Cytotoxic activities and structure-cytotoxic relationships of steroidal saponins

Dioscin: Therapeutic potential for diabetes and complications

Diabetes mellitus is a widespread metabolic disorder with increasing incidence worldwide, posing a considerable threat to human health because of its complications. Therefore, cost-effective antidiabetic drugs with minimal side effects are urgently needed. Dioscin, a naturally occurring compound, helps to reduce the complications of diabetes mellitus by regulating glucose and lipid metabolism, protecting islet β cells, improving insulin resistance, and inhibiting oxidative stress and inflammatory response. Plant-derived dioscin reduces the risk of toxicity and side effects associated with chemically synthesized drugs. It is a promising option for treating diabetes mellitus because of its preventive and therapeutic effects, which may be attributed to a variety of underlying mechanisms. However, data compiled by current studies are preliminary. Information about the molecular mechanism of dioscin remains limited, and no high-quality human experiments and clinical trials for testing its safety and efficacy have been conducted. As a resource for research in this area, this review is expected to provide a systematic framework for the application of dioscin in the treatment of diabetes mellitus and its complications.

Hemolysis by Saponin Is Accelerated at Hypertonic Conditions

Saponins are a large group of organic amphiphilic substances (surfactants) mainly extracted from herbs with biological activity, considered as one of the main ingredients in numerous remedies used in traditional medicine since ancient times. Anti-inflammatory, antifungal, antibacterial, antiviral, antiparasitic, antitumor, antioxidant and many other properties have been confirmed for some. There is increasing interest in the elucidation of the mechanisms behind the effects of saponins on different cell types at the molecular level. In this regard, erythrocytes are a very welcome model, having very simple structures with no organelles. They react to changing external conditions and substances by changing shape or volume, with damage to their membrane ultimately leading to hemolysis. Hemolysis can be followed spectrophotometrically and provides valuable information about the type and extent of membrane damage. We investigated hemolysis of erythrocytes induced by various saponin concentrations in hypotonic, isotonic and hypertonic media using measurements of real time and end-point hemolysis. The osmotic pressure was adjusted by different concentrations of NaCl, manitol or a NaCl/manitol mixture. Unexpectedly, at a fixed saponin concentration, hemolysis was accelerated at hypertonic conditions, but was much faster in NaCl compared to mannitol solutions at the same osmotic pressure. These findings confirm the colloid-osmotic mechanism behind saponin hemolysis with pore formation with increasing size in the membrane.

Cytotoxic steroidal glycosides from the rhizomes of Paris polyphylla var. yunnanensis

Paris polyphylla var. yunnanensis (Franch.) Hand.-Mazz. (Melanthiaceae), an important specie of the genus Paris, has long been in a traditional Chinese medicine (TCM) for a long time. This study aimed to isolate and identify the structures of bioactive saponins from the rhizomes of P. polyphylla var. yunnanensis and evaluate their cytotoxicity against BxPC-3, HepG2, U373 and SGC-7901 carcinoma cell lines. Seven previously undescribed and seven known saponins were identified, and Paris saponins VII (PSVII) showed significant cytotoxicity against the BxPC-3 cell line with IC₅₀ values of 3.59 μM. Furthermore, flow cytometry, transmission electron microscopy and western-bolt analysis revealed that PSVII inhibited the proliferation of BxPC-3 cells and might be involved in inducing apoptosis and pyroptosis by activating caspase-3, -7 and caspase-1, respectively.

Chemical Synthesis of Saponins

Saponins are a large family of amphiphilic glycosides of steroids and triterpenes found in plants and some marine organisms. By expressing a large diversity of structures on both sugar chains and aglycones, saponins exhibit a wide range of biological and pharmacological properties and serve as major active principles in folk medicines, especially in traditional Chinese medicines. Isolation of saponins from natural sources is usually a formidable task due to the microheterogeneity of saponins in Nature. Chemical synthesis can provide access to large amounts of natural saponins as well as congeners for understanding their structure-activity relationships and mechanisms of action. This article presents a comprehensive account on chemical synthesis of saponins. First highlighted are general considerations on saponin synthesis, including preparation of aglycones and carbohydrate building blocks, assembly strategies, and protecting-group strategies. Next described is the state of the art in the synthesis of each type of saponins, with an emphasis on those representative saponins having sophisticated structures and potent biological activities.

Steroidal glycosides from the Vietnamese cultivar Cordyline fruticosa "Fairchild red"

