Ultrasound-assisted extraction of alantolactone and isoalantolactone from Inula helenium roots

Roles of natural products on myokine expression and secretion in skeletal muscle atrophy

Skeletal muscles serve both in movement and as endocrine organs. Myokines secreted by skeletal muscles activate biological functions within muscles and throughout the body via autocrine, paracrine, and/or endocrine pathways. Skeletal muscle atrophy can influence myokine expression and secretion, while myokines can impact the structure and function of skeletal muscles. Regulating the expression and secretion of myokines through the pharmacological approach is a strategy for alleviating skeletal muscle atrophy. Natural products possess complex structures and chemical properties. Previous studies have demonstrated that various natural products exert beneficial effects on skeletal muscle atrophy. This article reviewed the regulatory effects of natural products on myokines and summarized the research progress on skeletal muscle atrophy associated with myokine regulation. The focus is on how small-molecule natural products affect the regulation of interleukin 6 (IL-6), irisin, myostatin, IGF-1, and FGF-21 expression. We contend that the development of small-molecule natural products targeting the regulation of myokines holds promise in combating skeletal muscle atrophy.

Anti-Leukemic Attributes of Natural Compounds Targeting Autophagy: A Closer Look into the Molecular Mechanisms

Leukemia is a heterogeneous clonal cancer that affects millions of individuals around the world. Despite substantial breakthroughs in cancer treatment, traditional chemotherapy and radiotherapy remain ineffective, and therapeutic resistance still stands as a big obstacle. As a result, there is an increasing attention being paid currently toward the potency of natural compounds as a complementary or alternative therapy for leukemia. Autophagy, a conserved cellular process where damaged or defective cytosolic components and macromolecules are destroyed and recycled, plays a dual role in promoting or suppressing the continuance of cancer at different junctures of its development. Current studies have reported that autophagy has a cardinal function in the genesis and progression of leukemia, making it a promising target for novel treatments. In this review, we have explored the effectiveness of certain natural compounds, such as curcumin, resveratrol, tanshinone IIA, quercetin, tetrandrine, parthenolide, berberine, pristimerin, and alantolactone, that modulate autophagy and regulate its associated signaling cascades at a molecular level in different types of leukemia. They have been shown to have synergistic effects with conventional chemotherapy, emphasizing their potential as supplementary medicines. However, additional research is required to fully comprehend their mechanisms of action and to maximize their role in clinical perspectives.

From Monographs to Chromatograms: The Antimicrobial Potential of Inula Helenium L. (Elecampane) Naturalised in Ireland

With antimicrobial resistance rising globally, the exploration of alternative sources of candidate molecules is critical to safeguard effective chemotherapeutics worldwide. Plant natural products are accessible, structurally diverse compounds with antimicrobial potential. The pharmacological applications of plants in medicine can be guided by the attestation of traditional use, as demonstrated in this study. In Irish ethnomedical literature, Inula helenium L. (elecampane) is often indicated for respiratory and dermal ailments. This is the first assessment of antimicrobial sesquiterpene lactones from the roots of elecampane, naturalised in Ireland. Traditional hydro-ethanolic extracts were prepared from multi-origin elecampane roots. A novel clean-up strategy facilitated the bioactivity-guided fractionation of a subset of anti-staphylococcal fractions (the compositions of which were investigated using HPLC-DAD, supported by ¹H NMR). The natural products attributing to the antimicrobial activity, observed in vitro, were identified as alantolactone (1), isoalantolactone (2), igalan (3), and an unseparated mixture of dugesialactone (4) and alloalantolactone (5), as major compounds. The findings suggest that the geographical origin of the plant does not influence the anti-bacterial potency nor the chemical composition of traditional elecampane root. Considering the prevalence of staphylococci-associated infections and associated broad spectrum resistance in Irish hospitals, currently, further research is warranted into the usage of the identified compounds as potential candidates in the control of staphylococcal carriage and infection.

Ethnopharmacology, phytochemistry, agrotechnology, and conservation of Inula racemosa Hook f. - A critically endangered medicinal plant of the western Himalaya

ETHNOPHARMACOLOGICAL RELEVANCE

Inula racemosa Hook. f., is a critically endangered perennial herb distributed throughout the Himalaya; commercially useful in pharmaceutical products mainly because of its expectorant, antispasmodic, hypotensive, anti-inflammatory, carminative, thermogenic, digestive, cardiotonic, acrid, alexipharmic, anodyne, aphrodisiac, febrifuge, and antiseptic properties. The roots including rhizomes of the plant were used in the treatment of various ailments like chest pain, liver dysfunction, dyspnoea, and cardiovascular diseases by the ethenic Himalayan residents.

