Medicinal Inula Species: Phytochemistry, Biosynthesis, and Bioactivities

Inubritantrimers A-D: Trimerized Sesquiterpenoid [4 + 2] Adducts Featuring a Distinctive Spiro-Polycyclic Scaffold from Inula britannica

Inubritantrimer A (1), a trace trimerized sesquiterpenoid [4 + 2] adduct featuring an unusual exo-exo type spiro-polycyclic scaffold, together with three new endo-exo [4 + 2] adducts, inubritantrimers B-D (2-4), were discovered from the flowers of Inula britannica. Their structures were elucidated using 1D/2D NMR, X-ray diffraction, and ECD approaches. 1 is characterized as a novel exo-exo trimer, synthesized biogenetically from three sesquiterpenoid monomers, featuring a unique linkage of C-11/C-1', C-13/C-3' and C-13'/C-3″, C-11'/C-1″ through a two-step exo [4 + 2] cycloaddition process. Compounds 1-4 exhibited modest cytotoxicity against breast cancer cells with IC50 values in the range of 5.84-12.01 μM.

Identification of diverse sesquiterpenoids with anti-fibrotic potential from Inula japonica Thunb

In the chemical investigation of Inula japonica, a total of 29 sesquiterpenoids (1-29) were obtained, including pseudoguaine-, xanthane-, eudesmane-, and 1,10-secoeudesmane-type compounds, as well as their dimers. Among them, six new dimeric sesquiterpenoids, bisinulains A-F (1-5, 7), characterized by a [4 + 2] biogenetic pathway between different sesquiterpenoid monomers were identified. Additionally, three new monomers named inulaterins A-C (13, 18 and 21) were discovered. The structures of these compounds were determined through analysis of spectroscopic data, X-ray crystallographic data, and ECD experiments. To assess their potential anti-inflammatory activities, the sesquiterpenoid dimers were tested for their ability to inhibit NO production in LPS-stimulated RAW 264.7 cells. Furthermore, the compounds that exhibited anti-inflammatory effects underwent evaluation for their anti-fibrotic potential using a TGF-β-induced epithelial-mesenchymal transition model in A549 cells. As a result, bisinulain B (2) was screened out to significantly inhibit the production of cytokines involved in pulmonary fibrosis such as NO, α-SMA, collagen I and fibronectin.

Essential oil from Inula japonica Thunb. And its phenolic constituents ameliorate pulmonary injury and fibrosis in bleomycin-treated mice

ETHNOPHARMACOLOGICAL RELEVANCE

Pulmonary injury and fibrosis can be caused by various factors because of their inflammatory nature, both can lead to serious clinical consequences. Inula japonica Thunb. is used in traditional Chinese medicine for the treatment of lung diseases. However, the effect and mechanism of action of the essential oil of I. japonica (EOI) on pulmonary injury and fibrosis are not well understood.

AIM OF THE STUDY

To investigate the therapeutic effects of EOI on mice with bleomycin (BLM)-induced acute pulmonary injury and chronic fibrosis formation, as well as its potential mechanism.

MATERIALS AND METHODS

A short-term mouse model of pulmonary injury was established by intratracheal injection of BLM to investigate the anti-inflammatory effect of EOI, and a long-term model of pulmonary fibrosis was used to explore the anti-fibrosis effect of EOI. High-dose EOI (200 mg/kg) was administered intragastrically, and low-dose (50 mg/kg) was administered by intratracheal injection. Gas chromatography-mass spectrometry (GC-MS) was used to identify the ingredients in EOI, and high-performance liquid chromatography (HPLC) was performed for the preparation of EOI compounds. Western blot and real-time qPCR were used to verify the effects of EOI and its active composition on inflammation, oxidative stress and fibrosis signaling pathway.

RESULTS

Treatment with EOI significantly reduced the inflammation and oxidative stress by reducing the levels of inflammatory and oxidative cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and malondialdehyde in BLM-treated mice with acute pulmonary injury. EOI treatment could also suppress the formation of fibrous tissue in mice with BLM-induced pulmonary fibrosis through inhibiting TGF-β/Smad and PI3K/Akt pathways. Chromatographic analysis and preparation suggested that fatty acid and phenol derivatives are present in EOI. Based on cellular inflammation and fibrosis models, the phenolic compounds in EOI can represent the anti-inflammatory and anti-fibrotic effects of EOI by regulating pro-inflammatory and pro-fibrotic cytokines such as NO, TNF-α, IL-6, TGF-β1, and α-SMA.

