Avicins: triterpenoid saponins from Acacia victoriae (Bentham) induce apoptosis by mitochondrial perturbation

Phytochemical profiling, antioxidant, and tyrosinase inhibitory potential of the Acacia cyclops trunk bark: in vitro combined with in silico approach

The aim of this study was to analyze the phytochemical profile of Acacia cyclops trunk bark ethyl acetate extract using LC-tandem mass spectrometry for the first time, along with evaluating its antioxidant and anti-tyrosinase properties. Consequently, we determined the total phenolic and flavonoid contents of the extract under investigation and identified and quantified 19 compounds, including phenolic acids and flavonoids. In addition to assessing their antioxidant potential against DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis-[3-ethylbenzothiazoline-6-sulfonic] acid) assays, in vitro and in silico studies were conducted to evaluate the tyrosinase inhibitory properties of the A. cyclops extract. The ethyl acetate trunk bark extract exhibited a substantial total phenolic content and demonstrated significant antioxidant activity in terms of free radical scavenging, as well as notable tyrosinase inhibitory action (half-maximal inhibitory concentration [IC50] = 14.08 ± 1.10 μg/mL). The substantial anti-tyrosinase activity of the examined extract was revealed through molecular docking analysis and druglikeness prediction of the main selected compounds. The findings suggest that A. cyclops extract holds promise as a potential treatment for skin hyperpigmentation disorders.

Chemical composition, antioxidant and anti-tyrosinase potentials of Acacia cyclops trunk bark using in vitro and in silico approaches

The purpose of this paper was to evaluate the phytochemical profile of Acacia cyclops trunk bark methanol extract using LC-MS/MS, as well as to assess its antioxidant and anti-tyrosinase activities. Thus, total phenolic and flavonoid contents of the studied extract were established and 19 compounds were detected and quantified. In addition of their antioxidant potential against DPPH and ABTS assays, in vitro and in silico studies were adopted to evaluate tyrosinase inhibitory property of A. cyclops extract. Methanol trunk bark extract showed significant total phenolic content, antioxidant potential in terms of free radical scavenging, as well as an interesting tyrosinase inhibitory action (IC50= 05.12 ± 0.41 μg/mL). The molecular docking analysis and the drug-likeness prediction of the major selected compounds supported the significant anti-tyrosinase activity of the studied extract. The obtained results suggest that A. cyclops extract could be a promising candidate in the treatment of skin hyperpigmentation disorders.

Shatavarin-IV saponin adjuvant elicits IgG and IgG2b responses against Staphylococcus aureus bacterin in a murine model

Asparagus adscendens Roxb. also known as "safed musli" or "shatavari" is a medicinal plant commonly found in South Asian countries. Shatavari is effective for the treatment of gastric ulcers, renal stones, bronchitis, diabetes, diabetic neuropathy, irritable bowel syndrome, alcohol withdrawal and has reported immunostimulatory effects. In this study, the adjuvant potential of Shatavarin-IV saponin against Staphylococcus aureus bacterin in mice was investigated. Shatavarin-IV was evaluated for its toxicity and immunomodulatory potential against S. aureus bacterin in mice. Cellular and humoral immune responses were assessed. Shatavarin-IV was isolated from the fruit extract of Asparagus adscendens. The confirmation of the isolated molecule as Shatavarin-IV was done via TLC-based comparison with the standard molecule. Further, the structure was confirmed by using extensive spectroscopic analyses and comparing the observed data with literature reports. It was found safe up to the dose of 0.1 mg in the mice model. Shatavarin-IV adjuvant elicited IgG and IgG2b responses at the dose of 40 μg against S. aureus bacterin. However, the cell-mediated immune response was lesser as compared with the commercial Quil-A saponin . We demonstrated that Shatavarin-IV saponin adjuvant produced an optimum humoral immune response against S. aureus bacterin. These results highlight the potential of Shatavarin-IV as an adjuvant in a combination adjuvant in vaccine formulations for induction of potent immune response.

A New Triterpenoid Saponin from Albizia zygia Induced Apoptosis by Reduction of Mitochondrial Potential Status in Malignant Melanoma Cells

In our ongoing research program on the proapoptotic function of saponins, two previously undescribed saponins, named zygiaosides E (1: ) and F (2: ), were isolated from the leaves of Albizia zygia. Their structures were established based on extensive analysis of 1D and 2D NMR data, HR-ESI-MS analysis, and by chemical degradation. The proapoptotic effect of zygiaoside E (1: ) was evaluated on human malignant melanoma (A375), human epidermoid cancer (A431), and normal Homo sapiens skin tissue (TE 353.SK.) cell lines by cytometric analysis. Zygiaoside E (1: ) induced apoptosis of the two human cancer cell lines (A375 and A431) in a dose-dependent manner at 1 µM but did not induce apoptosis in noncancerous skin cells (TE 353.Sk), even when treated with concentrations up to 15 µM. The underlying mechanism of the apoptosis induction activity of zygiaoside E (1: ) on the mitochondrial membrane potential status in A375 cells was further assessed by monitoring the uptake rate of DiOC6, a mitochondrial specific and voltage-dependent fluorescent dye. The number of malignant melanoma cells emitting high fluorescence levels was decreased when cells were treated with 3 or 5 µM of zygiaoside E (1: ) during either 12 or 24 h, thereby revealing a drop of mitochondrial membrane potential in A375 cells upon treatment, which indicated mitochondrial perturbation.

Ilimaquinone (Marine Sponge Metabolite) Induces Apoptosis in HCT-116 Human Colorectal Carcinoma Cells via Mitochondrial-Mediated Apoptosis Pathway

Ilimaquinone (IQ), a metabolite found in marine sponges, has been reported to have a number of biological properties, including potential anticancer activity against colon cancer. However, no clear understanding of the precise mechanism involved is known. The aim of this study was to examine the molecular mechanism by which IQ acts on HCT-116 cells. The anticancer activity of IQ was investigated by means of a cell viability assay followed by the determination of induction of apoptosis by means of the use of acridine orange–ethidium bromide (AO/EB) staining, Annexin V/PI double staining, DNA fragmentation assays, and TUNEL assays. The mitochondrial membrane potential (ΔΨm) was detected using the JC-1 staining technique, and the apoptosis-associated proteins were analyzed using real-time qRT-PCR. A molecular docking study of IQ with apoptosis-associated proteins was also conducted in order to assess the interaction between IQ and them. Our results suggest that IQ significantly suppressed the viability of HCT-116 cells in a dose-dependent manner. Fluorescent microscopy, flow cytometry, DNA fragmentation and the TUNEL assay in treated cells demonstrated apoptotic death mode. As an additional confirmation of apoptosis, the increased level of caspase-3 and caspase-9 expression and the downregulation of Bcl-2 and mitochondrial dysfunction were observed in HCT-116 cells after treatment with IQ, which was accompanied by a decrease in mitochondrial membrane potential (ΔΨm). Overall, the results of our studies demonstrate that IQ could trigger mitochondria-mediated apoptosis as demonstrated by a decrease in ΔΨm, activation of caspase-9/-3, damage of DNA and a decrease in the proportion of Bcl-2 through the mitochondrial-mediated apoptosis pathway.

