Low-density lipoprotein (LDL)-antioxidant lignans from Myristica fragrans seeds

Copper-Catalyzed Umpolung Reactivity of Propargylic Carbonates in the Presence of Diboronates: One Stone Four Birds

Allylation and propargylation are two powerful synthetic strategies for making new substances that have been of significant importance in chemistry, medicine, and material fields. Conventional tactics employ various preformed allylation and propargylation reagents. In this study, a conceptually novel copper-catalyzed and B2pin2-mediated Umpolung reactivity of propargylic carbonates has been achieved for the first time, realizing both allylation and propargylation of aldehydes and ketones without additional reductants. Three types of allylation products and one type of propargylation product are generated efficiently, and all allylation products are formed with syn-configurations predominantly. The choice of ligands plays a vital role in modulating the Umpolung modes. The synthetic applications have been demonstrated in a myriad of further transformations including natural product synthesis, and systematic mechanistic studies have been conducted to reveal detailed insights into the Umpolung processes.

Acylphenols and Dimeric Acylphenols from the Genus Myristica: A Review of Their Phytochemistry and Pharmacology

The genus Myristica is a medicinally important genus belonging to the Myristicaceae. Traditional medicinal systems in Asia have employed plants from the genus Myristica to treat a variety of ailments. Acylphenols and dimeric acylphenols are a rare group of secondary metabolites, which, to date, have only been identified in the Myristicaceae, in particular, in the genus Myristica. The aim of the review would be to provide scientific evidence that the medicinal properties of the genus Myristica could be attributed to the acylphenols and dimeric acylphenols present in the various parts of its plants and highlight the potential in the development of the acylphenols and dimeric acylphenols as pharmaceutical products. SciFinder-n, Web of Science, Scopus, ScienceDirect, and PubMed were used to conduct the literature search between 2013-2022 on the phytochemistry and the pharmacology of acylphenols and dimeric acylphenols from the genus Myristica. The review discusses the distribution of the 25 acylphenols and dimeric acylphenols within the genus Myristica, their extraction, isolation, and characterization from the respective Myristica species, the structural similarities and differences within each group and between the different groups of the acylphenols and dimeric acylphenols, and their in vitro pharmacological activities.

Phytochemical analysis and anticholinesterase activity of aril of Myristica fragrans Houtt

In this study, the ethyl acetate fraction of Myristica fragrans Houtt. was investigated for its in vitro anticholinesterase activity as well as neuroprotectivity against H₂O₂-induced cell death in PC12 neuronal cells and the ability to chelate bio-metals (Zn²⁺, Fe²⁺, and Cu²⁺). The fraction was inactive toward acetylcholinesterase (AChE); however, it inhibited the butyrylcholinesterase (BChE) with IC₅₀ value of 68.16 µg/mL, compared with donepezil as the reference drug (IC₅₀ = 1.97 µg/mL) via Ellman's method. It also showed good percentage of neuroprotection (86.28% at 100 µg/mL) against H₂O₂-induced neurotoxicity and moderate metal chelating ability toward Zn²⁺, Fe²⁺, and Cu²⁺. The phytochemical study led to isolation and identification of malabaricone A (1), malabaricone C (2), 4-(4-(3,4-dimethoxyphenyl)-2,3-dimethylbutyl)benzene-1,2-diol (3), nectandrin B (4), macelignan (5), and 4-(4-(benzo[d][1,3]dioxol-5-yl)-1-methoxy-2,3-dimethylbutyl)-2-methoxyphenol (6) which were assayed for their cholinesterase (ChE) inhibitory activity. Compounds 1 and 3 were not previously reported for M. fragrans. Among isolated compounds, compound 2 showed the best activity toward both AChE and BChE with IC₅₀ values of 25.02 and 22.36 μM, respectively, compared with donepezil (0.07 and 4.73 μM, respectively).

New Monoterpene-Conjugated Phenolic Constituents from Nutmeg and Their Autophagy Modulating Activities

The seed of Myristica fragrans Houtt (nutmeg) is one of the important spices that have been extensively used in the culinary, food, beverage, and also in medicinal products industry. Previous phytochemical studies on nutmeg were mainly focused on lignans and neolignans. However, the other constituents have been poorly studied. In this study, 11 new monoterpene-conjugated phenolic derivatives, named myrifratins A-K (1-11), and five known compounds were isolated from nutmeg. The novel neolignan-diarylnonanoid-monoterpene conjugates (1 and 2) were first isolated in nature. Compounds 3-7 were rarely monoterpene-diarylnonanoid-conjugated derivatives, and 8-11 were the first examples of monoterpene-neolignan conjugates. Compounds 4-6, 12, and 13 showed potent autophagy inhibitory activities in a concentration-dependent manner. Our findings showed an uncommon class of monoterpene-conjugated phenolic derivatives in nature and reported their autophagy inhibition activities for the first time, which may give a new insight into the benefits or safety of nutmeg in foods.

