Withaphysalin-type withanolides from Physalis minima

Nine new withaphysalin-type withanolides (1–9), named physaminimins (G-O) were isolated from the whole plants of Physalis minima Linn. The structures of these compounds were elucidated based on spectroscopic methods (1D NMR, HSQC, HMBC, ROESY) and HRESIMS. Physaminimins G, H, and K showed inhibitory activities against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in a macrophage (RAW264.7) cells with IC₅₀ values of 17.41 ± 1.04, 36.33 ± 1.95 and 21.48 ± 1.67 μM, respectively.     

Withanolides from Withania aristata and their cytotoxic activity

Seven new withanolides (1-7), along with three known ones (8-10), were isolated from the leaves of Withania aristata. Their structures were elucidated on the basis of spectroscopic analysis, including 2D NMR experiments and spectrometric techniques, and the absolute configuration of 1 and 2 was established by CD analysis. In the search for new cytotoxic compounds from Withania species, the isolated compounds 1-9, along with two derivatives, were assayed for their cytotoxicity against HeLa, MCF-7 and A-549 human tumor cell lines. Derivative (4S,20R,22R)-27-acetoxy-4-p-bromobenzoyloxy-1-oxo-witha-2,5,16,24-tetraenolide (13) showed cytotoxicity against all the cell lines assayed with IC₅₀ values ranging from 2.8 to 3.6 μM, and (4S,20R,22R)-4,27-diacetoxy-4-hydroxy-1-oxo-witha-2,5,16,24-tetraenolide (12) exhibited an IC₅₀ value of 5.4 μM on the MCF-7 cell line.     

Comparative interactions of withanolides and sterols with two members of sterol glycosyltransferases from Withania somnifera

Background

Sterol glycosyltransferases (SGTs) are ubiquitous but one of the most diverse group of enzymes of glycosyltransferases family. Members of this family modulate physical and chemical properties of secondary plant products important for various physiological processes. The role of SGTs has been demonstrated in the biosynthesis of pharmaceutically important molecules of medicinal plants like Withania somnifera.

Results

Analysis suggested conserved behaviour and high similarity in active sites of WsSGTs with other plant GTs. Substrate specificity of WsSGTs were analysed through docking performance of WsSGTs with different substrates (sterols and withanolides). Best docking results of WsSGTL1 in the form of stable enzyme-substrate complex having lowest binding energies were obtained with brassicasterol, transandrosteron and WsSGTL4 with solasodine, stigmasterol and 24-methylene cholesterol.

Conclusion

This study reveals topological characters and conserved nature of two SGTs from W. somnifera (WsSGTs) i.e. WsSGTL1 and WsSGTL4. However, besides being ubiquitous in nature and with broad substrate specificity, difference between WsSGTL1 and WsSGTL4 is briefly described by difference in stability (binding energy) of enzyme-substrate complexes through comparative docking.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-015-0563-7) contains supplementary material, which is available to authorized users.     

New antiproliferative and immunosuppressive withanolides from the seeds of Datura metel

Two new withanolides baimantuoluoside H (1) and baimantuoluoline K (2), and one known withanolide glycoside (3) were isolated and identified from the ethyl acetate-soluble fraction of ethanol extract of Datura metel seeds. The structures of the new compounds were determined using 1D and 2D NMR spectroscopy, and mass spectrometry. All isolated compounds were evaluated for their antiproliferative activity against human gastric adenocarcinoma (SGC-7901), human hepatoma (Hepg2), and human breast cancer (MCF-7) cells, as well as their immunosuppressive properties. It was determined that compounds 1–3 exhibited medium antiproliferative and potential immunosuppressive effects.     

Cytotoxic withanolides from the aerial parts of Tubocapsicum anomalum

Ten new withanolides (1–10) and three artificial withanolides (11–13) were isolated from the aerial parts of Tubocapsicum anomalum, together with five known analogues (14–18). Their structures were determined on the basis of extensive spectroscopic and chemical methods. They include seven acnistin–type (1–4, 11, 14 and 15), three withajardin–type (5–7), and eight normal–type (8–10, 12, 13 and 16–18) withanolides. Of normal–type withanolides, a chemical conversion from the 16α,17α–epoxywithanolide (16) to Δ^13,14–16α–hydroxywithanolide (18) was achieved by Wagner–Meerwein rearrangement. All isolates were evaluated for their cytotoxicity against four human tumor cell lines (HCT–116, HepG2, MCF–7 and A375). Among them, compounds 1–3, 6–8, 14, 16–18 showed cytotoxic activity with IC₅₀ values of 0.24–8.71 μM.     

