Cytotoxic phloroglucinols from the leaves of Myrtus communis

The therapeutic value of Myrtus communis L.: an updated review

Myrtus communis L. (Family: Myrtaceae) is naturally found in the western part of Asia, Southern Europe, and North Africa. It has been reportedly applied in pharmaceutical industry, traditional medicine, cosmetics, spices, and food. Pubmed, Google scholar, Web of Science, and Scopus were utilized to seek out relevant content concerning the therapeutic potential of M. communis. Subsequently, we conducted a review to identity noteworthy updates pertaining to M. communis. Myrtle berries, leaves, seeds, and essential oils are natural sources of several nutrients and bioactive compounds with marked health effects. The chemical analysis showed that M. communis contained oils, alkaloids, flavonoids, phenolics, coumarins, saponosides, tannins, quinines, and anthraquinones. A pharmacological investigation revealed that M. communis possessed anti-inflammatory, analgesic, antimicrobial, antiparasitic, antioxidant, antidiabetic, anticancer, antimutagenic, immunomodulatory, dermatological, cardiovascular, central nervous system, and gastrointestinal protective effects, among numerous other biological effects. This current review focused on the biochemical, pharmacological, therapeutic effects, and various biological activities of different parts of M. communis. It signifies that M. communis is a therapeutic plant with numerous applications in medicine and could be used as a drug isolate based on its safety and effectiveness.

α-Synuclein Aggregation Inhibitory and Antiplasmodial Activity of Constituents from the Australian Tree Eucalyptus cloeziana

Amyloid protein aggregates are linked to the progression of neurodegenerative conditions and may play a role in life stages of Plasmodium falciparum, the parasite responsible for malaria. We hypothesize that amyloid protein aggregation inhibitors may show antiplasmodial activity and vice versa. To test this hypothesis, we screened antiplasmodial active extracts from 25 Australian eucalypt flowers using a binding affinity mass spectrometry assay to identify molecules that bind to the Parkinson's disease-implicated protein α-syn. Myrtucommulone P (1) from a flower extract of Eucalyptus cloeziana was shown to have α-syn affinity and antiplasmodial activity and to inhibit α-syn aggregation. 1 exists as a mixture of four interconverting rotamers. Assignment of the NMR resonances of all four rotamers allowed us to define the relative configuration, conformations, and ratios of rotamers in solution. Four additional new compounds, cloeziones A-C (2-4) and cloeperoxide (5), along with three known compounds were also isolated from E. cloeziana. The structures of all compounds were elucidated using HRMS and NMR analysis, and the absolute configurations for 2-4 were determined by comparison of TDDFT-calculated and experimental ECD data. Compounds 1-3 displayed antiplasmodial activities between IC50 6.6 and 16 μM. The α-syn inhibitory and antiplasmodial activity of myrtucommulone P (1) supports the hypothesized link between antiamyloidogenic and antiplasmodial activity.

Recent advances in the synthesis of natural products containing the phloroglucinol motif

Covering: June 2009 to 2021Natural products containing a phloroglucinol motif include simple and oligomeric phloroglucinols, polycyclic polyprenylated acylphloroglucinols, phloroglucinol-terpenes, xanthones, flavonoids, and coumarins. These compounds represent a major class of secondary metabolites which exhibit a wide range of biological activities such as antimicrobial, anti-inflammatory, antioxidant and hypoglycaemic properties. A number of these compounds have been authorized for therapeutic use or are currently being studied in clinical trials. Their structural diversity and utility in both traditional and conventional medicine have made them popular synthetic targets over the years. In this review, we compile and summarise the recent synthetic approaches to the natural products bearing a phloroglucinol motif. Focus has been given on ingenious strategies to functionalize the phloroglucinol moiety at multiple positions. The isolation and bioactivities of the compounds are also provided.

