Phenolic Profile and Bioactivities of Sideritis perfoliata L.: The Plant, Its Most Active Extract, and Its Broad Biological Properties

Chemical profile of the Anatolian Sideritis species with bioactivity studies

CONTEXT

The genus Sideritis L. (Lamiaceae) is represented by 46 species in Turkey with an 79% endemism ratio, 42 of 46 belonging to the section Empodoclia.

OBJECTIVE

In this review article, Sideritis species growing in Turkey have been evaluated for phytochemical constituents and biological activities.

METHODS

The data for the isolates, components and extracts of the Anatolian Sideritis species and their bioactivity studies were retrieved from the main databases WoS, Scopus and PubMed from 1975 until 31 December 2022.

RESULTS

In this review article, terpenoids, flavonoids, phenolics and other secondary metabolites isolated from Turkish Sideritis species were reported. Anatolian Sideritis species, which primarily consist of monoterpenes and sesquiterpenes, were studied in detail. Sideritis plants are represented by 46 species in Turkey, and 25 of them were investigated for their diterpenoids through isolation or LC-MS studies. Most of the diterpenoids of Turkish Sideritis species have ent-kaurene skeleton, among them linearol, siderol, 7-epicandicandiol and sideridiol were found to be the main compounds. Exceptionally, labdane, pimarane and beyerene diterpenoids were only found in a few species. For phenolics and flavonoids, only 12 species were investigated until now, and they were found to be rich in phenylethanoid glycosides and flavonoid glycosides. In terms of activity, most of the species were tested for antioxidant activity, followed by antimicrobial and anti-ulcer/anti-inflammatory activities. Their cytotoxic, enzyme inhibitory, antinociceptive and antistress activities were less frequently studied.

CONCLUSIONS

Sideritis species should be considered promising therapeutic agents in the treatment of upper respiratory tract and ulcer/inflammatory diseases.

Siderol Inhibits Proliferation of Glioblastoma Cells and Acts Synergistically with Temozolomide

Glioblastoma (GBM) is the most aggressive primary central nervous system (CNS) tumor in adults with dismal prognosis. Currently, the therapeutic interventions include gross total resection, when possible, followed by radiotherapy and chemotherapy. However, despite treatment, tumor usually recurs within 7-9 months. The presence of glioma cells with stem-like properties and tumor's heterogeneity have been identified as the most important factors driving recurrence. Recently, research efforts have been focused on the use of natural substances as treatment for GBM. Siderol is an ent-kaurane diterpenoid, isolated from the genus Sideritis. Sideritis extracts have already been investigated for their anti-inflammatory, antioxidant, and anticancer effects. In this study, we investigated the antitumoral effects of siderol in GBM T98 and U87 cell lines, as well as the effects of combined treatment with temozolomide (TMZ). Cell viability was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue exclusion assay. Different concentrations of siderol were used in order to calculate the IC50 values at 72 h after treatment. Flow cytometry used for the DNA cell cycle analysis after treatment with siderol in concentrations of IC50 and twice the IC50 values for 72 h. Furthermore, the effect of siderol in cell's migratory ability was tested using wound healing assay. Cell viability and proliferation, after combined treatment with siderol and TMZ, also were evaluated with the trypan blue exclusion assay and the effects of the combination treatment were analyzed with CompuSyn software. Treatment with siderol significantly reduced cell viability in T98 and U87 cell lines in a dose-dependent manner and IC50 values were calculated, 18 μM and 13 μM, respectively. Moreover, siderol induced G₀/G₁ cell cycle arrest in a dose-dependent manner and inhibited the migration in both cell lines. In addition, siderol and TMZ seem to have synergistic action in the majority of tested concentrations in both T98 and U87 cells. In conclusion, siderol may represent an innovative strategy for the treatment of GBM, and further studies are needed on siderol's efficacy and mode of action.

Bioassay-Guided Skin-Beneficial Effects of Fractionated Sideritis raeseri subsp. raeseri Extract

This study aimed to evaluate the potentials for skin-beneficial effects of the hydroethanolic extract of the aerial parts of ironwort (Sideritis raeseri Boiss. & Heldr. subsp. raeseri) and its fractions (petroleum ether, ethyl acetate, n-butanol and water). For these purposes, chemical analysis and in vitro antioxidant, anti-tyrosinase and antimicrobial assays, as well as determination of sun protection factor (SPF), were performed. The highest total phenolic content and quantity of individual flavonoids, chlorogenic acid and verbascoside were determined in the n-butanol fraction, which is in line with results obtained for antioxidant activity. The greatest antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa, the most common causative agents of the skin infections in humans, was exhibited by the ethyl acetate fraction. The strongest anti-tyrosinase activity was shown by the hydroethanolic extract (52.64% of inhibition at 100 μg/mL). Almost all tested samples showed photoprotective activity with SPF higher than 6 obtained at a low concentration of 0.1 mg/mL, which was more than 15 for the butanol fraction. These findings revealed that the hydroethanolic extract of S. raeseri aerial parts could be a valuable ingredient in the formulation of cosmetic and medicinal products intended to overcome various skin disorders.

