Triterpenoid saponins from Aster auriculatus

Development of quality control parameters for two Bhutanese medicinal plants (Aster flaccidus Bunge and Aster diplostephioides (DC.) Benth. ex C.B.Clarke) using traditional and modern pharmacognostical platforms

Bhutan's scholarly traditional medical system is called Bhutanese Sowa Rigpa medicine (BSM). It was integrated with the modern healthcare system in 1967. Over 200 medicinal plants are used to produce more than 100 poly-ingredient medicinal formulations. Although BSM is supported by well-documented principles, pharmacopoeias, diagnostic procedures, treatment regimens, and traditional quality assurance systems, modern quality control parameters have become essential to distinguish closely related species and prevent contamination from exogenous impurities. This study aims to establish reliable analytical methods and quality control parameters for Aster flaccidus Bunge and Aster diplostephioides (DC.) Benth. ex C.B. Clarke used as ingredients in the BMS poly-ingredient medicinal formulations. Furthermore, their reported phytochemicals and biological activities are also discussed in this study. Standard pharmacognostic techniques, including macroscopical and microscopical examinations of crude drugs, were employed to establish the quality control parameters for two Aster species. The physicochemical limits were determined as per the World Health Organization (WHO)-recommended guidelines and methods described in the Thai herbal pharmacopoeia. A high-performance thin-layer liquid chromatography (HPTLC) was used to develop a comparative chromatogram/phytochemical fingerprint for the crude extracts obtained from two Aster species. A literature review was conducted to record their isolated phytochemicals and biological activities. Two Aster species possess macro- and microscopic features such as colour, appearance, and shape. Physicochemical analysis of crude drugs from two Aster species including HPTLC fingerprinting of their methanol crude extracts also yielded adequate data to differentiate and confirm two Aster species before adding them to the BSM poly-ingredient medicinal formulations. From the literature review, only A. flaccidus was found to be studied for its phytochemical constituents, whereby 11 pure compounds were isolated from aerial parts and roots. The current study revealed distinct species-specific distinguishing features, including ecological adaptation, micromorphology, anatomy, physicochemical values, HPTLC chromatograms. These parameters can be used to authenticate the species identity and prevent adulterations, thereby improving the quality and safety of BSM formulations.

EVALUATION OF THE ACUTE AND SUBCHRONIC TOXICITY OF Aster tataricus L. F

BACKGROUND

Aster tataricus L. f. is used as a traditional Chinese drug to relieve cough and asthma symptoms and to eliminate phlegm. However, Aster tataricus L. f. possesses toxicity, and little systematic research has been conducted on its toxic effects in the laboratory.

METHODS AND MATERIALS

The acute group was administered 75% alcohol extract of Aster tataricus L. f. in a single dose. A subchronic toxicity study was performed via daily oral administration of Aster tataricus L. f. at a dose of 0.34 g/kg body weight in SD rats. The rats were divided into six groups: a petroleum ether extract (PEA) group, an ethyl acetate extract (EEA) group, an n-butyl alcohol extract (NEA) group, a remaining lower aqueous phases (REA) group, a 75% alcohol extract (AEA) group and a control group. Quantitative measurements of cytokines were obtained by fluorescence with a laser scanner using a Cy3 equivalent dye.

RESULTS

The LD₅₀ of the 75% alcohol extract of Aster tataricus L. f. was 15.74 g/kg bw. In the subchronic toxicity study, no significant differences were observed among groups in relative organ weights, urine traits, liver antioxidase levels, or cytokine levels. However, significant sporadic differences were observed in body weight gains, haematology indices, biochemistry values, and histopathology features in PEA, EEA group. In addition, sporadic changes in other groups in measures such as WBC, MCHC, CK, ALP, AST, ALT, LDH, T-BIL, LDL-C, HDL-C, and TC were observed.