A phytochemical study of Cordyline fruticosa "Fairchild red" (Asparagaceae) from Vietnam, led to the isolation of fourteen steroidal glycosides, including twelve previously undescribed along with two known ones. Ten compounds were obtained by successive solid/liquid chromatographic methods from an aqueous-ethanolic extract of the roots, and four from the aerial parts. Their structures were elucidated mainly by spectroscopic analysis 2D NMR and mass spectroscopy (ESI-MS), as spirostanol glycosides, 5α-spirost-25(27)-ene-1β,3β,4α-triol 1-O-β-D-fucopyranoside, 5α-spirost-(25)27-ene-1β,3β,4α-triol 1-O-β-D-xylopyranoside, 5α-spirost-(25)27-ene-1β,3β,4α-triol 1-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranoside, 5α-spirost-(25)27-ene-1β,3β,4α-triol 1-O-α-L-rhamnopyranosyl-(1 → 2)-(4-O-sulfo)-β-D-fucopyranoside, 5α-spirost-25(27)-ene-1β,3β-diol 1-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranoside, and 5α-spirost-25(27)-ene-1β,3β-diol 1-O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranoside. Furostanol glycosides were also isolated as 26-O-β-D-glucopyranosyl-5α-furost-(25)27-ene-1β,3β,4α,22α,26-pentol 1-O-β-D-fucopyranoside, 26-O-β-D-glucopyranosyl-22α-methoxy-5α-furost-(25)27-ene-1β,3β,4α,26-tetrol 1-O-β-D-fucopyranoside, 26-O-β-D-glucopyranosyl-5α-furost-(25)27-ene-1β,3β,22α,26-tetrol 1-O-β-D-glucopyranoside, 26-O-β-D-glucopyranosyl-5α-furost-(25)27-ene-1β,3β,22α,26-tetrol 1-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-glucopyranoside, 26-O-β-D-glucopyranosyl-5α-furost-(25)27-ene-1β,3β,22α,26-tetrol 1-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranoside, and 26-O-β-D-glucopyranosyl-22α-methoxy-5α-furost-(25)27-ene-1β,3β,26-triol 1-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranoside. All the isolated compounds were further evaluated for their cytotoxicity against 4T1 cell line, from a mouse mammary gland tissue, using MTS method.

Structure and Undulations of Escin Adsorption Layer at Water Surface Studied by Molecular Dynamics

The saponin escin, extracted from horse chestnut seeds, forms adsorption layers with high viscoelasticity and low gas permeability. Upon deformation, escin adsorption layers often feature surface wrinkles with characteristic wavelength. In previous studies, we investigated the origin of this behavior and found that the substantial surface elasticity of escin layers may be related to a specific combination of short-, medium-, and long-range attractive forces, leading to tight molecular packing in the layers. In the current study, we performed atomistic molecular dynamics simulations of 441 escin molecules in a dense adsorption layer with an area per molecule of 0.49 nm2. We found that the surfactant molecules are less submerged in water and adopt a more upright position when compared to the characteristics determined in our previous simulations with much smaller molecular models. The number of neighbouring molecules and their local orientation, however, remain similar in the different-size models. To maintain their preferred mutual orientation, the escin molecules segregate into well-ordered domains and spontaneously form wrinkled layers. The same specific interactions (H-bonds, dipole-dipole attraction, and intermediate strong attraction) define the complex internal structure and the undulations of the layers. The analysis of the layer properties reveals a characteristic wrinkle wavelength related to the surface lateral dimensions, in qualitative agreement with the phenomenological description of thin elastic sheets.

Structure, Bioactivity and Analytical Methods for the Determination of Yucca Saponins

Yucca is one of the main sources of steroidal saponins, hence different extracts are commercialized for use as surfactant additives by beverage, animal feed, cosmetics or agricultural products. For a deeper understanding of the potential of the saponins that can be found in this genus, an exhaustive review of the structural characteristics, bioactivities and analytical methods that can be used with these compounds has been carried out, since there are no recent reviews on the matter. Thus, a total of 108 saponins from eight species of the genus Yucca have been described. Out of these, the bioactivity of 68 saponins derived from the isolation of Yucca or other genera has been evaluated. Regarding the evaluation and quality control of the saponins from this genus LC-MS technique is the most often used. Nevertheless, the development of methods for their routine analysis in commercial preparations are needed. Moreover, most of the studies found in the literature have been carried out on Y. schidigera extract, since is the most often used for commercial purposes. Only eight of the 50 species that belong to this genus have been studied, which clearly indicates that the identification of saponins present in Yucca genus is still an unresolved question.

Steroidal saponins with cytotoxic effects from the rhizomes of Asparagus cochinchinensis

In the ongoing research on potent antitumor agents from the rhizomes of Asparagus cochinchinensis, seven undescribed steroidal saponins asparagusoside A-G (1-7), along with twenty known ones (8-27), were isolated and elucidated via analyzing their 1D, 2D NMR, mass spectroscopic data and chemical methods. All isolated compounds were evaluated for their cytotoxic effects against human large cell lung carcinoma cells (NCI-H460) in vitro. Among them, compounds 7, 9 and 27 showed more significant antitumor activities than the positive control cisplatin (11.56 μM) with IC₅₀ values of 1.39, 3.04, and 2.25 μM, respectively. Further research about asparagusoside G (7) showed G0/G1 arrest in NCI-H460 cell line cycle and induced cell death by apoptosis in a dose‑dependent way.

Antitumor activities of Aspiletrein A, a steroidal saponin from Aspidistra letreae, on non-small cell lung cancer cells

BACKGROUND

Lung cancer is one of the leading causes of death worldwide due to its strong proliferative and metastatic capabilities. The suppression of these aggressive behaviors is of interest in anticancer drug research and discovery. In recent years, many plants have been explored in order to discover new bioactive secondary metabolites to treat cancers or enhance treatment efficiency. Aspiletrein A (AA) is a steroidal saponin isolated from the whole endemic species Aspidistra letreae in Vietnam. Previously, elucidation of the structure of AA and screening of its cytotoxic activity against several cancer cell lines were reported. However, the antitumor activities and mechanisms of action have not yet been elucidated. In this study, we demonstrated the anti-proliferative, anti-migrative and anti-invasive effects of AA on H460, H23 and A549 human lung cancer cells.