CONCLUSION

EOI ameliorated BLM-induced pulmonary injury and fibrosis in mice by inhibiting the inflammatory response and regulating the redox equilibrium, as well as by mediating TGFβ/Smad and PI3K/Akt, which suggested that EOI has potential to treat pulmonary diseases.

Phytochemical characterization and biological activities of Inula viscosa L. Aiton: a promising plant from Turkey

The methanol extract of Inula viscosa (IVM) was investigated for its antioxidant potential using the DPPH and ABTS radical scavenging as well as iron chelating assays (ICA). The total phenol (TPC) and flavonoid contents (TFC) of IVM were determined using the Folin-Ciocalteu and aluminum trichloride methods, respectively. Antimicrobial activity of different concentrations of I. viscosa methanol extract was investigated by disc diffusion and broth microdilution method. The IVM extract was found to be containing TPC (236.78 ± 7.63 mg GAE/g) and TFC (94.36 ± 1.86 mg QE/g). Antioxidant activity IC50 values for the DPPH, ABTS and ICA assays were found to be 277.7 ± 3.68, 2.44 ± 0.02, and 222.1 ± 0.71 µg/mL, respectively. The MIC values of the IVM on the tested microorganisms ranged from 0.48 to 7.81 mg/mL. Furthermore, IVM extract was demonstrated 18.32 ± 1.37%, 23.06 ± 1.05%, 4.72 ± 0.13%, 15.13 ± 0.37% and 37.64 ± 4.02% inhibition against tyrosinase, α-amylase, α-glucosidase, AChE and BChE, respectively. In the results of LC-MS/MS analysis, acacetin, quercetin, chlorogenic acid and protocatechuic acid were determined as most dominant compounds. These findings suggested that this plant may be a natural resource for creating novel medicinal compounds.

Research progress on antitumor mechanisms and molecular targets of Inula sesquiterpene lactones

The pharmacological effects of natural product therapy have received sigificant attention, among which terpenoids such as sesquiterpene lactones stand out due to their biological activity and pharmacological potential as anti-tumor drugs. Inula sesquiterpene lactones are a kind of sesquiterpene lactones extracted from Inula species. They have many pharmacological activities such as anti-inflammation, anti-asthma, anti-tumor, neuroprotective and anti-allergic. In recent years, more and more studies have proved that they are important candidate drugs for the treatment of a variety of cancers because of its good anti-tumor activity. In this paper, the structure, structure-activity relationship, antitumor activities, mechanisms and targets of Inula sesquiterpene lactones reported in recent years were reviewed in order to provide clues for the development of novel anticancer drugs.

Inula japonica ameliorated the inflammation and oxidative stress in LPS-induced acute lung injury through the MAPK/NF-κB and Keap1/Nrf2 signalling pathways

OBJECTIVES

To investigate the protective effect and underlying mechanism of Inula japonica (TEIJ) in the treatment of acute lung injury (ALI).

METHODS

Protective effects of TEIJ in the inflammation and oxidative stress were studied in lipopolysaccharide (LPS)-induced ALI mice. Meanwhile, Western blot and real-time qPCR were carried out to investigate the underlying mechanism of TEIJ for ALI as well as immunohistochemistry.

KEY FINDINGS

TEIJ significantly alleviated the course of ALI via suppressing the interstitial infiltrated inflammatory cells, the increase of inflammatory factors and the decrease of anti-oxidative factors. TEIJ inactivated the MAPK/NF-κB signalling pathway to suppress the transcription of its downstream target genes, such as TNF-α, IL-6, etc. Meanwhile, TEIJ activated the Keap1/Nrf2 signalling pathway to regulate expression levels of Nrf2 and its target proteins. The results of LC-QTOF-MS/MS indicated potential active constituents of I. japonica, terpenoids and flavonoids. Additionally, terpenoids and flavonoids synergistically alleviated LPS-induced ALI depending on MAPK/NF-κB and Keap1/Nrf2 signalling pathways.

CONCLUSION

I. japonica could be considered a potential agent to treat ALI via regulating the MAPK/NF-κB and Keap1/Nrf2 signalling pathways.

