Bioactive sesquiterpene lactones and other compounds isolated from Vernonia cinerea

Anti-inflammatory germacrane-type sesquiterpene lactones from Vernonia sylvatica

Nine new germacranolides, sylvaticalides A-H (1-9), and three known analogues (10-12) were isolated from the aerial part of Vernonia sylvatica. Their structures were established using comprehensive spectroscopic analysis, including high-resolution electrospray ionization mass spectroscopy (HR-ESI-MS) and 1D and 2D nuclear magnetic resonance (NMR) spectra. Their absolute configurations were determined by X-ray diffraction experiments. The anti-inflammatory activities of all isolated compounds were assessed by evaluating their inhibitory effects on the nuclear factor kappa B (NF-κB) pathway, which was activated by lipopolysaccharide (LPS)-stimulated human THP1-Dual cells, and the interferon-stimulated gene (ISG) pathway, activated by STING agonist MSA-2 in the same cell model. Compounds 1, 2 and 6 showed inhibitory effects on the NF-κB and ISG signaling pathways, with IC50 values ranging from 4.12 to 10.57 μmol·L-1.

Therapeutic and pharmacological efficacy of plant-derived bioactive compounds in targeting breast cancer

Breast cancer (BC) ranks number one among cancers affecting women globally. Serious concerns include delayed diagnosis, poor prognosis, and adverse side effects of conventional treatment, leading to residual morbidity. Therefore, an alternative treatment approach that is safe and effective has become the need of the hour. In this regard, plant-based medicines via a combination of conventional drugs are gaining increasing acceptance worldwide, playing a pivotal role in cancer management as proven by their efficacy evaluation studies. This review aims to fill the knowledge gaps by providing the preclinical evidence of cellular and molecular mechanisms of Indian phytomedicines in targeting varied pathways of breast cancer progression. A comprehensive search was performed on different platforms, followed by screening of relevant studies for review. In this article, the in-depth of various botanical drugs covering their nomenclature, dosage, toxicity, and modus operandi in BC cells have been extensively discussed. Various signaling pathways like Notch signaling, MAPK signaling, apoptosis, Wnt signaling, etc. regulated by herbal medicine treatment in BC are also highlighted to understand the drug mechanism better. This will guide the researchers to plan future strategies and generate more robust integrated evidence of plant-based drugs or botanical formulations for their potential role in the management of BC.

Traditional Uses, Phytochemistry, and Pharmacological Activities of Vernonia cinerea (L.) Less.: An Updated Review

Vernonia cinerea (L.) Less. is a perennial herbaceous plant found mainly in tropical areas, particularly in Southeast Asia, South America, and India. Various parts of V. cinerea have traditionally been used in folk medicine to treat several diseases, such as malaria, fever, and liver diseases. V. cinerea has so far yielded about 92 secondary metabolites. The majority of these are sesquiterpene lactones, but triterpenes, flavonoids, steroids, phenolics, and other compounds are present as well. V. cinerea crude extracts reportedly exhibit anti-inflammatory, antiprotozoal, antidiabetic, anticancer, antimicrobial, antioxidant, and renoprotective activities. This study aims to provide the latest up-to-date information on the botanical characterization, distribution, traditional uses, phytochemistry, and pharmacological activity of V. cinerea. Information on V. cinerea was thoroughly reviewed. The literature published between 1950 and 2024 was compiled through online bibliographic databases, including SciFinder, Web of Science, Google Scholar, PubMed, ScienceDirect, Springer Link, Wiley, and the MDPI online library. The keywords used for the literature search included Vernonia cinerea (L.) Less. and the synonyms Cyanthillium cinereum (L.) H.Rob., Conyza cinerea L., and various others.

A review of natural products and small-molecule therapeutics acting on central nervous system malignancies: Approaches for drug development, targeting pathways, clinical trials, and challenges

In 2021, the World Health Organization released the fifth edition of the central nervous system (CNS) tumor classification. This classification uses histopathology and molecular pathogenesis to group tumors into more biologically and molecularly defined entities. The prognosis of brain cancer, particularly malignant tumors, has remained poor worldwide, approximately 308,102 new cases of brain and other CNS tumors were diagnosed in the year 2020, with an estimated 251,329 deaths. The cost and time-consuming nature of studies to find new anticancer agents makes it necessary to have well-designed studies. In the present study, the pathways that can be targeted for drug development are discussed in detail. Some of the important cellular origins, signaling, and pathways involved in the efficacy of bioactive molecules against CNS tumorigenesis or progression, as well as prognosis and common approaches for treatment of different types of brain tumors, are reviewed. Moreover, different study tools, including cell lines, in vitro, in vivo, and clinical trial challenges, are discussed. In addition, in this article, natural products as one of the most important sources for finding new chemotherapeutics were reviewed and over 700 reported molecules with efficacy against CNS cancer cells are gathered and classified according to their structure. Based on the clinical trials that have been registered, very few of these natural or semi-synthetic derivatives have been studied in humans. The review can help researchers understand the involved mechanisms and design new goal-oriented studies for drug development against CNS malignancies.

