UHPLC-MS/MS phenolic profiling and in vitro antioxidant activities of Inula graveolens (L.) Desf

Polyphenols of the Inuleae-Inulinae and Their Biological Activities: A Review

Polyphenols are ubiquitous plant metabolites that demonstrate biological activities essential to plant-environment interactions. They are of interest to plant food consumers, as well as to the food, pharmaceutical and cosmetic industry. The class of the plant metabolites comprises both widespread (chlorogenic acids, luteolin, quercetin) and unique compounds of diverse chemical structures but of the common biosynthetic origin. Polyphenols next to sesquiterpenoids are regarded as the major class of the Inuleae-Inulinae metabolites responsible for the pharmacological activity of medicinal plants from the subtribe (Blumea spp., Dittrichia spp., Inula spp., Pulicaria spp. and others). Recent decades have brought a rapid development of molecular and analytical techniques which resulted in better understanding of the taxonomic relationships within the Inuleae tribe and in a plethora of data concerning the chemical constituents of the Inuleae-Inulinae. The current taxonomical classification has introduced changes in the well-established botanical names and rearranged the genera based on molecular plant genetic studies. The newly created chemical data together with the earlier phytochemical studies may provide some complementary information on biochemical relationships within the subtribe. Moreover, they may at least partly explain pharmacological activities of the plant preparations traditionally used in therapy. The current review aimed to systematize the knowledge on the polyphenols of the Inulae-Inulinae.

Unravelling the phenolic compound reserves, antioxidant and enzyme inhibitory activities of an endemic plant species, Achillea pseudoaleppica

The present ethnobotanical study unravelled the phenolic reservoir (UHPLC-MS/TQ-MS) and pharmacological activity (antioxidant and enzyme inhibitory activities) of an endemic plant, Achillea pseudoaleppica Hub.-Mor. (Asteraceae). The effective antioxidant properties of ethanol and water extracts of A. pseudoaleppica leaves were determined by using six different in vitro bioanalytical methods including three reducing antioxidant methods and three radical scavenging antioxidant methods. In the other step of the study, the enzyme inhibitory effects of water and ethanol extracts of A. pseudoaleppica were determined against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, and α-glucosidase enzymes. The ethanol extract was found to have effective inhibition potential for all four respected enzymes. The IC₅₀ values of A. pseudoaleppica extract against AChE, BChE, α-amylase, and α-glucosidase enzymes were found to be 2.67 mg/mL, 4.55 mg/mL, 16.51 mg/mL, and 12.37 mg/mL, respectively. Also, UHPLC-MS/TQ-MS analyses revealed quinic acid as the most abundant phenolic compound of the water extract (31.12 ± 1.65 µg/mg) and ethanol extract (11.75 ± 0.82 µg/mg). In addition, the molecular docking interaction of the most abundant phenolic compound of A. pseudoaleppica (quinic acid) with AChE, BChE, α-amylase, and α-glucosidase target enzymes were evaluated using Chimera and AutoDock Vina softwares. In conclusion, the rich phenolic content and the potent antioxidant and enzyme inhibitory properties of A. pseudoaleppica extracts may support the widespread ethnobotanical use of the plant application.Communicated by Ramaswamy H. Sarma.

Biologically Active Preparations from the Leaves of Wild Plant Species of the Genus Rubus

