Phenolics from Leontopodium leontopodioides inhibiting nitric oxide production

A new canthinone glycoside isolated from the root barks of Ailanthus altissima with NO inhibitory activity

One new canthinone glycoside (1), together with six known compounds (2-7) including three lignans (2-4), two coumarins (5-6) and one phenol (7) was isolated from the root barks of Ailanthus altissima. The structure of new compound 1 was established by the interpretation of UV, IR, MS and NMR data, while its absolute configuration was determined by acid hydrolysis and GIAO NMR calculations with DP4+ probability analysis. The inhibitory effects of all compounds on Nitric oxide (NO) production were investigated in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Results showed that compounds 2 and 5 displayed NO production inhibitory activity with IC50 values of 30.1 and 15.3 μM, respectively.

Neoerysiphe leontopodii sp. nov., a new powdery mildew from China

A powdery mildew was found on Leontopodium leontopodioides (Asteraceae) in China. Phylogenetic analyses using a combination of internal transcribed spacer and 28S rDNA sequences showed that this species, which clusters as sister to Neoerysiphe joerstadii, is allied to N. galii, N. geranii, and N. nevoi. This species differs from the closely allied N. joerstadii in the number and size of asci (3-10 asci, 55-75 × 20-40 µm versus 16-32 asci, 40-60 × 20-30 µm). This species is morphologically very similar to N. gnaphalii, but clearly differs from this species in having larger chasmothecia and colorless appendages. Therefore, the powdery mildew on L. leontopodioides is described as N. leontopodii sp. nov.

Phenylpropanoids from Brachybotrys paridiformis maxim. Ex oliv. And their anti-HBV activities (II)

Five undescribed phenylpropanoids, one undescribed phenolic glucoside, and sixteen known compounds were isolated from Brachybotrys paridiformis Maxim. Ex Oliv. The undescribed compounds were named brachoside B-C, brach acid A-B, brachnan A, and brachin D, respectively. Additionally, the anti-hepatitis B virus activities of all isolated compounds were studied. Among them, brachnan A, brach acid A, globoidnan A, 3-carboxy-6,7-dihydroxy-1-(3',4'-dihydroxy-phenyl)-naphthalene, and 3,4-dihydroxybenzaldehyde showed significant anti-hepatitis B virus activities.

Potential inhibitors of microglial activation from the roots of Vernicia montana Lour

During our continuous investigation of natural, herbal inhibitors of microglial over-activation in the Euphorbiaceae family, two plants of the Vernicia genus showed remarkable inhibitory effects on nitric oxide (NO) production in over-activated microglia. In this study, bioactivity-guided phytochemical research on the active fraction of the roots of V. montana was carried out. As a result, seven undescribed terpenoids and lignans, together with thirty-one known components, were isolated and identified using comprehensive spectral analysis. All the identified compounds were evaluated for their inhibitory effects on NO production in lipopolysaccharide-stimulated BV-2 cells. Combined with our previous research on the Vernicia genus, the effective material basis of different plants and medicinal components was analyzed systematically.

Acyl atractyligenin and carboxyatractyligenin glycosides from Antennaria rosea subsp. confinis

Eight previously undescribed acyl atractyligenin and carboxyatractyligenin glycosides were isolated from whole Antennaria rosea subsp. confinis (Greene) R. J. Bayer (Compositae) [syn. Leontopodium leontopodioides (Willd.) Beauv. (Asteraceae)] plants and their structures were determined by spectroscopic and chemical methods. The compounds were trivially named leontopodiosides F-M. Seven of the compounds showed potent in vitro inhibitory activity toward pancreatic lipase with IC₅₀ values ranging from 3.4 to 52.5 μM, suggesting that they participate in the previously observed effect this plant has in reducing triglyceride absorption in rats.

[Antidermatophyte Activity of the Gentiopicroside-Rich n-Butanol Fraction from Gentiana siphonantha Maxim. Root on a Guinea Pig Model of Dermatophytosis]

BACKGROUND

Gentiana siphonantha Maxim. is a traditional medicine for the treatment of rheumarthritis, icterepatitis, pain and hypertension; it is rich in gentiopicroside with anti-inflammatory, antibacterial, and free radical-scavenging activities. This study was to evaluate the antidermatophyte activity of G. siphonantha on a guinea pig model in vitro and in vivo. Material andMethods: The antidermatophyte activities of 10 plants were tested by the broth microdilution method. Fractions and an extract of G. siphonantha were tested against Trichophyton mentagrophytes by the disc diffusion method. The morphological changes of T. mentagrophytes were observed. Component analysis of the n-butanol (n-BuOH) fraction was made by HPLC. Finally, the antifungal activity in an in vivo guinea pig model of dermatophytosis was examined.

RESULTS

G. siphonantha had strong antidermatophyte activity with MIC50 values of 32-64 μg/mL. The n-BuOH fraction of G. siphonantha showed the most potent activity compared to the other fractions. After being exposed to the n-BuOH fraction at 80 and 160 μg/mL, the hyphae were distorted and collapsed. Gentiopicroside is the main active ingredient in the n-BuOH fraction of G. siphonantha. The lesion scores of the guinea pig model of dermatophytosis significantly declined in the 10% and 30% extract and positive control groups in comparison with the untreated control group. Periodic acid-Schiff and hematoxylin/eosin staining displayed similar results.

