Swerilactones C and D, anti-HBV new lactones from a traditional Chinese herb: Swertia mileensis

Structural characterization and anti-oxidation activity of pectic polysaccharides from Swertia mileensis

In this study, we isolated the pectic polysaccharide WSMP-A2b (37 kDa) from the stems and leaves of Swertia mileensis, and we investigated its compositional/structural features and antioxidant activity. FT-IR, NMR, monosaccharide composition, enzymatic hydrolysis and methylation analyses indicated that WSMP-A2b is composed of rhamnogalacturonan I (RG-I), rhamnogalacturonan II (RG-II) and homogalacturonan (HG) domains with mass ratios of 2.1:1.0:2.2. The RG-I domain is primarily substituted with α-L-1,5-arabinan and type II arabinogalactan (AG-II) side chains, as well as minor contributions of β-D-1,4-galactan and/or type I arabinogalactan (AG-I) side chains. The HG domain was released in the form of un-esterified and partly methyl-esterified and/or acetyl-esterified oligogalacturonides with a 1 to 7 degree of polymerization after endo-polygalacturonase degradation. WSMP-A2b showed stronger antioxidant activity in vitro, in part this might due to the presence of galacturonic acid (GalA). In addition, WSMP-A2b exerted a protective effect on tert-butyl hydroperoxide (tBHP)-induced oxidative stress in INS-1 cells by reducing reactive oxygen species (ROS) production and increasing the glutathione/oxidized glutathione (GSH/GSSG) ratio. Our results provide crucial structural information on this pectic polysaccharide from Swertia mileensis, thus prompting further investigation into its structure-activity relationship.

Total synthesis of (±)-swermirin

The synthesis of swermirin features two sequential regioselective Stille couplings and a spontaneous 6π-electrocyclization.

Phytochemistry and Pharmacological Activities of the Genus Swertia (Gentianaceae): A Review

Swertia plants have been considered to be medicinal plants useful for the treatment of various ailments for thousands of years, especially in Asian countries. This is due to the broad variety of chemical compounds that provide multiple ligands for bonding to different endogenous biomacromolecules for patients. Chemical constituents and pharmacological activities of Swertia plants are summarized in this paper. Approximately 419 metabolites and 40 bioactive compounds have been reported from 30 Swertia species, including xanthones, flavonoids, seco-iridiods, iridiods, triterpenoids, alkaloids, volatiles, and other secondary metabolites. The bioactivities of Swertia plants include anticarcinogenic, hepatoprotective, anti-oxidant, hypoglycemic, anthelmintic, antibacterial, antifungal, anti-diabetic, gut, and airways modulatory, metabolizing isozymes inhibitory, neuroprotective, HIV-I reverse transcriptases inhibitory, anticholinergic, and CNS-depressant activities, etc. In addition, biosynthetic pathways of xanthones, and seco-iridiods, two most important secondary metabolites for Swertia, are elucidated. The xanthones biosynthetic pathway is a mixed biosynthetic pathway involved the shikimate and the malonate routes, and the seco-iridoid pathway starts with geraniol derived from IPP which is produced either via the MEP or the MVA pathway. This review will offer a reference for future researches on the protection of natural resources, the investigation of therapeutic basis, new drug development, and so forth. Metabolic pathways of some crucial active compounds were also discussed in this review.

Using UHPLC and UV-vis Fingerprint Method to Evaluate Substitutes for Swertia mileensis: An Endangered Medicinal Plant

BACKGROUND

Millions of people are killed by viral hepatitis every year in the world, whereas many relevant medicines are too expensive to purchase. Swertia mileensis, a medicinal plant for hepatitis in the system of traditional Chinese medicine, has been vanishing gradually because of overexploitation.

OBJECTIVE

To find substitutes of S. mileensis and reduce the cost of purchasing drugs for hepatitis patients, the similarity of phytochemical constituents between S. mileensis and other three Swertia species was compared.

MATERIALS AND METHODS

Both ultra high performance liquid chromatographies and ultraviolet-vis fingerprints of four Swertia species were developed. Methanol extracts of the stems and leaves were used as samples to establish the fingerprint. The calibration curve was drawn for quantitative analysis of swertiamarin. The data of ultra high performance liquid chromatographies were evaluated statistically using similarity analysis and principal component analysis.