The plants of the genus Rubus (R.) are applied as antiseptic agents in the treatment of skin diseases. Despite the great interest in plants of this genus, there are few reports on the antioxidant and biological activities of preparations obtained from the leaves of these plants. Therefore, we decided to evaluate the antioxidant activity of preparations from leaves of wild plant species of the genus Rubus using the frequently applied DPPH, ABTS, and FRAP methods, as well as to determine the total polyphenol content using the Folin−Ciocalteau method and perform qualitative evaluation by gas chromatography−mass spectrometry (GC-MS). The bactericidal and fungicidal activities of the obtained preparations were evaluated by applying laboratory tests: using the disc and the well methods based on the standards EN 13697:2019, EN 13697:2015, and EN 1500:2013. Microbiological tests of the plant preparations against bacteria, fungi, and yeasts isolated from the environment and against reference strains were performed. Moreover, antimicrobial testing of antibiotics against the tested strains was performed for comparison. The n-octanol/water partition coefficient of the obtained preparations was determined by the shake-flask method to determine their lipophilicity. According to the results, a high content of polyphenols and other antioxidant and biologically active compounds can be thought of as the parameter responsible for the effective activity of plant preparations obtained from wild plant species of the genus Rubus. The methods for determining bactericidal and fungicidal activity clearly demonstrates that preparations with reduced ethanol content exhibit bactericidal and fungicidal activity on surfaces. Testing of hand disinfection by means of rubbing with the preparations confirmed their antimicrobial activity against Escherichia coli K12 NCTC 10538. The obtained results show that the tested preparations exhibit on average two times lower activity against the reference bacterial strains than comparable antibiotics. The preparations obtained from the leaves of R. idaeus L. and R. fruticosus L. could complement classical antibiotics. While environmental bacteria showed a similar response to the preparations and antibiotics, their sensitivity was about one-third less than that of the reference strains. Our studies have shown that the obtained preparations are highly hydrophilic (logP < 0). Thus, these preparations can only be used in lipid bilayers in the aqueous core of liposomes, not in the lipid envelope.

Network pharmacology combined with molecular docking to explore the potential mechanisms for the antioxidant activity of Rheum tanguticum seeds

Background

Rheum tanguticum (R. tanguticum) is an edible and medicinal plant that exhibits high antioxidant activity. The purpose of the present study was to investigate the bioactive components of its seeds and the potential mechanisms of antioxidant activity to provide a foundation for further developmental work on R. tanguticum seeds as a functional food.

Methods

In this study, the antioxidant activities of R. tanguticum seeds were measured using DPPH, ABTS and FRAP assays. LC-Q-TOF/MS was used to identify the active compounds in the seeds, and Swiss Target Prediction was used to identify their potential targets. The DisGENET, DrugBank, OMIM and GeneCard databases were used to search for antioxidant-related targets.

Results

The component–target–pathway network was constructed and included 5 compounds and 9 target genes. The hub genes included ESR1, APP, MAPK8, HSP90AA1, AKT1, MMP2, PTGS2, TGFB1 and JUN. The antioxidant activity signaling pathways of the compounds for the treatment of diseases were the cancer signaling pathway, estrogen signaling pathway, colorectal cancer signaling pathway, MAPK signaling pathway, etc. Molecular docking revealed that the compounds in R. tanguticum seeds could inhibit potential targets (AKT1, ESR1 and PTGS2).

Conclusion

Molecular docking studies revealed that the binding energy score between liriodenine and PTGS2 was the highest (8.16), followed by that of chrysophanol (7.10). This result supports the potential for PTGS2-targeted drug screening and design.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03611-3.

Biotechnology for propagation and secondary metabolite production in Bacopa monnieri