CONCLUSION

The n-BuOH fraction of G. siphonantha demonstrated antidermatophyte efficacy in experimental dermatophytosis.

Isobenzofuranones from the aerial parts of Leontopodium leontopodioides (Wild.) Beauv

A phytochemical investigation to obtain new triglyceride (TG) accumulation inhibitors resulted in the isolation of six new isobenzofuranones, leontopodiols A (1), B (2), leontopodiosides C (3), D (4), E (5), F (6), together with three known ones (7-9) from the aerial parts of Leontopodium leontopodioides (Willd.) Beauv. The structures of these isolates were identified by routine NMR experiments, optical rotation determination, electronic circular dichroism (ECD) calculation, along with chemical reaction. Moreover, compounds 1, 2, 5, and 7-9 displayed TG accumulation inhibitory effects on HepG2 cells.

Recent advances in research on lignans and neolignans

Covering: 2009 to 2015Lignans and neolignans are a large group of natural products derived from the oxidative coupling of two C6-C3 units. Owing to their biological activities ranging from antioxidant, antitumor, anti-inflammatory to antiviral properties, they have been used for a long time both in ethnic as well as in conventional medicine. This review describes 564 of the latest examples of naturally occurring lignans and neolignans, and their glycosides in some cases, which have been isolated between 2009 and 2015. It comprises the data reported in more than 200 peer-reviewed articles and covers their source, isolation, structure elucidation and bioactivities (where available), and highlights the biosynthesis and total synthesis of some important ones.

A Critical Evaluation of the Quality of Published 13C NMR Data in Natural Product Chemistry

Nuclear Magnetic Resonance spectroscopy contributes very efficiently to the structure elucidation process in organic chemistry. Carbon-13 NMR spectroscopy allows direct insight into the skeleton of organic compounds and therefore plays a central role in the structural assignment of natural products. Despite this important contribution, there is no established and well-accepted workflow protocol utilized during the first steps of interpreting spectroscopic data and converting them into structural fragments and then combining them, by considering the given spectroscopic constraints, into a final proposal of structure. The so-called "combinatorial explosion" in the process of structure generation allows in many cases the generation of reasonable alternatives, which are usually ignored during manual interpretation of the measured data leading ultimately to a large number of structural revisions. Furthermore, even when the determined structure is correct, problems may exist such as assignment errors, ignoring chemical shift values, or assigning lines of impurities to the compound under consideration. An extremely large heterogeneity in the presentation of carbon NMR data can be observed, but, as a result of the efficiency and precision of spectrum prediction, the published data can be analyzed in substantial detail.This contribution presents a comprehensive analysis of frequently occurring errors with respect to ¹³C NMR spectroscopic data and proposes a straightforward protocol to eliminate a high percentage of the most obvious errors. The procedure discussed can be integrated readily into the processes of submission and peer-reviewing of manuscripts.

Two new benzolactones from the leaves of Nicotiana tabacum and their anti-tobacco mosaic virus activities

Two new benzolactones, 5-methyl-6-prenyl-isobenzofuran-1(3H)-one (1), 5-hydroxymethyl-6-prenyl-isobenzofuran-1(3H)-one (2), together with four known phenolic compounds (3-6), were isolated from the leaves of Nicotiana tabacum. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-6 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compounds 1-6 exhibited high anti-TMV activities with inhibition rates in the range of 16.9-26.2%, respectively.

Determination of the absolute configuration of natural products

Structural elucidation of natural products is always one of the most important tasks for natural product researchers in related fields. Particularly, the absolute configuration (AC), being a great challenge for natural product chemists, has attracted much attention. During the past few decades, many techniques and approaches have been developed to determine the AC of natural products, including direct (or absolute) methods, e.g. X-ray diffraction (XRD), electronic and vibrational circular dichroism (ECD and VCD), and Raman optical activity (ROA), as well as indirect (or relative) methods using a reference or a derivatizing agent with known AC, e.g. CD with empirical rules and nuclear magnetic resonance (NMR) utilizing anisotropic effects of chiral derivatizing agents. However, none of the currently applied techniques is capable of dominating AC determination, since they each have their respective limitations corresponding to the different structural features. This mini review summarizes most of the techniques and methods which are commonly used in AC assignment of natural products, or have potential application prospects, and briefly describes their principles, advantages and limitations.

Biologically active steroids from the aerial parts of Vernonia anthelmintica Willd

A new steroid, vernoanthelsterone A (1), and five known steroids were isolated from the aerial parts of Vernonia anthelmintica Willd. Compound 1 possesses a Δ(8(14))-15-one moiety. To our best knowledge, few steroids with this moiety have been reported before. Compounds 1-6 were tested for their antibacterial activities and their effects on estrogen biosynthesis in human ovarian granulosa-like cells (KGN cells). Compound 2 showed the ability to promote estrogen biosynthesis with EC(50) of 56.95 μg/mL and also exhibited the antibacterial activities against Bacillus cereus, Staphyloccocus aureus, Bacillus subtilis and Escherichia coli with MICs ranging from 3.15 to 15.5 μg/mL. The structures of 1-6 were determined on the basis of IR, MS, 1D and 2D NMR.