AIM OF THE REVIEW

Even though there are plentiful studies involving I. racemosa for pharmacological properties, but there is gap or few records available on production technologies and patents. The purpose of review is to provide large unmanageable information in systematic form for researchers, health care contributors, and policy makers so that they efficiently integrate the existing information and provide balanced decision making.

MATERIALS AND METHODS

Relevant data search was completed through systematic searches using various scientific databases including e-resources viz., Scopus, Google Scholar, Science Direct, ACS, Springer Link, Taylor and Francis, Scifinder, PubMed, PubChem, Web of Science, LibGen, Wiley, and China National Knowledge Infrastructure (CNKI). The list of literature cited in this review are dated from 1959 to 2021.

RESULTS

Till date variety of ethnobotanical and pharmacological properties of essential oil including crude extract of I. racemosa have been documented. The shortlisted records revealed that the herb has a potential to treat stomach ulcer, respiratory tract infections including chronic obstructive pulmonary disease (COPD). Alantolactone and isoalloalantolactone were reported as the major bioactive constituents along with few fatty acids, phytosterols, and glycosides characterized by GC, GC/MS, HPLC, HPTLC and qNMR techniques.

CONCLUSIONS

Based on a detailed literature survey on the plant, evidences were found fascinating for biological, traditional, and pharmacological effects, whilst there are no genomic resources available for this medicinal herb. Thus, molecular studies are critical for unravelling the production process of bioactive metabolites inside herb, which will underlay a path for improving these metabolites at commercial scale. Moreover, the association and role of particular phytoconstituent in its biological properties still needs to be validated. In addition, there are no reports on measures on its conservation and mechanism of toxicity research, which also needs more attention. We hope this review can provide a basis for further studies concerning the protected and efficient utilization of I. racemosa.

Alantolactone ameliorates cancer cachexia-associated muscle atrophy mainly by inhibiting the STAT3 signaling pathway

BACKGROUND

Cancer cachexia is a serious metabolic disorder syndrome that is responsible for the deaths of approximately 30% of patients with cancer, but effective drugs for cancer cachexia are still lacking. Inflammatory cytokines such as TNF-α or IL-6 are involved in the induction of skeletal muscle atrophy and fat depletion in patients with cancer cachexia.

PURPOSE

In this study, we assessed the therapeutic effects of the natural compound alantolactone (AL) on cancer cachexia and tried to clarify the mechanisms by which it ameliorates muscle atrophy.

METHODS

The C26 tumor-bearing cancer cachexia mouse model was used to evaluate the efficacy of AL in alleviating cancer cachexia in vivo. The levels of IL-6 or TNF-α in mouse serum were detected using ELISA kits. Cultured C2C12 myotubes and 3T3-L1 adipocytes treated with conditioned medium of C26 tumor cells, IL-6 or TNF-α were employed as in vitro cancer cachexia models to examine the effects of AL in vitro.

RESULTS

AL (5 or 10 mg/kg, qd, i.p.) protected mice with C26 tumors and cachexia from a loss of body weight and muscle wasting but only slightly ameliorated fat loss. The circulating level of IL-6 but not TNF-α was significantly decreased by AL. AL treatment significantly inhibited STAT3 activation in the gastrocnemius (GAS) muscle of cancer cachexia mice. AL (0.125, 0.25, 0.5 and 1 µM) dose-dependently ameliorated myotube atrophy and STAT3 activation in cultured C2C12 myotubes induced by conditioned medium from C26 tumor cells. AL also ameliorated C2C12 myotube atrophy induced by IL-6 and inhibited IL-6-mediated STAT3 activation. AL exhibited weak effects on ameliorating TNF-α-mediated myotube atrophy and NF-κB activation. Only AL at high doses of more than 5 µM ameliorated lipolysis and STAT3 activation induced in mature 3T3-L1 adipocytes by conditioned medium from C26 tumor cells.