Hirsutinolide-type sesquiterpenoids with anti-prostate cancer activity from Cyanthillium cinereum

Four previously undescribed hirsutinolide-type sesquiterpenoids, cyanolides A-D (1-4), along with twelve known analogues (5-16), were isolated from the aerial parts of Cyanthillium cinereum. Their structures were determined by comprehensive analysis of NMR, HRESIMS, and ECD spectra. Compound 1 is a rarely occurring hirsutinolide-type sesquiterpenoid with 1,4-ether ring ruptured and containing a chlorine atom, and compounds 13-16 were reported from this plant for the first time. All compounds were tested for their inhibiting effects on prostate cancer cells. As a result, compounds 1, 3, and 8-14 exhibited significant anti-prostate cancer activity against PC-3 and LNCaP cells with IC50 values ranging from 2.2 ± 0.4 to 8.5 ± 0.7 μM and 3.0 ± 0.7 to 10.5 ± 1.1 μM, respectively. The preliminary structure-activity relationship was discussed. Further investigation showed that compound 1 induced apoptosis in PC-3 cells.

Antibacterial stigmastane-type steroids and other constituents from the leaves of Vernonia glabra (Steetz) Vatke (Asteraceae)

Two new stigmastane steroids (1 and 2) were isolated from the methanol extract of the leaves of Vernonia glabra, together with seventeen known compounds (3-19) including one fatty acid, four triterpenoids, four steroids, one trinitropropanoyl glucoside, and seven flavonoids. The structures of compounds 1 and 2 were assigned based on their IR, NMR and MS data, and by comparison with literature values. The MeOH extract, its fractions and isolated compounds were subjected to in vitro antibacterial assay against two Gram-positive (Staphylococcus aureus ATCC25923 and Streptococcus pneumoniae ATCC49619) and two Gram-negative (Escherichia coli ATCC8739 and Klebsiella pneumoniae ATCC10031) bacteria, using broth microdilution method. The extract and fractions exhibited (16 ≤ MIC ≤ 512 μg/mL) antibacterial activities. The isolated and tested compounds were also active (16 ≤ MIC ≤ 128 μg/mL) against the four pathogenic bacteria, with compound 2 being the most active and E. coli, the most sensitive microorganism.

Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance

Four polyoxygenated stigmastanes (1-4) alongside known analogues (7-8) and flavonoids (5-6) were isolated from a dichloromethane/methanol (1:1, v/v) extract of the whole plant of Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae). Their structures were determined by means of spectroscopic and spectrometric analysis. The relative stereochemistry of the new compounds was established and confirmed via biosynthesis evidence and cyclization of 1 under acidic conditions. A plausible biosynthetic pathway to the new compounds and the chemophenetic significance of the isolated constituents were also discussed. The crude extract, fractions, and compounds (1-3) were assessed for their antibacterial activity against five highly prevalent bacterial strains. The fractions and compounds showed low to moderate activity with minimal inhibitory concentrations (MICs) > 125 µg/mL.

Anti-Oxidant, Anti-Mutagenic Activity and Safety Evaluation of Antrocin

Antrocin is a novel compound isolated from Antrodia cinnamomea, and is classified as a sesquiterpene lactone. The therapeutic efficacy of antrocin has been studied, and it has shown an antiproliferative effect on various cancers. The aim of this study was to evaluate the anti-oxidant activity, potential genotoxicity, and oral toxicity of antrocin. Ames tests with five different strains of Salmonella typhimurium, chromosomal aberration tests in CHO-K1 cells, and micronucleus tests in ICR mice were conducted. The results of anti-oxidant capacity assays showed that antrocin has great anti-oxidant activity and is a moderately strong antimutagenic agent. In the results of the genotoxicity assays, antrocin did not show any mutagenic potential. In the 28-day oral toxicity test, Sprague Dawley rats were gavaged with 7.5 or 37.5 mg/kg of antrocin for 28 consecutive days. In addition, 7.5 mg/kg sorafenib, an anti-cancer drug, was used as a positive control for toxicity comparison. At the end of the study, antrocin did not produce any toxic effects according to hematology, serum chemistry, urine analysis, or histopathological examinations. According to the results of the genotoxicity and 28-day oral toxicity study, antrocin, at a dose of 37.5 mg/kg, did not cause adverse effects and can be a reference dose for therapeutic agents in humans.