Anticancer Activity of Cordia dichotoma against a Panel of Human Cancer Cell Lines and Their Phytochemical Profiling via HPLC and GCMS

The current study was conducted to examine the in vitro anticancer potential of Cordia dichotoma (bark, leaves, pulp and seed). The plant material was collected from UT of J&K and methodical bioassays were carried out on ten human cancer cell lines (Michigan Cancer Foundation-7 (MCF-7), M.D. Anderson-Metastatic Breast (MDA-MB-231), Neuroblastoma-2a (N2A), SH-SY5Y, U-251, HCT-116, SW-620, A-549, MIA PaCa-2, Panc-1) from five different origins (breast, CNS, colon, lung, pancreas) respectively. Methanolic extracts were produced and fractions were then obtained from the extracts and evaluated for cytotoxicity. Mechanistic assays, HPLC, and GCMS profiling were performed on the highest active fraction. The Sulforhodamine B (SRB) assay determined the in vitro cytotoxicity. The findings revealed that the bark portion had in vitro cytotoxicity against the A-549 human lung cancer cell line. To our knowledge, this is the first study to show that the plant’s bark has anticancer properties and induced chromatin condensation, confirmed cell death via ROS generation, and significantly decreased colony formation in A-549 cell line from lung origin in a dose-dependent manner. Furthermore, HPLC and GCMS investigations indicated the presence of a number of bioactive molecules such as gallic acid (144,969.86) uV*sec, caffeic acid (104.26) uV*sec, ferulic acid (472.87) uV*sec, vanillic acid (13,775.39) uV*sec, palmitic acid (18.34%), cis vaccenic acid (28.81%), etc. and one of the compounds was reported for the first time from the bark. As a result of its promising efficacy, it may become an essential cancer chemopreventive or chemotherapeutic medication for patients with lung carcinoma.

Triterpene saponins from the roots of Acacia senegal (L.) Willd

Six new triterpenoid saponins, named senegalosides A-F (1-6) were isolated from the seedpods and roots of Acacia senegal (Mimosaceae). Their structures were elucidated using 1D and 2D-NMR spectroscopic analysis and mass spectrometry. Compound 1 possesses an unusual sapogenin, 3β-hydroxy-21-oxo-olean-12-en-28-oic acid (machaeric acid), and was reported here in its natural form for the first time within the genus Acacia. Senegaloside A is the first example of a machaeric-type triterpenoid glycoside in the plant kingdom. The cytotoxic effect of isolated saponins was evaluated on the H4IIE rat hepatoma cell line. As a result, compounds 1, 3-6 were not significantly cytotoxic to H4IIE cells even at 200 μM. Compound 2 was suppressed cell viability at 50-200 μM.

Extraction and purification of saponins from Sapindus mukorossi

Fermentation was used to further purify saponins extracted from the pericarp of Sapindus; both the purity and foam half-life was greatly increased.

Avicin G is a potent sphingomyelinase inhibitor and blocks oncogenic K- and H-Ras signaling

K-Ras must interact primarily with the plasma membrane (PM) for its biological activity. Therefore, disrupting K-Ras PM interaction is a tractable approach to block oncogenic K-Ras activity. Here, we found that avicin G, a family of natural plant-derived triterpenoid saponins from Acacia victoriae, mislocalizes K-Ras from the PM and disrupts PM spatial organization of oncogenic K-Ras and H-Ras by depleting phosphatidylserine (PtdSer) and cholesterol contents, respectively,  at the inner PM leaflet. Avicin G also inhibits oncogenic K- and H-Ras signal output and the growth of K-Ras-addicted pancreatic and non-small cell lung cancer cells. We further identified that avicin G perturbs lysosomal activity, and disrupts cellular localization and activity of neutral and acid sphingomyelinases (SMases), resulting in elevated cellular sphingomyelin (SM) levels and altered SM distribution. Moreover, we show that neutral SMase inhibitors disrupt the PM localization of K-Ras and PtdSer and oncogenic K-Ras signaling. In sum, this study identifies avicin G as a new potent anti-Ras inhibitor, and suggests that neutral SMase can be a tractable target for developing anti-K-Ras therapeutics.

Interactions of OSW-1 with Lipid Bilayers in Comparison with Digitonin and Soyasaponin

OSW-1, a unique steroidal saponin isolated from the bulbs of Ornithogalum saundersiae, has potent cell-growth inhibition activity. In this study, we conducted fluorescence measurements and microscopic observations using palmitoyloleoylphosphatidylcholine (POPC)-cholesterol (Chol) bilayers to evaluate the membrane-binding affinity of OSW-1 in comparison with another steroidal saponin, digitonin, and the triterpenoid saponin, soyasaponin Bb(I). The membrane activities of these saponins were evaluated using calcein leakage assays and fitted to the binding isotherm by changing the ratios of saponin-lipids. Digitonin showed the highest binding affinity for the POPC-Chol membrane (K_app = 0.38 μM^-1) and the strongest membrane disruptivity in the bound saponin-lipid ratio at the point of 50% calcein leakage (r₅₀ = 0.47) occurrence. OSW-1 showed slightly lower activity (K_app = 0.31 μM^-1; r₅₀ = 0.78), and the soyasaponin was the lowest in the membrane affinity and the calcein leakage activity (K_app = 0.017 μM^-1; r₅₀ = 1.66). The effect of OSW-1 was further assessed using confocal microscopy in an experiment utilizing DiI and rhodamine 6G as the fluorescence probes. The addition of 30 μM OSW-1 induced inward membrane curvature in some giant unilamellar vesicles (GUVs). At the higher OSW-1 concentration (58 μM, r₅₀ = 0.78) where the 50% calcein leakage was observed, the morphology of some GUVs became elongated. With digitonin at the corresponding concentration (35 μM, r₅₀ = 0.47), membrane disruption and formation of large aggregates in aqueous solution were observed, probably due to a detergent-type mechanism. These saponins, including OSW-1, required Chol to exhibit their potent membrane activity although their mechanisms are thought to be different. At the effective concentration, OSW-1 preferably binds to the bilayers without prominent disruption of vesicles and exerts its activity through the formation of saponin-Chol complexes, probably resulting in membrane permeabilization.

Transcriptome analysis of Clinopodium gracile (Benth.) Matsum and identification of genes related to Triterpenoid Saponin biosynthesis

BACKGROUND

Clinopodium gracile (Benth.) Matsum (C. gracile) is an annual herb with pharmacological properties effective in the treatment of various diseases, including hepatic carcinoma. Triterpenoid saponins are crucial bioactive compounds in C. gracile. However, the molecular understanding of the triterpenoid saponin biosynthesis pathway remains unclear.

RESULTS

In this study, we performed RNA sequencing (RNA-Seq) analysis of the flowers, leaves, roots, and stems of C. gracile plants using the BGISEQ-500 platform. The assembly of transcripts from all four types of tissues generated 128,856 unigenes, of which 99,020 were mapped to several public databases for functional annotation. Differentially expressed genes (DEGs) were identified via the comparison of gene expression levels between leaves and other tissues (flowers, roots, and stems). Multiple genes encoding pivotal enzymes, such as squalene synthase (SS), or transcription factors (TFs) related to triterpenoid saponin biosynthesis were identified and further analyzed. The expression levels of unigenes encoding important enzymes were verified by quantitative real-time PCR (qRT-PCR). Different chemical constituents of triterpenoid saponins were identified by Ultra-Performance Liquid Chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS).

