Spirostanol Saponins from Flowers of Allium Porrum and Related Compounds Indicating Cytotoxic Activity and Affecting Nitric Oxide Production Inhibitory Effect in Peritoneal Macrophages

Saponins, a diverse group of natural compounds, offer an interesting pool of derivatives with biomedical application. In this study, three structurally related spirostanol saponins were isolated and identified from the leek flowers of Allium porrum L. (garden leek). Two of them were identical with the already known leek plant constituents: aginoside (1) and 6-deoxyaginoside (2). The third one was identified as new component of A. porrum; however, it was found identical with yayoisaponin A (3) obtained earlier from a mutant of elephant garlic Allium ampeloprasun L. It is a derivative of the aginoside (1) with additional glucose in its glycosidic chain, identified by MS and NMR analysis as (2α, 3β, 6β, 25R)-2,6-dihydroxyspirostan-3-yl β-D-glucopyranosyl-(1 → 3)-β-D-glucopranosyl-(1 → 2)-[β-D-xylopyranosyl-(1 → 3)]-β-D-glucopyranosyl]-(1 → 4)-β-D-galactopyranoside, previously reported also under the name alliporin. The leek native saponins were tested together with other known and structurally related saponins (tomatonin and digitonin) and with their related aglycones (agigenin and diosgenin) for in vitro cytotoxicity and for effects on NO production in mouse peritoneal cells. The highest inhibitory effects were exhibited by 6-deoxyaginoside. The obtained toxicity data, however, closely correlated with the suppression of NO production. Therefore, an unambiguous linking of obtained bioactivities of saponins with their expected immunobiological properties remained uncertain.

Spirostanol Sapogenins and Saponins from Convallaria majalis L. Structural Characterization by 2D NMR, Theoretical GIAO DFT Calculations and Molecular Modeling

Two new spirostanol sapogenins (5β-spirost-25(27)-en-1β,2β,3β,5β-tetrol 3 and its 25,27-dihydro derivative, (25S)-spirostan-1β,2β,3β,5β-tetrol 4) and four new saponins were isolated from the roots and rhizomes of Convallaria majalis L. together with known sapogenins (isolated from Liliaceae): 5β-spirost-25(27)-en-1β,3β-diol 1, (25S)-spirostan-1β,3β-diol 2, 5β-spirost-25(27)-en-1β,3β,4β,5β-tetrol 5, (25S)-spirostan-1β,3β,4β,5β-tetrol 6, 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 7 and (25S)-spirostan-1β,2β,3β,4β,5β-pentol 8. New steroidal saponins were found to be pentahydroxy 5-O-glycosides; 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 5-O-β-galactopyranoside 9, 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 5-O-β-arabinonoside 11, 5β-(25S)-spirostan-1β,2β,3β,4β,5β-pentol 5-O-galactoside 10 and 5β-(25S)-spirostan-1β,2β,3β,4β,5β-pentol 5-O-arabinoside 12 were isolated for the first time. The structures of those compounds were determined by NMR spectroscopy, including 2D COSY, HMBC, HSQC, NOESY, ROESY experiments, theoretical calculations of shielding constants by GIAO DFT, and mass spectrometry (FAB/LSI HR MS). An attempt was made to test biological activity, particularly as potential chemotherapeutic agents, using in silico methods. A set of 12 compounds was docked to the PDB structures of HER2 receptor and tubulin. The results indicated that diols have a higher affinity to the analyzed targets than tetrols and pentols. Two compounds (25S)-spirosten-1β,3β-diol 1 and 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 5-O-galactoside 9 were selected for further evaluation of biological activity.

Effects of Shengmai San on key enzymes involved in hepatic and intestinal drug metabolism in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Shengmai San (SMS) has been commonly used as a traditional Chinese medicine for the treatment of cardiovascular disorders, of which drug interactions need to be assessed for the safety concern. There is little evidence for the alterations of hepatic and intestinal drug-metabolizing enzymes after repeated SMS treatments to assess drug interactions.

AIM OF THE STUDY

The studies aim to illustrate the effects of repeated treatments with SMS on cytochrome P450s (CYPs), reduced nicotinamide adenine dinucleotide (phosphate)-quinone oxidoreductase (NQO), uridine diphosphate-glucuronosyltransferase (UGT), and glutathione S-transferase (GST) using in vivo rat model.

MATERIALS AND METHODS

The SMS was prepared using Schisandrae Fructus, Ginseng Radix, and Ophiopogonis Radix (OR) (1:2:2). Chromatographic analyses of decoctions were performed using ultra-performance liquid chromatography (UPLC) and LC-mass spectrometry. Sprague-Dawley rats were orally treated with the SMS and its component herbal decoctions for 2 or 3 weeks. Hepatic and intestinal enzyme activities were determined. CYP3A expression and the kinetics of intestinal nifedipine oxidation (NFO, a CYP3A marker reaction) were determined.

RESULTS

Schisandrol A, schisandrin B, ginsenoside Rb1 and ophiopogonin D were identified in SMS. SMS selectively suppressed intestinal, but not hepatic, NFO activity in a dose- and time-dependent manner. Hepatic and intestinal UGT, NQO and GST activities were not affected. A 3-week SMS treatment decreased the maximal velocity of intestinal NFO by 50%, while the CYP3A protein level remained unchanged. Among SMS component herbs, the decoction of OR decreased intestinal NFO activity.

CONCLUSIONS

These findings demonstrate that 3-week treatment with SMS and OR suppress intestinal, but not hepatic CYP3A function. It suggested that the potential interactions of SMS with CYP 3A drug substrates should be noticed, especially the drugs whose bioavailability depends heavily on intestinal CYP3A.

Outlining In Vitro and In Silico Cholinesterase Inhibitory Activity of Twenty-Four Natural Products of Various Chemical Classes: Smilagenin, Kokusaginine, and Methyl Rosmarinate as Emboldening Inhibitors

Cholinesterase (ChE) inhibition is an important treatment strategy for Alzheimer’s disease (AD) as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are involved in the pathology of AD. In the current work, ChE inhibitory potential of twenty-four natural products from different chemical classes (i.e., diosgenin, hecogenin, rockogenin, smilagenin, tigogenin, astrasieversianins II and X, astragalosides I, IV, and VI, cyclocanthosides E and G, macrophyllosaponins A-D, kokusaginin, lamiide, forsythoside B, verbascoside, alyssonoside, ipolamide, methyl rosmarinate, and luteolin-7-O-glucuronide) was examined using ELISA microtiter assay. Among them, only smilagenin and kokusaginine displayed inhibitory action against AChE (IC₅₀ = 43.29 ± 1.38 and 70.24 ± 2.87 µg/mL, respectively). BChE was inhibited by only methyl rosmarinate and kokusaginine (IC₅₀ = 41.46 ± 2.83 and 61.40 ± 3.67 µg/mL, respectively). IC₅₀ values for galantamine as the reference drug were 1.33 ± 0.11 µg/mL for AChE and 52.31 ± 3.04 µg/mL for BChE. Molecular docking experiments showed that the orientation of smilagenin and kokusaginine was mainly driven by the interactions with the peripheral anionic site (PAS) comprising residues of hAChE, while kokusaginine and methyl rosmarinate were able to access deeper into the active gorge in hBChE. Our data indicate that similagenin, kokusaginine, and methyl rosmarinate could be hit compounds for designing novel anti-Alzheimer agents.