Phytochemical Composition and Cytoprotective Properties of the Endemic Sideritis sipylea Boiss Greek Species: A Valorization Study

Sideritis sipylea Boiss. (Fam. Lamiaceae) is an endemic plant of the North Aegean Islands (Greece), commonly known as ironwort. Traditionally, its aerial parts have been used to relieve several ailments, especially gastrointestinal disorders, however, with scant knowledge about the pharmacological basis. In the present study, an endemic S. sipylea Greek species from Lesvos Island has been characterized for phytochemical composition and biological activities, in order to give a possible scientific basis to its traditional use and to highlight a further nutraceutical interest as a source of bioactive phytochemicals and extracts. Three different fractions obtained from a methanolic extract of S. sipylea aerial parts by using ethyl acetate with 10 (S10), 20 (S20), and 50% (S50) methanol as fractionation solvents were phytochemically characterized. Moreover, their antioxidant power and cytoprotective activity in different human cell lines were evaluated. The phytochemical analysis highlighted the presence of flavonoids, iridoids, and phenolic acids in all the tested samples. Particularly, the S10 fraction mainly contained iridoids, while S20 and S50 lavandulifolioside and chlorogenic acid, respectively. The fractions also showed antioxidant properties, S10 and S20 being the most potent. When assessed in human cholangiocytes, they counteracted the cytotoxicity of the tBOOH pro-oxidant agent, by reducing ROS levels and affecting GSH antioxidant system. The present findings highlight a possible interest in S10 and S20 fractions from S. sipylea as sources of bioactive molecules and stimulate further studies in order to characterize their possible application for nutraceutical and pharmaceutical purposes.

Polar constituents, biological effects and nutritional value of Sideritis sipylea Boiss

The present study focuses on the polar constituents and biological effects of the methanol extract and the infusion of wild Sideritis sipylea Boiss. from Samos island (Greece), as well as on the nutritional and mineral contents of this plant. The total phenolic content and antioxidant activity were examined. In addition, the anti-acetylcholinesterase property was evaluated, revealing strictly lower results than the control, galanthamine. Furthermore, the nutritional value of the plant is reported herein for the first time, revealing a promising source of protein. To the best of our knowledge, this study is the first work on the infusion of this species and the nutritional value of the plant.

Advantages of Hyaluronic Acid and Its Combination with Other Bioactive Ingredients in Cosmeceuticals

This study proposes a review on hyaluronic acid (HA) known as hyaluronan or hyaluronate and its derivates and their application in cosmetic formulations. HA is a glycosaminoglycan constituted from two disaccharides (N-acetylglucosamine and D-glucuronic acid), isolated initially from the vitreous humour of the eye, and subsequently discovered in different tissues or fluids (especially in the articular cartilage and the synovial fluid). It is ubiquitous in vertebrates, including humans, and it is involved in diverse biological processes, such as cell differentiation, embryological development, inflammation, wound healing, etc. HA has many qualities that recommend it over other substances used in skin regeneration, with moisturizing and anti-ageing effects. HA molecular weight influences its penetration into the skin and its biological activity. Considering that, nowadays, hyaluronic acid has a wide use and a multitude of applications (in ophthalmology, arthrology, pneumology, rhinology, aesthetic medicine, oncology, nutrition, and cosmetics), the present study describes the main aspects related to its use in cosmetology. The biological effect of HA on the skin level and its potential adverse effects are discussed. Some available cosmetic products containing HA have been identified from the brand portfolio of most known manufacturers and their composition was evaluated. Further, additional biological effects due to the other active ingredients (plant extracts, vitamins, amino acids, peptides, proteins, saccharides, probiotics, etc.) are presented, as well as a description of their possible toxic effects.