Acylphloroglucinol trimers from Callistemon salignus seeds: Isolation, configurational assignment, hAChE inhibitory effects, and molecular docking studies

Alzheimer's disease (AD) diagnoses are greatly increasing in frequency as the global population ages, highlighting an urgent need for new anti-AD strategies. With the aim to search for human acetylcholinesterase (hAChE) inhibitors from the species of Myrtaceae family, ten acylphloroglucinol trimers (APTs), including eight new APTs, callistemontrimers A-H (1a, 1b, 2a, 2b, 3a, 3b, 4b, and 5b), and two naturally occurring ones (4a and 5a), along with one reported triketone-acylphloroglucinol-monoterpene adduct (6), were obtained and structurally characterized from the hAChE inhibitory acetone extract of Callistemon salignus seeds. The structures and their absolute configurations for new APTs were unequivocally established via the detailed interpretation of extensive spectroscopic data (HRESIMS and NMR), ECD calculations, and single crystal X-ray diffraction, whereas the absolute configurations of known APTs were determined by further chiral separation, and calculated ECD calculations. The results of hAChE inhibitory assay revealed that an enantiomeric mixture of 2a/2b, 2a, and 2b are good hAChE inhibitors with IC₅₀ values of 1.22 ± 0.23, 2.28 ± 0.19, and 4.96 ± 0.39 μM, respectively. Molecular docking was used to uncover the modes of interactions for bioactive compounds with the active site of hAChE. In addition, 2 and 6 displayed moderate neurite outgrowth-promoting effects with differentiation rates of 6.16% and 6.19% at a concentration of 1.0 μM, respectively.

In Vitro Antibacterial Activity of Myrtus communis L. and Marrubium vulgare L. Leaves against Aggregatibacter actinomycetemcomitans and Eikenella corrodens

Materials and Methods

Clinical strains of Aggregatibacter actinomycetemcomitans and Eikenella corrodens and two reference strains of A. actinomycetemcomitans were tested. The antibacterial activity of each studied plant extract was evaluated using agar diffusion and broth microdilution assays.

Results

Both aqueous and methanolic extracts of M. communis exhibited high antibacterial activity against periodontal pathogens as compared to M. vulgare extracts. At concentrations of 2.5-0.32 mg/disc, inhibition zones of the methanolic extract of M. communis ranged from 19.66 ± 0.57 to 12.33 ± 0.57 mm. The methanolic extract of M. vulgare showed at concentrations of 5-0.63 mg/disc inhibition zones ranging from 15.66 ± 0.57 to 12 ± 0.00 mm. Its aqueous extract at concentration of 0.63 mg/disc showed no antimicrobial activity against the clinical and reference strain of A. actinomycetemcomitans. Conclusion. This study showed that methanolic and aqueous extracts of M. communis and M. vulgare have in vitro an antibacterial activity against periodontal pathogens. They could be use as ingredients of an oral antimicrobial agent for prevention or treatment of periodontal diseases. Further research on isolating the compounds from these plant extracts and their toxicity effect could be conducted.

Accessing HIV-1 Protease Inhibitors through Visible-Light-Mediated Sequential Photocatalytic Decarboxylative Radical Conjugate Addition-Elimination-Oxa-Michael Reactions

A photocatalytic decarboxylative radical conjugate addition-elimination-oxa-Michael reaction of hydroxyalkylated carboxylic acids with cyclopentenones is developed to construct diverse cyclopentanonyl-fused functionalized 5-7 membered cyclic ethers. The stereoselective synthetic strategy is amenable to substructural variation, establishing a direct total synthetic route to two diastereomers of C3-amino cyclopentyltetrahydrofuranyl-derived potent HIV-1 protease inhibitors with low nanomolar IC₅₀ values.

Antibacterial and antioxidant activities of a novel enol ether nor-sesquiterpene isolated from Myrtus nivellei Batt. & Trab

Myrtus nivellei is a plant traditionally used to treat diseases including infection of microbial origin. Several M. nivellei Batt. & Trab. extracts (dichloromethane, methanol and ethanol/water) were screened for their activity against 36 microorganisms, including strains resistant to antibiotics. These extracts inhibited on average 15 bacteria strains with minimum inhibition concentrations (MICs) ranging from 0.07 to 1.20 mg/mL. Bioassay guided fractionation was carried out with bioautography on TLC plates using four pathogenic bacteria strains, and following chromatographies (CPC and HPLC) led to the isolation of two novel enol ether nor-cadinane sesquiterpenes from the dichloromethane extract. The major compound (1) showed a strong antibacterial activity. Minimal inhibition concentration and minimal bactericidal concentration (MBC) values were determined against four bacteria: Acinetobacter baumanii, Stenotrophomonas maltophilia, Yersinia pseudotuberculosis and Staphylococcus lugdunensis. The best activity was observed against Acinetobacter baumanii with a MIC value of 9.7 μg/mL. This novel compound was also very active against a Staphylococcus aureus strain resistant to amoxicillin (MIC 19.5 μg/mL). In addition, compound 1 showed a very high antioxidant activity with both DPPH and metal chelate methods.