CONCLUSION

The toxicity study showed that Aster tataricus L. f. can produce toxic effects, mainly on the liver; much less on the heart. The LD₅₀ was 15.74 g/kg BW in mice, and the subchronic toxicity study, used a dosage of 0.34 g/kg/d.BW, showed that the toxic components of Aster tataricus L. f. were mainly concentrated in the petroleum ether fraction, followed by the ethyl acetate fraction, the n-butyl alcohol fraction, the lower aqueous phase and the 75% ethanol extracts. Abbreviations: PEA, petroleum ether extract of Aster tataricus L. f.; EEA, ethyl acetate extract of Aster tataricus L. f.; NEA: n-butyl alcohol extract of Aster tataricus L. f.; REA: lower aqueous phases of Aster tataricus L. f.; AEA, 75% alcohol extract of Aster tataricus L. f.; WBC, white blood cell; RBC, red blood cell, PLT, platelet; HCT, haematocrit; MCV, mean corpuscular volume; HGB, haemoglobin; MCH, mean corpuscular haemoglobin; MCHC, mean corpuscular haemoglobin concentration; CREA, creatinine; LDH, lactate dehydrogenase; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; T-BIL, total bilirubin; ALT, alanine aminotransferase; ALP, alkaline phosphatase; AST, aspartate aminotransferase; TP, total protein; ALB, albumin; Glu, glucose; TC, total cholesterol; TG, triglycerides; CK, creatine kinase; GSH, Glutathione; MDA, malondialdehyde; T-SOD, total superoxide dismutase; TNF, tumour necrosis factor; IFN, interferon; MCP, monocyte chemotactic protein C.

Isolation and Identification of Saponins from the Natural Pasturage Asterothamnus centrali-asiaticus Employing Preparative Two-Dimensional Reversed-Phase Liquid Chromatography/Hydrophilic Interaction Chromatography

Asterothamnus centrali-asiaticus, a kind of characteristic shrub abundant in grassland and desert areas, has been used as forage fodder for camels and goats in Central Asia, and this plant also plays a critical role in the maintenance of desert grassland ecosystems as a result of its tolerance to poor soils and sand burial. However, its chemical composition has been rarely reported. In this study, phytochemical investigation of this pasturage was performed and three new triterpenoid saponins (1-3) were isolated together with nine known triterpenoid saponins (4-12) using preparative two-dimensional reversed-phase liquid chromatography/hydrophilic interaction chromatography (2D RPLC/HILIC). Their structures were elucidated via diverse spectroscopic analyses, including infrared (IR) spectrometry, high-resolution electrospray ionization mass spectrometry (HR-ESIMS), and one-dimensional (1D) and 2D nuclear magnetic resonance (NMR). All isolated triterpenoid saponins (1-12) were reported from this genus for the first time, and they were further evaluated for their cytotoxicity against four cancer cell lines (A549, HepG2, MGC-803, and MFC), which indicated that compound 11 showed potent cytotoxicity against the HepG2 cell line, with an IC50 value of 6.85 μg/mL.

Preliminary evaluation for cancer chemopreventive and cytotoxic potential of naturally growing ethnobotanically selected plants of Pakistan

CONTEXT

Natural products are a very productive source of leads for the development of medicines. Six Pakistani plants were chosen for study based on ethnobotanical data.

OBJECTIVE

Exploration of important medicinal plants of Pakistan for cancer treatment.

MATERIALS AND METHODS

The crude extracts of the six plants and their fractions were tested for inhibition of nuclear factor κB (NFκB), aromatase, and nitric oxide (NO) production in lipopolysaccharide (LPS)-activated murine macrophage RAW 264.7 cells, induction of quinone reductase 1 (QR1), agonism of retinoid X receptor, and growth inhibition with MCF-7, LU-1 and MDA-MB-231 cancer cells.

RESULTS

Two samples of Withania coagulans (Stocks) Dunal (Solanaceae) demonstrated inhibition of TNF-α induced activity of NFκB with IC₅₀ values of 2.6 and 4.3 µg/mL, respectively. Two fractions from W. coagulans and Euphorbia wallichii Hook F. (Euphorbiaceae) aerial parts inhibited aromatase with IC₅₀ values of 17.0 and 17.7 µg/mL, respectively. A total of 13 samples (five from E. wallichii, one from Acer oblongifolium Hort. ex Dippel (Aceraceae), one from Aster thomsonii C. B. Clarke (Asteraceae) and six from W. coagulans aerial parts with fruits) inhibited NO production with IC₅₀ values ranging from 1.3 to 15.6 µg/mL. Fourteen samples demonstrated induction of QR1 with CD ranging from 1.0 to 20.6 µg/mL, and a total of eight extracts and fractions inhibited the proliferation of cancer cells in culture with IC₅₀ values ranging from 1.2 to 7.8 µg/mL.