Characterization of spirostanol glycosides and furostanol glycosides from anemarrhenae rhizoma as dual targeted inhibitors of 5-lipoxygenase and Cyclooxygenase-2 by employing a combination of affinity ultrafiltration and HPLC/MS

BACKGROUND

Modulation of the arachidonic acid (AA) cascade via 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) represent the two major pathways for treatments of inflammation and pain. The design and development of inhibitors targeting both 5-LOX and COX-2 has gained increasing popularity. As evidenced, 5-LOX and COX-2 dual targeted inhibitors have recently emerged as the front runners of anti-inflammatory drugs with improved efficacy and reduced side effects. Natural products represent a rich resource for the discovery of dual targeted 5-LOX and COX-2 inhibitors. By combining affinity ultrafiltration and high-performance liquid chromatography-mass spectrometry (AUF-LC-MS), an efficient method was developed to identify spirostanol glycosides and furostanol glycosides as the 5-LOX/COX-2 dual inhibitors from saponins extract of Anemarrhenae Rhizoma (SEAR).

METHODS

A highly efficient method by combining affinity ultrafiltration and high-performance liquid chromatography-mass spectrometry (AUF-LC-MS) was first developed to screen and characterize the 5-LOX/COX-2 dual targeted inhibitors from SEAR. The structures of compounds in the ultrafiltrate were characterized by high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). In addition, in vitro 5-LOX/COX-2 inhibition assays and their dual expression in vivo were performed to confirm the inhibitory activities of the compounds screened by AUF-LC-MS. Molecular docking studies with the corresponding binding energy were obtained which fit nicely to both 5-LOX and COX-2 protein cavities and in agreement with our affinity studies.

RESULTS

A total of 5 compounds, timosaponin A-II, timosaponin A-III, timosaponin B-II, timosaponin B-III and anemarrhenasaponin I, were identified as potential 5-LOX/COX-2 dual targeted inhibitors with specific binding values > 1.5 and IC₅₀ ≤ 6.07 μM.

CONCLUSION

The present work demonstrated that spirostanol glycoside and furostanol glycoside were identified as two novel classes of dual inhibitors of 5-LOX/COX-2 enzymes by employing a highly efficient screening method of AUF-LC-MS. These natural products represent a novel class of anti-inflammatory agents with the potential of improved efficacy and reduced side effects.

A Total of Eight Novel Steroidal Glycosides Based on Spirostan, Furostan, Pseudofurostan, and Cholestane from the Leaves of Cestrum newellii

Previously, various steroidal glycosides were reported from plants of Cestrum species. However, phytochemical investigation has not been conducted on Cestrum newellii. A systematic phytochemical investigation of the leaves of C. newellii resulted in the isolation of eight novel steroidal glycosides (1-8), which were classified into three spirostanol glycosides (1-3), two furostanol glycosides (4 and 5), two pseudofurostanol glycosides (6 and 7), and one cholestane glycoside (8). In addition, three known cholestane glycosides (9-11) were isolated and identified. The structures of the new compounds were determined based on spectroscopic data and chemical transformations. Compounds 1 and 2 are spirostanol glycosides having hydroxy groups at C-2, C-3, C-12, and C-24 of the aglycone moiety. Although C. newellii is known to be a poisonous plant, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay exhibited that none of the isolated compounds were cytotoxic to HL-60 human promyelocytic leukemia cells.

Characterization of 3-aminospirostane alkaloids from roots of Solanum paniculatum L. with hepatoprotective activity

RATIONALE

Solanum paniculatum L., popularly known as jurubeba, has traditionally been used in Brazilian folk medicine for liver diseases. However, there is a lack of knowledge about the chemical characterization of 3-aminospirostane alkaloids, an important class related to pharmacological activities. This work aimed to characterize the alkaloids using liquid chromatography with tandem mass spectrometry (LC/MS/MS) supported by molecular networking and theoretical calculations as well as to evaluate the contribution to hepatoprotective activity.

METHODS

S. paniculatum roots were collected and macerated with MeOH/H₂ O (8:2) obtaining the crude extract (SP-CE). From this, partition using EtOAc with pH variation yielded the alkaloidic fraction (SP-AF). Both were evaluated in an acute liver injury model (100 and 200 mg/kg), after intraperitoneal administration of carbon tetrachloride (CCl₄ ) in mice. AST (aspartate transaminase) and ALT (alanine transaminase) serum levels were investigated, as well as the histopathological characteristics. The SP-CE and SP-AF were analyzed by LC/MS/MS, using quadrupole/time-of-flight and ion-trap systems. The alkaloids annotated by the GNPS molecular network had their structures defined using gas-phase ionization and fragmentation reaction supported by theoretical calculations.

RESULTS

The SP-CE and SP-AF decreased the ALT serum levels compared with the negative control. The group treated with the SP-CE (at the highest dose) demonstrated a significant decrease of ALT. Hepatic cell degeneration decrease was observed mainly at the highest dose of the treatment. Detailed electrospray ionization MS/MS data allowed us to identify alkaloids not previously reported, to propose their gas-phase reactions and to redefine the initial open ring fragmentation mechanism of the steroidal alkaloids with the jurubidine moiety.

CONCLUSIONS

The results allowed us to identify seven steroidal alkaloids from jurubeba and redefine the initial mechanism of fragmentation. A significant hepatoprotective effect was also demonstrated, corroborating its traditional use.

Sarsasapogenin Suppresses RANKL-Induced Osteoclastogenesis in vitro and Prevents Lipopolysaccharide-Induced Bone Loss in vivo

INTRODUCTION

Osteoclasts are giant polynuclear cells; their main function is bone resorption. An increased number of osteoclasts and enhanced bone resorption exert significant effects on osteoclast-related bone-lytic diseases, including osteoporosis. Given the limitations of current therapies for osteolytic diseases, it is urgently required to develop safer and more effective alternatives. Sarsasapogenin, a major sapogenin from Anemarrhena asphodeloides Bunge, possesses potent antitumor effects and inhibits NF-κB and MAPK signaling. However, the manner in which it affects osteoclasts is unclear.

METHODS

We investigated the effects of anti-osteoclastogenic and anti-resorptive of sarsasapogenin on bone marrow-derived osteoclasts.

RESULTS

Sarsasapogenin inhibited multiple RANKL-induced signaling cascades, thereby inhibiting the induction of key osteoclast transcription factor NFATc1. The in vivo and in vitro results were consistent: sarsasapogenin treatment protected against bone loss in a mouse osteolysis model induced by lipopolysaccharide.

CONCLUSION

Our research confirms that sarsasapogenin can be used as a new treatment for osteoclast-related osteolytic diseases.

Synthesis of Thiol Derivatives of Biological Active Compounds for Nanotechnology Application

An efficient method of thiol group introduction to the structure of common natural products and synthetic active compounds with recognized biological efficacy such genistein (1), 5,11-dimethyl-5H-indolo[2,3-b]quinolin (2), capecitabine (3), diosgenin (4), tigogenin (5), flumethasone (6), fluticasone propionate (7), ursolic acid methyl ester (8), and β-sitosterol (9) was developed. In most cases, the desired compounds were obtained easily via two-step processes involving esterification reaction employing S-trityl protected thioacetic acid and the corresponding hydoxy-derivative, followed by removal of the trityl-protecting group to obtain the final compounds. The results of our preliminary experiments forced us to change the strategy in the case of genistein (1), and the derivatization of diosgenin (4), tigogenin (5), and capecitabine (3) resulted in obtaining different compounds from those designed. Nevertheless, in all above cases we were able to obtain thiol-containing derivatives of selected biological active compounds. Moreover, a modelling study for the two-step thiolation of genistein and some of its derivatives was accomplished using the density functional theory (B3LP). A hypothesis on a possible reason for the unsuccessful deprotection of the thiolated genistein is also presented based on the semiempirical (PM7) calculations. The developed methodology gives access to new sulphur derivatives, which might find a potential therapeutic benefit.