RESULTS

The result shows a significant difference at area of 204-290 nm in the ultraviolet fingerprint. Swertiamarin, the only one common peak, was defined in chromatographic fingerprints of four Swertia species. The quantitative analysis suggested that the highest concentration of swertiamarin is in S. davidii. The similarity indexes between different samples were almost under 0.60. In the principal component analysis, separate points not only represent the distinction among different species, but also perform chemical discrepancies in content between stems and leaves of one same species.

CONCLUSIONS

S. angustifolia, S. davidii, and S. punicea are not suitable as substitutes of S. mileensis because of their remarkable differences in entirety and local part. In order to address issues about substitutes and high cost of purchasing drugs, more studies need to undertake.

SUMMARY

The UHPLC fingerprint method indicated the significant difference on chemical ingredients in four plants from Swertia.Swertiamarin is the unique common compounds for four plants, which exist are in leaves of S. davidii with the highest content.The obvious diversity in four plants was displayed from comprehensive point of view though similarity assay and PCA analysis.The UV fingerprint method offsets the defect that the UHPLC fingerprint reflected messages of secoiridoid glycosides only. Abbreviation used: UHPLC: Ultra high performance liquid chromatography, UV-vis: Ultraviolet-vis, HBV: Anti-hepatitis virus, DNA: Deoxyribonucleic acid, PCA: Principal component analysis, D-GaIN: D-Galactosamine, BCG: Bacille Calmette-Guerin, LPS: Lipopolysaccharide.

Anti-hepatitis B virus active constituents from Swertia chirayita

Four new compounds swertiachiralatone A (1), swertiachoside A (2), swertiachirdiol A (3) and swertiachoside B (4), together with twenty-six known ones were isolated from the ethanol extract of Swertia chirayita. Their structures were elucidated by extensive spectroscopic analyses (1D- and 2D-NMR, HRESIMS, UV, IR and [α]D). All compounds were evaluated for anti-hepatitis B virus (anti-HBV) activities on HepG 2.2.15 cells line in vitro, of which compounds 14 and 19 showed inhibitory activity on hepatitis B surface antigen (HBsAg) secretion with IC50 values of 0.31 ± 0.045 and 1.49 ± 0.033 mM; compounds 14 and 28 exhibited activity against hepatitis B e antigen (HBeAg) secretion with IC50 values of 0.77 ± 0.076 and 5.92 ± 1.02 mM; and eight compounds (8,9,13,14,24-26,29) possessed activity against HBV DNA replication with IC50 values of 0.07-0.33 mM. In particular (+)-cycloolivil-4'-O-β-d-glucopyranoside (14) exhibited inhibition not only on the secretions of HBsAg and HBeAg with IC50 values of 0.31 ± 0.045 mM (SI=4.29) and 0.77 ± 0.076 mM (SI=1.75), respectively, but also on HBV DNA replication with an IC50 value of 0.29 ± 0.034 mM (SI=4.66).

Minor secoiridoid aglycones from the low-polarity part of the traditional Chinese herb: Swertia mileensis

Eleven new secoiridoid aglycones involving unusual C₉-skeleton: swerimilegenins A-F (1–6); bis-C9-skeleton: swerimilegenin G (7); and C₁₀-skeleton: swerimilegenins H-K (8–11), as well as six known ones, were isolated from the low-polarity part of the traditional Chinese herb medicine Swertia mileensis. Their structures were determined by extensive spectroscopic data and X-ray diffraction. Biogenetically, swerimilegenin A (1) belonged to 10-nor-secoiridoid, and swerimilegenins B-F (2–6) were 1-nor-secoiridoids. Erythrocentaurin (12) and gentiogenal (15) showed moderate anti-HBV activity on HepG 2.2.15 cell line in vitro.