Natural product preferentially targets redox and metabolic adaptations and aberrantly active STAT3 to inhibit breast tumor growth in vivo

Dysregulated gene expression programs and redox and metabolic adaptations allow cancer cells to survive under high oxidative burden. These mechanisms also represent therapeutic vulnerabilities. Using triple-negative breast cancer (TNBC) as a model, we show that compared to normal human breast epithelial cells, the TNBC cells, MDA-MB-231 and MDA-MB-468 that harbor constitutively active STAT3 also express higher glucose-6-phosphate dehydrogenase (G6PD), thioredoxin reductase (TrxR)1, NADPH, and GSH levels for survival. Present studies discover that the natural product, R001, targets these adaptation mechanisms. Treatment of TNBC cells with R001 inhibited constitutively active STAT3, STAT3-regulated gene expression, and the functions of G6PD and TrxR1. Consequently, in the TNBC, but not normal cells, R001 suppressed GSH levels, but raised NADPH levels, reflective of a loss of mitochondrial respiration and which led to reactive oxygen species (ROS) induction, all of which led to loss of viable cells and inhibition of anchorage-dependent and independent growth. R001 treatment further led to early pyroptosis and late DNA damage, cell cycle arrest, and apoptosis only in the TNBC cells. Oral administration of 5 mg/kg R001 inhibited MDA-MB-468 xenografts growth in mice, with reduced pY705-STAT3, G6PD, TrxR1, and GSH levels. R001 serves as a therapeutic entity that targets the vulnerabilities of TNBC cells to inhibit tumor growth in vivo.

Development of a DNA barcode library of plants in the Thai Herbal Pharmacopoeia and Monographs for authentication of herbal products

Traditional herbal medicine has long been practiced as a method of health care in many countries worldwide. The usage of herbal products has been increasing and is expected to continue to do so in the future. However, admixture and adulteration are concerns regarding the quality of herbal medicine, including its safety and efficacy. We aimed to develop a reference DNA barcode library of plants listed in the Thai Herbal Pharmacopoeia (THP) and Monographs of Selected Thai Materia Medica (TMM) (n = 101 plant species) using four core barcode regions, namely, the ITS2, matK, rbcL and trnH-psbA intergenic spacer regions, for authentication of the plant origin of raw materials and herbal products. Checking sequences from samples obtained from local markets and the Thai Food and Drug Administration (Thai FDA) against our digital reference DNA barcode system revealed the authenticity of eighteen out of twenty tested samples as claimed on their labels. Two samples, no. 3 and 13, were not Cyanthillium cinereum (L.) H.Rob. and Pueraria candollei Wall. ex Benth. as claimed, respectively. They were recognized as Emilia sonchifolia (L.) DC. and Butea superba (Roxb.), respectively. Hence, it is important for the Thai FDA or regulatory agencies to immediately initiate strict enforcement for the development of pharmacopoeial standards as well as revisions or modifications of available regulatory guidelines and to implement close monitoring for the quality control of herbal products in terms of authentication before they enter the herbal market. The centralized digital reference DNA barcode database developed here could play a very important role in monitoring or checking the authenticity of medicinal plants.

Synthetic and Naturally Occurring Heterocyclic Anticancer Compounds with Multiple Biological Targets

Cancer is a complex group of diseases initiated by abnormal cell division with the potential of spreading to other parts of the body. The advancement in the discoveries of omics and bio- and cheminformatics has led to the identification of drugs inhibiting putative targets including vascular endothelial growth factor (VEGF) family receptors, fibroblast growth factors (FGF), platelet derived growth factors (PDGF), epidermal growth factor (EGF), thymidine phosphorylase (TP), and neuropeptide Y4 (NY4), amongst others. Drug resistance, systemic toxicity, and drug ineffectiveness for various cancer chemo-treatments are widespread. Due to this, efficient therapeutic agents targeting two or more of the putative targets in different cancer cells are proposed as cutting edge treatments. Heterocyclic compounds, both synthetic and natural products, have, however, contributed immensely to chemotherapeutics for treatments of various diseases, but little is known about such compounds and their multimodal anticancer properties. A compendium of heterocyclic synthetic and natural product multitarget anticancer compounds, their IC50, and biological targets of inhibition are therefore presented in this review.