Immunosuppressive Withanolides from Withania coagulans

Six new withanolides, withacoagulins A–F ( 1 – 6 , resp.), together with ten known withanolides, 7 – 16 , were isolated from the aerial parts of Withania coagulans. Their structures were determined by spectroscopic techniques including 1D‐ and 2D‐NMR (¹H, ¹³C, HMQC, and HMBC) and MS experiments. These compounds, including the crude extracts of this herb, exhibited strong inhibitory activities on the T‐ and B‐cell proliferation.     

Unusual withanolides from aeroponically grown Withania somnifera

In an attempt to maximize production and the structural diversity of plant metabolites, the effect of growing the medicinal plant Withania somnifera under soil-less aeroponic conditions on its ability to produce withaferin A and withanolides was investigated. It resulted in the isolation and characterization of two compounds, 3α-(uracil-1-yl)-2,3-dihydrowithaferin A (1) and 3β-(adenin-9-yl)-2,3-dihydrowithaferin A (2), in addition to 10 known withanolides including 2,3-dihydrowithaferin A-3β-O-sulfate. 3β-O-Butyl-2,3-dihydrowithaferin A (3), presumably an artifact formed from withaferin A during the isolation process was also encountered. Reaction of withaferin A with uracil afforded 1 and its epimer, 3β-(uracil-1-yl)-2,3-dihydrowithaferin A (4). The structures of these compounds were elucidated on the basis of their high resolution mass and NMR spectroscopic data.     

13,14‐seco‐Withanolides from Physalis minima with Potential Anti‐inflammatory Activity

Four new 13,14‐seco‐withanolides, minisecolides A – D ( 1  –  4 ), together with three known analogues 5  –  7 , were isolated from the whole plants of Physalis minima. The structures of new compounds were determined on the basis of spectroscopic analysis, including ¹H‐, ¹³C‐NMR, 2D‐NMR (HMBC, HSQC, ROESY), and HR‐ESI‐MS. Evaluation of all isolates for their inhibitory effects on nitric oxide (NO) production was conducted on lipopolysaccaride‐activated RAW264.7 macrophages. Compounds 2 , 3 , 5 , and 6 showed inhibitory activities, especially for compound 5 with IC₅₀ value of 3.87 μm .     

Withanolides from Physalis peruviana showing nitric oxide inhibitory effects and affinities with iNOS

A phytochemical study to obtain new nitric oxide (NO) inhibitors resulted in the isolation of five new withanolides from the whole plants of Physalis peruviana. The structures were determined on the basis of extensive NMR spectroscopic data analysis as well as the time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) calculations. The NO inhibitory effects were examined by inhibiting NO release in lipopolysaccharide-stimulated murine microglial BV-2 cells. Molecular docking studies showed the strong interactions of bioactive compounds with the inducible nitric oxide synthase (iNOS) protein, revealing the potential mechanism of NO inhibition of bioactive compounds.     

Cytotoxic withanolides from Physalis angulata L

Four new withanolides, physagulins L-O (1-4), were isolated from the MeOH extract of the aerial parts of Physalis angulata L. (Solanaceae), together with seven known withanolides, compounds 5-11. Their structures were determined by spectroscopic techniques, including 1H-, 13C-NMR (DEPT), and 2D-NMR (HMBC, HMQC, 1H,1H-COSY, NOESY) experiments, as well as by HR-MS. All eleven compounds were tested for their antiproliferative activities towards human colorectal-carcinoma (HCT-116) and human non-small-cell lung-cancer (NCI-H460) cells. Compound 5 exhibited the highest anticancer activity against the HCT-116 cell line, with an IC50 value of 1.64+/-0.06 microM. Compound 9 exhibited the highest cytotoxicity towards the NCI-H460 cell line, with an IC50 value of 0.43+/-0.02 microM.