Bacopa monnieri (L.) Wettst. or water hyssop commonly known as "Brahmi" is a small, creeping, succulent herb from the Plantaginaceae family. It is popularly employed in Ayurvedic medicine as a nerve tonic to improve memory and cognition. Of late, this plant has been reported extensively for its pharmacologically active phyto-constituents. The main phytochemicals are brahmine, alkaloids, herpestine, and saponins. The saponins include bacoside A, bacoside B, and betulic acid. Investigation into the pharmacological effect of this plant has thrived lately, encouraging its neuroprotective and memory supporting capacity among others. Besides, it possesses many other therapeutic activities like antimicrobial, antioxidant, anti-inflammatory, gastroprotective properties, etc. Because of its multipurpose therapeutic potential, it is overexploited owing to the prioritization of natural remedies over conventional ones, which compels us to conserve them. B. monnieri is confronting the danger of extinction from its natural habitat as it is a major cultivated medico-botanical and seed propagation is restricted due to less seed availability and viability. The ever-increasing demand for the plant can be dealt with mass propagation through plant tissue culture strategy. Micropropagation utilizing axillary meristems as well as de novo organogenesis have been widely investigated in this plant which has also been explored for its conservation and production of different types of secondary metabolites. Diverse in vitro methods such as organogenesis, cell suspension, and callus cultures have been accounted for with the aim of production and/or enhancement of bacosides. Direct shoot-organogenesis was initiated in excised leaf and internodal explants without any exogenous plant growth regulator(s) (PGRs), and the induction rate was improved when exogenous cytokinins and other supplements were used. Moreover, biotechnological toolkits like Agrobacterium-mediated transformation and the use of mutagens have been reported. Besides, the molecular marker-based studies demonstrated the clonal fidelity among the natural and in vitro generated plantlets also elucidating the inherent diversity among the natural populations. Agrobacterium-mediated transformation system was mostly employed to optimize bacoside biosynthesis and heterologous expression of other genes. The present review aims at depicting the recent research outcomes of in vitro studies performed on B. monnieri which include root and shoot organogenesis, callus induction, somatic embryogenesis, production of secondary metabolites by in vitro propagation, acclimatization of the in vitro raised plantlets, genetic transformation, and molecular marker-based studies of clonal fidelity. KEY POINTS: • Critical and up to date records on in vitro propagation of Bacopa monnieri • In vitro propagation and elicitation of secondary metabolites from B. monnieri • Molecular markers and transgenic studies in B. monnieri.

Dittrichia&nbsp;graveolens (L.) Greuter, a Rapidly Spreading Invasive Plant: Chemistry and Bioactivity

Dittrichia graveolens L. Greuter belonging to the Asteraceae family, is an aromatic herbaceous plant native to the Mediterranean region. This plant species has been extensively studied for its biological activities, including antioxidant, antitumor, antimicrobial, antifungal, anti-inflammatory, anticholinesterase, and antityrosinase, and for its peculiar metabolic profile. In particular, bioactivities are related to terpenes and flavonoids metabolites, such as borneol (40), tomentosin (189), inuviscolide (204). However, D. graveolens is also well known for causing health problems both in animals and humans. Moreover, the species is currently undergoing a dramatic northward expansion of its native range related to climate change, now including North Europe, California, and Australia. This review represents an updated overview of the 52 literature papers published in Scopus and PubMed dealing with expansion, chemistry (262 different compounds), pharmacological effects, and toxicology of D. graveolens up to October 2021. The review is intended to boost further studies to determine the molecular pathways involved in the observed activities, bioavailability, and clinical studies to explore new potential applications.

Inula graveolens induces selective cytotoxicity in glioblastoma and chronic leukemia cells

OBJECTIVE

Crude oil extracts, components of extracts, and ethanolic extracts of Inula graveolens possess various pharmacological activities on various cancer cells including antioxidative and antiproliferative effects. Aqueous extract of this species has not been investigated on the liquid malignancies and solid tumors with a high incidence of treatment refractoriness and poor survival outcomes such as glioblastoma and leukemia. Hence, the present study aimed to evaluate the cytotoxic efficiency of I. graveolens aqueous extracts on human glioblastoma multiforme and chronic myelogenous leukemia cell lines in comparison to non-cancerous primary rat cerebral cortex and human peripheral blood mononuclear cells.

METHODS

The cells were treated with the extracts of I. graveolens (125-1000 μg/mL) for 48 h, the cellular viability was identified using 3'-(4,5dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and lactate dehydrogenase release was measured to determine the cytotoxic potential. Total oxidant status and apurinic/apyrimidinic endodeoxyribonuclease 1 assays were used to determine the oxidative status of cells and DNA damage, respectively.