Synthesis and application of steroidal 22,16β-carbolactones: A review

In the plant kingdom, steroidal lactones occur as glycosides, compounds consisting of a sugar moiety linked to a steroid aglycone. Steroidal lactones consist of five fused rings, with a total of 22 carbon atoms. Numerous methods for the preparation of steroidal lactones take advantage of the fact that steroid spirostanes may be degraded from six- to a five-rings structure. One of the most striking features common to reactions of steroid sapogenins is the C₂₂-lactone formation. In the review, different methods for the preparation of steroidal lactones are presented with consideration of the structure of starting material. In addition, examples of lactones used in the synthesis of biologically active compounds and their analogues are described.

Synthesis and anti-tumour, immunomodulating activity of diosgenin and tigogenin conjugates

A series of novel diosgenin (DSG) and tigogenin (TGG) derivatives with diosgenin or tigogenin steroid aglycons linked to levulinic and 3,4-dihydroxycinnamic acids, dipeptides and various amino acids by an ester bond at the C3-oxygen atom of the steroid skeleton has been synthesized. Diosgenyl esters have been prepared by an esterification reaction (DCC/DMAP) of diosgenin with the corresponding acids. All analogues have been evaluated in vitro for their antiproliferative profile against cancer cell lines (MCF-7, MDA-MB-231, PC-3) and human umbilical vein endothelial cells (HUVEC). Analogue2c (l-serine derivative of TGG), the best representative of the series showed IC₅₀ of 1.5 μM (MCF-7), and induced apoptosis in MCF-7 by activating caspase-3/7. The immunomodulatory properties of six synthesized analogues have been determined by examining their effects on the expression of cytokine genes essential for the functioning of the human immune system (IL-1, IL-4, IL-10, IL-12 and TNF-α). Biological evaluation has revealed that new compounds 4c and 16a do not induce the expression of pro-inflammatory cytokines in THP-1 cells after the lipopolysaccharide (LPS) stimulation. They also stimulate the expression of anti-inflammatory IL-10 that acts stronger than diosgenin itself. An in silico ADME properties(absorption, distribution, metabolism, excretion) study was also performed to predict the pharmacokinetic profile of the synthesized compounds. To shed light on the molecular interactions between the synthesized compounds and the glucocorticoid receptor and the estrogen receptor, 2c, 4c and 16a compounds were docked into the active binding sites of these receptors. The in silico and in vitro data suggested that this new group of compounds might be considered as a promising scaffold for further modification of more potent and selective anticancer and immunomodulatory agents.

Spirostanol and sesquiterpenoid glycosides from the rhizomes of Trillium tschonoskii

Three new spirostanol glycosides, trilliumosides K-M (1-3), one new sesquiterpenoid glycoside, tritschsesuquiside A (4), along with three known analogues (5-7) were obtained from the rhizomes of Trillium tschonoskii. The structures of new glycosides were elucidated by spectroscopic analyses (HRMS and NMR) and chemical methods. Glycosides 5-7 displayed cytotoxicities against five human cancer cell lines with IC₅₀ values ranging from 10.5 ± 1.0 to 1.0 ± 0.2 μM, with 7 being the most cytotoxic compound with IC₅₀ values of 1.0 ± 0.2, 2.2 ± 1.2, and 3.4 ± 0.4 μM against Huh7, CCRF-CEM, and HeLa cell lines, respectively. The flow cytometric results revealed that both 5 and 6 could induce apoptosis of HCT116 and Huh7 cells.

Sarsasapogenin: A steroidal saponin from Asparagus racemosus as multi target directed ligand in Alzheimer's disease

Alzheimer's disease (AD) is multi-factorial disorder characterized by impaired memory and cognition deficit. AD is characterized by impaired cholinergic transmission, extracellular amyloid beta deposits, neurofibrillary tangles and oxidative stress. A multi-target directed ligand (MTDL) approach is required to devise a therapeutic strategy against AD. In the present study, Asparagus racemosus aqueous extract was chosen, as it possess abundant medicinal properties including nootropic effect mentioned in ancient Ayurvedic texts. Moreover, its secondary metabolite sarsasapogenin (SRS) was also selected for this multi-target study for the very first time. The current study demonstrated that sarsasapogenin significantly inhibits key enzymes involved in pathogenesis of AD which are acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), BACE1 and MAO-B in a concentration dependent manner. SRS also exhibited anti-amyloidogenic, anti-oxidant and neuroprotective effects by in vitro studies. The IC₅₀ values of SRS is 9.9 μM and 5.4 μM for AChE and BuChE respectively. SRS also significantly inhibited Aβ42 fibrillization up to 68% at 40 μM concentration as compared to control. TEM visualization showed Aβ aggregates as short and scattered fibril clearly indicating SRS significantly inhibited peptide nucleation and fibril formation. Furthermore, the SRS was found to exert neuroprotective effect on PC12 cells against Aβ42 and H₂O₂-mediated cytotoxicity. The cell survival was 62% and 69% against Aβ42 and H₂O₂-mediated cytotoxicity, respectively. SRS also inhibited monoaminoxidase-B (MAO-B) and BACE1 enzymes in concentration dependent manner. Molecular docking studies indicated that SRS binds to the catalytic sites of multiple targets (AChE, BuChE, Aβ42, BACE1, and MAO-B) in a significant manner that might having disease-modifying effects. Thus SRS is acting as suitable lead and can be utilised as MTDL compound for factors implicated in AD.

Studies on the reactivity of 23E-benzylidene spirostanes

A study of the reactivity of 25R and 25S 23E-benzylidene spirostanes that includes epoxidation, catalytic hydrogenation as well as Lewis or Brønsted acid-catalyzed rearrangements is described. Exhaustive NMR characterization of the obtained compounds is presented. Additionally the structures of some of the obtained compounds were confirmed by single crystal X-Ray Diffraction studies.

Synthesis and biological evaluation of 3-carbamate smilagenin derivatives as potential neuroprotective agents

Studies indicated that smilagenin, isolated from Anemarrhena asphodeloides Bunge, could improve cognitive impairment and exhibit neuroprotective activity. On the basis of the structure of smilagenin, a series of derivatives were synthesized and evaluated for their neuroprotective effects of H₂O₂-induced, oxygen glucose deprivation-induced neurotoxicity in SH-SY5Y cells and LPS-induced NO production in RAW264.7 cells. Structure activity relationship of derivatives revealed that benzyl-substituted piperazine formate derivatives showed the potent neuroprotective activity such as A12. These findings may provide new insights for the development of neuroprotective agents against Alzheimer's disease.

Metabolic Profiling of Saponin-Rich Ophiopogon japonicus Roots Based on 1H NMR and HPTLC Platforms

Ideally, metabolomics should deal with all the metabolites that are found within cells and biological systems. The most common technologies for metabolomics include mass spectrometry, and in most cases, hyphenated to chromatographic separations (liquid chromatography- or gas chromatography-mass spectrometry) and nuclear magnetic resonance spectroscopy. However, limitations such as low sensitivity and highly congested spectra in nuclear magnetic resonance spectroscopy and relatively low signal reproducibility in mass spectrometry impede the progression of these techniques from being universal metabolomics tools. These disadvantages are more notorious in studies of certain plant secondary metabolites, such as saponins, which are difficult to analyse, but have a great biological importance in organisms. In this study, high-performance thin-layer chromatography was used as a supplementary tool for metabolomics. A method consisting of coupling ¹H nuclear magnetic resonance spectroscopy and high-performance thin-layer chromatography was applied to distinguish between Ophiopogon japonicus roots that were collected from two growth locations and were of different ages. The results allowed the root samples from the two growth locations to be clearly distinguished. The difficulties encountered in the identification of the marker compounds by ¹H nuclear magnetic resonance spectroscopy was overcome using high-performance thin-layer chromatography to separate and isolate the compounds. The saponins, ophiojaponin C or ophiopogonin D, were found to be marker metabolites in the root samples and proved to be greatly influenced by plant growth location, but barely by age variation. The procedure used in this study is fully described with the purpose of making a valuable contribution to the quality control of saponin-rich herbal drugs using high-performance thin-layer chromatography as a supplementary analytical tool for metabolomics research.