METHODS

MTT, wound healing and Transwell invasion assays were used to evaluate the anti-proliferation, anti-migration and anti-invasion effects of AA, respectively. Moreover, the inhibitory effect of AA on the activity of protein kinase B (Akt), a central mediator of cancer properties, and apoptotic regulators in the Bcl-2 family proteins were investigated by Western blotting.

RESULTS

AA exhibits antimetastatic effects in human lung cancer cells through the inhibition of the pAkt/Akt signaling pathway, which in turn resulted in a significant inhibitory effect of AA on the migration and invasion of the examined lung cancer cells.

CONCLUSIONS

Aspiletrein A may be a potent inhibitor of protein kinase B (Akt). Hence, AA could be further explored as a potential antimetastatic lead compound.

Anthelmintic efficacy of natural saponins against Gyrodactylus kobayashii in goldfish (Carassius auratus) and their 3D-QSAR analysis

Gyrodactylus spp. are common monogenean ectoparasites that may lead to significant fish mortality. To find effective anthelmintic agents with lower toxicity, a series of natural saponins were obtained and evaluated for their anthelmintic activity against Gyrodactylus kobayashii and acute toxicity to goldfish (Carassius auratus). Among all tested compounds, six compounds (1, 2, 3, 8, 10, and 13) shown higher anthelmintic activity and safety than widely used formaldehyde-based parasiticides, especially compound 1 having 100% anthelmintic efficacy against G. kobayashii at 0.3 mg/L and a therapeutic index of 16.6. Also, the three-dimensional quantitative structure-activity relationship (3D-QSAR) studies of these saponins have been performed to explore the structural features reasonable for the anthelmintic activity against G. kobayashii. These models demonstrated that the hydroxyl group at C-17 position and the sugar moieties at C-3 position, especially the hydroxyl groups of the sugar moieties, were critical to the anthelmintic activity. The QSAR studies could provide useful information for further rational design and optimization of novel saponins for the control of gyrodactylosis.

Features in the NMR spectra of the aglycones of Agave spp. saponins. HMBC method for aglycone identification (HMAI)

INTRODUCTION

The analysis and detection of steroidal saponins is mainly performed using chromatographic techniques coupled with mass spectrometry. However, nuclear magnetic resonance (NMR) spectroscopy is a potential tool that can be combined with these techniques to obtain unambiguous structural characterisation.

OBJECTIVE

This work provides a review of the carbon-13 (¹³ C)- and proton (¹ H)-NMR spectroscopic data of aglycones from Agave saponins reported in the literature and also the development of an easy identification method for these natural products.

METHODS

The database Scifinder was used for spectroscopic data collection in addition to data obtained from the Cadiz Allelopathy research group. The keywords used were Agave, spirostanic, furostanic, and saponin.

RESULTS

The shielding variations produced by functional groups on the aglycone core and the structural features of the most representative aglycones from Agave species are described. The effects are additive for up to four long-range connectivities. A method for the identification of aglycones (HMAI) is proposed to classify aglycones from Agave spp. through the use of ¹ H-NMR and heteronuclear multiple bond correlation (HMBC) experiments.

CONCLUSIONS

The HMBC spectrum is representative of the structural features of aglycones from Agave spp. The HMBC method for aglycone identification (HMAI) method allowed the identification of pure saponins or mixtures thereof and this method can be used in combination with chromatographic techniques coupled with mass spectrometry to provide a more thorough analysis of Agave samples that contain aglycones.

Synthesis, Modification and Biological Activity of Diosgenyl β-d-Glycosaminosides: An Overview

Saponins are a structurally diverse class of natural glycosides that possess a broad spectrum of biological activities. They are composed of hydrophilic carbohydrate moiety and hydrophobic triterpenoid or steroid aglycon. Naturally occurring diosgenyl glycosides are the most abundant steroid saponins, and many of them exhibit various pharmacological properties. Herein, we present an overview of semisynthetic saponins syntheses-diosgenyl β-d-glycosaminosides (d-gluco and d-galacto). These glycosides possess a 2-amino group, which creates great possibilities for further modifications. A wide group of glycosyl donors, different N-protecting groups and various reaction conditions used for their synthesis are presented. In addition, this paper demonstrates the possibilities of chemical modifications of diosgenyl β-d-glycosaminosides, associated with functionalisation of the amino group. These provide N-acyl, N-alkyl, N,N-dialkyl, N-cinnamoyl, 2-ureido and 2-thiosemicarbazonyl derivatives of diosgenyl β-d-glycosaminosides, for which the results of biological activity tests (antifungal, antibacterial, anti-cancer and hemolytic) are presented.

GC-MS Phytochemical Profiling, Pharmacological Properties, and In Silico Studies of Chukrasia velutina Leaves: A Novel Source for Bioactive Agents