CONCLUSIONS

Our results greatly extend the public transcriptome dataset of C. gracile and provide valuable information for the identification of candidate genes involved in the biosynthesis of triterpenoid saponins and other important secondary metabolites.

Testicular Caspase-3 and β-Catenin Regulators Predicted via Comparative Metabolomics and Docking Studies

Many routes have been explored to search for effective, safe, and affordable alternatives to hazardous female contraceptives. Herbal extracts and their secondary metabolites are some of the interesting research areas to address this growing issue. This study aims to investigate the effects of ten different plant extracts on testicular spermatogenesis. The correlation between the chemical profile of these extracts and their in vivo effect on male reproductive system was evaluated using various techniques. Approximately 10% of LD₅₀ of hydro-methanolic extracts were orally administrated to rats for 60 days. Semen parameters, sexual organ weights, and serum levels of male sex hormones in addition to testes histopathology, were evaluated. Moreover, metabolomic analysis using (LC-HRESIMS), multivariate analysis (PCA), immunohistochemistry (caspase-3 and β-catenin), and a docking study were performed. Results indicated that three plant extracts significantly decreased epididymal sperm density and motility. Moreover, their effects on testicular cells were also assured by histopathological evaluations. Metabolomic profiling of the bioactive plant extracts showed the presence of diverse phytochemicals, mostly oleanane saponins, phenolic diterpenes, and lupane triterpenes. A docking study on caspase-3 enzyme showed that oleanane saponins possessed the highest binding affinity. An immunohistochemistry assay on β-catenin and caspase-3 indicated that Albizzia lebbeck was the most active extract for decreasing immunoexpression of β-catenin, while Rosmarinus officinalis showed the highest activity for increasing immunoexpression of caspase-3. The spermatogenesis decreasing the activity of A. lebbeck, Anagallis arvensis, and R. officinalis can be mediated via up-regulation of caspase-3 and down-regulation of β-catenin existing in testis cells.

Phytochemicals in Anticancer Drug Development

BACKGROUND

In spite of major technological advances in conventional therapies, cancer continues to remain the leading cause of mortality worldwide. Phytochemicals are gradually emerging as a rich source of effective but safer agents against many life-threatening diseases.

METHODS

Various phytochemicals with reported anticancer activity have been simply categorized into major phytoconstituents- alkaloids, polyphenols, saponins, tannins and terpenoids.

RESULTS

The adverse effects associated with currently available anticancer medications may be overcome by using plant-derived compounds either alone or in combination. Exploration of plant kingdom may provide new leads for the accelerated development of new anticancer agents.

CONCLUSION

Although numerous potent synthetic drugs have been introduced for cancer chemotherapy, yet their serious toxicity concerns to normal cells apart from drug resistance have emerged as the major obstacles for their clinical utility over a prolonged duration of time. Current status and potential of phytochemicals and their derivatives in cancer therapy have been briefly reviewed in the present manuscript.

In silico evaluation of apoptogenic potential and toxicological profile of triterpenoids

AIM:

Caspases-3 and 8 are key mediators of intrinsic and extrinsic pathway of apoptosis, respectively. Triterpenoids of natural and synthetic origin reported as anticancer agents with apoptotic potential and hence may prove to be good candidates for in silico testing against caspases-3 and 8.

MATERIALS AND METHODS:

Various naturally-occurring and synthetic triterpenoids were subjected to activity prediction using PASS Online software, and among them, 67 compounds were selected for further processing. Protein structure of caspase-3 (3DEI) and caspase-8 (3KJQ) was obtained from the protein data bank and docked with selected triterpenoids using AutoDock Tools and AutoDock Vina. Toxicological profile was predicted based on clinical manifestations using PASS online software.

RESULTS:

The high docking score of -10.0, -9.9, -9.8, and -9.5 were shown by friedelin, tingenone, albiziasaponin A, and albiziasaponin C, respectively, for caspase-3, and -11.0, -9.6, -9.6, and -9.4 by β-boswellic acid, bryonolic acid, canophyllic acid, and CDDO, respectively, for caspase-8. Possible adverse events were predicted with varying degree of probability and major relevant effects were reported. Hydrostatic interactions along with formation of hydrogen bonds with specific amino acids in the binding pocket were identified with each triterpenoid.

CONCLUSION:

Lead molecules identified through this in silico study such as friedelin, tingenone, albiziasaponin, bryonolic acid, and canophyllic acid may be utilized for further in vitro/in vivo studies as apoptotic agents targeting caspases-3 and 8.

Integrated metabolomics identifies CYP72A67 and CYP72A68 oxidases in the biosynthesis of Medicago truncatula oleanate sapogenins

INTRODUCTION

Triterpene saponins are important bioactive plant natural products found in many plant families including the Leguminosae.

OBJECTIVES

We characterize two Medicago truncatula cytochrome P450 enzymes, MtCYP72A67 and MtCYP72A68, involved in saponin biosynthesis including both in vitro and in planta evidence.

METHODS

UHPLC-(-)ESI-QToF-MS was used to profile saponin accumulation across a collection of 106 M. truncatula ecotypes. The profiling results identified numerous ecotypes with high and low saponin accumulation in root and aerial tissues. Four ecotypes with significant differential saponin content in the root and/or aerial tissues were selected, and correlated gene expression profiling was performed.

RESULTS

Correlation analyses between gene expression and saponin accumulation revealed high correlations between saponin content with gene expression of β-amyrin synthase, MtCYP716A12, and two cytochromes P450 genes, MtCYP72A67 and MtCYP72A68. In vivo and in vitro biochemical assays using yeast microsomes containing MtCYP72A67 revealed hydroxylase activity for carbon 2 of oleanolic acid and hederagenin. This finding was supported by functional characterization of MtCYP72A67 using RNAi-mediated gene silencing in M. truncatula hairy roots, which revealed a significant reduction of 2β-hydroxylated sapogenins. In vivo and in vitro assays with MtCYP72A68 produced in yeast showed multifunctional oxidase activity for carbon 23 of oleanolic acid and hederagenin. These findings were supported by overexpression of MtCYP72A68 in M. truncatula hairy roots, which revealed significant increases of oleanolic acid, 2β-hydroxyoleanolic acid, hederagenin and total saponin levels.

CONCLUSIONS

The cumulative data support that MtCYP72A68 is a multisubstrate, multifunctional oxidase and MtCYP72A67 is a 2β-hydroxylase, both of which function during the early steps of triterpene-oleanate sapogenin biosynthesis.

Targeting the Thioredoxin System as a Strategy for Cancer Therapy

Thioredoxin reductase (TrxR) participates in the regulation of redox reactions in organisms. It works mainly via its substrate molecule, thioredoxin, to maintain the redox balance and regulate signal transduction, which controls cell proliferation, differentiation, death, and other important physiological processes. In recent years, increasing evidence has shown that the overactivation of TrxR is related to the development of tumors. The exploration of TrxR-targeted antitumor drugs has attracted wide attention and is expected to provide new therapies for cancer treatment. In this perspective, we highlight the specific relationship between TrxR and apoptotic signaling pathways. The cytoplasm and mitochondria both contain TrxR, resulting in the activation of apoptosis. TrxR activity influences reactive oxygen species (ROS) and further regulates the inflammatory signaling pathway. In addition, we discuss representative TrxR inhibitors with anticancer activity and analyze the challenges in developing TrxR inhibitors as anticancer drugs.