Dioscin-6'-O-acetate inhibits lung cancer cell proliferation via inducing cell cycle arrest and caspase-dependent apoptosis

BACKGROUND

Lung cancer is the leading cause of global cancer-related mortality. Dioscin-6'-O-acetate (DA), a novel natural steroidal saponin, was firstly isolated from the rhizomes of Dioscorea althaeoides R. Knuth. Until now, there were no studies on its pharmacological activities.

PURPOSE

Here, we investigated the growth inhibitory effect and explored the underlying molecular mechanisms of DA against lung cancer cells.

METHODS/STUDY DESIGNS

NSCLC H460, H1299, H520 cells and SCLC H446 cells were treated with DA. To display the cytotoxic effects and possible mechanism of DA on these cells, MTT assay, flow cytometry and western blot analysis were carried out.

RESULTS

Our results showed that DA exerted strong anti-proliferative activity against lung cancer cells in a concentration- and time-dependent manner. Flow cytometry demonstrated DA induced the cell cycle arrest at S-phase (NCI-H460, NCI-H1299, NCI-H520) or G1-phase (NCI-H446), caused cellular apoptosis, generation of reactive oxygen species (ROS) and loss of mitochondrial membrane potential. Western blotting analysis showed DA treatment increased the levels of caspase 3, 8, 9, Bax, p21, p53, phosphorylated JNK and p38 MAPK and markedly decreased the expression of Bcl-2, p-ERK, p-PI3K, p-AKT and NF-κB. Blockade of caspases with Z-VAD-FMK converted apoptosis-related proteins. Suppression of p53 with pifithrin-α (PFT) attenuated cell cycle-related protein. Inhibition of ROS with N-acetyl-cysteine (NAC) adjusted apoptosis-related proteins and phosphorylated MAPK and PI3K, as well as NF-κB.

CONCLUSION

Overall, our study indicated that DA suppressed lung cancer cells proliferation via inducing cell-cycle arrest and enhancing caspase-dependent apoptosis, at least partly, through ROS-mediated PI3K/AKT, MAPK and NF-κB signaling pathways.

Synthesis of dimeric spirostanols linked through a 1,4-dimethylidenebenzene moiety by double BF3·Et2O-catalyzed aldol condensation of steroid sapogenins and terephtalaldehyde

BF₃·Et₂O-catalyzed double aldol condensation between acetylated steroid sapogenins and terephtalaldehyde led to acetylated dimeric spirostanols linked through a 1,4-dimethylidenebenzene moiety in moderate to good yields. The E configurations of the introduced double bonds were corroborated by NOE experiments. Saponification of the dimeric steroids led to the corresponding dimeric spirostanols.

Biotransformation of ruscogenins by Cunninghamella blakesleeana NRRL 1369 and neoruscogenin by endophytic fungus Neosartorya hiratsukae

Biotransformation of steroidal ruscogenins (neoruscogenin and ruscogenin) was carried out with Cunninghamella blakesleeana NRRL 1369 and endophytic fungus Neosartorya hiratsukae yielding mainly P450 monooxygenase products together with a glycosylated compound. Fermentation of ruscogenins (75:25, neoruscogenin-ruscogenin mixture) with C. blakesleeana yielded 8 previously undescribed hydroxylated compounds. Furthermore, microbial transformation of neoruscogenin by endophytic fungus N. hiratsukae afforded three previously undescribed neoruscogenin derivatives. While hydroxylation at C-7, C-12, C-14, C-21 with further oxidation at C-1 and C-7 were observed with C. blakesleeana, N. hiratsukae biotransformation provided C-7 and C-12 hydroxylated compounds along with C-12 oxidized and C-1(O) glycosylated derivatives. The structures of the metabolites were elucidated by 1-D (¹H, ¹³C and DEPT135) and 2-D NMR (COSY, HMBC, HMQC, NOESY, ROESY) as well as HR-MS analyses.

Design, synthesis and biological evaluation of 3-piperazinecarboxylate sarsasapogenin derivatives as potential multifunctional anti-Alzheimer agents

A series of multifunctional 3-piperazinecarboxylate sarsasapogenin derivatives were designed and synthesized against Alzheimer's disease (AD). The protection against H₂O₂-triggered oxidative stress in PC12 cells, and inhibition on LPS-induced NO production in RAW264.7 cell lines in vitro by these derivatives were firstly evaluated. Most of the compounds showed better antioxidant and antiinflammatory activities compared with sarsasapogenin, especially AA34 and AA36. Structure-activity relationships revealed that benzyl group, electron-donating group and intramolecular hydrogen bond might be beneficial to enhancing their neuroprotective activities. Moreover, Aβ42 was the optimum predicted target based on the high 3D molecular similarity between compound AA36 and caprospinol. In the following experiments, AA36 significantly protected PC12 cells from Aβ-induced damage and improved learning and memory impairments in Aβ-injected mice. Thus AA36 is regarded as a potent anti-AD agent and N-substituted piperazinecarboxylate can be served as a promising structural unit for anti-AD drug design.

Apoptosis and pro-death autophagy induced by a spirostanol saponin isolated from Rohdea chinensis (Baker) N. Tanaka (synonym Tupistra chinensis Baker) on HL-60 cells

BACKGROUND

Our previous study has revealed that the spirostanol saponins isolated from the rhizomes of Rohdea chinensis (Baker) N. Tanaka (synonym Tupistra chinensis Baker) (Convallariaceae) (a reputed folk medicine) exhibited potent antiproliferative activity. However, the underlying mechanism of purified saponins remains unclear. More studies are necessary to assess the apoptosis and autophagy activities of the saponins from R. chinensis and clarify their antiproliferative mechanisms.

PURPOSE

The present study certificated the potential antiproliferative activity and mechanism of 5β-spirost-25(27)-en-1β,3β-diol-1-O-α-L-rhamnopyranosyl-(1→2)- β-D-xylopyranosyl-3-O-α-L-rhamnopyranoside (SPD), a spirostanol saponin from R. chinensis, against human acute promyelocytic leukemia cells (HL-60).

METHODS

The antiproliferative activity of SPD in vitro was evaluated by MTT assay compared with cis-dichlorodiammineplatinum (II). The autophagic activity was assessed using MDC staining and western blot, cell apoptosis inspection was detected by Annexin V-FITC/PI double staining and the mitochondrial membrane potential was detected by JC-1 fluorescence dye combined with flow cytometry. The potential mechanisms for protein levels of apoptosis and autophagy were evaluated by western blot.

RESULTS

Treatment of HL-60 cells with SPD resulted in growth inhibition (IC₅₀ value of 2.0 ± 0.2 µM, after 48 h treatment) and induction of apoptosis and autophagy. Results from Annexin V-FITC/PI double-staining assay and mitochondrial membrane potential detection showed that apoptosis was happened after SPD treatment. The regulation of caspase-3, Bax, Bcl-2, PARP following SPD treatment contributed to the induction of mitochondria-dependent apoptosis. Meanwhile, SPD induced autophagy related with Akt/mTOR/p70S6K signaling and activated of AMPK signaling pathway. Furthermore, blocking autophagy with bafilomycin A1 reduced the cytotoxicity of SPD in HL-60 cells.