Chukrasia velutina is a local medicinal plant commonly known as chikrassy in Bangladesh, India, China, and other South Asian countries. The leaves, bark, and seeds are vastly used as herbal medicine for fever and diarrhea, and its leaves essential oils are used for antimicrobial purposes. In this study, we discuss the neuropsychiatric properties of C. velutina leaves through several animal models, quantitative and qualitative phytochemical analysis, and computational approaches. Neuropsychiatric effects were performed in rodents on the methanolic extract of C. velutina leaves (MECVL). Antidepressant, anxiolytic, and sedative effects experimented through these rodent models were used such as the force swimming test (FST), tail suspension test (TST), hole board test (HBT), elevated plus maze test (EPMT), light/dark box test (LDBT), open field test (OFT), and hole cross test (HCT). In these rodent models, 200 and 400 mg/kg doses were used which exhibited a significant result in the force swimming and tail suspension test (p < 0.001) for the antidepressant effect. In the anxiolytic study, the results were significant in the hole board, elevated plus maze, and light/dark box test (p < 0.001) for doses of 200 and 400 mg/kg. The result was also significant in the open field and hole cross test (p < 0.001) for sedative action in the sake of similar doses. Moreover, qualitative and quantitative studies were also performed through phytochemical screening and GC-MS analysis, and fifty-seven phytochemical compounds were found. These compounds were analyzed for pharmacokinetics properties using the SwissADME tool and from them, thirty-five compounds were considered for the molecular docking analysis. These phytoconstituents were docking against the human serotonin receptor, potassium channel receptor, and crystal structure of human beta-receptor, where eight of the compounds showed a good binding affinity towards the respective receptors considered to the reference standard drugs. After all of these analyses, it can be said that the secondary metabolite of C. velutina leaves (MECVL) could be a good source for inhibiting the neuropsychiatric disorders which were found on animal models as well as in computational studies.

Selective Cytotoxicity and Antioxidant Effects of Compounds from Dioscorea membranacea Rhizomes

Bioassay-guided isolation was used to separate the active ingredients of the ethanolic extract of Dioscorea membranacea by testing cytotoxic activity against three human cancer cell lines, i.e. large cell lung carcinoma (COR-L23), colon cell line (LS-174T) and breast cancer cell line (MCF-7), and two normal human cell lines, keratinocytes (SVK-14) and normal human fibroblasts (HF), using the SRB assay. The DPPH test for antioxidant activity was also employed, as was a test for LDH release as an indicator of damage to the cell membrane. Eight compounds were isolated, two naphthofuranoxepins (dioscorealides A [1] and B [2]), a 1,4-phenanthraquinone (dioscoreanone [3]), three steroids (β-sitosterol [4], stigmasterol [5] and β-D-sitosterol glucoside [8]) and two steroid saponins diosgenin-(3- O-α-L-rhamnopyranosyl (1→2)-β-D-glucopyranoside [6] and diosgenin 3- O-β-D-glucopyranosyl (1→3)-β-D-glucopyranoside [7]). Cytotoxic activity of 2, 3 and 6 was shown against three cancer cell lines, and 2 showed selective cytotoxic activity against lung and breast cancer, but was less active against the two normal cells, and was not toxic to cell membranes in the LDH assay. The highest antioxidant activity was shown by 3.

Responses of the weed Bidens pilosa L. to exogenous application of the steroidal saponin protodioscin and plant growth regulators 24-epibrassinolide, indol-3-acetic acid and abscisic acid

The exogenous application of plant hormones and their analogues has been exploited to improve crop performance in the field. Protodioscin is a saponin whose steroidal moiety has some similarities to plant steroidal hormones, brassinosteroids. To test the possibility that protodioscin acts as an agonist or antagonist of brassinosteroids or other plant growth regulators, we compared responses of the weed species Bidens pilosa L. to treatment with protodioscin, brassinosteroids, auxins (IAA) and abscisic acid (ABA). Seeds were germinated and grown in agar containing protodioscin, dioscin, brassinolides, IAA and ABA. Root apex respiratory activity was measured with an oxygen electrode. Malondialdehyde (MDA) and antioxidant enzymes activities were assessed. Protodioscin at 48-240 μm inhibited growth of B. pilosa seedlings. The steroidal hormone 24-epibrassinolide (0.1-5 μm) also inhibited growth of primary roots, but brassicasterol was inactive. IAA at higher concentrations (0.5-10.0 μm) strongly inhibited primary root length and fresh weight of stems. ABA inhibited all parameters of seedling growth and also seed germination. Respiratory activity of primary roots (KCN-sensitive and KCN-insensitive) was activated by protodioscin. IAA and ABA reduced KCN-insensitive respiration. The content of MDA in primary roots increased only after protodioscin treatment. All assayed compounds increased APx and POD activity, with 24-epibrassinolide being most active. The activity of CAT was stimulated by protodioscin and 24-epibrassinolide. The results revealed that protodioscin was toxic to B. pilosa through a mechanism not related to plant growth regulator signalling. Protodioscin caused a disturbance in mitochondrial respiratory activity, which could be related to overproduction of ROS and consequent cell membrane damage.

Holotoxin A₁ Induces Apoptosis by Activating Acid Sphingomyelinase and Neutral Sphingomyelinase in K562 and Human Primary Leukemia Cells

Marine triterpene glycosides are attractive candidates for the development of anticancer agents. Holotoxin A₁ is a triterpene glycoside found in the edible sea cucumber, Apostichopus (Stichopus) japonicus. We previously showed that cladoloside C₂, the 25(26)-dihydro derivative of holotoxin A₁, induced apoptosis in human leukemia cells by activating ceramide synthase 6. Thus, we hypothesized that holotoxin A₁, which is structurally similar to cladoloside C₂, might induce apoptosis in human leukemia cells through the same molecular mechanism. In this paper, we compared holotoxin A₁ and cladoloside C₂ for killing potency and mechanism of action. We found that holotoxin A₁ induced apoptosis more potently than cladoloside C₂. Moreover, holotoxin A₁-induced apoptosis in K562 cells by activating caspase-8 and caspase-3, but not by activating caspase-9. During holotoxin A₁ induced apoptosis, acid sphingomyelinase (SMase) and neutral SMase were activated in both K562 cells and human primary leukemia cells. Specifically inhibiting acid SMase and neutral SMаse with chemical inhibitors or siRNAs significantly inhibited holotoxin A₁–induced apoptosis. These results indicated that holotoxin A₁ might induce apoptosis by activating acid SMase and neutral SMase. In conclusion, holotoxin A₁ represents a potential anticancer agent for treating leukemia. Moreover, the aglycone structure of marine triterpene glycosides might affect the mechanism involved in inducing apoptosis.