CONCLUSIONS

AL significantly ameliorated muscle atrophy in a cancer cachexia model mainly through the inhibition of the STAT3 pathway. AL might be a promising lead compound in the development of drug candidates for cancer cachexia therapy.

Selective STAT3 Inhibitor Alantolactone Ameliorates Osteoarthritis via Regulating Chondrocyte Autophagy and Cartilage Homeostasis

Osteoarthritis (OA), which is identified by chronic pain, impacts the quality of life. Cartilage degradation and inflammation are the most relevant aspects involved in its development. Signal transducer and activator of transcription 3(STAT3), a member of the STATs protein family, is associated with inflammation. Alantolactone (ALT), a sesquiterpene lactone compound, can selectively suppress the phosphorylation of STAT3. However, the pharmacological effect of ALT on OA is still imprecise. In this study, IL-1β (10 ng/ml) was applied to cartilage chondrocytes, which were treated with different concentrations of Alantolactone for 24 h. The expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2(COX2), matrix metalloproteinases (MMPs) and thrombospondin motifs-5 (ADAMTS5) were detected by western blot. Protein expression of Collagen Ⅱ was observed by western blot, safranin O staining and immunofluorescence. Manifestation of autophagy related proteins such as autophagy-related gene-5 (ATG5), P62, LC3Ⅱ/Ⅰ and PI3K/AKT/mTOR-related signaling molecules were measured by western blot and autophagic flux monitored by confocal microscopy. Expression of STAT3 and NF-κB-related signaling molecules were evaluated by western blot and immunofluorescence. In vivo, 2 mg/kg ALT or equal bulk of vehicle was engaged in the destabilization of medial meniscus (DMM) mouse models by intra-articular injection, the degree of cartilage destruction was classified by Safranin O/Fast green staining. Our findings reported that the enhance of inflammatory factors containing iNOS, COX2, MMPs and ADAMTS5 induced by IL-1β could be ameliorated by ALT. Additionally, the diminish of Collagen Ⅱ and autophagy which was stimulated by IL-1β could be alleviated by ALT. Mechanistically, STAT3, NF-κB and PI3K/AKT/mTOR signal pathways might be involved in the effect of ALT on IL-1β-induced mouse chondrocytes. In vivo, ALT protected cartilage in the DMM mouse model. Overall, this study illustrated that ALT attenuated IL-1β-induced inflammatory responses, relieved cartilage degeneration and promoted impaired autophagy via restraining of STAT3 and NF-κB signal pathways, implying its auspicious therapeutical effect for OA.

A comprehensive review of anticancer mechanisms of action of Alantolactone

Cancer is considered as the main challenge of human communities, and it annually imposes a significant economic burden on society. Natural products have been used for treatment of many diseases including inflammation, infections, neurological disorders, atherosclerosis, asthma and cancer for many years. Sesquiterpene lactones (STLs) refers to a group of natural products with different biological activities. A type of STL that has recently attracted much attention is Alantolactone (ALT). In recent years, many studies have investigated the molecular mechanism of this compound affecting cancer cells and results suggest that this compound exerts its anticancer effects by providing free radicals and inhibiting some of the signaling pathways that are effective in progression of cancer cells. The present study is aimed to introduce the latest molecular mechanisms of ALT proposed by researchers in recent years.

Applications of Sesquiterpene Lactones: A Review of Some Potential Success Cases

Sesquiterpene lactones, a vast range of terpenoids isolated from Asteraceae species, exhibit a broad spectrum of biological effects and several of them are already commercially available, such as artemisinin. Here the most recent and impactful results of in vivo, preclinical and clinical studies involving a selection of ten sesquiterpene lactones (alantolactone, arglabin, costunolide, cynaropicrin, helenalin, inuviscolide, lactucin, parthenolide, thapsigargin and tomentosin) are presented and discussed, along with some of their derivatives. In the authors’ opinion, these compounds have been neglected compared to others, although they could be of great use in developing important new pharmaceutical products. The selected sesquiterpenes show promising anticancer and anti-inflammatory effects, acting on various targets. Moreover, they exhibit antifungal, anxiolytic, analgesic, and antitrypanosomal activities. Several studies discussed here clearly show the potential that some of them have in combination therapy, as sensitizing agents to facilitate and enhance the action of drugs in clinical use. The derivatives show greater pharmacological value since they have better pharmacokinetics, stability, potency, and/or selectivity. All these natural terpenoids and their derivatives exhibit properties that invite further research by the scientific community.