CONCLUSION

The antiproliferative, apoptosis and pro-death autophagy activities of SPD suggested that spirostanol saponins from R. chinensis would be a potential cytotoxic candidate against acute promyelocytic leukemia.

Synthesis of new sarsasapogenin derivatives with antiproliferative and apoptotic effects in MCF-7 cells

Sarsasapogenin, a kind of mainly effective component of Anemarrhena asphodeloides Bunge, possesses good antitumor properties. Two series of new sarsasapogenin derivatives were synthesized and evaluated for their cytotoxicities against three human cancer cell lines (HepG2, A549, MCF-7) using the MTT assay. The structure-activity relationship revealed that the N, N-dimethylamino, pyrrolidinyl, and imidazolyl substituted at the C26 position could increase the antitumor efficacy of the 3-oxo sarsasapogenin series of compounds. Compound 4c with pyrrolidinyl substituted at the C26 position exhibited the greatest cytotoxic activity against MCF-7 cell line (IC₅₀ = 10.66 μM), which was 4.3-fold more potent than sarsasapogenin. Action mechanism investigations showed that 4c could inhibit the colony formation and induce the apoptosis of MCF-7 cells. Further researches showed that a decrease in mitochondrial membrane potential and increases in the expression level of cleaved-PARP and the ratio of Bax/Bcl-2 were observed in MCF-7 cells after treatment with 4c, suggesting that the mitochondrial pathway was involved in the 4c-mediated apoptosis. These results show that compound 4c may serve as a lead for further optimization.

Synthesis and in vitro anticancer activity of 23(23')E-benzylidenespirostanols derived from steroid sapogenins

Benzylidenespirostanols were prepared by two-step synthesis including BF₃·Et₂O-catalyzed aldol condensation of several acetylated steroid sapogenins with benzaldehyde followed by saponification. The obtained compounds showed moderate cytotoxicity against three cancer cell lines (T-lymphoblastic leukemia cell line CEM, breast carcinoma cell line MCF7 and cervical carcinoma cell line HeLa) and normal human fibroblasts (BJ). The most active of the five tested substances was 3c (lowest IC₅₀ for MCF7 cells 19.9±0.1µM) without any selectivity towards human cancer and normal cells, respectively.

Synthesis and evaluation of 26-amino acid methyl ester substituted sarsasapogenin derivatives as neuroprotective agents for Alzheimer's disease

Sarsasapogenin, extracted from Anemarrhena asphodeloides Bunge., has been reported to protect neurons from H₂O₂-induced damage. In the current study, four series of 26-amino acid methyl ester substituted sarsasapogenin derivatives (5a-5e, 5f-5j, 6a-6e and 7a-7e) were synthesized and tested for neuroprotective activity by evaluating their neuroprotective ratio against SH-SHY5Y cell lines. Studies showed that most of the target compounds displayed better neuroprotective effects than that of sarsasapogenin. Structure-activity relationship analysis suggested that 3-methoxy derivatives (5f-5j) were more potent than other series and the phenylalanine methyl ester moiety at C-26 was important for exhibiting apparent neuroprotective activity. It was worth noting that compound 5h exhibited optimal neuroprotective activity (102.2%) compared with sarsasapogenin (27.3%) and trolox (40.5%), and this encouraged us to investigate the cellular mechanism of 5h further. Our investigation revealed that 5h could attenuate H₂O₂-induced cell damage by inhibiting the expression of cleaved poly (ADP-ribose) polymerase (PARP) and cleaved caspase-3 as well as rescuing the downregulation of brain-derived neurotrophic factor (BDNF) and its tyrosine receptor kinase B (TrkB). Taken together, these results suggest that the representative compound 5h is a profound lead compound for further investigation and the sarsasapogenin skeleton could be a promising structural template for the development of new anti-Alzheimer drug candidates.

Spirostanol saponins from Ypsilandra parviflora induce platelet aggregation

Phytochemical investigation on the whole plants of Ypsilandra parviflora led to the isolation of seven new spirostanol saponins, named ypsiparosides A-G, together with 14 known saponins. Their structures were unambiguously established based on extensive spectroscopic evidence and chemical methods. The induced rabbit platelet aggregation activities of the isolates were tested. Compounds 4, 15, and 17 showed maximal platelet aggregation rates ranging from 43 to 55% at a concentration of 300μg/mL. Further experiments exhibited that compounds 4, 15, and 17 possessed EC₅₀ values of 642.9, 95.3, and 300.8μg/mL, respectively.

New steroids from Anemarrhena asphodeloides rhizome and their α-glucosidase inhibitory activity

Two new steroids were isolated from acid hydrolysis residue of the rhizomes of Anemarrhena asphodeloides. Their structures were identified on the basis of several spectroscopic analysis approaches including 1D, 2D-NMR techniques, and MS data, and by the comparison of spectral data of the known compounds. The biological activities of these two isolated compounds were explored on α-glucosidase. Compound 1 displayed 4.7 folds inhibitory activity against α-glucosidase compared with the positive control acarbose.

Spirostanol glycosides with hemostatic and antimicrobial activities from Trillium kamtschaticum

Ten spirostanol glycosides, trillikamtosides A-J, together with eleven known analogues, were isolated from the hemostatic fraction of the 75% aqueous EtOH extract of the whole herbs of Trillium kamtschaticum. Their structures were established by extensive spectroscopic data analysis and chemical methods. The aglycones of three of these compounds had unique 3β,17α-dihydroxy-spirostanes featuring a double bond between C-4 and C-5, while two others represent a rare class of spirostanol glycosides which possess a 5(6 → 7) abeo-steroidal aglycone. All the compounds were evaluated for their hemostatic and antimicrobial activities. Three of the spirostanol glycosides exhibited induced-platelet aggregation at a concentration of 300 μg/mL with maximal induced-platelet aggregation rates of 72%, 71%, and 62% in rabbits, respectively, and their EC₅₀ values were 492.7, 203.3, and 109.8 μM. Five of the spirostanol glycosides showed an anti-Candida albicans effect with MIC values of 21.1, 10.6, 8.8, 21.6, and 11.0 μM, respectively.

Steroidal saponins from Chlorophytum deistelianum

Phytochemical investigation of the aerial parts of Chlorophytum deistelianum led to the isolation of four previously undescribed steroidal saponins called chlorodeistelianosides A-D with five known ones. Their structures were established mainly by extensive 1D and 2D NMR spectroscopic techniques and mass spectrometry as (25R)-3β-[(β-D-glucopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→4)]-β-D-xylopyranosyl-(1→3)-[β-D-glucopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranosyl)oxy]-5α-spirostan-12-one, (24S,25S)-24-[(β-D-glucopyranosyl)oxy]-3β-[(β-d-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranosyl)oxy]-5α-spirostan-12-one, (25R)-26-[(β-D-glucopyranosyl)oxy]-2α-hydroxy-22α-methoxy-5α-furostan-3β-yl β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside, and (25R)-26-[(β-D-glucopyranosyl)oxy]-3β-[(β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranosyl)oxy]-5α-furost-20(22)-en-12-one. Cytotoxicity of most compounds was evaluated against one human cancer cell line (SW480) and one rat cardiomyoblast cell line (H9c2). Among them, three known spirostane-type glycosides exhibited cytotoxicity on both cell lines with IC50 ranging from 8 to 10 μM.