DISCUSSION AND CONCLUSION

Selected plants can be a valuable source of chemopreventive and anticancer products. W. coagulans aerial parts showed the strongest activity.

Inhibition of human gastric carcinoma cell growth in vitro by a polysaccharide from Aster tataricus

A water-soluble polysaccharide (WATP), with a molecular weight of 6.3 × 10⁴ Da, was isolated from Aster tataricus. According to gas chromatography (GC) analysis, WATP was composed of galactose, glucose, fucose, rhamnose, arabinose and mannose with molar ratios of 2.1:1.3:0.9:0.5:0.3:0.6. The effects of WATP on cell proliferation and apoptosis in human gastric cancer SGC-7901 cells were examined. MTT assay showed that WATP had a perfectly tumor growth inhibitory activity on SGC-7901 cells, but no cytotoxicity on SGC-7901 and primary human polymorphonuclear (PMN) cells analyzed using LDH assay. Flow cytometry analysis indicated that WATP could significantly induce apoptosis of SGC-7901 cells. Furthermore using Rh123 and Fluo-3 as fluorescent probes, respectively, it was found that mitochondrial transmembrane potential (ΔΨ(m)) of treatment groups was significantly lower than that in un-treatment group and the concentration of calcium in cells exposed to WATP for 24 h was increased in a dose dependent manner compared with unexposed group. These results suggest that WATP induces apoptosis of SGC-7901 cells through calcium- and ΔΨ(m)-dependent pathways, indicating that it is potentially useful as a natural anti-cancer agent.

The phenylpropanoids of Aster flaccidus

Aster flaccidus bge has been used as traditional medicine in northwestern China. Two new phenylpropanoids (1-2) including one lignan: (7'R, 8S)-9'-lariciresinol-(alpha-methyl)-butanoate (1), 5,9-dimethoxyl-7-(alpha-methyl)-butanoxyl-phenyl-2E-propenol-(alpha-methyl)-butanoate (2) isolated from the chloroform extract of the root of Aster flaccidus bge were identified by means of extensive spectroscopic studies: 1D and 2D NMR spectra as well as HRMS analysis. They have not obvious anti-HIV-1 therapeutic activity (TI=1.0-1.1) compared with AZT (TI=55,556) as the result of the determination of their in vitro anti-HIV-1 activity while compound 2 displays strong antitumor activity against BEL 7402 (human liver carcinoma) with cisplatin as a positive control and the effect increases with the measuring-time going on (24 h, IC(50): 106.67+/-8.47 microM - 72 h, IC(50): 50.51+/-6.11 microM).

Synthesis and assignment of absolute configuration of (-)-oleocanthal: a potent, naturally occurring non-steroidal anti-inflammatory and anti-oxidant agent derived from extra virgin olive oils

[structure: see text] Effective total syntheses and the assignment of absolute configurations of both the (+)- and (-)-enantiomers of oleocanthal 1 (a.k.a. deacetoxy ligstroside aglycon), the latter derived from extra virgin olive oils and known to be responsible for the back of the throat irritant properties of olive oils, have been achieved. The absolute and relative stereochemistry of the naturally occurring enantiomer (-)-1 proved to be 3S,4E. Both syntheses begin with d-(-)-ribose, proceed in 12 steps, and are achieved with an overall yield of 7%. Both enantiomers proved to be non-steroidal anti-inflammatory and anti-oxidant agents.

Two new terpenoid glucosides from Aster flaccidus

Two new terpenoid glucosides, namely 2-O-beta-D-glucopyranoside-vicodiol (1) and 10-O-beta-D-glucopyranoside-oplopanone (2), along with seven known compounds, were isolated from the aerial part of Aster flaccidus (composite), a traditional Chinese herb medicine. The structures of 1 and 2 were established by spectroscopic methods, especially 2D NMR experiments.