Design, synthesis, and molecular hybrids of caudatin and cinnamic acids as novel anti-hepatitis B virus agents

Forty-six conjugated derivatives of caudatin with substituted cinnamic acids were synthesized, and their anti-hepatitis B virus (HBV) activity was evaluated in HepG 2.2.15 cells. Most of the derivatives exhibited potent anti-HBV activity, especially inhibiting the HBV DNA replication with the IC(50) values from 2.44 to 22.89 μΜ. Compound 18 showed significant activity against the secretion of HBsAg, HBeAg, and HBV DNA replication with IC(50) values of 5.52, 5.52, 2.44 μΜ, respectively, and had good safety (LD(50) > 1250 mg/kg) according to the acute toxicity study. Preliminary mechanism investigation suggested that compound 18 exerted antivirus effects via interfering HBV X promoter and enhancer I to influence HBV transcriptions.

An Overview of Antimicrobial Properties of Different Classes of Phytochemicals

Plants produce a great diversity of phytochemicals, the beneficial properties of which have been used by humans for centuries since the advent of human civilization. With the discovery of effective and potent antimicrobial compounds, these synthetic antimicrobial compounds are widely used to prevent and cure microbial diseases. However, the development of antibiotic resistant strains of bacteria, reduced efficacy and safety of antimicrobials and the search of new antimicrobials against emerging incurable diseases by conventional antimicrobial agents have revived to explore phytochemicals as an alternative to synthetic antimicrobial compounds. Although numerous studies have been conducted in vitro and in vivo in the recent years on the efficacy of plant phytochemicals as antimicrobial agents, this chapter provides an overview of the antimicrobial properties of some major group of phytochemicals, namely, different phenolic compounds, alkaloids, saponins, iridoids and secoiridoids, polyacetylenes, glucosinolates, terpenoids, sulfinate, limonoids (tetranortepenoids) and anthranoids against pathogenic bacteria, fungi, viruses and commensal bacteria in the intestinal tracts of humans and animals. This chapter also discusses their antimicrobial mechanisms of action, the efficiency of different groups of phytochemicals against multiple-drug resistant bacteria, the effect of active dietary phytometabolites on the beneficial and pathogenic microbes of the gastrointestinal tracts and the outcomes of combination of phytofactors and drugs interactions.

Anti-hepatitis B virus active secoiridoids from Swertia kouitchensis

Three new secoiridoids, swertiakoulactone (1) and swertiakosides A and B (2 and 3), were isolated from Swertia kouitchensis. Their structures were elucidated by comprehensive spectroscopic analyses including MS, IR, 1D and 2D NMR data. By the anti-hepatitis B virus (HBV) assay on Hep G 2.2.15 cells line in vitro, compound 1 showed moderate activities inhibiting the HBsAg secretion (IC₅₀ = 1.10 mM, SI = 4.39) and HBV DNA replication (IC₅₀ = 1.16 mM, SI = 4.12).

Swerilactones L-O, secoiridoids with C₁₂ and C₁₃ skeletons from Swertia mileensis

Swerilactones L-O (1-4), four unusual secoiridoids with unprecedented C₁₂ and C₁₃ skeletons, were isolated from the traditional Chinese herb Swertia mileensis. Compounds 1 and 2 had moderate inhibitory activities against the secretion of hepatitis B virus surface antigen (IC₅₀ = 1.47 and 1.20 mM, with SI < 1 and 1.53, respectively) and hepatitis B virus e antigen (IC₅₀ = 0.88 and >2.69 mM, with SI 1.62 and <1, respectively) in an antihepatitis B virus assay on the Hep G 2.2.15 cell line in vitro.

Anti-hepatitis B virus active lactones from the traditional Chinese herb: Swertia mileensis

Swerilactones H-K (1-4), which are four novel lactones with an unprecedented C29 skeleton, were isolated from Swertia mileensis (Qing-Ye-Dan), an endemic Chinese herb used for treating viral hepatitis. Their structures were determined by extensive spectroscopic and X-ray crystallographic diffraction analyses. Swerilactones H-K exhibit potent anti-hepatitis B virus activity against HBV DNA replication with IC(50) values ranging from 1.53 to 5.34 μM. For the first time, a plausible biogenetic pathway for swerilactones H-K, together with the previously reported swerilactones A-D is proposed. From a biogenetic point of view, swerilactones A-D are ascribed as secoiridoid dimers, and swerilactones H-K as secoiridoid trimers.