Bioactive spirostanol saponins from the rhizome of Tupistra chinensis

Phytochemical investigations of the rhizome of Tupistra chinensis led to the isolation of six new spirostanol saponins, one new spirostanol, along with eight known spirostanols. Their chemical structures were elucidated on the basis of spectroscopic and chemical methods, including IR, NMR, MS, and GC analyses. The antiproliferative effects against five human cancer cell lines were assayed for all the isolated compounds. Compounds 8, 12 and 15 showed potent cytotoxic activities against K562 cells. The isolated compounds were evaluated for their inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide in a macrophage cell line RAW 264.7. Compounds 2 and 12 showed significant inhibition on NO production with IC50 values of 16.1±1.8 and 13.5±1.2 μM, respectively.

Bioactive spirostane glycosides from Tacca plantaginea

Eight new spirostane glycosides, taccaosides E-L (2-7, 11, and 14), along with 7 known spirostane glycosides were isolated from the extract of the whole plants of Tacca plantaginea (Hance) Drenth. Their structures were established on the basis of physical data, spectroscopic analysis (MS, 1D and 2D NMR), and chemical methods. The cytotoxicities of the isolates were evaluated in vitro against two human cancer cell lines (HEK293 and HepG2). The results showed that compound 1 had the strongest cytotoxic activity with IC50 values of 1.7 μM and 1.2 μM against the two cancer cell lines, respectively. Furthermore, the spirostane glycosides with 17α-hydroxyl group at their aglycones (10, 12, and 15) were tested for the induced platelet aggregation activity.

Spirostanol glucosides from the leaves of Cestrum laevigatum L

Two new steroidal saponins, (25R)-spirost-5-ene-3β,26β-diol 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-[(1 → 2)-α-L-rhamnopyranosyl]-β-D-glucopyranoside (1) and (25R)-spirost-6-ene-3β,5β-diol 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-[(1 → 2)-α-L-rhamnopyranosyl]-β-D-glucopyranoside (2), along with the known diosgenin 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-β-D-glucopyranoside (3), chonglouoside SL-5 (4) and Paris saponin Pb (5) were isolated from the leaves of Cestrum laevigatum. The structures of the compounds were determined using spectroscopic analyses including HRESI-MS, 1D and 2D NMR data, followed by comparison with data from the literature. Among them, two are particularly unique, compound 1 is the first (6)Δ-spirostanol saponin and compound 2 has an unusual C-26 hydroxyl in the (5)Δ-spirostanol skeleton. Antifungal testing showed a potent activity to formosanin C against Candida albicans and Candida parapsilosis. Evaluation of the cytotoxic activity indicated that compound 1 has a moderate activity against HL-60 and SF-295 cell lines, while compound 2 were active only against HL-60.

Ruscogenin exerts beneficial effects on monocrotaline-induced pulmonary hypertension by inhibiting NF-κB expression

This study aims to examine the effect of ruscogenin on pulmonary arterial hypertension (PAH) and to determine the mechanism underlying this effect. We isolated pulmonary vascular smooth muscle cells (PVSMCs) from the pulmonary artery of the rats; the PVSMCs were cultured in vitro and then were treated with platelet-derived growth factor (PDGF), PDGF + ruscogenin, or PDGF + ruscogenin + parthenolide. We randomized Sprague-Dawley rats into five groups as follows: control group, PAH group, low-dose group, medium-dose group, and high-dose group; the rats in the low-, medium-, and high-dose groups received the vehicle and ruscogenin 0.1, 0.4, and 0.7 mg/kg, respectively, from day 1 to day 21 after injection of monocrotaline (MCT). We measured the mean pulmonary arterial pressure (mPAP), right ventricular systolic pressure (RVSP), and medial wall thickness of the pulmonary artery (PAWT). We examined the levels of the nuclear factor kappa B (NF-κB) protein by using immunohistochemistry and western blot analysis, and the mRNA levels of NF-κB in PVSMCs were evaluated using real-time polymerase chain reaction (PCR). The mPAP, RVSP, and PAWT and the protein and mRNA levels of NF-κB were significantly higher in the PAH model group than in the control group (P < 0.05). Ruscogenin induced a significant dose-dependent decrease in the mPAP, RVSP, and PAWT and in the NF-κB expression in the PAH group (P < 0.05), which suggests that ruscogenin will also exert dose-dependent effects on MCT-induced PAH through the inhibition of NF-κB.

Spirostanol steroids from the roots of Allium tuberosum

Three new spirostanol saponins named tuberosines A-C (1-3), together with three known ones tuberoside O (4), 25(S)-Schidigera-saponin D5 (5), and shatavarin IV (6) were isolated from the roots of Allium tuberosum. Their structures were established on the basis of extensive spectroscopic analyses. Whereas compounds 5 and 6 exhibited potent antibacterial activities against Bacillus subtilis (32 μg/mL) and Escherichia coli (16 μg/mL), the new saponin 2 showed only moderate antibacterial activities against these pathogens. The relationship between the antibacterial activities and the structures of these saponins are described.

Ophiopogonin D: A new herbal agent against osteoporosis

Excessive reactive oxygen species (ROS) play an important role in the development of osteoporosis. Ophiopogonin D (OP-D), isolated from the traditional Chinese herbal agent Radix Ophiopogon japonicus, is a potent anti-oxidative agent. We hypothesized that OP-D demonstrates anti-osteoporosis effects via decreasing ROS generation in mouse pre-osteoblast cell line MC3T3-E1 subclone 4 cells and a macrophage cell line RAW264.7 cells. We investigated OP-D on osteogenic and osteoclastic differentiation under oxidative status. Hydrogen peroxide (H2O2) was used to establish an oxidative damage model. In vivo, we established a murine ovariectomized (OVX) osteoporosis model. Then, we searched the molecular mechanism of OP-D against osteoporosis. Our results revealed that OP-D significantly promoted the proliferation of MC3T3-E1 cells and improved some osteogenic markers. Moreover, OP-D reduced TRAP activity and the mRNA expressions of osteoclastic genes in RAW264.7 cells. OP-D suppressed ROS generation in both MC3T3-E1 and RAW264.7 cells. OP-D treatment reduced the activity of serum bone degradation markers, including CTX-1 and TRAP. Further research showed that OP-D displayed anti-osteoporosis effects via reducing ROS through the FoxO3a-β-catenin signaling pathway. In summary, our results indicated that the protective effects of OP-D against osteoporosis are linked to a reduction in oxidative stress via the FoxO3a-β-catenin signaling pathway, suggesting that OP-D may be a beneficial herbal agent in bone-related disorders, such as osteoporosis.

Steroidal saponins with induced platelet aggregation activity from the aerial parts of Paris verticillata

In order to utilize and protect the resources of Rhizoma Paridis rationally, we carried out a phytochemical investigation on the non-medicinal (aerial) parts of Paris verticillata that led to the isolation of fifteen steroidal saponins. Among them, three are new spirostanol saponins, named parisverticosides A–C (1–3), as well as one new cholestane glycoside, named parisverticoside D (4). Their structures were elucidated by extensive spectroscopic analysis and acid hydrolysis. The aglycone of compound 1 is a new spirostane and identified as (23S,24S,25S)-spirost-5-en-1b,3b,23, 24-tetraol. The selected isolates were evaluated for induced platelet aggregation activity and compound 5 showed 62% maximal platelet aggregation rate at the concentration of 300 lg/mL.

Steroidal glycosides from the underground parts of Dracaena thalioides and their cytotoxic activity

Six spirostanol glycosides (1-6) and 12 known compounds (7-18) were isolated from the underground parts of Dracaena thalioides (Agavaceae). Their structures were determined by spectroscopic analysis, including 2D NMR spectroscopic data, and chemical transformations. The isolated compounds were evaluated for cytotoxic activity against HL-60 human leukemia cells. Compounds 1, 3-6, and 8-18 showed cytotoxicity against HL-60 cells, of which 10, a bisdesmosidic spirostanol derivative, showed potent cytotoxicity against HL-60 cells with an IC50 value of 0.38μM and induced apoptosis in HL-60 cells.

