elimination of allylic acetate provides the target compounds with an excellent enantiomeric excess and yield. Additionally, the novel 4,5-didehydro-α-ionone 13 is obtained from readily prepared (2,6,6-trimethylcyclohexa-2,4-dien-1-yl) methanol 9. The structures of all newly synthesized compounds have been elucidated by (1)H, (13)C NMR, GC-MS, and IR spectrometry. These compounds represent a new class of odorants that may be of pivotal relevance in industrial perfumery.

Design, synthesis and biological evaluation of new ionone derivatives as potential neuroprotective agents in cerebral ischemia.

A new series of ionone derived allylic alcohols have been evaluated for anti-ischemic activity. Out of them, 12f and 13b decreased infarct volume to 23.98+/-4.7 mm3 and 93.98+/-24.8 mm3 as compared to ischemic group.

Synthesis and in vitro characterization of ionone-based chalcones as novel antiandrogens effective against multiple clinically relevant androgen receptor mutants.

A crucial event in prostate cancer progression is the transition from a hormone-sensitive to a lethal castration-refractory disease state. The antagonist-to-agonist conversion due to mutation in AR is a critical problem with the current clinically used antiandrogens. We aim to identify novel antiandrogens that remain as a pure antagonist even in the mutated ARs. By synthesizing a series of ionone-based chalcones, we have identified a novel chalcone (17) that is a pan-antagonist of the wild type and the clinically relevant T877A, W741C and H874Y mutated ARs in luciferase reporter assays in PC-3 cells. Further, chalcone 17 demonstrates sub-micromolar to low micromolar antiproliferative activity in LNCaP, MDA-PCa-2b, 22Rv1 and C4-2B prostate cancer cells, all of which express mutated ARs and confer resistance to the current clinically used antiandrogens. The results suggest that chalcone 17 could be a good candidate for further pre-clinical development as a novel antiandrogen for advanced prostate cancer.

Syntheses and potential anti-prostate cancer activities of ionone-based chalcones.

We report the SAR studies of 43 ionone-based chalcones that demonstrate substantial in vitro anti-proliferative activities in LNCaP, MDA-PCa-2b, 22Rv1, C4-2B and PC-3 prostate cancer cell lines. Compound 25 with an IC(50) value of 0.74 microM in LNCaP cells potently antagonizes DHT-induced transactivation of the wild type and the clinically relevant T877A, W741C and H874Y mutated androgen receptors, representing a novel chalcone as pan-antagonist of androgen receptor.

A simple synthesis of four stereoisomers of roseoside and their inhibitory activity on leukotriene release from mice bone marrow-derived cultured mast cells.

Four stereoisomers of roseoside (vomifoliol glucosides) were synthesized using glucose as a chiral resolving reagent. The four synthetic stereoisomers exhibited inhibitory activity on leukotriene release from mouse bone marrow-derived cultured mast cells (BMCMC). The (6S)-isomers of roseoside were about twice as active as (6R)-isomers.

Synthetic applications of enantioselective protonation and case study for (S)-alpha-damascone.

Among the fragrance compounds synthesized by enantioselective protonation, (S)-alpha-damascone, (R)-muscone, and (S,S)-Vulcanolide are the most prominent ones. (S)-alpha-damascone has been prepared by four different procedures: from the magnesium enolate, from the lithium enolate, from the enol, and from the corresponding thiol ester. We now present a new, industrially viable protocol for the addition of allyl magnesium chloride to the 'cyclogeranoketene' by a Barbier reaction, followed by protonation of the ensuing magnesium enolate by an aggregate formed from (-)-N-isopropylephedrine, lithium isopropylate, and acetic acid, furnishing (S)-alpha-damascone in 91% yield and with 71% ee.

Enantioselective synthesis and olfactory evaluation of 13-alkyl-substituted alpha-ionones.

To study the influence of the steric bulk of the substituents at C(5) on the olfactory characteristics of alpha-ionone, the (S)-antipodes of compounds 8-10 were synthesized starting from (S)-alpha-cyclogeraniol (14a). The latter was available in useful preparative yield with 95% ee by enantioselective lipase-PS-mediated acetylation of the racemic mixture. Key step in the conversion of 14a to 8-10 was an S(N)2'-type reaction of an organocuprate on the allylic phosphate 20, which appears to be a general method for the introduction of an alkyl substituent at the cyclohexene C=C bond of ionones. Olfactory evaluation showed that, compared to the parent (S)-alpha-ionone (1), the odor strength and fragrance facets of the three analogues 8-10 are significantly influenced by the bulkiness of the substituent at C(13), giving further evidence that hydrophobic interactions of this group play a significant role in the chemoreception of ionones. In particular, the odor of the ethyl derivative 8 was found to be significantly stronger than that of the parent (S)-alpha-ionone (1).