Meroterpenoids: A Comprehensive Update Insight on Structural Diversity and Biology

Meroterpenoids are secondary metabolites formed due to mixed biosynthetic pathways which are produced in part from a terpenoid co-substrate. These mixed biosynthetically hybrid compounds are widely produced by bacteria, algae, plants, and animals. Notably amazing chemical diversity is generated among meroterpenoids via a combination of terpenoid scaffolds with polyketides, alkaloids, phenols, and amino acids. This review deals with the isolation, chemical diversity, and biological effects of 452 new meroterpenoids reported from natural sources from January 2016 to December 2020. Most of the meroterpenoids possess antimicrobial, cytotoxic, antioxidant, anti-inflammatory, antiviral, enzyme inhibitory, and immunosupressive effects.

In silico and in vitro studies of isolated constituents from Callistemon citrinus leaves: Anti-microbial potential and inhibition of iNOS activity

Phytochemical investigation of Callistemon citrinus (Curtis) Skeels (syn. Callistemon lanceolatus (Sm.) Sweet and Melaleuca citrina (Curtis) Dum.Cours.) leaves resulted in the isolation of five undescribed compounds, including one acylphloroglucinol derivative and four monoterpene galloylglucosides, in addition to 29 known diverse secondary metabolites. Interestingly, this study reports chemosystematically significant isolation of the monoterpene galloylglucosides from the genus for the first time. Furthermore, exploration of the isolated compounds as inhibitors of inflammation-related molecular targets, molecular docking studies targeting human adipocyte lipid-binding protein FABP4 (3P6H) and human nitric oxide synthase (3E7G) were carried out in order with the in vitro evaluation of the isolated compounds for their anti-microbial and inhibitory of inducible nitric oxide synthase (iNOS) activities. Molecular docking studies revealed that eighteen compounds showed lower docking scores than ibuprofen, the native ligand in the crystal structure 3P6H, and nine compounds showed lower docking scores than AR-C95791, the native ligand in the binding site of 3E7G. Additionally, in vitro studies revealed that seven compounds showed moderate iNOS inhibitory activity. They also were moderately cytotoxic to HepG2, LLC-PK₁ and Vero cells. Pulverulentone A showed moderate antibacterial activity against MRSA (IC₅₀ 22.2 μM) and antifungal activity against C. neoformans, while corosolic acid showed strong antibacterial activity against VRE (IC₅₀ 15.9 μM).Thus, the in silico and in vitro studies indicated that some isolated compounds hold potentials as inhibitors of iNOS activity and anti-microbial agents.

Rhodomentosones A and B: Two Pairs of Enantiomeric Phloroglucinol Trimers from Rhodomyrtus tomentosa and Their Asymmetric Biomimetic Synthesis

Rhodomentosones A and B (1 and 2), two pairs of novel enantiomeric phloroglucinol trimers featuring a unique 6/5/5/6/5/5/6-fused ring system were isolated from Rhodomyrtus tomentosa. Their structures with absolute configurations were elucidated by NMR spectroscopy, X-ray crystallography, and ECD calculation. The bioinspired syntheses of 1 and 2 were achieved in six steps featuring an organocatalytic asymmetric dehydroxylation/Michael addition/Kornblum-DeLaMare rearrangement/ketalization cascade reaction. Compounds 1 and 2 exhibited promising antiviral activities against respiratory syncytial virus (RSV).

Antibacterial Triketone-Phloroglucinol-Triketone Adducts from Myrtus communis

Myrtucyclitones A-C ((+)- and (-)-1-3), three pairs of new triketone-phloroglucinol-triketone hybrids were isolated from the plant Myrtus communis. Their structures with absolute configurations were established by NMR analysis and chemical calculations. Myrtucyclitones B and C exhibited remarkable antibacterial effect.