Anti-Inflammatory Spirostanol and Furostanol Saponins from Solanum macaonense

Eight new spirostanol saponins, macaosides A-H (1-8), and 10 new furostanol saponins, macaosides I-R (9-18), together with six known spirostanol compounds (19-24) were isolated from Solanum macaonense. The structures of the new compounds were determined from their spectroscopic data, and the compounds were tested for in vitro antineutrophilic inflammatory activity. It was found that both immediate inflammation responses including superoxide anion generation and elastase release were significantly inhibited by treatment with compounds 20, 21, and 24 (superoxide anion generation: IC50 7.0, 7.6, 4.0 μM; elastase release: IC50 3.7, 4.4, 1.0 μM, respectively). However, compounds 1 and 4 exhibited effects on the inhibition of elastase release only, with IC50 values of 3.2 and 4.2 μM, respectively, while 19 was active against superoxide anion generation only, with an IC50 value of 6.1 μM. Accordingly, spirostanols may be promising lead compounds for further neutrophilic inflammatory disease studies.

Ruscogenin protects against high-fat diet-induced nonalcoholic steatohepatitis in hamsters

The protective effects of ruscogenin on nonalcoholic steatohepatitis in hamsters fed a high-fat diet were investigated. Ruscogenin (0.3, 1.0, or 3.0 mg/kg/day) was orally administered by gavage once daily for eight weeks. A high-fat diet induced increases in plasma levels of total cholesterol, triglycerides, and free fatty acids, while the degree of insulin resistance was lowered by ruscogenin. High-fat diet-induced hepatic steatosis and necroinflammation were improved by ruscogenin. Gene expression of inflammatory cytokines and activity of nuclear transcription factor-κB were also increased in the high-fat diet group, which were attenuted by ruscogenin. Ruscogenin decreased hepatic mRNA levels of sterol regulatory element-binding protein-1c and its lipogenic target genes. The hepatic mRNA expression of peroxisome proliferator-activated receptor α, together with its target genes responsible for fatty acid β-oxidation were upregulated by ruscogenin. In conclusion, these findings suggest that ruscogenin may attenuate high-fat diet-induced steatohepatitis through anti-inflammatory mechanisms, reducing hepatic lipogenic gene expression, and upregulating proteins in the fatty acid oxidation process.

Longipetalosides A-C, new steroidal saponins from Tribulus longipetalus

Longipetalosides A-C (1-3); three new furostane steroidal saponins together with (25S)-5α-furastan-3β,22,26-triol (4) and gitogenin (5) were isolated from the methanolic extract of the whole plant of Tribulus longipetalus. The structures of these compounds (1-5) were established by using 1D ((1)H, (13)C) and 2D NMR (HMQC, HMBC, COSY, NOESY) spectroscopy, and mass spectrometry (ESIMS, HRESIMS), and in comparison with literature data reported for related compounds. Compounds 1-5 were evaluated for their inhibitory activities against enzymes α-glucosidase, lipoxygenase, acetylcholinesterase, and butyrylcholinesterase. Only the compounds 4 and 5 were found as the inhibitors of enzyme α-glucosidase with IC50 values of 33.5±0.22 and 37.2±0.18μM, respectively.

Isolation and structural elucidation of novel cholestane glycosides and spirostane saponins from Polygonatum odoratum

Much attention has been paid to cholestane-type steroidal glycosides because of their importance from the perspectives of both chemical diversity and significant biological activities. A phytochemical investigation of the rhizomes of Polygonatum odoratum (Liliaceae) resulted in the isolation of three novel cholestane-type steroidal glycosides (1-3) with unique Δ(14,16)-unsaturated D-ring structures as well as two novel spirostane-type steroidal saponins (4 and 5) and three known steroidal glycosides (6-8). Their structures were determined by various spectroscopic methods and chemical reactions. Steroidal saponin 7 showed significant antifungal activity against Candida albicans JCM1542 (MIC 3.1 μg/mL) and Aspergillus fumigatus JCM1738 (MIC 6.3 μg/mL).

Anti-neutrophilic inflammatory steroidal glycosides from Solanum torvum

Torvpregnanosides A and B, two pregnane glycosides, and torvoside Q, a 23-keto-spirostanol glycoside, along with twelve known steroidal saponins were isolated from aerial parts of Solanum torvum. Of the latter, four of the 23-hydroxy-spirostanol glycosides, and, a yamogenin glycoside, were in this plant discovered. All structures were identified from spectroscopic data, and all the compounds were tested for in vitro anti-neutrophilic inflammatory activity. Two compounds showed selective inhibition against elastase release and superoxide anion generation, respectively, by human neutrophils with IC50 values of 5.66 and 3.59 μM, while two others inhibited both inflammatory mediators with IC50 values of 0.66-3.49 μM. Structure-activity relationships are discussed.

Diacetoxyiodobenzene-mediated synthesis of unnatural furospirostane sapogenins derived from diosgenin and tigogenin

Two unnatural steroid sapogenins bearing a furospirostane side chain were prepared starting from the readily available spirostane sapogenins, tigogenin and diosgenin following a synthetic protocol that included: (i) introduction of a carbonyl group at position C-23, (ii) diacetoxyiodobenzene-induced F-ring contraction and (iii) LiAlH4 reduction of the newly emerged methoxycarbonyl moiety. The structures of the new compounds were corroborated by NMR and X-ray studies.

Mechanistic insights on the reactivity of furospirostanes with the 16β,22:22,25-diepoxy-23-acetoxymethyl-24-methyl side chain

F-ring opening in spirostanes with the 16β,22:22,25-diepoxy-23-acetoxymethyl-24-methyl side chain produces a Δ(22)-intermediate with an allylic acetoxy group. For this reason the reactivity profile of these compounds deviates from that observed in other naturally occurring or synthetic spirostanes and furospirostanes.

Spirostanol saponins and esculin from Rusci rhizoma reduce the thrombin-induced hyperpermeability of endothelial cells

Rusci rhizoma extracts are traditionally used against chronic venous disorders (CVD). To determine the effect of its secondary plant metabolites on the endothelium, phenolic compounds and saponins from Butcher's broom were isolated from a methanolic extract, and their activity on the thrombin-induced hyperpermeability of human microvascular endothelial cells (HMEC-1) was investigated in vitro. In addition to the six known spirostanol saponins deglucoruscin (5), 22-O-methyl-deglucoruscoside (6), deglucoruscoside (7), ruscin (8), ruscogenin-1-O-(α-l-rhamnopyranosyl-(1→2)-β-d-galactopyranoside (9) and 1-O-sulpho-ruscogenin (10), three new spirostanol derivatives were isolated and identified: 3'-O-acetyl-4'-O-sulphodeglucoruscin (1), 4'-O-(2-hydroxy-3-methylpentanoyl)-deglucoruscin (2) and 4'-O-acetyl-deglucoruscin (3). Furthermore, the coumarin esculin (4), which is also prominently present in other medicinal plants used in the treatment of CVD, was isolated for the first time from Rusci rhizoma. Five of the isolated steroid derivatives (2, 5, 8, 9 and 10) and esculin (4) were tested for their ability to reduce the thrombin-induced hyperpermeability of endothelial cells in vitro, and the results were compared to those of the aglycone neoruscogenin (11). The latter compound showed a slight but concentration-dependent reduction in hyperpermeability to 71.8% at 100μM. The highest activities were observed for the spirostanol saponins 5 and 8 and for esculin (4) at 10μM, and these compounds resulted in a reduction of the thrombin-induced hyperpermeability to 41.9%, 42.6% and 53.3%, respectively. For 2, 5 and 8, the highest concentration tested (100μM) resulted in a drastic increase of the thrombin effect. The effect of esculin observed at a concentration of 10μM was diminished at 100μM. These in vitro data provide insight into the pharmacological mechanism by which the genuine spirostanol saponins and esculin can contribute to the efficacy of Butcher's broom against chronic venous disorders.