Antimicrobial and Antioxidant Potential of Vernonia Cinerea Extract Coated AuNPs

Abstract

Green synthesis of nanoparticles is an important tool to reduce the harmful effects associated with traditional methods. In the present investigation, we have synthesised gold nanoparticles (AuNPs) using aqueous extract prepared from fresh aerial parts (leaf and stem) of Vernonia cinerea as bioreducing agent. The visual indication of change in colour from pale yellow to brown to ruby-red indicated the successful formation of the AuNPs. Characterization of nanoparticles was carried out by UV-visible spectroscopy, X-ray crystallography (XRD), Transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDX). UV-Vis spectra showed a specific peak at 546 nm which was the initial confirmation of the biosynthesized AuNPs. TEM images showed spherical and triangular shape of AuNPs with an average size of 25 nm. From FTIR spectrum, different functional groups were identified that could be responsible for the formation, stabilization, and capping of biosynthesized AuNPs. Aqueous plant extract and biosynthesised AuNPs were separately tested for their antimicrobial activity against six bacterial strains and four fungal strains. Biosynthesised AuNPs (2 mg/ml) showed significantly high zone of inhibition against the selected bacterial strains as compared to the aqueous plant extract. Maximum zone of inhibition (18.2 mm) was observed with AuNPs against Streptococcus pyogenes whereas comparatively less value (12.5 mm) was recorded with the plant extract. Interestingly, the inhibitory activity observed against bacterial strains was even better than ampicillin. Antifungal activity recorded with AuNPs (5 mg/ml) was maximum (17.4 mm) against R. oryzae and it was higher than positive control (17.00 mm) and plant extract (13.2 mm).The present study clearly showed that AuNPs coated with Vernonia cinerea extract were as good as positive control in inhibiting bacterial and fungal growth. In addition, these AuNPs also showed good antioxidant potential which was comparable to ascorbic acid.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-021-00976-w.

Chemoprevention and therapeutic role of essential oils and phenolic compounds: Modeling tumor microenvironment in glioblastoma

Glioblastoma (GBM) is the most common primary tumor of the central nervous system. Current treatments available for GBM entails surgical resection followed by temozolomide chemotherapy and/or radiotherapy, which are associated with multidrug resistance and severe side effects. While this treatment could yield good results, in almost all cases, patients suffer from relapse, which leads to reduced survival rates. Thus, therapeutic approaches with improved efficiency and reduced off-target risks are needed to overcome these problems. Regarding this, natural products appear as a safe and attractive strategy as chemotherapeutic agents or adjuvants in the treatment of GBM. Besides the increasing role of natural compounds for chemoprevention of GBM, it has been proposed to prevent carcinogenesis and metastasis of GBM. Numerous investigations showed that natural products are able to inhibit proliferation and angiogenesis, to induce apoptosis, and to target GBM stem cells, which are associated with tumor development and recurrence. This review gives a timely and comprehensive overview of the current literature regarding chemoprevention and therapy of GBM by natural products with a focus on essential oils and phenolic compounds and their molecular mechanisms.

Implication of Lactucopicrin in Autophagy, Cell Cycle Arrest and Oxidative Stress to Inhibit U87Mg Glioblastoma Cell Growth

In this study, we propose lactucopicrin (LCTP), a natural sesquiterpene lactone from Lactucavirosa, as a molecule able to control the growth of glioblastoma continuous cell line U87Mg. The IC50 of U87Mg against LCTP revealed a strong cytotoxic effect. Daily administration of LCTP showed a dose and time-dependent reduction of GBM cell growth and viability, also confirmed by inhibition of clonogenic potential and mobility of U87Mg cells. LCTP activated autophagy in U87Mg cells and decreased the phosphorylation of proliferative signals pAKT and pERK. LCTP also induced the cell cycle arrest in G2/M phase, confirmed by decrease of CDK2 protein and increase of p53 and p21. LCTP stimulated apoptosis as evidenced by reduction of procaspase 6 and the increase of the cleaved/full-length PARP ratio. The pre-treatment of U87Mg cells with ROS scavenger N-acetylcysteine (NAC), which reversed its cytotoxic effect, showed the involvement of LCTP in oxidative stress. Finally, LCTP strongly enhanced the sensitivity of U87Mg cells to canonical therapy Temozolomide (TMZ) and synergized with this drug. Altogether, the growth inhibition of U87Mg GBM cells induced by LCTP is the result of several synergic mechanisms, which makes LCTP a promising adjuvant therapy for this complex pathology.