Apoptosis-promoting and migration-suppressing effect of alantolactone on gastric cancer cell lines BGC-823 and SGC-7901 via regulating p38MAPK and NF-κB pathways

BACKGROUND

Gastric cancer is a malignant tumor with high incidence rate and mortality rate.

PURPOSE

In this study, we investigated the anti-cancer effect of alantolactone, a sesquiterpene lactone, on gastric cancer cell lines BGC-823 and SGC-7901.

METHODS

BGC-823 and SGC-7901 cells were treated with different concentrations of alantolactone, Hoechst 33258 staining, flow cytometry, wound healing assay, invasion assay, colony forming assay, quantative polymerase chain reaction, and western blot analysis were used to evaluate the anticancer activity of alantolactone to gastric cancer.

RESULTS

Alantolactone induced apoptosis of gastric cancer cells by regulating the expression of Bax, Bcl-2, and p53, which related to intrinsic apoptotic pathway, and suppressed colony formation, migration, and invasion by mediating the expression of matrix metalloproteinase (MMP)-2, MMP-7, and MMP-9. Cell signaling pathway analysis showed that alantolactone enhanced the phosphorylation of p38 and decreased the translocation of nucleus p65, suggesting that the apoptosis-promoting and migration-suppressing effect of alantolactone might at least partially rely on regulating p38 mitogen-activated protein kinase (p38MAPK) pathway and nuclear factor-κB (NF-κB) pathway.

CONCLUSIONS

Alantolactone can be used as a potential therapeutic agent for treating gastric cancer.

Production Technologies of Pharmacologically Active Sesquiterpene Lactones

Sesquiterpene lactones form a large group belonging to natural terpenoids series, generally found in plants of Asteraceae family and exhibiting anti-tumor, antiviral, immunostimulant, antifungal, antimicrobial, anti-inflammatory, antimutagenic, growth stimulating, antifeedant effects. Therefore, search for new compounds with a broad spectrum of pharmacological activity in this series provides the opportunities for effective and conceptually new drug design. The basis of the technology for the isolation of sesquiterpene lactones is the extraction of raw materials with various organic solvents, followed by chromatographic purification. Sesquiterpene lactones have no common properties that can be used in their isolation. Some of them are well soluble in non – polar solvents, others-only in polar, in this regard, the methods of isolation of sesquiterpene lactones are diverse. The greatest number of sesquiterpene lactones is isolated from leaves and flowers, slightly less – from roots and bark. Therefore, the development of methods for their isolation is associated with the selection of solvents and optimization of the extraction mode. Unfortunately, very few medicines based on sesquiterpene lactones are produced by the pharmaceutical companies today. Complexity of introduction of pharmacologically active sesquiterpene lactones technology into pharmaceutical production is in imperfection of their isolation methods from plant raw material, their purification and separation from obtained extracts. Production technologies of the patented medicines "Santonin", "Alanton" on the basis of sesquiterpene lactones are multiphase, labor-intensive, implying the use of many toxic organic solvents which is against the international GMP standards.

Extraction and recovery processes for cynaropicrin from Cynara cardunculus L. using aqueous solutions of surface-active ionic liquids

Due to the wide range of relevant biological activities and high commercial value of cynaropicrin, and aiming at developing cost-effective processes, aqueous solutions of ionic liquids (ILs) were investigated for the extraction and recovery of cynaropicrin from the leaves of Cynara cardunculus L. Both cationic (1-alkyl-3-methylimidazolium chloride) and anionic (cholinium carboxylate) surface-active ILs were investigated, as well as a wide range of conventional surfactants and molecular organic solvents, allowing us to conclude that aqueous solutions of cationic surface-active ILs display a better performance for the extraction of cynaropicrin. Operational conditions were optimized, leading to a cynaropicrin extraction yield of 3.73 wt%. The recycling of both the biomass and the solvent were further investigated to appraise the extraction media saturation and to achieve a higher cynaropicrin extraction yield (6.47 wt%). Finally, it was demonstrated that 65 wt% of the extracted cynaropicrin can be efficiently recovered by precipitation from the IL aqueous extract through the addition of water as anti-solvent, allowing us to put forward both the extraction and recovery processes of the target value-added compound from biomass followed by solvent recycling. This approach opens the door to the development of more sustainable processes using aqueous solutions of ILs instead of the volatile organic solvents commonly used in biomass processing.