Highly Potent Antiausterity Agents from Callistemon citrinus and Their Mechanism of Action against the PANC-1 Human Pancreatic Cancer Cell Line

Human pancreatic cancer cells display remarkable tolerance to nutrition starvation that help them to survive in a hypovascular tumor microenvironment, a phenomenon known as "austerity". The elucidation of agents countering this tolerance is an established antiausterity strategy in anticancer drug discovery. In this study, a Callistemon citrinus leaf extract inhibited the viability of PANC-1 human pancreatic cancer cells preferentially under nutrient-deprived medium (NDM) with a PC₅₀ value of 7.4 μg/mL. Workup of this extract resulted in the isolation of three new meroterpenoids, callistrilones L-N (1-3), together with 14 known compounds (4-17). The structure elucidation of the new compounds was achieved by HRFABMS and by NMR and ECD spectroscopic analysis. The new compounds showed highly potent preferential cytotoxicity against PANC-1 cells with PC₅₀ values ranging from 10 to 65 nM in NDM. Of these, callistrilone L (1) inhibited PANC-1 cell migration and colony formation in a normal nutrient-rich condition. Callistrilone L (1) also strongly suppressed the migration of PANC-1 cells in real time. Mechanistically, 1 was found to inhibit the Akt/mTOR and autophagy activation pathway. Callistrilone L (1) and related meroterpenoids are promising leads for anticancer drug development based on the antiausterity strategy used in this work.

Bio-inspired enantioselective total syntheses of (-)-viminalins A, B, H, I, and N and structural reassignment of (-)-viminalin M

Bio-inspired enantioselective total syntheses of (-)-viminalins A, B, H, I, and N, isolated from the Myrtaceae family, were accomplished in a convergent fashion in 5, 5, 1, 1, and 3 steps, respectively. A highly regio- and diastereoselective oxidative [3 + 2] cycloaddition reaction of acylphloroglucinols with α-phellandrene, diastereoselective modified Friedel-Crafts reaction of acylphloroglucinols with piperetol, and stereoselective epoxidation of extremely hindered β-face were described as key reactions.

Recent trends in the structural revision of natural products

Covering: 2012 to 2017 This article reviews recent reports on the structural revision of natural products. Through a critical assessment of the original and revised published structures, the article addresses why each structure was targeted for revision, discusses the techniques and key discrepancies that led to the proposal of the revised structure, and offers measures that may have been taken during the original structure determination to prevent error. With the revised structures in hand, weaknesses of original proposals are assessed, providing a better understanding on the logic behind structure determination.

Fe(III)-Catalyzed Diastereoselective Friedel-Crafts Alkylation-Hemiketalization-Lactonization Cascade for the Synthesis of Polycyclic Bridged 2-Chromanol Lactones

An unprecedented Fe(III)-catalyzed Friedel-Crafts alkylation-hemiketalization-lactonization cascade of electron-rich hydroxy arenes and distinctively functionalized unsaturated 4-keto esters is developed for the construction of polycyclic bridged 2-chromanol lactones. Following this simple and facile protocol, a broad range of products was prepared in good to excellent yields as a single diastereomer. An unusual conglomerate (enantiomerically pure polymorph) of 3ac is reported along with the absolute stereochemistry, and the remaining products were rigorously confirmed by single-crystal X-ray analysis and analogy.

A Two-Year Bio-Agronomic and Chemotaxonomic Evaluation of Wild Sicilian Myrtle (Myrtus communis L.) Berries and Leaves

A collection of nine Myrtus communis samples from different localities of Sicily was evaluated. Morphological traits and production characteristics have been chosen as parameters to arrange the samples into homogeneous groups and to identify the best biotypes for possible future agro-industrial exploitation. The plant material has been subjected to taxonomic characterization from biometric and phytochemical perspectives. Myrtle berries and leaves have been analyzed for their content in metabolites, applying a cascade extraction protocol for M. communis leaves and a single hydroalcoholic extraction for berries, whereas hydrodistillation procedures have been applied to obtain the essential oils from berries and leaves. The analyses of non-volatile components were carried out by LC-UV-DAD-ESI-MS. All the extracts were characterized by the presence of numerous polyphenols, namely highly hydroxylated flavonols such as quercetin and myricetin; and ellagic acid detected in all samples. In addition, myrtle berries contained nine different anthocyanins, namely delphinidin, petunidin, cyanidin and malvidin derivatives. The essential oils (EOs) were analyzed by a combination of GC-FID and GC/MS. A total of 33 and 34 components were fully characterized with the predominance of α-pinene, myrtenyl acetate, linalool, 1,8-cineole and linalyl acetate. All phytochemical profiles were subjected to cluster analyses, which allowed subdividing the myrtle samples in different chemical groups.