Potential Antiosteoporotic Natural Product Lead Compounds That Inhibit 17β-Hydroxysteroid Dehydrogenase Type 2

17β-Hydroxysteroid dehydrogenase type 2 (17β-HSD2) converts the active steroid hormones estradiol, testosterone, and 5α-dihydrotestosterone into their weakly active forms estrone, Δ4-androstene-3,17-dione, and 5α-androstane-3,17-dione, respectively, thereby regulating cell- and tissue-specific steroid action. As reduced levels of active steroids are associated with compromised bone health and onset of osteoporosis, 17β-HSD2 is considered a target for antiosteoporotic treatment. In this study, a pharmacophore model based on 17β-HSD2 inhibitors was applied to a virtual screening of various databases containing natural products in order to discover new lead structures from nature. In total, 36 hit molecules were selected for biological evaluation. Of these compounds, 12 inhibited 17β-HSD2 with nanomolar to low micromolar IC50 values. The most potent compounds, nordihydroguaiaretic acid (1), IC50 0.38 ± 0.04 μM, (-)-dihydroguaiaretic acid (4), IC50 0.94 ± 0.02 μM, isoliquiritigenin (6), IC50 0.36 ± 0.08 μM, and ethyl vanillate (12), IC50 1.28 ± 0.26 μM, showed 8-fold or higher selectivity over 17β-HSD1. As some of the identified compounds belong to the same structural class, structure-activity relationships were derived for these molecules. Thus, this study describes new 17β-HSD2 inhibitors from nature and provides insights into the binding pocket of 17β-HSD2, offering a promising starting point for further research in this area.

A Comparative Pharmacokinetic Study of Myrislignan by UHPLC-MS After Oral Administration of a Monomer and Myristica fragrans Extract to Rats

An ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS) method was developed and validated to quantify myrislignan in rat plasma using podophyllotoxin as an internal standard (IS). The chromatographic separation of myrislignan and IS was performed on a 3.0 µm Hypersil C18 column (50 mm × 4.6 mm) with methanol and water containing 0.1% acetic acid (80:20, v/v) as the mobile phase at a flow rate of 0.3 mL/min. An electrospray ionization was used in the positive selective-ion monitoring mode for the target ions at m/z 397 and m/z 437 for the quantification of myrislignan and IS. The total run time was 3.6 min for each run. The calibration curve was linear over the range of 0.75-300 ng/mL (r> 0.995) with the lower limit of quantitation at 0.75 ng/mL. Intra- and interday precision was below 11.49%, and the mean accuracy ranged from -9.75 to 7.45%. The proposed method was successfully applied to evaluate the pharmacokinetic properties of myrislignan after oral administration of the myrislignan monomer and Myristica fragrans extract in rats. Statistical analyses indicate that the pharmacokinetic properties of myrislignan in rats have significant differences between two groups.

Meso-dihydroguaiaretic acid induces apoptosis and inhibits cell migration via p38 activation and EGFR/Src/intergrin β3 downregulation in breast cancer cells

AIMS

Meso-dihydroguaiaretic acid (MDA) is known for its anti-inflammatory, anti-oxidant, anti-bacterial, and anti-tumor activity. However, the anti-breast cancer effect and the mechanism of MDA remain undefined.

MAIN METHODS

In this study, we examined the anti-cancer activity and the mechanisms of action of MDA in breast cancer cell lines, 4T-1 and MCF-7 cells; and 4T-1 bearing mouse model.

KEY FINDINGS

MDA showed cytotoxic effects on 4T-1 and MCF-7 cells in a dose-dependent manner. Moreover, MDA increased the amount of Annexin V-positive apoptotic bodies, phosphorylated JNK and p38 in 4T-1 cells. MDA also down-regulated cell-cycle dependent proteins, CDK-4 and cyclin D1; and induced cleaved caspase-3 in MDA-treated 4T-1 cells. We further verified that MDA-induced apoptosis is mediated by p38 and caspase-3 activation in 4T-1 cells. Next, we studied the effect of MDA treatment on cell migration and found that MDA significantly reduced cell migration. Moreover, MDA reduced EGFR and intergrin β3 expression, and dephosphorylated Src in a dose-dependent manner in 4T-1 cells. Furthermore, we observed in vivo effect of MDA in 4T-1 cell inoculated mice. MDA (20mg/kg/day) significantly suppressed mammary tumor volume and activated caspase-3 in tumor tissues.