Deep Eutectic Solvents as Efficient Media for the Extraction and Recovery of Cynaropicrin from Cynara cardunculus L. Leaves

In recent years a high demand for natural ingredients with nutraceutical properties has been witnessed, for which the development of more environmentally-friendly and cost-efficient extraction solvents and methods play a primary role. In this perspective, in this work, the application of deep eutectic solvents (DES), composed of quaternary ammonium salts and organic acids, as alternative solvents for the extraction of cynaropicrin from Cynara cardunculus L. leaves was studied. After selecting the most promising DES, their aqueous solutions were investigated, allowing to obtain a maximum cynaropicrin extraction yield of 6.20 wt %, using 70 wt % of water. The sustainability of the extraction process was further optimized by carrying out several extraction cycles, reusing either the biomass or the aqueous solutions of DES. A maximum cynaropicrin extraction yield of 7.76 wt % by reusing the solvent, and of 8.96 wt % by reusing the biomass, have been obtained. Taking advantage of the cynaropicrin solubility limit in aqueous solutions, water was added as an anti-solvent, allowing to recover 73.6 wt % of the extracted cynaropicrin. This work demonstrates the potential of aqueous solutions of DES for the extraction of value-added compounds from biomass and the possible recovery of both the target compounds and solvents.

Ultrasound and Microwave-Assisted Extraction of Elecampane (Inula helenium) Roots

The aim of the current research was to perform two “green chemistry” extractions (ultrasound and microwave irradiation) with methanol, 70% (v/v) ethanol and water for extraction of biologically active substances from elecampane ( Inula helenium L.) roots and to compare their contents in all extracts. The presence of carbohydrates (sugars, fructooligosaccharides and inulin), total phenols and flavonoids were established. In vitro antioxidant potential was also evaluated by four assays (DPPH, ABTS, FRAP and CUPRAC). Water extracts obtained by ultrasound-assisted extraction (UAE) showed the highest value of inulin (38 g/100 g dry weight plant material). The highest antioxidant activity was possessed by the 70% (v/v) ethanol extracts obtained by UAE: DPPH – 107.2 mM TE/g dw, ABTS – 86.0 mM TE/g dw, FRAP – 67.0 mM TE/g dw and CUPRAC −173.0 mM TE/g dw, respectively. The reason for this probably depended on the highest content of total phenols in the 70% UAE ethanol extract {7.9 mg GAE/g dw, phenolic acids (chlorogenic, caffeic, p-coumaric, sinapic and ferulic acids)}, especially chlorogenic acid (1.84 mg/g) and flavonoids (quercetin, kaempferol and catechin; 26.4 mg QE/g dw). UAE was evaluated as a promising approach for the simultaneous extraction of bioactive compounds (dietary fibers and antioxidants) from elecampane roots in comparison with microwave irradiation.

Metabolomic Profile of the Genus Inula

Plants have a long history as therapeutics in the treatment of human diseases and have been used as source of medicines for ages. Searching for new biologically active natural products, many plants and herbs are screened for natural products with pharmacological activities. In this field, the genus Inula, which comprises more than 100 species, several of them being used in traditional medicine, is very important, especially due to the finding that several of the isolated pure secondary metabolites proved to possess important biological activities. Inula species have been reported as rich sources of sesquiterpene lactones, including eudesmanes, germacranes, guaianes, and dimeric structures, and since 2006 ca. 400 secondary metabolites, including more than 100 new natural products, some of them with relevant pharmacological activities, have been identified. Herein, we critically compile and update the information regarding the types of secondary metabolites found in the genus Inula and the progress in their isolation.