RESULTS

I. graveolens showed selective cytotoxicity toward human glioblastoma multiforme and chronic myelogenous leukemia cell lines and exhibited a higher antiproliferative effect against cancer cells in comparison to non-cancerous cells. Moreover, it significantly reduced the apurinic/apyrimidinic endodeoxyribonuclease 1 levels on both cancer cell lines as compared with their control cells without changing the levels of an oxidative stress marker.

CONCLUSION

The extracts of I. graveolens have anti-cancer potential on human glioblastoma multiforme and chronic myelogenous leukemia cell lines without causing oxidative stress.

Isolation, identification, and activity evaluation of antioxidant components from Inula viscosa: A bioguided approach

Oxidative stress is linked to several invasive diseases which causes significant clinical and economic impact, therefore, there is a need to develop new antioxidants. The natural products could play an important role in overcoming the current need. In the present work, the antioxidant bioassay-guided fractionation of the ethanolic extract of Inula viscosa leaves (Asteraceae) was performed using DPPH and ABTS assays affording three known compounds, which were successfully characterized as ilicic acid (1), taxifolin (2) and quercetin (3) based on 1D, 2D NMR. Compounds 2 and 3 were identified as the most active, displaying similar or higher potency against ABTS (value 41.27 for quercetin and 142.58 for taxifolin) and similar activity against DPPH (value 41.27 for quercetin and 142.58 for taxifolin) than the well-known reference, ascorbic acid (value 65.36 for quercetin and 58.43 for taxifolin) but less potency than the standard gallic acid. The discussion of SAR of the antioxidant potential revealed that the type of natural product is crucial for the activity and the substitution pattern on the flavonoid skeleton modulate the antioxidant profile. Our findings show that I. viscosa leaves may be a natural source of antioxidants and once again the role of flavonoids health benefits is more strongly endorsed.

Enzyme inhibitory function and phytochemical profile of Inula discoidea using in vitro and in silico methods

Many plant species have a large diversity of secondary metabolites with different biological activities. This study aims to assess the phenolic constituent, enzyme inhibitory and antioxidant activities of the aqueous (water) and methanol extracts of Inula discoidea. The enzyme assays showed effective enzyme inhibition of the methanol extract against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), glutathione S-transferase (GST), and α-glycosidase (α-Gly) enzymes. The IC50 values for AChE, BChE, GST, and α-Gly were found as 38.5 mg/mL, 34.65 mg/mL, 77.0 mg/mL, and 40.76 mg/mL, respectively. Antioxidant properties of the aqueous and methanol extracts of I. discoidea were determined by four well-known in vitro techniques (ABTS, CUPRAC, DPPH, and FRAP methods). The antioxidant values of both water and methanol extracts were found to be better than the standard antioxidants (BHA, BHT, ascorbic acid, and α-tocopherol) in ABTS and CUPRAC methods. According to an updated LC-MS/MS technique analysis, quinic acid (21.08 mg/g), protocatechuic acid (4.49 mg/g), and gallic acid (0.48 mg/g) were found as major phenolic compounds of the plant extract. The binding interactions of major phenolic compounds of I. discoidea with the AChE, BChE, GST, and α-Gly enzymes were investigated by the molecular docking studies.

Tandem mass spectrometry of aqueous extract from Ficus dubia sap and its cell-based assessments for use as a skin antioxidant

Since 2006, Ficus dubia has been reported as a new Ficus species in Thailand. As per our recent report, the red-brown aqueous extract of F. dubia sap (FDS) has been determined to strongly exhibit in vitro anti-radicals. However, the phytochemicals in the FDS extract related to health-promoting antioxidation have not been explored. Thus, in this study, we aimed to investigate the chemical components of the F. dubia sap extract by liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-MS/QTOF-MS) and its potential use in cosmetics in terms of cellular antioxidation on keratinocytes (HaCaT), phototoxicity, and irritation on 3D skin cell models following standard tests suggested by the Organization for Economic Cooperation and Development (OECD). It was found that the sap extract was composed of quinic acid and caffeoyl derivatives (e.g., syringoylquinic acid, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, and dimeric forms of caffeoylquinic acids). The extract has significantly exhibited antioxidant activity against H2O2-induced oxidative stress in HaCaT cells. The cellular antioxidative effect of the FDS extract was remarkably dependent on the presence of 3- and 4-O-caffeoylquinic acid in the extract. Furthermore, the FDS extract showed negative results on skin phototoxicity and irritation. Overall, the results reveal that the FDS extract could be developed as a new antioxidant candidate for a skin healthcare product.