Ophiopogonin D', a Natural Product From Radix Ophiopogonis, Induces in Vitro and in Vivo RIPK1-Dependent and Caspase-Independent Apoptotic Death in Androgen-Independent Human Prostate Cancer Cells

Objective: The purpose of this study was to evaluate the anticancer effects of Ophiopogonin D′ (OPD′, a natural product extracted from a traditional Chinese medicine (Radix Ophiopogonis) against androgen-independent prostate cancer cells and to explore the underlying molecular mechanism(s) of action.

Methods: The CCK-8 assay was used to assess the viability of prostate cancer cells. The cell morphology was examined by an ultrastructural analysis via transmission electron microscopy. Cells in apoptosis (early and late stages) were detected using an Annexin V-FITC/propidium iodide kit with a FACSCaliber flow cytometer. JC-1, a cationic lipophilic probe, was employed to measure the mitochondrial membrane potential (MMP) of PC3 cells. Changes in the protein expression of RIPK1, C-RIPK1, caspase 8, cleaved-caspase 8, Bim, Bid, caspase 10, and cleaved-caspase 10 were evaluated by Western blotting. The mRNA expression of Bim was examined by quantitative real-time reverse transcription polymerase chain reaction. Z-VAD-FMK (a caspase inhibitor) and necrostatin-1 (a specific inhibitor of RIPK1) were utilized to determine whether the cell death was mediated by RIPK1 or caspases. PC3 and DU145 xenograft models in BALB/c nude mice were used to evaluate the anticancer activity of OPD′ in vivo.

Results: OPD′ was shown to exert potent anti-tumor activity against PC3 cells. It induced apoptosis via a RIPK1-related pathway, increased the protein expression levels of RIPK1 and Bim, and decreased the levels of cleaved-RIPK1, caspase 8, cleaved-caspase 8, Bid, caspase 10, and cleaved-caspase 10. OPD′ also increased the mRNA expression of Bim. The protein expression of Bim was decreased when cells were pre-treated with necrostatin-1. Treatment with OPD′ inhibited the growth of PC3 and DU145 xenograft tumors in BALB/c nude mice.

Conclusion: OPD′ significantly inhibited the in vitro and in vivo growth of prostate cells via RIPK1, suggesting that OPD′ may be developed as a potential anti-prostate cancer agent.

VDAC1 as Pharmacological Target in Cancer and Neurodegeneration: Focus on Its Role in Apoptosis

Cancer and neurodegeneration are different classes of diseases that share the involvement of mitochondria in their pathogenesis. Whereas the high glycolytic rate (the so-called Warburg metabolism) and the suppression of apoptosis are key elements for the establishment and maintenance of cancer cells, mitochondrial dysfunction and increased cell death mark neurodegeneration. As a main actor in the regulation of cell metabolism and apoptosis, VDAC may represent the common point between these two broad families of pathologies. Located in the outer mitochondrial membrane, VDAC forms channels that control the flux of ions and metabolites across the mitochondrion thus mediating the organelle's cross-talk with the rest of the cell. Furthermore, the interaction with both pro-apoptotic and anti-apoptotic factors makes VDAC a gatekeeper for mitochondria-mediated cell death and survival signaling pathways. Unfortunately, the lack of an evident druggability of this protein, since it has no defined binding or active sites, makes the quest for VDAC interacting molecules a difficult tale. Pharmacologically active molecules of different classes have been proposed to hit cancer and neurodegeneration. In this work, we provide an exhaustive and detailed survey of all the molecules, peptides, and microRNAs that exploit VDAC in the treatment of the two examined classes of pathologies. The mechanism of action and the potential or effectiveness of each compound are discussed.

A naturally occuring triterpene saponin ardisiacrispin B displayed cytotoxic effects in multi-factorial drug resistant cancer cells via ferroptotic and apoptotic cell death

INTRODUCTION

Multidrug resistance of cancer cells constitutes a serious problem in chemotherapy and a challenging issue in the discovery of new cytotoxic drugs. Many saponins are known to display anti-cancer effects. In this study, the cytotoxicity and the modes of action of a naturally occuring oleanane-type tritepene saponin, ardisiacrispin B isolated from the fruit of Ardisia kivuensis Taton (Myrsinaceae) was evaluated on a panel of 9 cancer cell lines including various sensitive and drug-resistant phenotypes.

METHODS

Resazurin reduction assay was used to evaluate cytotoxicity and ferroptotic cell death of samples; caspase-Glo assay was used to detect the activation of caspases in CCRF-CEM leukemia cells. Flow cytometry was used for cell cycle analysis and detection of apoptotic cells by annexin V/PI staining, analysis of mitochondrial membrane potential (MMP) and measurement of reactive oxygen species (ROS).

RESULTS

Ardisiacrispin B displayed significant cytotoxic effects in the 9 tested cancer cell lines with IC₅₀ values below 10 µM. The IC₅₀ values ranges were 1.20 µM (towards leukemia CCRF-CEM cells) to 6.76 µM [against heptocarcinoma HepG2 cells] for ardisiacrispin B and 0.02 µM (against CCRF-CEM cells) to 122.96 µM (against resistant CEM/ADR5000 leukemia cells) for doxorubicin. Collateral sensitivity of resistant HCT116p53^-/- colon adenocarcinoma cells to ardisiacripsin B was observed. Ardisiacrispin B induced apoptosis in CCRF-CEM cells via activation of inititator caspases 8 and 9 and effector caspase 3/7, alteration of MMP and increase in ROS production. Ferroptosis also contributed to the cytotoxicity of ardisiacrispin B.

CONCLUSIONS

The studied oleanane-type triterpene saponin is a good cytotoxic molecule that deserve more detailed exploration in the future, to develop novel cytotoxic drugs to combat both sensitive and drug-resistant cancers.

Antioxidant activity of polyphenolic compounds isolated from ethyl-acetate fraction of Acacia hydaspica R. Parker

Background

Acacia hydaspica belongs to family leguminosae possess antioxidant, anti-inflammatory and anticancer activities. During our search for antioxidant compounds from A. hydaspica, we carried out bioassay guided fractionation and obtained antioxidant compounds with free radical scavenging activity.

Materials and methods

The polyphenol compounds in the plant extract of A. hydaspica were isolated by combination of different chromatographic techniques involving vacuum liquid chromatography and medium pressure liquid chromatography. The structural heterogeneity of isolated compounds was characterized by high pressure liquid chromatography, MS–ESI and NMR spectroscopic analyses. The antioxidant potential of isolated compounds has been investigated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide scavenging potential, hydroxyl radical scavenging potential, ferric reducing/antioxidant power (FRAP) model systems and total antioxidant capacity measurement.

Results

The isolated compounds show the predominance of signals representative of 7-O-galloyl catechins, catechins and methyl gallate. Flash chromatographic separation gives 750 mg of 7-O galloyl catechin, 400 mg of catechin and 150 mg of methyl gallate from 4 g loaded fraction on ISCO. Results revealed that C1 was the most potent compound against DPPH (EC₅₀ 1.60 ± 0.035 µM), nitric oxide radical (EC₅₀ 6 ± 0.346 µM), showed highest antioxidant index (1.710 ± 0.04) and FRAP [649.5 ± 1.5 µM Fe(II)/g] potency at 12.5 µM dose compared to C2, C3 and standard reference, whereas C3 showed lower EC₅₀ values (4.33 ± 0.618 µM) in OH radical scavenging assay.