Cytotoxic steroidal saponins from Panicum turgidum Forssk

Three new bidesmosidic cholestane-type steroidal glycosides, 16-O-β-d-glucopyranosyl-cholest-5-en-3β,16β-diol-22-one-3-O-α-l-rhamnopyranosyl-(1→2)-O-[(β-d-glucopyranosyl(1→4)]-O-β-d-glucopyranoside (1), 16-O-β-d-glucopyranosylcholest-5-en-3β,16β-diol-22-one-3-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranoside (2), and 16-O-β-d-glucopyranosylcholestan-3β,16β-diol-6,22-dione-3-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranoside (3) were isolated from a methanolic extract of Panicum turgidum. In addition four known compounds, pennogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (4), yamogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (5), yamogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (6), and pennogenin 3β-O-α-l-rhamnopyranosyl-(1→2)-O-[α-l-rhamnopyranosyl-(1→4)]-O-β-d-glucopyranoside (7) were also isolated and characterized. Their structures were established using extensive spectroscopic methods including 1D and 2D NMR and HRESIMS. The isolated compounds were screened for cytotoxicity towards a panel of mammalian cell lines and 4-7 were found to be cytotoxic.

Immunoaffinity Knockout of Saponin Glycosides from Asparagus racemosus to Assess Anti-lipid Peroxidation

INTRODUCTION

Asparagus racemosus Willd (Asparagaceae family), known as Shatavari, is important in Ayurveda and traditional Thai medicines. The saponin glycosides, shatavarin I and IV are major constituents in its roots and may be responsible for their actions including protection against lipid peroxidation and carcinogenesis.

OBJECTIVE

To develop an immunoaffinity column for isolating compounds with structures related to shatavarin IV from crude extracts of A. racemosus root.

METHODOLOGY

The monoclonal antibody recognising shatavarin IV (mAbShavIV) was coupled to an Affi-Gel Hz gel to isolate compounds with structures related to shatavarin IV from the other components of crude extracts of A. racemosus root. The saponin glycosides in each fraction were analysed by mAbShavIV ELISA and LC-MS/MS.

RESULTS

The pooled wash-through fractions contained 3% of loaded mAbShavIV reactive saponin glycosides, while eluted fractions released ~ 90% of shatavarin saponin glycosides in a single step. Using thiobarbiturate (TBARs) to measure lipid-peroxidation, the extract, and the pooled wash-through fractions showed moderate protection against Cu⁺ -induced oxidation of human low density lipoprotein (LDL) (IC₅₀ 11.3 ± 1.4 and 12.6 ± 0.9 μg/mL, respectively). In contrast, the saponin glycosides eluted from the mAbShavIV-column had weaker protectant (IC₅₀ 29.7 ± 1.8 μg/mL) suggesting that A. racemosus shatavarins do not inhibit carcinogenesis through preventing lipid peroxidation.

CONCLUSION

The strategy described here demonstrates its utility for isolating a group of related compounds from the rest of the extract with selectivity and recovery rate. Pharmacological efficacy and synergistic effects of the components obtained can be further investigated. Copyright © 2017 John Wiley & Sons, Ltd.

Quantification of Saponins in Asparagus racemosus by HPLC-Q-TOF-MS/MS

Asparagus racemosus Willd. or Shatavari (Asparagaceae family) is an important medicinal plant in Ayurvedic medicine as a rejuvenate for women. A method for quantitative analysis of saponin glycosides bioactive constituents in A. racemosus is reported. A high performance liquid chromatography quadrupole time of flight mass spectrometry (HPLC-Q-TOF-MS/MS) method was developed and validated for simultaneous determination of five saponin glycosides, asparacoside, shatavarin IX, shatavarin IV, asparanin A and shatavarin V in A. racemosus extracted with 70% MeOH. The method was validated through intra-and inter-day precision, with the relative standard deviation (RSD) less than 6%, limits of detection (LOD) and limits of quantification (LOQ) <10 and 50 ng, respectively. Overall recoveries ranged from 95% to 105%, with RSD ranging from 0.7% to 4.5%. The method was applied to saponin glycoside contents in the leaves, stems, and roots of A. racemosus sourced from different geographical locations, including four provinces in Thailand, and a sample from India. Saponin glycosides were detected predominantly in the roots, the part used in traditional medicines and these showed wide variations in saponin glycoside profiles from undetectable to 12 mg/g dry weight. The quality control of A. racemosus is crucial for reliable and predictable therapies and only methods like the one developed has the necessary flexibility, sensitivity, accuracy, and selectivity for reliable routine quality control.