Isoalantolactone induces autophagic cell death in SKOV₃ human ovarian carcinoma cells via upregulation of PEA-15

We investigated the effects of isoalantolactone on cell growth inhibition and underlying cell death mechanisms in SKOV3 human ovarian cancer cells. The effects of isoalantolactone on cell proliferation and cell cycle were examined by EdU incorporation assay and DNA content assay. Western blotting was performed to determine the protein expression effects of isoalantolactone on cell cycle‑related proteins, autophagic regulators and PEA‑15. Autophagic vacuoles were observed by acridine orange staining. PEA‑15 knockdown by siRNA was used to confirm that PEA‑15 was involved in isoalantolactone‑induced autophagy of SKOV3 cells. Isoalantolactone inhibited the viability and proliferation of SKOV3 cells in a dose‑ and time‑dependent fashion. Isoalantolactone induced cell cycle arrest at G2/M phase and decreased the expression of cell cycle‑related proteins cyclin B1 and CDK1 in SKOV3 cells. Accordingly, isoalantolactone also induced SKOV3 cell autophagy via accumulation of autophagic vacuoles in the cytoplasm, increased Beclin1 protein expression, and increased LC3 cleavage. Furthermore, we observed that isoalantolactone‑induced autophagy was through increased PEA‑15 expression and the phosphorylation of ERK, whereas less change was observed to autophagy on SKOV3 cells through PEA‑15 knockdown by siRNA. Isoalantolactone‑induced autophagic cell death was further confirmed by pretreatment with the autophagy inhibitor 3‑methyladenine (3‑MA). In conclusion, isoalantolactone induced cell cycle arrest and autophagy and inhibited cell proliferation of SKOV3 cells via the upregulated PEA‑15 expression and the phosphorylation of ERK.

Mechanism-based inhibition of Alantolactone on human cytochrome P450 3A4 in vitro and activity of hepatic cytochrome P450 in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alantolactone (AL), one of the main active ingredients in Inula helenium L., has been included in various prescriptions of traditional Chinese medicine. The effects of AL on cytochrome P450 (CYP450) were still unclear. This study evaluated the inhibitory effect of AL on cytochrome P450s in vitro and in vivo.

MATERIALS AND METHODS

The inhibitory effects of AL on the CYPs activity were evaluated in human liver microsomes (HLMs) and recombinant cDNA-expressed enzymes incubation system, and then determined by LC-MS/MS based CYPs probe substrate assay. C57BL/6 mice were treated AL orally (0, 25, 50, 100 mg/kg) for 15 days. The inhibitory effects of AL on major Cyps in mice were examined at both the mRNA and enzyme activity levels.

RESULTS

AL showed a potent inhibitory effect on CYP3A4 activity with IC50 values of 3.599 (HLMs) and 3.90 (recombinant CYP3A4) μM, respectively. AL strongly decreased CYP3A4 activity in a dose-dependent but not time-dependent way in HLMs. Results from typical Lineweaver-Burk plots showed that AL could inhibit CYP3A4 activity noncompetitively, with a Ki value of 1.09 μM in HLMs. Moreover, activity of CYP2C19 could also be inhibited by AL with IC50 of 36.82 μM. Other CYP450 isoforms were not markedly affected by AL. The inhibition was also validated by in vivo study of mice. AL significantly decreased mRNA expression of Cyp2c and 3a family.

CONCLUSION

The study indicates that herb-drug interaction should be paid more attention between AL and drugs metabolized by CYP3A4.

Microwave-assisted Extraction of Alantolactone and Isoalantolactone from Inula helenium

Microwave-assisted extraction was used for the extraction of alantolactone and isoalantolactone from Inula helenium. Effects of various experimental factors including ethanol concentration, particle size, microwave radiation time, the ratio of material to liquid and extraction temperature on yield of alantolactone and isoalantolactone were evaluated. The optimal extracting process of the alantolactone and isoalantolactone from the root of the Inula helenium was 1 g plant sample (sifted through 140 mesh) mixed with 15 ml of 80% ethanol solution, microwave radiation 120 s at 50°. Under these optimal conditions, the yield of alantolactone and isoalantolactone was 31.83±2.08 mg/g and 21.25±1.37 mg/g, respectively. Compared with heat reflux extraction, ultrasound-assisted extraction, microwave-assisted extraction was more efficient and timesaving for the extraction of alantolactone and isoalantolactone from Inula helenium.