A new antibacterial dibenzofuran-type phloroglucinol from myrtus communis linn

Our continuation on the bio-assay guided isolation from Myrtus communis Linn. led to the discovery of a new dibezofuran type phloroglucinol 1,1'-(1,3,7,9-tetrahydroxydibenzo[b,d]furan-2,8-diyl)bis(ethan-1-one) 1. The structure was established through detailed spectroscopic studies including one and two dimensional NMR spectroscopy and electrospray ionization high resolution mass spectrometer (ESI-HRMS). The crude acetone extract from M. communis (AMA), dichloromethane fraction (DCM), and the isolated pure compound 1 were tested against pathogenic bacteria. Compound 1 displayed higher antibacterial activity against the Gram-positive and Gram-negative Staphlocococus aureus and Escherichia coli respectively as compared to the crude extract and fractions.

Structures and Bioactive Properties of Myrtucommulones and Related Acylphloroglucinols from Myrtaceae

Myrtaceae are a group of plants that include a number of renowned species used in ethnomedicine in many areas worldwide. Their valuable therapeutic properties have stimulated a fruitful research activity addressed to the identification of the bioactive components of their extracts yielding a great diversity of terpenes; polyphenols; and other exclusive products. Among the latter, starting with the discovery of myrtucommulone A from myrtle (Myrtus communis), a series of structurally-related acylphloroglucinol compounds have been characterized from several species that represent the basic active principles to be considered in view of possible drug development. Aspects concerning chemical and biological properties of these products are reviewed in the present paper.

Antioxidant Activity of Myrtus communis L. and Myrtus nivellei Batt. & Trab. Extracts: A Brief Review

Myrtus communis L. (myrtle) and Myrtus nivellei Batt. & Trab. (Saharan myrtle) have been used in folk medicine for alleviating some ailments. M. communis is largely distributed in the Mediterranean Basin, whereas M. nivellei is confined in specific zones of the central Saharan mountains. The chemical composition and antioxidant activity of berry and leaf extracts isolated from myrtle are deeply documented, whereas those isolated from Saharan myrtle extracts are less studied. In both species, the major groups of constituents include gallic acid derivatives, flavonols, flavonol derivatives, and hydroxybenzoic acids. In coloured berries, anthocyanins are also present. In M. nivellei extracts are reported for some compounds not described in M. communis so far: 2-hydroxy-1,8-cineole-β-d-glucopyranoside, 2-hydroxy-1,8-cineole 2-O-α-l-arabinofuranosyl (1→6)-β-d-glucopyranoside, rugosin A, and rugosin B. Berries and leaves extracts of both species had antioxidant activity. Comparative studies of the antioxidant activity between leaf and berry myrtle extracts revealed that leaf extracts are best antioxidants, which can be assigned to the galloyl derivatives, flavonols, and flavonols derivatives, although the ratio of these groups of compounds might also have an important role in the antioxidant activity. The anthocyanins present in myrtle berries seem to possess weak antioxidant activity. The antioxidant activity of sample extracts depended on various factors: harvesting time, storage, extraction solvent, extraction type, and plant part used, among other factors. Leaf extracts of myrtle revealed to possess anti-inflammatory activity in several models used. This property has been attributed either to the flavonoids and/or hydrolysable tannins, nevertheless nonprenylated acylphloroglucinols (e.g., myrtucommulone and semimyrtucommulone) have also revealed a remarkable role in that activity. The biological activities of myrtle extracts found so far may direct its use towards for stabilizing complex lipid systems, as prebiotic in food formulations, and as novel therapeutic for the management of inflammation.

Antiplasmodial β-Triketone-Flavanone Hybrids from the Flowers of the Australian Tree Corymbia torelliana

The methanol extract of the flowers of the Australian eucalypt tree Corymbia torelliana yielded six new β-triketone-flavanone hybrids, torellianones A-F (1-6), the tetrahydroxycyclohexane torellianol A (7), and known β-triketones (4 S)-ficifolidione (8) and (4 R)-ficifolidione (9), and β-triketone-flavanones kunzeanone A (10) and kunzeanone B (11). Torellianones A and B, C and D, and E and F were each isolated as inseparable diastereomeric mixtures. Exchange correlations observed in a ROESY spectrum indicated that 5 and 6 also interconverted between stable conformers. The structures of 1-7 were elucidated from the analysis of 1D/2D NMR and MS data. Relative configurations of torellianones C-F and torrellianol A were determined from analysis of ROESY data. Compounds 1-10 were tested for antiplasmodial activity against a drug-sensitive (3D7) strain of Plasmodium falciparum, with 3-6 and 8-10 showing limited antiplasmodial activity, with IC₅₀ values ranging from 3.2 to 16.6 μM.