Conclusion

Present research reports for the first time the antioxidant activity of polyphenolic compounds of A. hydaspica. Result showed good resolution and separation from other constituents of extract and method was found to be simple and precise. The isolation of catechin from this new species could provide a varied opportunity to obtain large quantities of catechin and catechin isomers beside from green tea. Free radical scavenging properties of isolated catechin isomers from A. hydaspica merit further investigations for consumption of this plant in oxidative stress related disorders.

Electronic supplementary material

The online version of this article (10.1186/s13065-018-0373-x) contains supplementary material, which is available to authorized users.

Isolation and Structural Characterization of Echinocystic Acid Triterpenoid Saponins from the Australian Medicinal and Food Plant Acacia ligulata

The Australian plant Acacia ligulata has a number of traditional food and medicinal uses by Australian Aboriginal people, although no bioactive compounds have previously been isolated from this species. Bioassay-guided fractionation of an ethanolic extract of the mature pods of A. ligulata led to the isolation of the two new echinocystic acid triterpenoid saponins, ligulatasides A (1) and B (2), which differ in the fine structure of their glycan substituents. Their structures were elucidated on the basis of 1D and 2D NMR, GC-MS, LC-MS/MS, and saccharide linkage analysis. These are the first isolated compounds from A. ligulata and the first fully elucidated structures of triterpenoid saponins from Acacia sensu stricto having echinocystic acid reported as the aglycone. Compounds 1 and 2 were evaluated for cytotoxic activity against a human melanoma cancer cell line (SK-MEL28) and a diploid fibroblast cell line (HFF), but showed only weak activity.

Ultrafast Delivery of Aggregation-Induced Emission Nanoparticles and Pure Organic Phosphorescent Nanocrystals by Saponin Encapsulation

Saponins are a class of naturally occurring bioactive and biocompatible amphiphilic glycosides produced by plants. Some saponins, such as α-hederin, exhibit unique cell membrane interactions. At concentrations above their critical micelle concentration, they will interact and aggregate with membrane cholesterol to form transient pores in the cell membrane. In this project, we utilized the unique permeabilization and amphiphilic properties of saponins for the intracellular delivery of deep-red-emitting aggregation-induced emission nanoparticles (AIE NPs) and pure organic room-temperature phosphorescent nanocrystals (NCs). We found this method to be biocompatible, inexpensive, ultrafast, and applicable to deliver a wide variety of AIE NPs and NCs into cancer cells.

Evaluation of in vitro anticancer activity of 1,8-Cineole-containing n-hexane extract of Callistemon citrinus (Curtis) Skeels plant and its apoptotic potential

Plants are the source of a variety of secondary metabolites, which are often used in the anticancer activity. Discovering new anticancer drug from herbal source is more important in both biological and pharmacological activities. Hence, the objective of this study is to identify the anticancer agent in Callistemon citrinus (Curtis) Skeels (CC) for the treatment of cancer. Very recently we have reported an increased antioxidant activity in the ethanolic and methanolic extracts (EE and ME) of CC but significantly reduced activity (rather increased cytotoxicity), in the n-hexane extract (HE). In this study, the cytotoxicity of all the three solvent extracts was tested against A431, MG-63 and HaCaT cell lines by MTT assay. Interestingly HE has showed increased anti-proliferative effect against the cancer cells but was resisted by non-malignant cells. HPLC and GC-MS analysis revealed the presence of 1,8-Cineole as a predominant compound in HE, the semi-purified bioactive extract. Henceforth, this would be called HE-C and be used for further analyses to understand its mode of action on induced apoptosis/necrosis. Alamar blue assay of HE-C showed cytotoxicity and change in morphological characteristics, which was confirmed by AO/EB staining using fluorescence microscopy, ultra-structural features of apoptosis using SEM and TEM. HE-C induced cell death was also detected by FACS using FITC-labelled Annexin-V and Propidium iodide. ROS generation was monitored using DCF-DA by flow cytometry. The overall results suggested that the selective extract (HE-C) containing 1,8-Cineole has shown potential anti-cancer activity in a dose-dependent manner, and cell death was induced through ROS-mediated apoptosis. Our findings provide an insight into the potential of 1,8-Cineole as a novel drug for killing cancer cells.

A Selenium-Modified Ginseng Polysaccharide Promotes the Apoptosis in Human Promyelocytic Leukemia (HL-60) Cells via a Mitochondrial-Mediated Pathway

A ginseng polysaccharide was extracted, purified, and modified by nitric acid-selenious acid (HNO₃-H₂SeO₃) method to yield one selenylation-modified polysaccharide (sGP). We reported for the first time the anticancer potential of sGP on the human promyelocytic leukemia HL-60 cell line and evaluated its relevant underlying mechanism. Our results showed that sGP markedly inhibited the growth of HL-60 cells via induction of apoptosis. The event of apoptosis was accompanied by the formation of apoptotic bodies; the release of cytochrome c; loss of mitochondrial membrane potential; and activation of caspase-9, caspase-3, and cleavage of poly ADP ribose polymerase (PARP) in HL-60 cells. In addition, western blot analysis showed that sGP inhibited antiapoptotic Bcl-2 protein expression and increased proapoptotic Bax protein expression in cells under identical conditions. Together, our study suggests that sGP induces apoptosis of HL-60 cells through the mitochondrial-dependent pathway.

The Saponin-Mediated Enhanced Uptake of Targeted Saporin-Based Drugs is Strongly Dependent on the Saponin Structure

Saponins are a group of plant glycosides consisting of a steroid or triterpenoid aglycone to which one or more sugar chains are attached. They exhibit cell membrane–permeabilizing properties and, thus, have been investigated for their therapeutic potential. Recently, at a nonpermeabilizing concentration saponinum album from Gypsophila paniculata L. has been described to enhance the cytotoxicity of a chimeric toxin in a cell culture model. To elucidate whether this enhancing effect is also mediated by other saponins, we analyzed the ability of seven different saponins to enhance the cytotoxicity of a targeted chimeric toxin. The chimeric toxin is composed of saporin, a plant ribosome-inactivating toxin, a cleavable adapter, and human epidermal growth factor (EGF). Cytotoxicity on EGF receptor (EGFR)-bearing cells was analyzed both alone and after combined application of saponin and chimeric toxin. Only two of the tested saponins, quillajasaponin and saponinum album, enhanced cytotoxicity by more than 1000-fold, whereas the enhancement factors of the other saponins were only approximately 10-fold. In contrast to saponinum album, quillajasaponin enhanced the cytotoxicity both on control cells lacking EGFR and on target cells, indicating that, in this case, the enhancement is not target cell receptor specific. This is also the case for some of the saponins with low enhancement factors. Saponinum album resulted in a more than 13,600-fold receptor-specific enhancement, decreasing the 50% inhibitory concentration (IC50) from 2.4 nM to 0.18 pM, which renders it the best option to promote saporin-3-based drug uptake while retaining specificity for the EGFR.