Acetylated Triterpene Glycosides and Their Biological Activity from Holothuroidea Reported in the Past Six Decades

Sea cucumbers have been valued for many centuries as a tonic and functional food, dietary delicacies and important ingredients of traditional medicine in many Asian countries. An assortment of bioactive compounds has been described in sea cucumbers. The most important and abundant secondary metabolites from sea cucumbers are triterpene glycosides (saponins). Due to the wide range of their potential biological activities, these natural compounds have gained attention and this has led to their emergence as high value compounds with extended application in nutraceutical, cosmeceutical, medicinal and pharmaceutical products. They are characterized by bearing a wide spectrum of structures, such as sulfated, non-sulfated and acetylated glycosides. Over 700 triterpene glycosides have been reported from the Holothuroidea in which more than 145 are decorated with an acetoxy group having 38 different aglycones. The majority of sea cucumber triterpene glycosides are of the holostane type containing a C18 (20) lactone group and either Δ(7(8)) or Δ(9(11)) double bond in their genins. The acetoxy group is mainly connected to the C-16, C-22, C-23 and/or C-25 of their aglycone. Apparently, the presence of an acetoxy group, particularly at C-16 of the aglycone, plays a significant role in the bioactivity; including induction of caspase, apoptosis, cytotoxicity, anticancer, antifungal and antibacterial activities of these compounds. This manuscript highlights the structure of acetylated saponins, their biological activity, and their structure-activity relationships.

Steroidal Glucosides from the Rhizomes of Tacca Chantrieri and Their Inhibitory Activities of NO Production in BV2 Cells

Two new steroidal glucosides, chantriolides D and E (1 and 2), along with four known compounds, chantriolide A (3), chantriolide B (4), chantriolide C (5), and (25 S)-spirost-5-en-3-ol 3- O-α-L-rhamnopyranosyl-(1→2)- O-[α-L-rhamnopyranosyl-(1→3)]-β-D-glucopyranoside (6) were isolated from the rhizomes of Tacca chantrieri. Their structures were determined by 1D and 2D NMR spectroscopic and HR-ESI-MS data, as well as by comparison with reported data. Compounds 1 and 2 were found to show strong inhibitory NO effect in BV2 cells, with IC50 values of 12.45 and 59.03 μM, respectively.

Chemical synthesis of saponins

Saponins are a large family of amphiphilic glycosides of steroids and triterpenes found in plants and some marine organisms. By expressing a large diversity of structures on both sugar chains and aglycones, saponins exhibit a wide range of biological and pharmacological properties and serve as major active principles in folk medicines, especially in traditional Chinese medicines. Isolation of saponins from natural sources is usually a formidable task due to the microheterogeneity of saponins in Nature. Chemical synthesis can provide access to large amounts of natural saponins as well as congeners for understanding their structure-activity relationships and mechanisms of action. This article presents a comprehensive account on chemical synthesis of saponins. First highlighted are general considerations on saponin synthesis, including preparation of aglycones and carbohydrate building blocks, assembly strategies, and protecting-group strategies. Next described is the state of the art in the synthesis of each type of saponins, with an emphasis on those representative saponins having sophisticated structures and potent biological activities.

Structure elucidation of new acetylated saponins, Lessoniosides A, B, C, D, and E, and non-acetylated saponins, Lessoniosides F and G, from the viscera of the sea cucumber Holothuria lessoni

Sea cucumbers produce numerous compounds with a wide range of chemical structural diversity. Among these, saponins are the most diverse and include sulfated, non-sulfated, acetylated and methylated congeners with different aglycone and sugar moieties. In this study, MALDI and ESI tandem mass spectrometry, in the positive ion mode, were used to elucidate the structure of new saponins extracted from the viscera of H. lessoni. Fragmentation of the aglycone provided structural information on the presence of the acetyl group. The presence of the O-acetyl group was confirmed by observing the mass transition of 60 u corresponding to the loss of a molecule of acetic acid. Ion fingerprints from the glycosidic cleavage provided information on the mass of the aglycone (core), and the sequence and type of monosaccharides that constitute the sugar moiety. The tandem mass spectra of the saponin precursor ions [M + Na]⁺ provided a wealth of detailed structural information on the glycosidic bond cleavages. As a result, and in conjunction with existing literature, we characterized the structure of five new acetylated saponins, Lessoniosides A–E, along with two non-acetylated saponins Lessoniosides F and G at m/z 1477.7, which are promising candidates for future drug development. The presented strategy allows a rapid, reliable and complete analysis of native saponins.

Epimerization of C-22 in (25R)- and (25S)-sapogenins

Most of the naturally occurring steroidal sapogenins (C-23 non-substituted frameworks), possess an R configuration at the spiro C-22 center. Their C-22 epimers have become important targets in biological research. This paper describes a procedure to obtain 22S-spirostans from 22R-sapogenins and pseudosapogenin skeletons, without affecting the chirality at either C-25 or C-20. An optimal way to synthesize the pair of C-22 stereoisomers of 23-acetyldiosgenin is also reported. The latter was obtained from a 22,26-epoxycholestane or from 23-acetylfurostene compounds.

Chemistry and biological activity of steroidal glycosides from the Lilium genus

This review provides a chronological account of the scientific progress made, between the years of 1989 up to 2014, on the structural elucidation and biological activity of steroidal glycosides isolated from plants of theLiliumgenus.

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.

Steroidal saponins from the genus Allium

Steroidal saponins are widely distributed among monocots, including the Amaryllidaceae family to which the Allium genus is currently classified. Apart from sulfur compounds, these are important biologically active molecules that are considered to be responsible for the observed activity of Allium species, including antifungal, cytotoxic, enzyme-inhibitory, and other. In this paper, literature data concerning chemistry and biological activity of steroidal saponins from the Allium genus has been reviewed.