Catalytic asymmetric total syntheses of myrtucommuacetalone, myrtucommuacetalone B, and callistrilones A, C, D and E

Herein, we describe a concise catalytic approach to the first asymmetric total syntheses of myrtucommuacetalone, myrtucommuacetalone B, and callistrilones A, C, D and E. The syntheses proceed in only 5-7 steps from the readily available compound 11, without the need for protecting groups. Key features of the syntheses include a unique organocatalytic asymmetric Friedel-Crafts-type Michael addition with high enantioselectivity and a broad substrate scope, a novel Michael-ketalization-annulation cascade reaction, and an oxidative [3 + 2] cycloaddition. Furthermore, the new compound 7 exhibited potent antibacterial activities against several multidrug-resistant strains (MRSA, VISA and VRE), and showed greater potency than vancomycin.

Asymmetric total syntheses of callistrilones B, G and J

A highly concise approach for the first asymmetric and gram-scale total syntheses of callistrilones B, G and J is reported.

Isolation, Structure Elucidation, and Absolute Configuration of Syncarpic Acid-Conjugated Terpenoids from Rhodomyrtus tomentosa

Three new syncarpic acid-conjugated sesquiterpenoids, tomentodiones E-G (1-3), and six new syncarpic acid-conjugated monoterpenoids, tomentodiones H-M (4-9), were isolated from the leaves of Rhodomyrtus tomentosa. Compounds 1-3 represent the first examples of β-calacorene-based meroterpenoids. Their structures and absolute configurations were determined by a combination of NMR and ECD spectroscopy and X-ray diffraction analysis. On the basis of ECD data analysis for isolated and synthesized compounds, an empirical rule was proposed to determine the absolute configuration at C-7' of syncarpic acid-conjugated terpenoids. Additionally, a study of the reversal effect of multidrug resistance in doxorubicin-resistant human breast cancer cells showed that the noncytotoxic (+)-4 exerted the strongest potentiation effect of doxorubicin susceptibility, with an enhancement of 16.5-fold at a concentration of 30 μM.

Antiplasmodial β-triketones from the flowers of the Australian tree Angophora woodsiana

Chemical investigations of the MeOH extract of air dried flowers of the Australian tree Angophora woodsiana (Myrtaceae) yielded two new β-triketones, woodsianones A and B (1, 2) and nine known β-triketones (3-11). Woodsianone A is a β-triketone-sesquiterpene adduct and woodsianone B is a β-triketone epoxide derivative. The structures of the new and known compounds were elucidated from the analysis of 1D/2D NMR and MS data. The relative configurations of the compounds were determined from analysis of ¹H-¹H coupling constants and ROESY correlations. All compounds (1-11) had antiplasmodial activity against the chloroquine sensitive strain 3D7. The known compound rhodomyrtone (5) and new compound woodsianone B (2) showed moderate antiplasmodial activities against the 3D7 strain (1.84µM and 3.00µM, respectively) and chloroquine resistant strain Dd2 (4.00µM and 2.53µM, respectively).

Callistiviminenes A-O: Diverse adducts of β-triketone and sesqui- or monoterpene from the fruits of Callistemon viminalis

Callistiviminenes A-O, fifteen adducts of β-triketone with sesqui- or monoterpene, along with a known compound, were isolated from the fruits of Callistemon viminalis. Callistiviminenes A and B are β-triketone-coupled (-)-bicyclosequiphellandrene contained an oxaspiro[5.5]undecene unit, and callistiviminenes C-E are rare adducts of β-triketone and bicyclogermacrene. Their structures and absolute configurations were elucidated by spectroscopic and computational methods, as well as by single-crystal X-ray diffraction experiment. A plausible biosynthetic pathway to these compounds involves a hetero-Diels-Alder reaction. Callistiviminenes C and D exhibited inhibition against lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages with IC₅₀ value of 20.3 μM and 32.5 μM, respectively.