One compound of saponins from Disocorea zingiberensis protected against experimental acute pancreatitis by preventing mitochondria-mediated necrosis

Acute pancreatitis (AP) is a painful inflammatory disorder of the exocrine pancreas, ranking as the most common gastrointestinal reasons for hospitalization with no specific therapy currently. Diosgenyl saponins extracted from natural products and diosgenin or its derivatives have been shown to exert anti-inflammatory effects in various diseases. However, the therapeutic effects of diosgenyl saponins from Dioscorea zingiberensis C. H. Wright in AP have not yet been determined. Five compounds were extracted and screened for taurocholate-induced necrosis in mouse pancreatic acinar cells. Particularly, 26-O-β-d-glucopyranosyl-3β, 22α, 26-trihydroxy-25(R)-furosta-5-en-3-O-[α-L-rhamnopyranosyl-(1 → 4)]-β-d-glucopyranoside (compound 1) exhibited the best protective effects with no toxicity observed. Next, we showed compound 1 concentration-dependently inhibited necrotic cell death pathway activation and 2.5 mM compound 1 also prevented the loss of mitochondrial membrane potential, adenosine triphosphate production, and reactive oxygen species generation in mouse pancreatic acinar cells. Finally, we showed compound 1 protected against three clinically representative murine models of AP and significantly improved pancreatitis-associated acute lung injury. These data provide in vitro and in vivo evidence that one compound of diosgenyl saponins can be potential treatment for AP. This study suggests natural saponins may serve as fruitful sources for exploring/identifying potential therapies for inflammatory diseases.

Terpenoids with Special Pharmacological Significance: A Review

Terpenoids are a very prominent class of natural compounds produced in diverse genera of plants, fungi, algae and sponges. They gained significant pharmaceutical value since prehistoric times, due to their broad spectrum of medical applications. The fragrant leaves of Eucalyptus trees are a rich source of terpenoids. Therefore this review starts by summarizing the main terpenoid compounds present in Eucalyptus globulus, E. citriodora, E. radiata and E. resinifera and describing their biosynthetic pathways. Of the enormous number of pharmaceutically important terpenoids, this paper also reviews some well established and recently discovered examples and discusses their medical applications. In this context, the synthetic processes for (–)-menthol, (–)- cis-carveol, (+)-artemisinine, (+)-merrilactone A and (–)-sclareol are presented. The tricyclic sesquiterpene (–)-englerin A isolated from the stem bark of the Phyllanthus engleri plant ( Euphorbiaceae) is highly active against certain renal cancer cell lines. In addition, recent studies showed that englerin A is also a potent and selective activator of TRPC4 and TRPC5 calcium channels. These important findings were the motivation for several renowned research labs to achieve a total synthesis of (–)-englerin A. Two prominent examples – Christmann and Metz – are compared and discussed in detail.

Selective glucocorticoid receptor-activating adjuvant therapy in cancer treatments

Although adverse effects and glucocorticoid resistance cripple their chronic use, glucocorticoids form the mainstay therapy for acute and chronic inflammatory disorders, and play an important role in treatment protocols of both lymphoid malignancies and as adjuvant to stimulate therapy tolerability in various solid tumors. Glucocorticoid binding to their designate glucocorticoid receptor (GR), sets off a plethora of cell-specific events including therapeutically desirable effects, such as cell death, as well as undesirable effects, including chemotherapy resistance, systemic side effects and glucocorticoid resistance. In this context, selective GR agonists and modulators (SEGRAMs) with a more restricted GR activity profile have been developed, holding promise for further clinical development in anti-inflammatory and potentially in cancer therapies. Thus far, the research into the prospective benefits of selective GR modulators in cancer therapy limped behind. Our review discusses how selective GR agonists and modulators could improve the therapy regimens for lymphoid malignancies, prostate or breast cancer. We summarize our current knowledge and look forward to where the field should move to in the future. Altogether, our review clarifies novel therapeutic perspectives in cancer modulation via selective GR targeting.

Exploring the Potential Role of Chemopreventive Agent, Hesperetin Conjugated Pegylated Gold Nanoparticles in Diethylnitrosamine-Induced Hepatocellular Carcinoma in Male Wistar Albino Rats

Liver cancer is the fifth most common cancer and is still one of the leading causes of death world wide, due to food additives, alcohol, fungal toxins, air, toxic industrial chemicals, and water pollutants. Chemopreventive drugs play a potential role in liver cancer treatment. Obviously in the production of anticancer drugs, the factors like poor solubility, bioavailability, biocompatibility, limited chemical stability, large amount of dose etc., plays a major role. Against this backdrop, the idea of designing the chemopreventive nature of bio flavanoid hesperetin (HP) drug conjugated with pegylated gold nanoparticles to increasing the solubility, improve bioavailability and enhance the targeting capabilities of the drug during diethylnitrosamine (DEN) induced liver cancer in male wistar albino rats. The dose fixation studies and the toxicity of pure HP and HP conjugated gold nanoparticles (Au-mPEG(5000)-S-HP) were analysed. After concluded the dose fixation and toxicity studies the experimental design were segregated in six groups for the anticancer analysis of DEN induced HCC for 16 weeks. After the experimental period the body weight, relative liver weight, number of nodules and size of nodules, the levels of tumor markers like CEA, AFP and the level of lipid peroxidation, lipid hydroperoxides and the activities of antioxidant enzymes were assessed. The administration of DEN to rats resulted in increased relative liver weight and serum marker enzymes aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, and gamma glutamyl transpeptidase. The levels of lipid peroxides elevated (in both serum and tissue) with subsequent decrease in the final body weight and tissue antioxidants like superoxide dismutase, catalase, reduced glutathione, glutathione peroxidise, and glutathione reductase. HP supplementation (20 mg/kg b.wt) significantly attenuated these alterations, thereby showing potent anticancer effect in liver cancer and the HP loaded gold nanoparticels (Au-mPEG(5000)-S-HP) treated animals shows the better treatment than the pure HP due to the solubility of drug, bioavailability and the target drug delivery of the biodegradable polymer. Histological observations were also carried out, which added supports to the chemopreventive action of the pure HP and HP loaded gold nanoparticles (Au-mPEG(5000)-S-HP) against DEN induction during liver cancer progression. These findings suggest that HP loaded gold nanoparticels (Au-mPEG(5000)-S-HP) shows better efficacy than the pure HP against lipid peroxidation, hepatic cell damage and protects the antioxidant system in DEN induced hepatocellular carcinogenesis.

Safety assessment of saponins extract in Dolichos falcatus Klein: Subchronic study in Sprague-Dawley rats

ETHNOPHARMACOLOGICAL RELEVANCE

Dolichos falcatus Klein (DF), a Chinese Dai ethnic medicine popularly known as "Tuoyeteng" in Yunnan province of China, has been widely used in China to treat fracture, rheumatoid arthritis and soft tissue injuries for a long time. Our previous study showed that saponins in DF (DFS) ameliorated the gouty arthritis induced by MSU crystals in vivo and in vitro. The present study was carried out to evaluate the no-observed-adverse-effect level (NOAEL) of DFS.

MATERIALS AND METHODS

Sprague-Dawley rats (10/sex/group) were gavaged with DFS at dose level of 0, 50, 100 and 200 mg/kg body weight /day for 90-days.