Synthesis of Two Stereoisomers of Potentially Bioactive 13,19,20-Trihydroxy Derivative of Docosahexaenoic Acid

The C16-C22 fragment with the acetylene terminus was constructed through the asymmetric dihydroxylation of the corresponding olefin, while the 15-iodo-olefin corresponding to the C11-C15 part was prepared via the asymmetric transfer hydrogenation of the corresponding acetylene ketone followed by hydrozirconation/iodination. Both pieces were joined by a Sonogashira coupling, and the product was further converted into the title compound via a Wittig reaction with the remaining C1-C10 segment and Boland reduction using Zn with TMSCl.

Natural Sesquiterpene Lactones in the Prevention and Treatment of Inflammatory Disorders and cancer: A Systematic Study of this Emerging Therapeutic Approach based on Chemical and Pharmacological Aspect

Background and Introduction:

Sesquiterpene lactones are a class of secondary metabolite that contains sesquiterpenoids and lactone ring as pharmacophore moiety. A large group of bioactive secondary metabolites such as phytopharmaceuticals belong to this category. From the Asteraceae family-based medicinal plants, more than 5,000 sesquiterpene lactones have been reported so far. Sesquiterpene lactone-based pharmacophore moieties hold promise for broad-spectrum biological activities against cancer, inflammation, parasitic, bacterial, fungal, viral infection and other functional disorders. Moreover, these moiety based phytocompounds have been highlighted with a new dimension in the natural drug discovery program worldwide after the 2015 Medicine Nobel Prize achieved by the Artemisinin researchers.

Objective:

These bitter substances often contain an α, β-unsaturated-γ-lactone as a major structural backbone, which in recent studies has been explored to be associated with anti-tumor, cytotoxic, and anti-inflammatory action. Recently, the use of sesquiterpene lactones as phytomedicine has been increased. This study will review the prospect of sesquiterpene lactones against inflammation and cancer.

Methods:

Hence, we emphasized on the different features of this moiety by incorporating its structural diversity on biological activities to explore structure-activity relationships (SAR) against inflammation and cancer.

Results:

How the dual mode of action such as anti-inflammatory and anti-cancer has been exhibitedby these phytopharmaceuticals will be forecasted in this study. Furthermore, the correlation of anti-inflammatory and anti-cancer activity executed by the sesquiterpene lactones for fruitful phytotherapy will also be revealed in the present review in the milieu of pharmacophore activity relation and pharmacodynamics study as well.

Conclusion:

So, these metabolites are paramount in phytopharmacological aspects. The present discussion on the future prospect of this moiety based on the reported literature could be a guide for anti-inflammatory and anti-cancer drug discovery programs for the upcoming researchers.

Differentiation of Cyanthillium cinereum, a smoking cessation herb, from its adulterant Emilia sonchifolia using macroscopic and microscopic examination, HPTLC profiles and DNA barcodes

Cyanthillium cinereum (L.) H.Rob. is one of the most popular herbal smoking cessation aids currently used in Thailand, and its adulteration with Emilia sonchifolia (L.) DC. is often found in the herbal market. Therefore, the quality of the raw material must be considered. This work aimed to integrate macro- and microscopic, chemical and genetic authentication strategies to differentiate C. cinereum raw material from its adulterant. Different morphological features between C. cinereum and E. sonchifolia were simply recognized at the leaf base. For microscopic characteristics, trichome and pappus features were different between the two plants. HPTLC profiles showed a distinct band that could be used to unambiguously differentiate C. cinereum from E. sonchifolia. Four triterpenoid compounds, β-amyrin, taraxasterol, lupeol, and betulin, were identified from the distinct HPTLC band of C. cinereum. The use of core DNA barcode regions; rbcL, matK, ITS and psbA-trnH provided species-level resolution to differentiate the two plants. Taken together, the integration of macroscopic and microscopic characterization, phytochemical analysis by HPTLC and DNA barcoding distinguished C. cinereum from E. sonchifolia. The signatures of C. cinereum obtained here can help manufacturers to increase the quality control of C. cinereum raw material in commercialized smoking cessation products.