Two spirostan steroid glycoside fatty esters from Dioscorea cayenensis

Two new fatty acid-spirostan steroid glycoside esters, progenin III palmitate (1) and progenin III linoleate (2), were isolated from the MeOH extract of Dioscorea cayenensis rhizomes. The extract also yielded seven previously known spirostan and furostan steroid glycosides (3-9). The structures of the new compounds were established as (25R)-spirost-5-en-3beta-yl O-alpha-L-rhamnopyranosyl-(1 --> 2)-[6-O-palmitoyl]-O-beta-D-glucopyranoside (1) and (25R)-spirost-5-en-3beta-yl O-alpha-L-rhamnopyranosyl-(1 --> 2)-[6-O-linoleoyl]-O-beta-D-glucopyranoside (2) by chemical and spectroscopic methods, including 1D and 2D NMR. The known compounds were identified as progenin III (3), dioscin (4), deltonin (5), asperin (6), gracillin (7), protodioscin (8)], and methyl protodioscin (9).

7-Oxodioscin, a new spirostan steroid glycoside from the rhizomes of Dioscorea nipponica

Nine glycosides of spirostan (1-7) and furostan (8 and 9) type steroids including a new compound, 7-oxodioscin (1), were isolated from the rhizomes of Dioscorea nipponica. The structure of 1 was established as (25R)-3beta-O-[(alpha-L-rhamnopyranosyl-(1 --> 4)-O-[alpha-L-rhamnopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl)oxy]spirost-5-en-7-one by extensive spectroscopic techniques including HRESI-TOFMS, 1D and 2D NMR, and chemical methods. Known compounds were elucidated as dioseptemloside G (2), (25R)-dracaenoside G (3), orbiculatoside B (4), dioscin (5), progenin III (6), gracillin (7), (3beta3,22alpha,25R)-26-(beta-D-glucopyranosyloxy)-22-methoxyfurost-5-en-3-yl O-[alpha-L-rhamnopyranosyl-(1 --4)]-beta-D-glucopyranoside (8), and methylprotodioscin (9).

Pennogenin tetraglycoside induces rat myometrial contraction and MLC20 phosphorylation via PLC-IP(3) and RhoA/Rho kinase signaling pathways

BACKGROUND

Total steroidal saponins extracted from the rhizome of Paris polyphylla Sm. var. yunnanensis (TSSPs) have been widely used in China for the treatment of abnormal uterine bleeding. We previously studied the main active constituents of TSSPs and their structure-activity relationships with respect to rat myometrial contractions. Tg (pennogenin tetraglycoside) was identified as one of the active ingredients in TSSPs able to induce rat myometrial contractions. However, the mechanisms underlying the pharmacological actions on uterine activity have not been described clearly.

METHODS

Here Tg was screened for effects on contractile activity in isolated uterine strips from estrogen-primed rats and on MLC20 phosphorylation and related signaling pathways in cultured rat myometrial cells as determined by Western blot. Intracellular calcium ([Ca(2+)](i)) was monitored under a confocal microscope using Fluo-4 AM-loaded myometrial cells.

RESULTS

Tg dose-dependently stimulated rat myometrial contractions as well as MLC20 phosphorylation in vitro, which could be completely suppressed by an inhibitor of myosin light chain kinase (MLCK). Use of Ca(2+) channel blockers and kinase inhibitors demonstrated that Tg-induced myometrial contractions are mediated by activation of the phospholipase C (PLC)-inositol triphosphate (IP3) signaling pathway, resulting in increased MLC20 phosphorylation. Furthermore, Y27632, a specific inhibitor of Rho kinase (ROK), notably suppressed Tg-stimulated myometrial contractions and decreased MLC20 phosphorylation.

CONCLUSIONS

These data provide evidence that rat myometrial contractility induced by Tg results from enhanced MLC20 phosphorylation, while both PLC-IP3 and RhoA/ROK signaling pathways mediate the process. These mechanisms may be responsible for the therapeutic effects of TSSPs on abnormal uterine bleeding.

New steroidal saponins and sterol glycosides from Paris polyphylla var. yunnanensis

Four new steroidal saponins, pariposides A-D (1-4), and two new sterol glycosides, pariposides E-F (5-6), along with eight known steroidal saponins (7-14), two known sterol glycosides (15-16), and two known ecdysteroids (17-18), were isolated from the roots of Paris polyphylla var. yunnanensis. Among them, compounds 1-4 are the first spirostanol saponins with a peroxy group located between C-5 and C-8 of the aglycone. Their structures were determined by detailed spectroscopic analyses and chemical methods. All the isolated compounds were evaluated for their in vitro cytotoxicities against human nasopharyngeal carcinoma epithelial (CNE) cells, and steroidal saponins 7, 11, 13, and 14 showed a potent antiproliferative effect on CNE cells with IC₅₀ values of 9.2, 4.7, 11.1, and 2.7 µM, respectively.

Steroidal saponins from Paris polyphylla var. yunnanensis

Eleven steroidal saponins, along with seven known steroidal saponins, were isolated from rhizomes of Paris polyphylla var. yunnanensis. Their chemical structures were elucidated on the basis of spectroscopic analyses and acid hydrolysis. Two of these compounds contained a spirostanol saponin aglycone, hitherto unknown in Nature. The isolated compounds were tested for their cytotoxic effects on human nasopharyngeal carcinoma epithelial (CNE) cells, and seven compounds displayed more potent inhibitory effects than cisplatin (the positive control). One compound with diosgenin and tetrasaccharide moieties possessed the strongest inhibitory effect on CNE cells through the induction of apoptosis and cell cycle arrest.

Application of high-speed countercurrent chromatography-evaporative light scattering detection for the separation of seven steroidal saponins from Dioscorea villosa

INTRODUCTION

Steroidal saponins in Dioscorea species are chemically characterised as spirostanol and furostanol saponins, and have been used as standard marker compounds due to their chemotaxonomical significance and their important biological activities.

OBJECTIVE

To design a simple, rapid and efficient method for the separation of steroidal saponins with a high degree of purity using high-speed countercurrent chromatography (HSCCC) coupled with evaporative light scattering detection (ELSD).

METHODOLOGY

In the first step, reversed-phase mode HSCCC (flow rate: 1.5 mL/min; revolution speed: 800 rpm) using n-hexane:n-butanol:water [3:7:10 (v/v/v)] was employed to separate furostanol saponins from n-butanol soluble extracts of Dioscorea villosa. After the first HSCCC run, spirostanol saponins retained in the stationary phase were subjected to the second HSCCC (normal-phase mode; flow rate: 2.0 mL/min; revolution speed: 800 rpm). A two-phase solvent system composed of chloroform:methanol:isopropanol:water [10:6:1:4 (v/v/v/v)] was employed in the second HSCCC. The structures of isolates were elucidated by (1) H-NMR, (13)  C-NMR, ESI-MS and HPLC analysis.

RESULTS

Three furostanol saponins, parvifloside (27.3 mg), methyl protodeltonin (67.1 mg) and trigofoenoside A-1 (18.5 mg) were isolated from the n-butanol soluble extract of D. villosa by the first HSCCC run. Subsquent normal-phase HSCCC of the spirostanol-rich extract led to the separation of four spirostanol saponins: zingiberensis saponin I (15.2 mg), deltonin (31.5 mg), dioscin (7.7 mg) and prosapogenin A of dioscin (3.4 mg).