The genus Inula and their metabolites: from ethnopharmacological to medicinal uses

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Inula comprises more than one hundred species widespread in temperate regions of Europe and Asia. Uses of this genus as herbal medicines have been first recorded by the Greek and Roman ancient physicians. In the Chinese Pharmacopoeia, from the 20 Inula spp. distributed in China, three are used as Traditional Chinese medicines, named Tumuxiang, Xuanfuhua and Jinfeicao. These medicines are used as expectorants, antitussives, diaphoretics, antiemetics, and bactericides. Moreover, Inula helenium L. which is mentioned in Minoan, Mycenaean, Egyptian/Assyrian pharmacotherapy and Chilandar Medical Codex, is good to treat neoplasm, wound, freckles and dandruff. Many other Inula spp. are used in Ayurvedic and Tibetan traditional medicinal systems for the treatment of diseases such as bronchitis, diabetes, fever, hypertension and several types of inflammation. This review is a critical evaluation of the published data on the more relevant ethnopharmacological and medicinal uses of Inula spp. and on their metabolites biological activities. This study allows the identification of the ethnopharmacological knowledge of this genus and will provide insight into the emerging pharmacological applications of Inula spp. facilitating the prioritirization of future investigations. The corroboration of the ethnopharmacological applications described in the literature with proved biological activities of Inula spp. secondary metabolites will also be explored.

MATERIALS AND METHODS

The major scientific databases including ScienceDirect, Medline, Scopus and Web of Science were queried for information on the genus Inula using various keyword combinations, more than 180 papers and patents related to the genus Inula were consulted. The International Plant Name Index was also used to confirm the species names.

RESULTS

Although the benefits of Inula spp. are known for centuries, there are insufficient scientific studies to certify it. Most of the patents are registered by Chinese researchers, proving the traditional use of these plants in their country. Although a total of sixteen Inula species were reported in the literature to have ethnopharmacological applications, the species Inula cappa (Buch.-Ham. ex D.Don) DC., Inula racemosa Hook.f., Inula viscosa (L.) Aiton [actually the accepted name is Dittrichia viscosa (L.) Greuter], Inula helenium, Inula britannica L. and Inula japonica Thunb. are the most frequently cited ones since their ethnopharmacological applications are vast. They are used to treat a large spectrum of disorders, mainly respiratory, digestive, inflammatory, dermatological, cancer and microbial diseases. Fifteen Inula spp. crude extracts were investigated and showed interesting biological activities. From these, only 7 involved extracts of the reported spp. used in traditional medicine and 6 of these were studied to isolate the bioactive compounds. Furthermore, 90 bioactive compounds were isolated from 16 Inula spp. The characteristic compounds of the genus, sesquiterpene lactones, are involved in a network of biological effects, and in consequence, the majority of the experimental studies are focused on these products, especially on their cytotoxic and anti-inflammatory activities. The review shows the chemical composition of the genus Inula and presents the pharmacological effects proved by in vitro and in vivo experiments, namely the cytotoxic, anti-inflammatory (with focus on nitric oxide, arachidonic acid and NF-κB pathways), antimicrobial, antidiabetic and insecticidal activities.

CONCLUSIONS

Although there are ca. 100 species in the genus Inula, only a few species have been investigated so far. Eight of the sixteen Inula spp. with ethnopharmacological application had been subjected to biological evaluations and/or phytochemical studies. Despite Inula royleana DC. and Inula obtusifolia A. Kerner are being used in traditional medicine, as far as we are aware, these species were not subjected to phytochemical or pharmacological studies. The biological activities exhibited by the compounds isolated from Inula spp., mainly anti-inflammatory and cytotoxic, support some of the described ethnopharmacological applications. Sesquiterpene lactone derivatives were identified as the most studied class, being britannilactone derivatives the most active ones and present high potential as anti-inflammatory drugs, although, their pharmacological effects, dose-response relationship and toxicological investigations to assess potential for acute or chronic adverse effects should be further investigated. The experimental results are promising, but the precise mechanism of action, the compound or extract toxicity, and the dose to be administrated for an optimal effect need to be investigated. Also human trials (some preclinical studies proved to be remarkable) should be further investigated. The genus Inula comprises species useful not only in medicine but also in other domains which makes it a high value-added plant.