Bioactive Sesquiterpene Lactones Isolated from the Whole Plants of Vernonia cinerea

Twelve sesquiterpene lactones were isolated from the whole plants of Vernonia cinerea. These included eight new compounds, vercinolides A-H (1-8), along with four known substances (9-12). The structures of the new compounds were determined by 1D and 2D NMR experiments and mass spectrometric methods. The absolute configurations of compounds 1-8 were determined by Mosher experiments and ECD data. Compounds 1-8 are the first examples of a new class of sesquiterpene lactones possessing a rare 4α,10α-ether ring and a 2,14-ether ring. Compounds 1-4, 6, 8, 10, and 12 were evaluated for their cytotoxic and anti-inflammatory activities. Compounds 10 and 12 exhibited inhibitory effects against nitric oxide production in lipopolysaccharide-activated RAW 264.7 mouse macrophage cells with IC₅₀ values of 21 and 23 μM, respectively. Both compounds were inactive for HeLa cells (IC₅₀ > 10 μM).

Antiproliferative, cytotoxic and apoptotic activity of the bentonite transformation of sesquiterpene lactone glaucolide B to 5β-hydroxy-hirsutinolide on tumor cell lines

Numerous chemical compounds isolated from medicinal plants have anti-tumor properties, the effects of which on human cancer cells are currently under study. Here, the chemical transformation of glaucolide B were performed to produce a hirsutinolide. The antiproliferative and cytotoxic activity of 5β-hydroxy-hirsutinolide and its ability to induce apoptosis in tumor and non-tumor cells (lymphocyte cultures and the normal HaCaT cell line) (1a) are reported. We ascertained that compound 1a exerts an inhibitory effect on the proliferation of SK-Lu-1, MDA-MB-231 and CaSki cells in a dose-dependent manner at IC₅₀ values of 15, 18 and 30 μg/ml, respectively. The proliferation of lymphocyte cells treated with 1a was inhibited at a range from 14 to 28%, but the HaCaT cell line was not affected, suggesting that compound 1a has a selective action. Cytotoxic activity was evaluated by detecting the lactate dehydrogenase enzyme in supernatants from tumor and non-tumor cells. The 1a compound exhibited low or null cytotoxic activity in both cell types. The presence of apoptotic bodies and active caspase-3 in tumor cell lines treated with compound 1a are suggestive of apoptotic cell death. Notably, flow cytometry evaluation did not detect the presence of active caspase-3 on lymphocytes treated with this compound. Our results suggest that 5β-hydroxy-hirsutinolide is a molecule with antiproliferative activity and low cytotoxic activity in tumor and non-tumor cells; this induces apoptotic cell death in tumor cell lines through selective action. Hence, this lactone could be considered a molecule worthy of study as an anti-tumor agent with therapeutic potential.

Kinetics studies on effects of extraction techniques on bioactive compounds from Vernonia cinerea leaf

Recently, unconventional methods especially microwave-assisted hydrodistillation extraction (MAHE) is being used as an alternative technique for extracting bioactive compounds from plant materials due to its advantages over conventional methods such as Soxhlet extraction (SE). In this study, bioactive compounds were extracted from Vernonia cinerea leaf using both MAHE and SE methods. In addition, the kinetic study of MAHE and SE methods were carried out using first- and second-order kinetic models. The results obtained showed that MAHE can extract higher yield of bioactive compounds from V. cinerea leaf in a shorter time and reduced used of extracting solvent compared with SE method. Based on the results obtained, second-order kinetic models can actually describe the extraction of bioactive compounds from V. cinerea leaf through MAHE with extraction rate coefficient of 0.1172 L/gmin and extraction capacity of 1.0547 L/g as compared to SE with 0.0157 L/gmin and 1.1626 L/g of extraction rate coefficient and extraction capacity, respectively. The gas chromatography-mass spectrometry analysis of the oil showed the presence of numerous heavy fractions in the oil obtained through MAHE as compared with the SE method. Moreover, the electric consumption and environmental impacts analysis of the oil suggested that MAHE can be a suitable green technique for extracting bioactive compounds from V. cinerea leaf.

Anti-proliferative effect of 8α-tigloyloxyhirsutinolide-13-O-acetate (8αTGH) isolated from Vernonia cinerea on oral squamous cell carcinoma through inhibition of STAT3 and STAT2 phosphorylation

BACKGROUND

The high mortality rate of oral cancers has stimulated the search for effective herbal medicines and their pharmacological targets. Vernonia cinerea, a perennial tropical herb, is wildly used as a traditional folk medicine for treatment of intestinal diseases and various skin diseases in addition to possessing anti-cancer activity. However, the effect of 8α-tigloyloxyhirsutinolide-13-O-acetate (8αTGH) as a major sesquiterpene lactone compound found in V. cinerea and the underlying mechanism of its action on oral cancer cells remains unknown.

