A new flavonoid, a new phenylethanoid glycoside and related compounds isolated from the inflorescences of Plantago lanceolata L

Cytotoxic Effect of Phenylethanoid Glycosides Isolated from Plantago lanceolata L

The aim of the study is to investigate whether the bioactive compounds isolated from P. lanceolata inflorescences, namely, phenylethanoid glucosides, acteoside, plantamajoside, and a flavonoid, isorhamnetin-3-O-rutinoside-4'-O-glucoside, possessed cytotoxic activity against the selected cancer cell lines. The potential antitumor effects of two phenylethanoid glycosides and one flavonoid were evaluated via MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on seven human carcinoma cell lines (MCF-7, MDA-MB-231, Caco-2, HepG2, OVCAR-3, U138-MG, U251-MG) and one nontumorigenic mammary epithelial cell line (MCF-12A). For the first time, acteoside was studied in ovarian cancer cell line OVCAR-3, and plantamajoside in all cell lines except breast adenocarcinoma MDA-MB-281 and hepatocarcinoma HepG2. The phenylethanoid glycosides showed stronger cytotoxic activity than that of the glycoside flavonoid. Acteoside and plantamajoside, at concentrations of 200 and 300 μM, respectively, had a highly toxic effect on the selected two cancer cell lines of breast adenocarcinoma MDA-MB-231 and MCF-7, ovarian cancer cell line OVCAR-3, glioblastoma cell line U138-MG, and hepatocarcinoma cell line HepG2. Both glycosides were significantly less cytotoxic towards nontumorigenic cell line MCF-12A; the effect appeared at a concentration of 400 μM. For the first time, the activity of acteoside and plantamajoside was compared in one parallel investigation. The results are discussed against a broad background of existing knowledge on biological effects, their mechanisms, and structure-activity relationships. Phenylethanoids may be potential compounds with cytotoxic activity against the selected cancer types.

Effects of Host Plants on Development and Immunity of a Generalist Insect Herbivore

Secondary plant chemistry mediates a variety of communication signals among species, playing a fundamental role in the evolutionary diversification of communities and ecosystems. Herein, we explored diet-mediated host plant effects on development and immune response of a generalist insect herbivore. Vanessa cardui (Nymphalidae) caterpillars were reared on leaves of three host plants that vary in secondary metabolites, Plantago lanceolata (Plantaginaceae), Taraxacum officinale (Asteraceae) and Tithonia diversifolia (Asteraceae). Insect development was evaluated by larval and pupal viabilities, survivorship, and development rate. Immune response was measured as phenoloxidase (PO) activity. Additionally, chemical profiles of the host plants were obtained by liquid chromatograph-mass spectrometry (LC-MS) and the discriminant metabolites were determined using a metabolomic approach. Caterpillars reared on P. lanceolata exhibited the highest larval and pupal viabilities, as well as PO activity, and P. lanceolata leaves were chemically characterized by the presence of iridoid glycosides, phenylpropanoids and flavonoids. Taraxacum officinale leaves were characterized mainly by the presence of phenylpropanoids, flavones O-glycoside and germacranolide-type sesquiterpene lactones; caterpillars reared on this host plant fully developed to the adult stage, however they exhibited lower larval and pupal viabilities compared to individuals reared on P. lanceolata. Conversely, caterpillars reared on T. diversifolia leaves, which contain phenylpropanoids, flavones and diverse furanoheliangolide-type sesquiterpene lactones, were not able to complete larval development and exhibited the lowest PO activity. These findings suggested that V. cardui have adapted to tolerate potentially toxic metabolites occurring in P. lanceolata (iridoid glycosides), however caterpillars were not able to cope with potentially detrimental metabolites occurring in T. diversifolia (furanoheliangolides). Therefore, we suggest that furanoheliangolide-type sesquiterpene lactones were responsible for the poor development and immune response observed for caterpillars reared on T. diversifolia.

Ethnobotanical Uses, Chemical Constituents, and Application of Plantago lanceolata L

The medicinal benefits of P. lanceolata L. have been acknowledged worldwide for hundreds of years. The plant is now distributed worldwide, especially in temperate zones. This review gives an overview of ethnomedicinal use, phytochemistry, pharmacological activities, and other potential application of P. lanceolate L. Several effective chemical constituents such as polyphenols, tannins, flavonoids, alkaloids, terpenoids, iridoid glycosides, fatty acids, and polysaccharides are found in P. lanceolata L., which contribute to its exerting specific therapeutic effects. Correspondingly, studies have found that P. lanceolata L. has different biological activities, including antioxidant, antibacterial, wound-healing, anti-inflammatory, cytotoxic, and antiulcerogenic activity. The plant also treats various diseases related to the skin, respiratory organs, digestive organs, reproduction, circulation, cancer, pain relief, and infections. The plant has many applications in cosmetics such as lotion and creams; it is also used as an excellent indicator to know the presence and absence of heavy metals and the accumulation in industrial and urban areas. The plant suppresses soil nitrogen mineralization in agriculture due to allelochemicals such as aucubin. The biological activities, medicinal properties, and industrial application of P. lanceolata mainly depend on the activities of the responsible, active chemical constituents. However, this field still needs more study to determine the exact mechanisms and the main bioactive compound activity accountable for these activities. Also, most of the studies have been performed in vitro, so further in vivo studies are recommended for the future.

Antioxidant Contents in a Mediterranean Population of Plantago lanceolata L. Exploited for Quarry Reclamation Interventions

Plantago lanceolata L. (plantain) is an interesting multipurpose perennial species whose aerial parts are used in herbal medicine due to its precious phytochemicals and are palatable to animals. Moreover, peculiar traits such as drought tolerance, an extended growth season and a deep root system, make plantain a promising pioneer plant for quarry reclamation based on the use of native species. This study evaluated the effects of different environmental conditions and seasons on the accumulation of the bioactive compounds of its aerial organs. An autochthonous plantain population was grown in three locations in Sardinia (Italy). Leaves, peduncles and inflorescences were collected between October 2020 and July 2021. Phenolic contents and antioxidant capacity were determined. The analysis of the individual phenolic compounds was performed using liquid chromatography. In leaves, the content of total phenolics, antioxidant capacity and total flavonoids were significantly influenced by location and season. Total phenolic content ranged from 65 to 240 g gallic acid equivalent kg^-1, whereas total flavonoids were from 16 to about 89 g catechin equivalent kg^-1. Neochlorogenic, chlorogenic, cryptochlorogenic acids, verbascoside, diosmin and luteolin were identified in the methanolic extracts of leaves, peduncles and inflorescences. Verbascoside was the main antioxidant isolated from plantain extracts. Results evidenced an increasing accumulation pattern of phenolics from vegetative stage to flowering, followed by a decrement towards the seed ripening as well as site-specific differences with amounts of phenolics even 25% higher for same plantain accession.