Alantolactone induces cell apoptosis partially through down-regulation of testes-specific protease 50 expression

Testes-specific protease 50 (TSP50) is aberrantly expressed in many cancer biopsies and plays a crucial role in tumorigenesis, which make it a potential cancer therapeutic target for drug discovery. Here, we constructed a firefly luciferase reporter driven by the TSP50 gene promoter to screen natural compounds capable of inhibiting the expression of TSP50. Then we identified alantolactone, a sesquiterpene lactone, could efficiently inhibit the promoter activity of TSP50 gene, further results revealed that alantolactone also efficiently inhibited the expression of TSP50 in both mRNA and protein levels. Moreover, we found alantolactone could increase the ratio of Bax/Bcl-2, and activate caspase-9 and caspase-3 in the cancer cells with high expression of TSP50, surprisingly, the same effects can also be observed in the same cells just by knockdown of TSP50 gene expression. Furthermore, our results suggested that overexpression of TSP50 decreased the cell sensitivity to alantolactone-induced apoptosis in those cancer cells. Taken together, these results suggest that alantolactone induces mitochondrial-dependent apoptosis at least partially via down-regulation of TSP50 expression.

Structural investigation and biological activity of sesquiterpene lactones from the traditional Chinese herb Inula racemosa

Five new sesquiterpene lactones, racemosalactones A-E (1-5), along with 19 known sesquiterpene latones (6-24), were isolated from the roots of Inula racemosa. Their structures were elucidated by extensive spectroscopic analysis, and the absolute configuration of 2 was deduced from X-ray diffraction analysis. Compounds 1, 6, 8, 10, 12, 14, and 17 exhibited antiproliferative activities with IC50 values ranging from 0.38 to 4.19 μg/mL against human non-small-cell lung cancer A549, hepatocellular carcinoma HepG2, and human fibrosarcoma HT1080 cells. Compounds 6 and 8 exhibited antiproliferative activities against endothelial cells with IC50 values of 2.4 and 2.5 μg/mL, respectively. Furthermore, compounds 6 and 8 both inhibited endothelial cell tube formation at 1.0 μg/mL. A method for the rapid and straightforward preparative-scale isolation of compound 6 from alantolides is described.

Alantolactone induces apoptosis in HepG2 cells through GSH depletion, inhibition of STAT3 activation, and mitochondrial dysfunction

Signal transducer and activator of transcription 3 (STAT3) constitutively expresses in human liver cancer cells and has been implicated in apoptosis resistance and tumorigenesis. Alantolactone, a sesquiterpene lactone, has been shown to possess anticancer activities in various cancer cell lines. In our previous report, we showed that alantolactone induced apoptosis in U87 glioblastoma cells via GSH depletion and ROS generation. However, the molecular mechanism of GSH depletion remained unexplored. The present study was conducted to envisage the molecular mechanism of alantolactone-induced apoptosis in HepG2 cells by focusing on the molecular mechanism of GSH depletion and its effect on STAT3 activation. We found that alantolactone induced apoptosis in HepG2 cells in a dose-dependent manner. This alantolactone-induced apoptosis was found to be associated with GSH depletion, inhibition of STAT3 activation, ROS generation, mitochondrial transmembrane potential dissipation, and increased Bax/Bcl-2 ratio and caspase-3 activation. This alantolactone-induced apoptosis and GSH depletion were effectively inhibited or abrogated by a thiol antioxidant, N-acetyl-L-cysteine (NAC). The data demonstrate clearly that intracellular GSH plays a central role in alantolactone-induced apoptosis in HepG2 cells. Thus, alantolactone may become a lead chemotherapeutic candidate for the treatment of liver cancer.

Ultrasound-assisted extraction of total flavonoids from Inula helenium

BACKGROUND

Inula helenium was a perennial herb belonging to composite family and the roots of I. helenium have been widely used in traditional Chinese medicine. In this study, I. helenium was used as an experimental matrix.

MATERIALS AND METHODS

Ultrasound-assisted extraction (UAE) of total flavonoids from I. helenium was studied with dual wavelength UV-VIS spectrophotometer. Effects of various factors including ratio of material to liquid, ultrasonic time, ethanol concentration and extraction times on extraction yield of total flavonoids were evaluated. Then, orthogonal design of four factors at three levels was applied for optimization the extraction yields of flavonoids from the root of I. helenium.

RESULT

The optimal extracting process of the total flavonoids from the root of the I. helenium was 1 g plant sample with 20 ml of 60% ethanol, extracting twice and each time for 20 min.

CONCLUSION

Under these optimal conditions, the yield of total flavonoids was (17.36±0.94) mg/g. UAE was more efficient and time saving for the extraction of flavonoids from plant materials.