PURPOSE

To investigate the anti-cancer activity of 8αTGH extracted from V. cinerea and the underlying mechanism of its action in oral cancer cells.

METHODS

The anti-proliferative effect of 8αTGH on oral squamous cell carcinoma (HSC4) and lung carcinoma (A549) was determined using the SRB colorimetric method. The molecular mechanism of 8αTGH was explored using kinase inhibitors, followed by Western blotting or RT-qPCR. Flow cytometry and Western blotting were used to assess cell cycle arrest.

RESULTS

8αTGH inhibited cancer cell growth more effectively on HSC4 than A549 and was much less effective on tested normal oral cells. 8αTGH inhibited STAT3 phosphorylation on both cancer cells. Notably, 8αTGH was able to suppress the constantly activated STAT2 found only in HSC4. The STAT2 inhibition by 8αTGH consequently caused down-regulation of ISG15 and ISG15 conjugates. As a result, decreased expression of CDK1/2 and Cyclin B1 was detected leading to G2/M cell cycle arrest.

CONCLUSION

8αTGH isolated from V. cinerea preferentially inhibits the proliferation of oral cancer cells by causing G2/M cell cycle arrest via inhibition of both STAT3 and STAT2 phosphorylation. The results provide molecular bases for developing 8αTGH as a drug candidate or a complementary treatment of oral cancer.

Natural products: a hope for glioblastoma patients

Glioblastoma (GBM) is one of the most aggressive malignant tumors with an overall dismal survival averaging one year despite multimodality therapeutic interventions including surgery, radiotherapy and concomitant and adjuvant chemotherapy. Few drugs are FDA approved for GBM, and the addition of temozolomide (TMZ) to standard therapy increases the median survival by only 2.5 months. Targeted therapy appeared promising in in vitro monolayer cultures, but disappointed in preclinical and clinical trials, partly due to the poor penetration of drugs through the blood brain barrier (BBB). Cancer stem cells (CSCs) have intrinsic resistance to initial chemoradiation therapy (CRT) and acquire further resistance via deregulation of many signaling pathways. Due to the failure of classical chemotherapies and targeted drugs, research efforts focusing on the use of less toxic agents have increased. Interestingly, multiple natural compounds have shown antitumor and apoptotic effects in TMZ resistant and p53 mutant GBM cell lines and also displayed synergistic effects with TMZ. In this review, we have summarized the current literature on natural products or product analogs used to modulate the BBB permeability, induce cell death, eradicate CSCs and sensitize GBM to CRT.

Synthesis and anticancer studies of Michael adducts and Heck arylation products of sesquiterpene lactones, zaluzanin D and zaluzanin C from Vernonia arborea

Sesquiterpene lactones containing α-methylene-γ-lactones, zaluzanin D 1 and zaluzanin C 2 were isolated from the leaves of Vernonia arborea. Several diverse Michael adducts (3–22) and Heck arylation analogs (23–34) of 1 have been synthesized by reacting with various amines and aryl iodides, respectively and were assayed for their in vitro anticancer activities against human breast cancer cell lines MCF7 and MDA-MB-231. Among all the synthesized analogs, Michael adducts 9 and 10 showed better anticancer activities as compared to 1. However, among these compounds, only 10 has minimal cytotoxic effect on normal breast epithelial MCF10A cells. Our detailed mechanistic studies reveal that compounds 9 and 10 execute their antiproliferative activity through induction of apoptosis and thereby inhibit the cancer cells proliferation and compound 10 could be a lead compound for designing potential anti-cancer compound.

Sesquiterpene lactones containing α-methylene-γ-lactones, zaluzanin D 1 and zaluzanin C 2 were isolated from the leaves of Vernonia arborea.

Effects of Vernonia cinerea on reproductive performance in streptozotocin-induced diabetic rats

The present study investigated the effects of Vernonia cinerea (VC) on the reproductive function in streptozotocin (STZ)-induced diabetic male rats. Six-week-old male Sprague-Dawley rats were randomly divided into four groups: group 1, normal control rats; group 2, diabetic untreated rats; group 3, diabetic rats treated with VC (10 mg/kg); and group 4, diabetic rats treated with VC (40 mg/kg). Diabetes mellitus (DM) was induced by intraperitoneal injection of STZ (60 mg/kg). All animals were treated for 30 consecutive days. Body weight, blood glucose, food intake, epididymal sperm parameters, testicular microstructure and serum testosterone levels were evaluated. VC treatment significantly restored the sperm motility and testosterone concentration, and decreased the testicular histopathological changes in DM rats. Moreover, high-dose VC exhibited an antidibetic activity and significantly improved the sperm count. In conclusion, we found, for the first time, that administration of VC significantly restored the testicular function and testosterone concentration in diabetic male rats.