RESULTS

DFS administration did not result in mortality or show treatment-related changes in clinical signs of toxicity, body weights gain or feed consumption. Similarly, in addition to slightly hemolytic anemia and gastrointestinal tract lesion in males of high-dose treatment group, no toxicologically significant treatment-related changes in hematological, clinical chemistry, urine analysis parameters, organ weights, and macroscopic and microscopic abnormalities were noted during the testing period.

CONCLUSION

The results of subchronic toxicity study support the NOAEL for DFS as 200 mg/kg/d in females and as 100mg/kg/d in males. These results provide an important reference for further DFS-related clinical trials or new drug exploration.

Investigation of the transdermal transport of charged local anesthetics in the presence of triterpene saponin glycosides

Percutaneous absorption and transdermal delivery of water-soluble drugs have proven to be challenging due to their low permeability through skin. Avicins which are triterpene saponin glycosides (TSGs) derived from the desert plant Acacia victoriae have not been investigated to date as chemical penetration enhancers due to their higher molecular weight (MW 2,000 Da). It was recently shown that avicins exhibit remarkable mobility across skin lipids in spite of their large size due to their unique chemical structure. In this study, the permeation of local anesthetics, lidocaine-HCl, prilocaine-HCl, and bupivacaine-HCL from aqueous vehicle, across full-thickness porcine skin was investigated in the presence of F094-a mixture of avicins. F094 was capable of enhancing the permeability of all three anesthetics from aqueous formulations at extremely low concentrations ranging from 0.1 to 1 % w/v. The enhancement, which ranged from 2- to 5-fold, was surprisingly independent of molecular weight of the anesthetics and showed clear correlation with aqueous phase solubility of the anesthetics. Since F094 was found to have no impact on the octanol/water partition coefficients of the anesthetics, this suggests that TSGs like avicins most likely impact the aqueous pathways (pericellular/pores within lipids) and as such represent an alternative means of enhancing the transdermal transport of charged drugs from water-based formulations.

Integrated metabolomics and transcriptomics reveal enhanced specialized metabolism in Medicago truncatula root border cells

Integrated metabolomics and transcriptomics of Medicago truncatula seedling border cells and root tips revealed substantial metabolic differences between these distinct and spatially segregated root regions. Large differential increases in oxylipin-pathway lipoxygenases and auxin-responsive transcript levels in border cells corresponded to differences in phytohormone and volatile levels compared with adjacent root tips. Morphological examinations of border cells revealed the presence of significant starch deposits that serve as critical energy and carbon reserves, as documented through increased β-amylase transcript levels and associated starch hydrolysis metabolites. A substantial proportion of primary metabolism transcripts were decreased in border cells, while many flavonoid- and triterpenoid-related metabolite and transcript levels were increased dramatically. The cumulative data provide compounding evidence that primary and secondary metabolism are differentially programmed in border cells relative to root tips. Metabolic resources normally destined for growth and development are redirected toward elevated accumulation of specialized metabolites in border cells, resulting in constitutively elevated defense and signaling compounds needed to protect the delicate root cap and signal motile rhizobia required for symbiotic nitrogen fixation. Elevated levels of 7,4'-dihydroxyflavone were further increased in border cells of roots exposed to cotton root rot (Phymatotrichopsis omnivora), and the value of 7,4'-dihydroxyflavone as an antimicrobial compound was demonstrated using in vitro growth inhibition assays. The cumulative and pathway-specific data provide key insights into the metabolic programming of border cells that strongly implicate a more prominent mechanistic role for border cells in plant-microbe signaling, defense, and interactions than envisioned previously.

Terpenoids and their biosynthesis in cyanobacteria

Terpenoids, or isoprenoids, are a family of compounds with great structural diversity which are essential for all living organisms. In cyanobacteria, they are synthesized from the methylerythritol-phosphate (MEP) pathway, using glyceraldehyde 3-phosphate and pyruvate produced by photosynthesis as substrates. The products of the MEP pathway are the isomeric five-carbon compounds isopentenyl diphosphate and dimethylallyl diphosphate, which in turn form the basic building blocks for formation of all terpenoids. Many terpenoid compounds have useful properties and are of interest in the fields of pharmaceuticals and nutrition, and even potentially as future biofuels. The MEP pathway, its function and regulation, and the subsequent formation of terpenoids have not been fully elucidated in cyanobacteria, despite its relevance for biotechnological applications. In this review, we summarize the present knowledge about cyanobacterial terpenoid biosynthesis, both regarding the native metabolism and regarding metabolic engineering of cyanobacteria for heterologous production of non-native terpenoids.

In vitro and in vivo anticancer activity of surface modified paclitaxel attached hydroxyapatite and titanium dioxide nanoparticles

Targeted drug delivery using nanocrystalline materials delivers the drug at the diseased site. This increases the efficacy of the drug in killing the cancer cells. Surface modifications were done to target the drug to a particular receptor on the cell surface. This paper reports synthesis of hydroxyapatite and titanium dioxide nanoparticles and modification of their surface with polyethylene glycol (PEG) followed by folic acid (FA). Paclitaxel, an anticancer drug, is attached to functionalized hydroxyapatite and titanium dioxide nanoparticles. The pure and functionalised nanoparticles are characterised with XRD, TEM and UV spectroscopy. Anticancer analysis was carried out in DEN induced hepatocarcinoma animals. Biochemical, hematological and histopathological analysis show that the surface modified paclitaxel attached nanoparticles have an higher anticancer activity than the pure paclitaxel and surface modified nanoparticles without paclitaxel. This is due to the targeting of the drug to the folate receptor in the cancer cells.

Toxins in botanical dietary supplements: blue cohosh components disrupt cellular respiration and mitochondrial membrane potential

Certain botanical dietary supplements have been associated with idiosyncratic organ-specific toxicity. Similar toxicological events, caused by drug-induced mitochondrial dysfunction, have forced the withdrawal or U.S. FDA "black box" warnings of major pharmaceuticals. To assess the potential mitochondrial liability of botanical dietary supplements, extracts from 352 authenticated plant samples used in traditional Chinese, Ayurvedic, and Western herbal medicine were evaluated for the ability to disrupt cellular respiration. Blue cohosh (Caulophyllum thalictroides) methanol extract exhibited mitochondriotoxic activity. Used by some U.S. midwives to help induce labor, blue cohosh has been associated with perinatal stroke, acute myocardial infarction, congestive heart failure, multiple organ injury, and neonatal shock. The potential link between mitochondrial disruption and idiosyncratic herbal intoxication prompted further examination. The C. thalictroides methanol extract and three saponins, cauloside A (1), saponin PE (2), and cauloside C (3), exhibited concentration- and time-dependent mitochondriotoxic activities. Upon treatment, cell respiration rate rapidly increased and then dramatically decreased within minutes. Mechanistic studies revealed that C. thalictroides constituents impair mitochondrial function by disrupting membrane integrity. These studies provide a potential etiological link between this mitochondria-sensitive form of cytotoxicity and idiosyncratic organ damage.

