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.

Microwave-assisted extraction optimization of sesquiterpene lactones from Inula helenium roots: A sustainable approach to reduce energy consumption and carbon footprint

Inula helenium roots are consumed as natural flavor components and raw or cooked as food, and their extracts are rich in sesquiterpene lactones such as alantolactone (AL) and isoalantolactone (IAL), which have recently attracted great attention due to their pharmacological properties. The industrial utilization of these compounds requires the development of green, efficient, cost-effective, and sustainable extraction protocols. Therefore, this study focused on the optimization of microwave-assisted extraction (MAE) process variables using Face-Centered Central Composite Design (FC-CCD). Then, maceration was applied as a conventional technique, and these techniques were compared in terms of extraction efficiency, morphological changes, antimicrobial activities, carbon emissions, and energy consumption. As a result, optimal MAE conditions, i.e., EtOH: water ratio (X 1) = 100:0, liquid/sample ratio (X 2) = 30:1 mL/g, microwave power (X 3) = 300 W, and irradiation time (X 4) = 5 min, were obtained with AL and IAL yields of 54.99 ± 0.11 (mg/g) and 48.40 ± 0.19 (mg/g), respectively. The extract obtained by MAE had similar or better activity than positive controls in most cases and formed the largest inhibition zones against E. coli (29.5 ± 0.71 mm) and A. niger (34.75 ± 1.06 mm). Morphological changes of I. helenium roots after extraction were observed by scanning electron microscopy. Additionally, MAE was 43.4 times faster than maceration, resulting in 228.6 times less energy consumption and carbon emissions. Based on these findings, it is recommended to use MAE as an industrial green technique for the extraction of sesquiterpene lactones with potential applications in nutraceuticals and food products in terms of sustainable economy and environmental protection.

Biological Activities and Chemical Profile of Gentiana asclepiadea and Inula helenium Ethanolic Extracts

This study aimed to investigate the antioxidant, antimicrobial, and cytotoxic potential of ethanolic extracts obtained from Gentiana asclepiadea L. and Inula helenium L. roots, in relation to their chemical composition. The total polyphenols, flavonoids, and phenolic acids were determined by spectrophotometric methods, while LC-MS analysis was used to evaluate the individual constituents. The antioxidant properties were tested using the FRAP and DPPH methods. The standard well diffusion and broth microdilution assays were carried out to establish in vitro antimicrobial efficacy and minimum inhibitory and bactericidal concentrations. The cytotoxicity was tested on rat intestinal epithelial cells using the MTT assay. The results pointed out important constituents such as secoiridoid glycoside (amarogentin), phenolic acids (caffeic acid, chlorogenic acid, trans-p-coumaric acid, salicylic acid), and flavonoids (apigenin, chrysin, luteolin, luteolin-7-O-glucoside, quercetin, rutoside, and naringenin) and promising antioxidant properties. The in vitro antimicrobial effect was noticed towards several pathogens (Bacillus cereus > Staphylococcus aureus > Enterococcus faecalis > Salmonella typhimurium and Salmonella enteritidis > Escherichia coli), with a pronounced bactericidal activity. Rat intestinal epithelial cell viability was not affected by the selected concentrations of these two extracts. These data support the ethnomedicinal recommendations of these species and highlight them as valuable sources of bioactive compounds.

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.