Relationships between chemical structures and functions of triterpene glycosides isolated from sea cucumbers

Many marine triterpene glycosides have in vitro and in vivo activities with very low toxicity, suggesting that they are suitable agents for the prevention and treatment of different diseases, particularly cancer. However, the molecular mechanisms of action of natural marine compounds in cancer, immune, and other various cells are not fully known. This review focuses on the structural characteristics of marine triterpene glycosides and how these affect their biological activities and molecular mechanisms. In particular, the membranotropic and membranolytic activities of frondoside A and cucumariosides from sea cucumbers and their ability to induce cytotoxicity and apoptosis have been discussed, with a focus on structure-activity relationships. In addition, the structural characteristics and antitumor effects of stichoposide C and stichoposide D have been reviewed along with underlying their molecular mechanisms.

Saponin profile of green asparagus genotypes

The main goal of this study was to determine the saponin profiles of different "triguero" asparagus genotypes and to compare them to green asparagus commercial hybrids. The samples consisted of 31 commercial hybrids and 58 genotypes from the Huétor-Tájar (HT) population variety ("triguero"). The saponin analysis by high-performance liquid chromatography-mass spectrometry allowed for the determination of 12 saponins derived from a furostan-type steroidal genin, 4 of which had never been described in the edible part of asparagus. The saponin profile of "triguero" asparagus was a combination of these new saponins and protodioscin. Although protodioscin was the major saponin found in commercial hybrids, some of these 12 saponins were detected as major components in some of the commercial hybrids. The total contents of saponins described in some of these HT genotypes reach values as high as 10-100 times higher than those found in commercial hybrids.

Steroidal glycosides from the bulbs of Easter lily (Lilium longiflorum Thunb.) promote dermal fibroblast migration in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Preparations derived from bulbs of various Lilium species have been used to promote the healing of skin abrasions, sores and burns and to aid in healing wounds in Traditional Chinese and Greco-Roman Medicine.

AIM OF THE STUDY

To evaluate fractionated Easter lily bulb extracts and their steroidal glycosides (1-5) for the promotion of dermal fibroblast migration in vitro, a model for the early events in wound healing.

MATERIALS AND METHODS

An activity-guided screening approach was used by coupling sequential solvent extraction, gel permeation chromatography (GPC), and semi-preparative reverse-phase high performance liquid chromatography (RP-HPLC) with an in vitro dermal fibroblast migration assay. Cytotoxicity was evaluated with methyl thiazole tetrazolium (MTT). To gain insight into the mode of action of the steroidal glycosides, nitric oxide (NO) production, and expression of genes for transforming growth factor beta-1 (TGF-β) and its receptors were evaluated.

RESULTS

Fractionated bulb extracts and the two isolated steroidal glycoalkaloids (1) and (2) induced NO production and TGF-β receptor I mRNA expression in fibroblast cell culture. In a cytotoxicity assay, steroidal glycosides (1) and (3) had IC50 values of 8.2 and 8.7 µM, but the natural acetylation of the C-6″' hydroxy of the terminal glucose unit in (2) resulted in a 3-fold decrease in cell cytotoxicity when compared with (1). Results from the dermal fibroblast migration assay revealed that the steroidal glycoalkaloids (1) and (2), and the furostanol saponin (3) promoted fibroblast migration from the range of 23.7±5.7 to 37.7±5.1%, as compared with the control.

CONCLUSION

Collectively, our data demonstrate that the steroidal glycosides present in Easter lily bulbs induce, at least in part, the observed dermal fibroblast migration activity of the bulb extracts. This is the first evidence that steroidal glycosides from Lilium longiflorum may potentially play a role in the wound healing process and may provide a scientific basis for the historical use of lily bulbs for this purpose.

Optimization of a method for the profiling and quantification of saponins in different green asparagus genotypes

The main goal of this study was the optimization of a HPLC-MS method for the qualitative and quantitative analysis of asparagus saponins. The method includes extraction with aqueous ethanol, cleanup by solid phase extraction, separation by reverse phase chromatography, electrospray ionization, and detection in a single quadrupole mass analyzer. The method was used for the comparison of selected genotypes of Huétor-Tájar asparagus landrace and selected varieties of commercial diploid hybrids of green asparagus. The results showed that while protodioscin was almost the only saponin detected in the commercial hybrids, eight different saponins were detected in the Huétor-Tájar asparagus genotypes. The mass spectra indicated that HT saponins are derived from a furostan type steroidal genin having a single bond between carbons 5 and 6 of the B ring. The total concentration of saponins was found to be higher in triguero asparagus than in commercial hybrids.

Inhibitory effect of resveratrol against duck enteritis virus in vitro

Duck viral enteritis (DVE) is an acute, contagious herpesvirus infection of ducks, geese, and swans of all ages and species. This disease has been responsible for significant economic losses in domestic and wild waterfowl as a result of mortality, and decreased egg production. Resveratrol is a naturally occurring phytoalexin in specific plants and exhibits inhibitory activity against many kinds of virus. In this paper, resveratrol was found to inhibit duck enteritis virus (DEV) replication in a dose-dependent manner, with a 50% inhibition concentration of 3.85 μg/mL. The inhibition in virus multiplication in the presence of resveratrol was not attributed to direct inactivation or inhibition of virus attachment to the host cells, but to the inhibition of viral multiplication in host cells. The assay of the time of addition limited the drug effect during the first 8 h of infection. This conclusion was supported by the ultrastructure images of the early stage of DEV infection, which showed that the replication of virus nucleic acid and the formation of the capsid in the cell nucleus were suppressed. In the indirect immunofluorescence assay, proteins expression in DEV infected duck embryo fibroblasts (DEFs) within 24 h post-infection (p.i.) was also effectively suppressed by resveratrol. In summary, the resveratrol has a good activity against DEV infection in vitro, which could be attributed to that fact that several essential immediate early viral proteins for virus replication were impacted by resveratrol.