Phytochemical and pharmacological properties of Gymnema sylvestre: an important medicinal plant

Gymnema sylvestre (Asclepiadaceae), popularly known as “gurmar” for its distinct property as sugar destroyer, is a reputed herb in the Ayurvedic system of medicine. The phytoconstituents responsible for sweet suppression activity includes triterpene saponins known as gymnemic acids, gymnemasaponins, and a polypeptide, gurmarin. The herb exhibits a broad range of therapeutic effects as an effective natural remedy for diabetes, besides being used for arthritis, diuretic, anemia, osteoporosis, hypercholesterolemia, cardiopathy, asthma, constipation, microbial infections, indigestion, and anti-inflammatory. G. sylvestre has good prospects in the treatment of diabetes as it shows positive effects on blood sugar homeostasis, controls sugar cravings, and promotes regeneration of pancreas. The herbal extract is used in dietary supplements since it reduces body weight, blood cholesterol, and triglyceride levels and holds great prospects in dietary as well as pharmacological applications. This review explores the transition of a traditional therapeutic to a modern contemporary medication with an overview of phytochemistry and pharmacological activities of the herb and its phytoconstituents.

Research Progress on Natural Triterpenoid Saponins in the Chemoprevention and Chemotherapy of Cancer

Triterpenoid saponins are glycosides with remarkable structural and bioactive diversity. They are becoming increasingly significant in the treatment of cancer due to their efficacy and safety. This chapter provides an update on the sources, pharmacological effects, structure-activity relationships, and clinical studies of anticancer triterpenoid saponins with a particular focus on the molecular mechanisms underlying their therapeutic properties. The correlative references and study reports described were collected through PubMed. The anticancer triterpenoid saponins enable the inhibition of cancer formation and progression by modulating multiple signaling targets related to cellular proliferation, apoptosis, autophagy, metastasis, angiogenesis, inflammation, oxidative stress, multidrug resistance, cancer stem cells, and microRNAs. This review provides new insights into the molecular basis of triterpenoid saponins in the chemoprevention and chemotherapy of cancer.

Macromolecular interactions of triterpenoids and targeted toxins: role of saponins charge

Macromolecular interaction of protein toxins with certain plant triterpenoids holds potential for application in tumor therapy. The ability of only certain saponins to enhance the endosomal escape of toxins specifically in tumor cells was evaluated and set into correlation with the electrophoretic mobility. Saponins from Saponaria officinalis Linn, were selected as a lead to understand this evolutionarily conserved principle in detail. Agarose gel electrophoresis was utilized to procure pure saponin fractions with different electrophoretic mobility, which were tested for their ability to enhance the toxicity by live cell monitoring. Five fractions (SOG1-SOG5) were isolated with a relative electrophoretic mobility of (-0.05, 0.41, 0.59, 0.75 and 1.00) and evaluated using thin layer chromatography, HPLC, and mass spectroscopic analysis. Cytotoxicity experiments revealed highest effectiveness with SOG3. Live cell imaging experiments with SOG3 revealed that this saponin with a specific REM of 0.59 could assist in the lyso/endosomal release of the toxic payload without affecting the integrity of plasma membrane and could lead to the induction of apoptosis. This charge dependent enhancement was also found to be highly specific to type I ribosome inactivating proteins compared to bacterial toxins. Charge interaction of plant toxins and saponins with tumor cells, plays a major role in toxin specific modulation of response. The finding opens up newer ways of finding protein saponin interaction conserved evolutionarily and to test their role in endosomal escape of therapeutic molecules.

SB365, Pulsatilla saponin D, targets c-Met and exerts antiangiogenic and antitumor activities

SB365, Pulsatilla saponin D isolated from the root of Pulsatilla koreana, has exhibited potential beneficial effects as a chemopreventive agent for critical health conditions including cancer. However, the molecular mechanisms underlying the activity of SB365 remain unknown. Here, we examined anticancer efficacy of SB365 against gastric cancer and its mechanism of action. SB365 effectively inhibited the growth of gastric cancer cells. Its apoptotic effect was accompanied by increased evidence of cleaved caspase-3 and poly(ADP ribose) polymerase. To elucidate the anticancer mechanism of SB365, we used an array of 42 different receptor tyrosine kinases (RTKs). Of the 42 different phospho-RTKs, SB365 strongly inhibited expression of activated c-mesenchymal-epithelial transition factor (c-Met) in gastric cancer cells. Also, the activation of the c-Met signal cascade components, including Akt and mammalian target of rapamycin, was inhibited by SB365 in a dose-dependent manner. In angiogenesis studies, SB365 inhibited tube formation in hepatocyte growth factor (HGF)-induced human umbilical vein endothelial cells and suppressed microvessel sprouting from the rat aortic ring, ex vivo, and blood vessel formation in the Matrigel plug assay in mice. In xenograft animal models, SB365 significantly delayed tumor growth in a dose-dependent manner. In tumor tissue, SB365 suppressed c-Met signaling, proliferation and angiogenesis and induced apoptosis. These findings suggest that SB365 docks at an allosteric site on c-Met and thereby targets c-Met signaling pathway, cell growth/angiogenesis inhibition and apoptosis induction. Therefore, SB365 may be a novel drug candidate for the treatment of gastric cancer.

Cell wall proteomics of crops

Cell wall proteins play key roles in cell structure and metabolism, cell enlargement, signal transduction, responses to environmental stress, and many other physiological events. Agricultural crops are often used for investigating stress tolerance because cultivars with differing degrees of tolerance are available. Abiotic and biotic stress factors markedly influence the geographical distribution and yields of many crop species. Crop cell wall proteomics is of particular importance for improving crop productivity, particularly under unfavorable environmental conditions. To better understand the mechanisms underlying stress response in crops, cell wall proteomic analyses are being increasingly utilized. In this review, the methods of purification and purity assays of cell wall protein fractions from crops are described, and the results of protein identification using gel-based and gel-free proteomic techniques are presented. Furthermore, protein composition of the cell walls of rice, wheat, maize, and soybean are compared, and the role of cell wall proteins in crops under flooding and drought stress is discussed. This review will be useful for clarifying the role of the cell wall of crops in response to environmental stresses.

Molecular cloning and characterization of three isoprenyl diphosphate synthase genes from alfalfa

Isoprenoid is the precursor for the biosynthesis of saponins, abscisic acid, gibberellins, chlorophylls and many other products in plants. Saponins are an important group of bioactive plant natural products. The alfalfa (Medicago sativa L.) saponins are glycosides of different triterpene aglycones and possess many biological activities. We isolated three genes (MsFPPS, MsGPPS and MsGGPPS) encoding isoprenyl diphosphate synthases (IDS) from alfalfa via a homology-based PCR approach. The enzyme activity assay of purified recombined MsFPPS and MsGGPPS expressed in Escherichia coli indicated that they all had IDS activity. Expression analysis of the three genes in different alfalfa tissues using real time PCR displayed that they were expressed in all tissues although they had a different expression patterns. MsFPPS and MsGPS displayed a significant increase in transcript level in response to methyl jasmonate, but the transcript level of MsGGPPS decreased obviously. To elucidate the functions of the three IDSs, their overexpression driven by a constitutive cauliflower mosaic virus-35S promoter in tobacco plants was applied and analyzed. The T(0) transgenic plants of MsFPPS showed high levels of squalene content when compared with control. However, no differences were detected in T(0) transgenic plants of MsGPPS and MsGGPPS. In addition, the overexpression of MsFPPS induced senescence response in transgenic plant leaves. This result may indicate that MsFPPS performs a role not only in phytosterol and triterpene biosynthesis, but also in growth regulation.