Stereoselective synthesis of 17,18-epoxy derivative of EPA and stereoisomers of isoleukotoxin diol by ring opening of TMS-substituted epoxide with dimsyl sodium

The title three compounds were synthesized using the reaction of TMS-substituted epoxides with dimsyl sodium to produce 1-alkene-3,4-diol derivatives.

Analysis and fragmentation mechanisms of hirsutinolide-type sesquiterpene lactones by ultra-high-performance liquid chromatography/electrospray ionization linear ion trap Orbitrap mass spectrometry

RATIONALE

Hirsutinolide-type sesquiterpene lactones (SLs) are natural biologically active compounds mainly found in the genus Vernonia. Very few studies have been published about the fragmentation mechanisms of SLs generally and none about hirsutinolides, although they have drawn attention through their biological and taxonomical interest. This work aims to propose a mass spectrometry fragmentation pattern for hirsutinolides in order to detect and to identify them in a botanical extract.

METHODS

The fragmentation pathways of six pure hirsutinolides isolated from Pseudelephantopus spiralis were established by positive ion electrospray high-resolution linear ion trap Orbitrap tandem mass spectrometry (ESI(+)-HRMS(n) ). A resolutive, hyphenated ultra-high-performance liquid chromatography (UHPLC) coupled to diode array detection (DAD) and ESI(+)-HRMS(n) method was then implemented to separate and analyze them. The ionization behaviour and diagnostic product ions were investigated by both methods. The UHPLC/DAD-ESI-HRMS(n) method was applied for the dereplication of a plant extract.

RESULTS

For the six standard compounds, the main fragmentation pattern consists first in the loss of the side chain in the C-8 position followed by the loss of the substituent in the C-13 position. UHPLC/HRMS analyses of hirsutinolides mainly produced sodiated molecules or [M+H-H2 O](+) ions. The high-abundance product ions at m/z 299 and 259 were established to be the characteristic diagnostic ions of the hirsutinolide core. The analysis of a P. spiralis extract further led to the identification of two putative hirsutinolides.

CONCLUSIONS

The UHPLC/DAD-HRMS(n) method combining characteristic fragmentation patterns and the profiles of the product ions generated in the MS and MS/MS spectra is an effective technique for characterizing hirsutinolide-type SLs.

Hirsutinolide Series Inhibit Stat3 Activity, Alter GCN1, MAP1B, Hsp105, G6PD, Vimentin, TrxR1, and Importin α-2 Expression, and Induce Antitumor Effects against Human Glioma

We report that hirsutinolide series, 6, 7, 10, 11, 20, and 22, and the semisynthetic analogues, 30, 31, 33, and 36, inhibit constitutively active signal transducer and activator of transcription (Stat)3 and malignant glioma phenotype. A position 13 lipophilic ester group is required for activity. Molecular modeling and nuclear magnetic resonance structural analyses reveal direct hirsutinolide:Stat3 binding. One-hour treatment of cells with 6 and 22 also upregulated importin subunit α-2 levels and repressed translational activator GCN1, microtubule-associated protein (MAP)1B, thioredoxin reductase (TrxR)1 cytoplasmic isoform 3, glucose-6-phosphate 1-dehydrogenase isoform a, Hsp105, vimentin, and tumor necrosis factor α-induced protein (TNAP)2 expression. Active hirsutinolides inhibited anchorage-dependent and three-dimensional spheroid growth, survival, and migration of human glioma lines and glioma patients' tumor-derived xenograft cells harboring constitutively active Stat3. Oral gavage delivery of 6 or 22 inhibited human glioma tumor growth in subcutaneous mouse xenografts. The inhibition of Stat3 signaling represents part of the hirsutinolide-mediated mechanisms to induce antitumor effects.

Iridoid glycosides from Barleria lupulina

Phytochemical investigation of an extract of the aerial part of Barleria lupulina resulted in the identification of four new iridoid glycosides (1-4), together with 14 known analogues (5-18). The structures of 1-4 were determined through 1D and 2D NMR spectroscopic data analysis, HRMS, and acid hydrolysis. This is the first report of iridoid glycosides with a formate group. The free-radical scavenging activity of compounds 9, 12, and 15-17 was assessed using the DPPH assay. Compounds 16 and 17 scavenged DPPH radicals weakly with IC50 values of 97.5 and 78.6 μg/mL, respectively.