The Therapeutic Wound Healing Bioactivities of Various Medicinal Plants

The skin serves as the body's first line of defense, guarding against mechanical, chemical, and thermal damage to the interior organs. It includes a highly developed immune response that serves as a barrier against pathogenic infections. Wound healing is a dynamic process underpinned by numerous cellular activities, including homeostasis, inflammation, proliferation, and remodeling, that require proper harmonious integration to effectively repair the damaged tissue. Following cutaneous damage, microorganisms can quickly enter the tissues beneath the skin, which can result in chronic wounds and fatal infections. Natural phytomedicines that possess considerable pharmacological properties have been widely and effectively employed forwound treatment and infection prevention. Since ancient times, phytotherapy has been able to efficiently treat cutaneous wounds, reduce the onset of infections, and minimize the usage of antibiotics that cause critical antibiotic resistance. There are a remarkable number of wound-healing botanicals that have been widely used in the Northern Hemisphere, including Achiella millefolium, Aloe vera, Althaea officinalis, Calendula officinalis, Matricaria chamomilla, Curcuma longa, Eucalyptus, Jojoba, plantain, pine, green tea, pomegranate, and Inula. This review addresses the most often used medicinal plants from the Northern Hemisphere that facilitate the treatment of wounds, and also suggests viable natural alternatives that can be used in the field of wound care.

Total flavonoids of Inula japonica alleviated the inflammatory response and oxidative stress in LPS-induced acute lung injury via inhibiting the sEH activity: Insights from lipid metabolomics

BACKGROUND

Acute lung injury (ALI) is a severe respiratory disease characterized by diffuse lung interstitial and respiratory distress and pulmonary edema with a mortality rate of 35%-40%. Inula japonica Thunb., known as "Xuan Fu Hua" in Chinese, is a traditional Chinese medicine Inulae Flos to use for relieving cough, eliminating expectorant, and preventing bacterial infections in the clinic, and possesses an anti-pulmonary fibrosis effect. However, the effect and action mechanism of I. japonica on ALI is still unclear.

PURPOSE

This study aimed to investigate the protective effect and underlying mechanism of total flavonoids of I. japonica (TFIJ) in the treatment of ALI.

STUDY DESIGN AND METHODS

A mouse ALI model was established through administration of LPS by the intratracheal instillation. Protective effects of TFIJ in the inflammation and oxidative stress were studied in LPS-induced ALI mice based on inflammatory and oxidative stress factors, including MDA, MPO, SOD, and TNF-α. Lipid metabolomics, bioinformatics, Western blot, quantitative real-time PCR, and immunohistochemistry were performed to reveal the potential mechanism of TFIJ in the treatment of ALI.

RESULTS

TFIJ significantly alleviated the interstitial infiltration of inflammatory cells and the collapse of the alveoli in LPS-induced ALI mice. Lipid metabolomics demonstrated that TFIJ could significantly affect the CYP2J/sEH-mediated arachidonic acid metabolism, such as 11,12-EET, 14,15-EET, 8,9-DHET, 11,12-DHET, and 14,15-DHET, revealing that sEH was the potential target of TFIJ, which was further supported by the recombinant sEH-mediated the substrate hydrolysis in vitro (IC₅₀ = 1.18 μg/ml). Inhibition of sEH by TFIJ alleviated the inflammatory response and oxidative stress via the MAPK, NF-κB, and Nrf2 signaling pathways.

CONCLUSION

These results demonstrated that TFIJ could suppress the sEH activity to stabilize the level of EETs, allowing the alleviation of the pathological course of lung injury in LPS-treated mice, which suggested that TFIJ could serve as the potential agents in the treatment of ALI.

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.

1β-Hydroxyalantolactone from Inulae Flos alleviated the progression of pulmonary fibrosis via inhibiting JNK/FOXO1/NF-κB pathway