Meroterpenoids with New Skeletons from Myrtus communis and Structure Revision of Myrtucommulone K

Five sesquiterpene-based meroterpenoids with three kinds of new skeletons [1, 2, 3, (+)-4, and (-)-4] were isolated from the leaves of Myrtus communis. Compound 1 featured a new carbon skeleton with an unprecedented octahydrospiro[bicyclo[7.2.0]undecane-2,2'-chromene] tetracyclic ring system, which possessed two preferred conformations detected by variable-temperature NMR spectroscopy experiments. In addition, the structure of reported myrtucommulone K was revised to be compound 3. The plausible biosynthetic pathways of these meroterpenoids and their cytotoxicities are discussed.

Stereoisomeric Composition of Natural Myrtucommulone A

Myrtucommulone A (MC A) (1), isolated from Myrtus communis (myrtle), shows the same pharmacological activity for inhibition of inflammation and induction of apoptosis as synthetic MC A, which consists of three stereoisomers, i.e., two enantiomers and one meso form. This led to the question of whether the natural MC A is a pure stereoisomer or a mixture of stereoisomers. The specific rotation and electronic circular dichroism (ECD) data of natural MC A (1) as well as of a pentacyclic derivative 4 revealed that naturally occurring MC A (1) consists of the racemate and the meso form in a 1:1 ratio. A probable precursor of MC A (1), nor-semimyrtucommulone (5), was also isolated from myrtle as a racemate. The absolute configurations of the enantiomers of 1 and 5 were determined using a combination of experimental and quantum-chemical calculated ECD spectra.

Revised stereochemistry of ficifolidione and its biological activities against insects and cells

Ficifolidione (1), a moderately active insecticidal compound from two species of Myrtaceae, and its derivatives were synthesized to evaluate their insecticidal activity. X-ray crystallographic analyses and specific rotation values of ficifolidione and its C-4 (2) demonstrated that the structure of ficifolidione differs from the reported absolute structure; that is, the C-4 configuration of ficifolidione should have an S configuration. The reported insecticidal activity of ficifolidione (1) and its C-4 epimer (2) against adult houseflies (Musca domestica), mosquito larvae (Culex pipiens), and cutworms (Spodoptera litura) was not observed. The cytotoxicities of ficifolidione and its derivatives (1-4) against four cell lines, Sf9, Colon26, HL60, and Vero, were also measured because ficifolidione has a phloroglucinol-derived moiety, a motif that is often present in the structure of cytotoxic chemicals. Compound 1 exhibited IC50 values of ca. 32, 9, 3, and 12 μM for Sf9, Colon26, HL60, and Vero cells, respectively, indicating that ficifolidione possesses selective cytotoxicity against the four cell lines. In HL60 cells treated with 1, DNA fragmentation and the activation of procaspase 3 were observed, suggesting that the cytotoxicity is induced by apoptosis.

Efficacy of Myrtus communis L. and Descurainia sophia L. Versus Salicylic Acid for Wart Treatment

Background:

Wart is a skin disease with circular appendages, which is called “suloul” in Iranian traditional medicine (ITM). According to ITM literature, warts have different types and causes. The most important mechanism is excretion of materials (Khelt) from body to skin and mucus; its causative material is often phlegm, black bile or a combination of them. To treat warts, it is necessary to consider the patient’s life style, modify his dietary intake and moisturize his temperament.

Objectives:

This study aimed to compare Myrtus communis L. and Descurainia sophia L. as a method of ITM, versus salicylic acid in treatment of wart.

Patients and Methods:

In this study, conducted in Yazd, Iran, 100 patients were selected and randomly divided into four groups. Group 1) salicylic acid, group 2) salicylic acid and D. sophia L. group 3) M. communis L. group 4) M. communis L. and D. sophia L. Numbers, sizes of lesions and symptoms, on days 0, 20, 40 and 90 were examined and analyzed. The relapse rate was investigated three months after. Changes of sizes and numbers of warts in each period of time in each group, compared to baseline, were assessed by Wilcoxon Signed Rank test. To compare these changes between the groups, Kruskal Wallis test was used.

Results:

In this study 100 patients participated, 69% of which were female. Compared to baseline, mean ± SD of changes for the number of warts in day 40 were 1.12 ± 4.2, 0.96 ± 2.5, 1.32 ± 5.1 and 0.04 ± 0.2 respectively in the four groups (P = 0.02). Mean ± SD of changes for the number of warts in day 90 were 1.84 ± 4.5, 1.56 ± 2.8, 1.24 ± 5.1 and 0.04 ± 0.6 respectively in the four groups (P = 0.03). In addition mean ± SD of changes for the size of warts in day 40 were 0.96 ± 1.8, 1.03 ± 2.4, 2.47 ± 3.0 and 0.45 ± 1.7 respectively in the four groups (P < 0.001). Mean ± SD of changes for the size of warts in day 90 were 1.24 ± 2.1, 1.3 ± 2.3, 2.45 ± 3.1 and 0.45 ± 1.7 respectively in the four groups (P < 0.001). Relapse was not seen in any groups after three months. The frequency of side effects was similar after three months.