Chemical composition and in vitro antioxidant properties of water-soluble extracts obtained from Bangladesh vegetables

The aim of this study was to evaluate the nutritional value and antioxidant properties of aqueous extracts of some Bangladesh vegetables using fruits of ash gourd, bitter gourd, brinjal, okra, ridge gourd, snake gourd, and leaves of Indian spinach, kangkong, and stem amaranth. Proximate composition showed that the dried extracts were composed mainly of crude protein (14.6%-46.7%) and non-fibre carbohydrates (26.4%-53.5%). With the exception of stem amaranth, all the extracts had >40% DPPH radical scavenging ability at 0.5 mg/ml. In contrast metal chelation was lower, except in Indian spinach with ~46%. The ferric reducing antioxidant power (FRAP) was highest for the kangkong (10.9 mM Fe³⁺ reduced), which is similar to the 9.9 mM for butylated hydroxytoluene (BHT). All the extracts suppressed linoleic acid oxidation better than BHT within the first 5 days of the incubation period. We conclude that the Indian spinach, kangkong, and okra could be considered as the most promising sources of antioxidant compounds. PRACTICAL APPLICATIONS: Vegetables are commonly consumed as part of a regular diet but the high water and fiber contents usually mean that large quantities are required to provide long-term health benefits. Therefore, in this work, aqueous extracts of nine Bangladesh vegetables were prepared to provide a more concentrated form of nutrients and bioactive compounds. The extracts had strong nutritional value based on the high contents of crude protein, potassium, iron, and non-fibre carbohydrates. The high content of polyphenolic compounds in the extracts can also provide health benefits, which was demonstrated through strong free radical scavenging, metal chelation, ferric iron reduction, and inhibition of linoleic acid oxidation. These vegetable extracts have the potential to be used as sources of bioactive compounds to prevent or treat non-communicable diseases that are associated with high oxidative stress.

Phenolic Compounds and Antioxidant Activity of <i>Nepeta nuda </i>subsp.<i> Albiflora</i>

Phenolic content and antioxidant activity of Nepeta nuda subsp. albiflora Boiss. were reported in this study. The ethanol and water extracts of Nepeta nuda subsp. albiflora were prepared and used for biochemical analyses. Antioxidant capacities of the extracts were evaluated by three different in vitro bioanalytical methods including a reducing antioxidant method and two radical scavenging antioxidant methods. The water and ethanol extracts of the plant sample were found to have effective antioxidant potentials. Phenolic content of Nepeta nuda subsp. albiflora was determined by high performance liquid chromatography (HPLC). Rosmarinic acid (182.0±4.5 µg/g), apigenin (84.5±57.6 µg/g), and quercetin (44.5±62.9 µg/g) were identified as major compounds in the ethanol extract of the plant sample. This study has a potential scientific base for further studies about Nepeta nuda subsp. albiflora related to plant biochemistry and plant based pharmacological industry.

Phenolic Compounds and Antioxidant Activity of <i>Nepeta nuda </i>subsp.<i> Albiflora</i>

Phenolic content and antioxidant activity of Nepeta nuda subsp. albiflora Boiss. were reported in this study. The ethanol and water extracts of Nepeta nuda subsp. albiflora were prepared and used for biochemical analyses. Antioxidant capacities of the extracts were evaluated by three different in vitro bioanalytical methods including a reducing antioxidant method and two radical scavenging antioxidant methods. The water and ethanol extracts of the plant sample were found to have effective antioxidant potentials. Phenolic content of Nepeta nuda subsp. albiflora was determined by high performance liquid chromatography (HPLC). Rosmarinic acid (182.0±4.5 µg/g), apigenin (84.5±57.6 µg/g), and quercetin (44.5±62.9 µg/g) were identified as major compounds in the ethanol extract of the plant sample. This study has a potential scientific base for further studies about Nepeta nuda subsp. albiflora related to plant biochemistry and plant based pharmacological industry.