Inulae Flos was widely distributed throughout Europe, Africa, and Asia, and was commonly used as a folk medicine in clinic for treating various respiratory diseases, including cough, asthma, bronchitis, pulmonary fibrosis, and pneumonia. However, the ingredients responsible for the pharmacology effects of I. Flos and the underlying mechanisms remain unclear. In this study, the effects of 16 known sesquiterpene lactones and flavonoids from I. Flos on TGF-β1-induced fibroblast activation were assessed by phenotypic high-content screening. Among those sixteen compounds, 1β-hydroxy alantolactone (HAL), the main characteristic sesquiterpene lactone from I. Flos, exhibited remarkable inhibitory activity. The further studies showed that HAL significantly inhibited the proliferation and induced the apoptosis of human fibroblast cell lines HELF and MRC-5 in a concentration-dependent manner. It also reduced intracellular ROS production, suppressed the mRNA expressions of E-cad, TGF-β1, Smad3, Col I, α-SMA and TNF-α, and downregulated protein expressions of α-SMA and F-actin. Furthermore, HAL significantly reduced the levels of HA, LN, PC-III and IV-C in serum, TNF-α and IL-6 in BALF, and TGF-β1, HYP and Col I in lung tissues of bleomycin (BLM)-treated rats. HAL significantly downregulated the expressions of p-JNK, FOXO1, p-p65, α-SMA, p-smad3 and Col I but upregulated p-FOXO1, which could be reversed by JNK agonist anisomycin. These results demonstrated that HAL induced the apoptosis of lung fibroblast cells activated by TGF-β1 and improved BLM-induced lung fibrosis in rats via inhibiting JNK/FOXO1/NF-κB pathway.

Induction of Apoptosis by Isoalantolactone in Human Hepatocellular Carcinoma Hep3B Cells through Activation of the ROS-Dependent JNK Signaling Pathway

Isoalantolactone (IALT) is one of the isomeric sesquiterpene lactones isolated from the roots of Inula helenium L. IALT is known to possess various biological and pharmacological activities, but its anti-cancer mechanisms are not well understood. The aim of the present study was to investigate the anti-proliferative effects of IALT in human hepatocellular carcinoma (HCC) cells and to evaluate the potential anti-cancer mechanisms. Our results demonstrated that IALT treatment concentration-dependently suppressed the cell survival of HCC Hep3B cells, which was associated with the induction of apoptosis. IALT increased the expression of death-receptor-related proteins, activated caspases, and induced Bid truncation, subsequently leading to cleavage of poly (ADP-ribose) polymerase. In addition, IALT contributed to the cytosolic release of cytochrome c by destroying mitochondrial integrity, following an increase in the Bax/Bcl-2 expression ratio. However, IALT-mediated growth inhibition and apoptosis were significantly attenuated in the presence of a pan-caspase inhibitor, suggesting that IALT induced caspase-dependent apoptosis in Hep3B cells. Moreover, IALT activated the mitogen-activated protein kinases signaling pathway, and the anti-cancer effect of IALT was significantly diminished in the presence of a potent c-Jun N-terminal kinase (JNK) inhibitor. IALT also improved the generation of intracellular reactive oxygen species (ROS), whereas the ROS inhibitor significantly abrogated IALT-induced growth reduction, apoptosis, and JNK activation. Furthermore, ROS-dependent apoptosis was revealed as a mechanism involved in the anti-cancer activity of IALT in a 3D multicellular tumor spheroid model of Hep3B cells. Taken together, our findings indicate that IALT exhibited anti-cancer activity in HCC Hep3B cells by inducing ROS-dependent activation of the JNK signaling pathway.

Biocatalysis in the Chemistry of Lupane Triterpenoids

Pentacyclic triterpenes are important representatives of natural products that exhibit a wide variety of biological activities. These activities suggest that these compounds may represent potential medicines for the treatment of cancer and viral, bacterial, or protozoal infections. Naturally occurring triterpenes usually have several drawbacks, such as limited activity and insufficient solubility and bioavailability; therefore, they need to be modified to obtain compounds suitable for drug development. Modifications can be achieved either by methods of standard organic synthesis or with the use of biocatalysts, such as enzymes or enzyme systems within living organisms. In most cases, these modifications result in the preparation of esters, amides, saponins, or sugar conjugates. Notably, while standard organic synthesis has been heavily used and developed, the use of the latter methodology has been rather limited, but it appears that biocatalysis has recently sparked considerably wider interest within the scientific community. Among triterpenes, derivatives of lupane play important roles. This review therefore summarizes the natural occurrence and sources of lupane triterpenoids, their biosynthesis, and semisynthetic methods that may be used for the production of betulinic acid from abundant and inexpensive betulin. Most importantly, this article compares chemical transformations of lupane triterpenoids with analogous reactions performed by biocatalysts and highlights a large space for the future development of biocatalysis in this field. The results of this study may serve as a summary of the current state of research and demonstrate the potential of the method in future applications.