Antimicrobial Effects of Inula viscosa Extract on the In Situ Initial Oral Biofilm

Given the undesirable side effects of commercially used mouth rinses that include chemically synthesized antimicrobial compounds such as chlorhexidine, it is essential to discover novel antimicrobial substances based on plant extracts. The aim of this study was to examine the antimicrobial effect of Inula viscosa extract on the initial microbial adhesion in the oral cavity. Individual test splints were manufactured for the participants, on which disinfected bovine enamel samples were attached. After the initial microbial adhesion, the biofilm-covered oral samples were removed and treated with different concentrations (10, 20, and 30 mg/mL) of an I. viscosa extract for 10 min. Positive and negative controls were also sampled. Regarding the microbiological parameters, the colony-forming units (CFU) and vitality testing (live/dead staining) were examined in combination with fluorescence microscopy. An I. viscosa extract with a concentration of 30 mg/mL killed the bacteria of the initial adhesion at a rate of 99.99% (log₁₀ CFU value of 1.837 ± 1.54). Compared to the negative control, no killing effects were determined after treatment with I. viscosa extract at concentrations of 10 mg/mL (log₁₀ CFU value 3.776 ± 0.831; median 3.776) and 20 mg/mL (log₁₀ CFU value 3.725 ± 0.300; median 3.711). The live/dead staining revealed a significant reduction (p < 0.0001) of vital adherent bacteria after treatment with 10 mg/mL of I. viscosa extract. After treatment with an I. viscosa extract with a concentration of 30 mg/mL, no vital bacteria could be detected. For the first time, significant antimicrobial effects on the initial microbial adhesion in in situ oral biofilms were reported for an I. viscosa extract.

Development of Inula graveolens (L.) Plant Extract Electrospun/Polycaprolactone Nanofibers: A Novel Material for Biomedical Application

Recently, there has been a growing interest in research on nanofibrous scaffolds developed by electrospinning bioactive plant extracts. In this study, the extract material obtained from the medicinal plant Inula graveolens (L.) was loaded on polycaprolactone (PCL) electrospun polymeric nanofibers. The combined mixture was prepared by 5% of I. graveolens at 8% (PCL) concentration and electrospun under optimal conditions. The chemical analysis, morphology, and crystallization of polymeric nanofibers were carried out by (FT-IR) spectrometer, scanning electron microscopy (SEM), and XRD diffraction. Hydrophilicity was determined by a contact angle experiment. The strength was characterized, and the toxicity of scaffolds on the cell line of fibroblasts was finally investigated. The efficiency of nanofibers to enhance the proliferation of fibroblasts was evaluated in vitro using the optimal I. graveolens/PCL solutions. The results show that I. graveolens/PCL polymeric scaffolds exhibited dispersion in homogeneous nanofibers around 72 ± 963 nm in the ratio 70/30 (V:V), with no toxicity for cells, meaning that they can be used for biomedical applications.

Cytotoxicity and Apoptosis Induction of Coumarins and Carbazole Alkaloids from Clausena harmandiana

Seven compounds, carbazole alkaloids (heptaphylline, 7-methoxyheptaphylline, 7-methoxymukonal) and coumarins (clausarin, dentatin, nordentatin, and xanthoxyletin), were isolated from the root bark of Clausena harmandiana. Antioxidation, cytotoxicity and apoptosis induction were evaluated in vitro. Results showed that clausarin exerted the highest DPPH radical scavenging and 7-methoxymukonal had the highest ferric reducing antioxidant power. In contrary, dentatin was the least DPPH radical scavenger, and heptaphylline was the least reducing antioxidant power. The isolated compounds showed different cytotoxicity. The hepatocellular carcinoma (HepG2) was generally more sensitive to the isolated compounds than lung cancer (SK-LU-1), colon cancer (HCT-116), and noncancerous (Vero) cell lines, respectively. Clausarin possessed the highest cytotoxicity selectively against cancer cell lines tested. 7-Methoxymukonal and 7-methoxyheptaphylline exhibited less cytotoxicity only in HepG2 cells and were inactive in the SK-LU-1 and HCT116 cells. Despite xantoxyletin possessing low antioxidant and low cytotoxic activity, it induced the highest apoptosis percentage with the lowest necrosis percentage of HepG2 cells after 24 h. In conclusion, xantoxyletin primarily show potential anticancer activity. The root bark of C. harmandiana is a good source of bioactive compounds or the lead for the development of new pharmaceutical agent.