SIGNIFICANCE

These results suggest novel targets of MDA in breast cancer in vitro and in vivo, making it a potential candidate as a chemotherapeutic drug.

New lignans and their biological activities

Lignans, which are widely distributed in higher plants, represent a vast and rather diverse group of phenylpropane derivatives. They have attracted considerable attention due to their pharmacological activities. Some of the lignans have been developed approved therapeutics, and others are considered as lead structures for new drugs. This article is based on our previous review of lignans discovered in the period 2000-2004, and it provides a comprehensive compilation of the 354 new naturally occurring lignans obtained from 61 plant families between 2005 and 2011. We classified five main types according to their structural features, and provided the details of their sources, some typical structures, and diverse biological activities. A tabular compilation of the novel lignans by species is presented at the end. A total of 144 references were considered for this review.

Potent Acetylcholinesterase Inhibitory Compounds from Myristica fragrans

The anti-cholinesterase activity was evaluated of the ethyl acetate fraction of the methanol extract of Myristica fragrans Houtt (Myristicaceae) seeds and of compounds isolated from it by various chromatographic techniques. The chemical structures of the compounds were determined from spectroscopic analyses (NMR data). Thirteen compounds (1—13) were isolated and identified. Compound 8 {[(7S)-8′-(4′-hydroxy-3′-methoxyphenyl)-7-hydroxypropyl]benzene-2,4-diol} showed the most effective activity with an IC50 value of 35.1 μM, followed by compounds 2 [(8R,8′S)-7′-(3′,4′-methylenedioxyphenyl)-8,8′-dimethyl-7-(3,4-dihydroxyphenyl)-butane] and 11 (malabaricone C) with IC50 values of 42.1 and 44.0 μM, respectively. This is the first report of significant anticholinesterase properties of M. fragrans seeds. The findings demonstrate that M. fragrans could be used beneficially in the treatment of Alzheimer's disease.

Nectandrin B activates endothelial nitric-oxide synthase phosphorylation in endothelial cells: role of the AMP-activated protein kinase/estrogen receptor α/phosphatidylinositol 3-kinase/Akt pathway

We revealed previously that nectandrin B isolated from Myristica fragrans (nutmeg, Myristicaceae) functions as a potent AMP-activated protein kinase (AMPK) activator and showed its antiobesity effect. In this study, we investigated whether nectandrin B affects phosphorylation of endothelial nitric-oxide synthase (eNOS) in human endothelial cells. Nectandrin B increased the phosphorylation of eNOS and nitric oxide (NO) production in a concentration-dependent manner and maximal effect was found at 10 μg/ml. Nectandrin B activates AMPK, presumably via Ca(2+)/calmodulin kinase II activation and nectandrin B-stimulated eNOS phosphorylation was reversed by AMPK inhibition. Both the enzyme activity of phosphatidylinositol 3-kinase (PI3K) and the estrogen receptor (ER)-dependent reporter gene transcription were enhanced by nectandrin B. ERα inhibition by specific antagonist or small interfering siRNA (siRNA) suppressed nectandrin B-mediated eNOS phosphorylation. Moreover, AMPK inhibition significantly reversed the activation of ER-dependent transcription and PI3K activation in response to nectandrin B. Nectandrin B evoked endothelium-dependent relaxation in rat aortic rings, and this was blocked by inhibition of AMPK, ER, or PI3K. These results suggest that potent AMPK activator nectandrin B enhances NO production via eNOS phosphorylation in endothelial cells and ERα-dependent PI3K activity is required.

Low density lipoprotein (LDL)-antioxidant flavonoids from roots of Sophora flavescens

Oxidation of low density lipoprotein (LDL) is strongly implicated as a key process in the onset of atherosclerosis. In this study, nine alkylated (C10-C5) flavonoids from Sophora flavescens were examined for their inhibitory effects on copper-induced LDL oxidation. Of the flavonoids tested, sophoraflavanone G (1), kurarinone (2), kurarinol (3), norkurarinol (4), and kuraridin (9) inhibited the generation of thiobarbituric acid reactive substances (TBARS) with IC50s of 7.9, 14.5, 22.0, 26.9, and 17.5 microM, respectively. The most potent inhibitor, compound 1, also demonstrated significant activities in complementary in vitro investigations, such as lag time (130 min at 5 microM), relative electrophoretic mobility (REM) of ox-LDL (80% inhibition at 20 microM), and fragmentation of apoB-100 (inhibition of 71% at 20 microM). Analysis of the structures of these compounds reveals that a resorcinol moiety in the B-ring is strongly correlated with protection of LDL-oxidation.