Caffeoylquinic Acids, Cytotoxic, Antioxidant, Acetylcholinesterase and Tyrosinase Enzyme Inhibitory Activities of Six Inula Species from Bulgaria

Chlorogenic (5-CQA), 1,5-, 3,5-, 4,5- and 3,4-dicaffeoylquinic (DCQA) acids were identified and quantified in the methanol extracts of Inula oculus-christi L., I. bifrons L., I. aschersoniana Janka var. aschersoniana, I. ensifolia L., I. conyza (Griess.) DC. and I. germanica L. by HPLC analysis. The amount of 5-CQA varied from 5.48 to 28.44 mg/g DE and the highest content was detected in I. ensifolia. 1,5-DCQA (4.05-55.25 mg/g DE) was the most abundant dicaffeoyl ester of quinic acid followed by 3,5-DCQA, 4,5-DCQA and 3,4-DCQA. The extract of I. ensifolia showed the highest total phenolic content (119.92±0.95 mg GAE/g DE) and exhibited the strongest DPPH radical scavenging activity (69.41±0.55 %). I. bifrons extract was found to be the most active sample against ABTS^.+ (TEAC 0.257±0.012 mg/mL) and the best tyrosinase inhibitor. The studied extracts demonstrated a low inhibitory effect towards acetylcholinesterase and possessed low cytotoxicity in concentration range from 10 to 300 μg/mL toward non-cancer (MDCK II) and cancer (A 549) cells.

Phytochemical content, antioxidant activity, and enzyme inhibition effect of Salvia eriophora Boiss. & Kotschy against acetylcholinesterase, α-amylase, butyrylcholinesterase, and α-glycosidase enzymes

Many taxa of Salvia genus have been used in herbal beverages, food flavoring, cosmetics, and pharmaceutical industry. In this paper, chemical compounds of Salvia eriophora (S. eriophora) leaves were determined by LC-MS/MS (Liquid Chromatography tandem Mass Spectrometry). Salvigenin (158.64 ± 10.8 mg/kg), fumaric acid (123.09 ± 8.54 mg/kg), and quercetagetin-3.6-dimethylether (37.85 ± 7.09 mg/kg) were detected as major compounds in the ethanol extract, whereas fumaric acid (555.96 ± 38.56 mg/kg), caffeic acid (103.62 ± 20.51 mg/kg), and epicatechin (83.19 ± 8.43 mg/kg) were detected as major compounds in the water extract. Furthermore, enzyme inhibition of S. eriophora against acetylcholinesterase (AChE), α-amylase (AM), butyrylcholinesterase (BChE), and α-glycosidase (AG) enzymes were detected. AChE, BChE, AG, and AM enzymes were very strongly inhibited by S. eriophora water extract (WES) and S. eriophora methanol extract (MES). Additionally, antioxidant potential of S. eriophora was determined by in vitro analytical methods. IC₅₀ values of WES and MES were performed for radicals. PRACTICAL APPLICATIONS: Metabolic enzymes have crucial functions on living systems due to inhibition or activation of them mainly attributed with some health disorders. AChE, BChE, AM, and AG enzymes have important roles on carbohydrate metabolism or cholinergic pathways. The relation between enzyme inhibition effect and phenolic compounds or antioxidant activity need to be confirmed. Thus, many studies tested to clarify this relation for pure samples or plant extracts. To the best of our knowledge, this is the first report about inhibition effects of Salvia eriophora extracts against AChE, BChE, AM, and AG enzymes as well as their phenolic contents and antioxidant activities.