Influence of Accelerated Solvent Extraction Conditions on the LC-ESI-MS/MS Polyphenolic Profile, Triterpenoid Content, and Antioxidant and Anti-lipoxygenase Activity of Rhododendron luteum Sweet Leaves

Evaluation of native plant resources and their efficient use is one of the current trends in phytochemistry. The main aim of the present study was to investigate the biological activities of different Rhododendron luteum Sweet leaf extracts obtained with the use of accelerated solvent extraction using different solvents and extraction temperatures. All extracts were subjected to bioactivity assays, which revealed considerable anti-lipoxygenase (23.07-90.13% lipoxygenase inhibition) and antiradical potential. All samples exhibited high 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) (234.18-621.90 mg Trolox equivalents (TE)/g) and 2,2'-azino-bis-3(ethylbenzthiazoline-6-sulphonic acid) (ABTS^•+) (88.79-349.41 mg TE/g) scavenging activity, high antioxidant potential in the Oxygen Radical Absorbance Capacity (ORAC) assay (495.77-1011.59 mg TE/g), and moderate ion chelating (Fe2+) capacity. The chemical profile of each sample was determined using liquid chromatography/electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS) and spectrophotometric procedures. Twenty-three compounds representing seven polyphenol subclasses were detected and quantified, including some phenolic acids and flavonoids that had not been previously reported for this plant material. It was shown that 5-O-caffeoylquinic acid, protocatechuic acid, catechin, quercetin and its glycosides (hyperoside, isoquercetin, quercitrin), and pentacyclic triterpenes were the dominant secondary metabolites in R. luteum leaves. The antioxidant activity was found to be strongly related to different polyphenol groups and total triterpene content, while the anti-lipoxygenase potential was highly dependent on catechin.

Polyphenols and Other Bioactive Compounds of Sideritis Plants and Their Potential Biological Activity

Due to the growing problem of obesity associated with type 2 diabetes and cardiovascular diseases, causes of obesity are extensively investigated. In addition to a high caloric diet and low physical activity, gut microbiota disturbance may have a potential impact on excessive weight gain. Some reports indicate differences in the composition of the intestinal microflora of obese people in comparison to lean. Bioactive compounds of natural origin with beneficial and multifaceted effects on the body are more frequently used in prevention and treatment of many metabolic diseases including obesity. Sideritis scardica is traditionally consumed as mountain tea in the Balkans to strengthen the body and improve mood. Many reports indicate a positive effect on digestive system, weight loss, and prevention of insulin resistance. Additionally, it exhibits antioxidant activity and anti-inflammatory effects. The positive effect of Sideritis scardica extracts on memory and general cognitive abilities is indicated as well. The multilevel positive effect on the body appears to originate from the abundant occurrence of phenolic compounds, especially phenolic acids in Sideritis scardica extracts. However, mechanisms underlying their action require careful discussion and further research. Therefore, the objective of this review is to summarize the available knowledge on the role and mechanism of action of biologically active compounds of Sideritis scardica and other related species from the genus Sideritis.

Water Extract from Inflorescences of Industrial Hemp Futura 75 Variety as a Source of Anti-Inflammatory, Anti-Proliferative and Antimycotic Agents: Results from In Silico, In Vitro and Ex Vivo Studies

Industrial hemp (Cannabis sativa) is traditionally cultivated as a valuable source of fibers and nutrients. Multiple studies also demonstrated antimicrobial, anti-proliferative, phytotoxic and insecticide effects of the essential oil from hemp female inflorescences. On the other side, only a few studies explored the potential pharmacological application of polar extracts from inflorescences. In the present study, we investigated the water extract from inflorescences of industrial hemp Futura 75 variety, from phytochemical and pharmacological point of view. The water extract was assayed for phenolic compound content, radical scavenger/reducing, chelating and anti-tyrosinase effects. Through an ex vivo model of toxicity induced by lipopolysaccharide (LPS) on isolated rat colon and liver, we explored the extract effects on serotonin, dopamine and kynurenine pathways and the production of prostaglandin (PG)E₂. Anti-proliferative effects were also evaluated against human colon cancer HCT116 cell line. Additionally, antimycotic effects were investigated against Trichophyton rubrum, Trichophyton interdigitale, Microsporum gypseum. Finally, in silico studies, including bioinformatics, network pharmacology and docking approaches were conducted in order to predict the putative targets underlying the observed pharmacological and microbiological effects. Futura 75 water extract was able to blunt LPS-induced reduction of serotonin and increase of dopamine and kynurenine turnover, in rat colon. Additionally, the reduction of PGE₂ levels was observed in both colon and liver specimens, as well. The extract inhibited the HCT116 cell viability, the growth of T. rubrum and T. interdigitale and the activity of tyrosinase, in vitro, whereas in silico studies highlighting the inhibitions of cyclooxygenase-1 (induced by carvacrol), carbonic anhydrase IX (induced by chlorogenic acid and gallic acid) and lanosterol 14-α-demethylase (induced by rutin) further support the observed pharmacological and antimycotic effects. The present findings suggest female inflorescences from industrial hemp as high quality by-products, thus representing promising sources of nutraceuticals and cosmeceuticals against inflammatory and infectious diseases.