Conclusions:

M. communis L. can be used as a topical treatment for warts. It not only shows more rapid response than salicylic acid, but also has fewer side effects. It seems that D. sophia L. can modify the digestion process and patients can excrete large amounts of the substance that causes warts. Therefore, it is better to use it more than 40 days. According to our investigation, in ITM, considering the cause and mechanism of disease generation and the causing materials of the disease, different treatments should be applied for each patient. Although applying an appropriate treatment is necessary, a unique treatment for all the patients cannot be available.

Targeting microsomal prostaglandin E2synthase-1 (mPGES-1): the development of inhibitors as an alternative to non-steroidal anti-inflammatory drugs (NSAIDs)

AA cascade and several key residues in the 3D structure of mPGES-1.

Calliviminones C–H: six new hetero- and carbon-Diels–Alder adducts with unusual skeletons from the fruits of Callistemon viminalis

Calliviminones C–H (1–6), six novel Diels–Alder adducts of a polymethylated phloroglucinol derivative and acyclic monoterpene (myrcene), were isolated from the fruits of Callistemon viminalis.

Studies with Myrtus communis L.: Anticancer properties

Myrtus communis (MC) L. is a well-known Mediterranean plant with important cultural significance in this region. In ancient times, MC was accepted as a symbol of immortality. Maybe due to this belief, it is used during cemetery visits in some regions. Although it is a well-known plant in cosmetics, and there is a lot of studies about its different medical properties, anticancer studies performed using its different extracts or oils are not so much, but increasing. We collected these anticancer property-related studies in this review.

UPLC-QTOF/MS for a rapid characterisation of phenolic compounds from leaves of Myrtus communis L

INTRODUCTION

Although continuous research has been conducted on the biological activities of myrtle and the characterisation of its essential oil, few studies have focused on its phenolic composition despite major beneficial properties.

OBJECTIVE

To carry out a comprehensive characterisation of infusion and methanolic extract from myrtle leaves by UPLC-QTOF/MS.

METHODS

Myrtle-leaf infusions, prepared using deionised water, and the methanolic extracts were analysed by reversed-phase ultra-performance liquid chromatography (UPLC) coupled to electrospray ionisation quadrupole time-of-flight mass spectrometry (ESI/QTOF/MS). The MS and MS/MS experiments were conducted using the negative-ionisation mode, in order to provide molecular-mass information and production spectra of the compounds for structural elucidation.

RESULTS

The analytical method applied enabled the characterisation of several compounds such as gallic acid and galloyl derivatives, ellagic acid and derivatives, hexahydroxydiphenolyl and derivatives, flavonoids, lignans and gallomyrtucommulones. Flavonoids, ellagic acid and its derivatives and gallic acid and its derivatives formed the major fractions.

CONCLUSION

UPLC combined with QTOF/MS is a powerful analytical method for characterising infusions and alcoholic extracts from myrtle leaves.

Antiproliferative and antiplasmodial dimeric phloroglucinols from Mallotus oppositifolius from the Madagascar Dry Forest (1)

Bioassay-guided fractionation of an ethanol extract of the leaves and inflorescence of Mallotus oppositifolius collected in Madagascar led to the isolation of the two new bioactive dimeric phloroglucinols mallotojaponins B (1) and C (2), together with the known mallotophenone (3). The structures of the new compounds were determined on the basis of spectroscopic evidence, including their 1D- and 2D-NMR spectra, mass spectrometry, and an X-ray crystal structure. Compounds 1 and 2 showed potent antimalarial activity against chloroquine-resistant Plasmodium falciparum, with IC50 values of 0.75 ± 0.30 and 0.14 ± 0.04 μM, while 3 was inactive in this assay. Compounds 1-3 also displayed strong antiproliferative activity against the A2780 human ovarian cancer cell line (IC50 1.10 ± 0.05, 1.3 ± 0.1 and 6.3 ± 0.4 μM, respectively).