Preparation of progenin III from total steroidal saponins of Dioscorea nipponica Makino using a crude enzyme from Aspergillus oryzae strain

Progenin III, one of the most active spirostanol saponins, is a potential candidate for anti-cancer therapy due to its strong antitumor activity and low hemolytic activity. However, the concentration of progenin III is extremely low in natural Dioscorea plants. In this paper, the progenin III production from total steroidal saponins of Dioscorea nipponica Makino was studied using the crude enzyme from Aspergillus oryzae DLFCC-38. The crude enzyme converting total steroidal saponins into progenin III was obtained from the A. oryzae DLFCC-38 culture. For enzyme production, the strain was cultured for 72 h at 30 °C with shaking at 150 rpm in 5 % (w/v) malt extract medium containing 2 % (v/v) extract of D. nipponica as the enzyme inducer. The crude enzyme converted total steroidal saponins into major progenin III with a high yield when the reaction was carried out for 9 h at 50 °C and pH 5.0 with the 20 mg/ml of substrate. In the preparation of progenin III, 117 g of crude progenin III was obtained from 160 g of substrate, and the crude product was purified with silica gel column to obtain 60.3 g progenin III of 93.4 % purity.

Open-chain steroidal glycosides, a diverse class of plant saponins

Saponins are an important class of plant natural products that consist of a triterpenoid or steroidal skeleton that is glycosylated by varying numbers of sugar units attached at different positions. Steroidal saponins are usually divided into two broad structural classes, namely spirostanol and furostanol saponins. A third, previously unrecognized structural class of plant saponins, the open-chain steroidal saponins, is introduced in this review; these possess an acyclic sidechain in place of the heterocyclic ring/s present in spirostanols and furostanols. Open-chain steroidal saponins are numerous and structurally diverse, with over 150 unique representatives reported from terrestrial plants. Despite this, they have to date been largely overlooked in reviews of plant natural products. This review catalogs the structural diversity of open-chain steroidal saponins isolated from terrestrial plants and discusses aspects of their structure elucidation, biological activities, biosynthesis, and distribution in the plant kingdom. It is intended that this review will provide a point of reference for those working with open-chain steroidal saponins and result in their recognition and inclusion in future reviews of plant saponins.

Steroidal Saponins from Dracaena marginata

Three new steroidal saponins and ten known ones were isolated from the bark of Dracaena marginata, along with two known steroidal saponins from the roots. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments and mass spectrometry as (25R)-26-(β-D-glucopyranosyloxy)- 3β,22α-dihydroxyfurost-5-en-1β-yl O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→-4)]-β-D-glucopyranoside (1), (25R)-26-(β-D-glucopyrano- syloxy)-3β,22α-dihydroxyfurost-5-en-1β-yl O-α-L-rhamnopyranosyl-(1→-2)-4-O-sulfo-α-L-arabinopyranoside (2), and (25 S)-3β-hydroxyspirost-5-en-1β-yl O- α-L-rhamnopyranosyl-(1→2)-4-O-sulfo-α-L-arabinopyranoside (3).

Cytotoxic steroidal saponins from Ophiopogon japonicus

Four new steroidal saponins, named ophiopogonin P-S (1-4), together with eleven known ones (5-15) were isolated from the tuberous roots of Ophiopogon japonicus. Their structures were elucidated by spectroscopic and chemical analysis. Compounds 2-15 were evaluated for their cytotoxic activity against five human tumor cell lines (HepG2, HLE, BEL7402, BEL7403 and Hela). Compounds 2, 5, 6, 8 and 9 were cytotoxic for all cell lines tested. Compounds 7, 11 and 15 showed selective cytotoxicity against some of the cell lines. The structure-activity relationship of these compounds was discussed.

Antiviral activity and mode of action of extracts from neem seed kernel against duck plague virus in vitro1

Four fractions obtained from alcohol extracts of neem (Azadirachta indica) seed kernel by column chromatography were investigated for antivirus activity against the duck plague virus (DPV) in vitro. Duck embryo fibroblasts (DEF) infected with DPV were treated with the neem seed kernel extracts, and the effect of antivirus was judged by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide colorimetric method assay and direct immunofluorescence assay. The mode of action was tested by the plaque reduction assay. The results showed that fractions 1 to 3 were inactive. The median inhibitory concentration (IC(50)) of fraction 4 was 10.9 μg/mL and inhibited the virus protein expression in the direct immunofluorescence assay. In the plaque reduction assay, fraction 4 could significantly reduce the number of plaques compared with the negative control (P < 0.01) in all modes of action. This study indicated that the fourth fraction obtained from neem seed kernel could improve the viability of infected cells, and reduce the cytopathic effects caused by DPV and the amount of the virus protein expressed in virus-infected cells. The antiviral activity works in the whole process of virus infecting the normal cells.