Characterization of Secondary Metabolites, Biological Activity and Glandular Trichomes of Stachys tymphaeaHausskn. from the Monti Sibillini National Park (Central Apennines, Italy)

Abstract

Stachys tymphaea (Lamiaceae) is a perennial herb growing in forest openings and dry meadows of central and southern Italy. It was investigated for the first time here, determining the content of secondary metabolites, the micromorphology of glandular trichomes, the histochemical localization of secretion, and the biological activity of the volatile oil, namely, the cytotoxic, antioxidant, and antimicrobial properties. The plant showed a peculiar molecular pattern, being rich of biophenolic compounds as flavonoids, phenylethanoid glycosides, and caffeoylquinic acid derivatives, but poor of iridoids, which are known as marker compounds of the genus Stachys. The essential oil was characterized by GC-FID and GC/MS analyses, revealing a high percentage of sesquiterpene hydrocarbons (54.6%), with germacrene D (30.0%) and (E)-β-farnesene (12.4%) as the most abundant compounds, while other main components were representatives of the diterpenes (19.2%), represented mainly by (E)-phytol (11.9%). This composition supported the taxonomic relationships in the genus Stachys, which comprises oil-poor species producing essential oils rich in hydrocarbons, with germacrene D as one of the predominant components. The micromorphological study revealed three types of glandular hairs, i.e., Type A peltate trichomes, being the primary sites of essential oil biosynthesis, Type B short-stalked trichomes, typical mucopolysaccharide producers, and Type C long capitate trichomes, secreting a complex mixture of both lipophilic and hydrophilic substances, with a major phenolic fraction. Moreover, the MTT assay revealed the potential of the volatile oil to inhibit A375, HCT116, and MDA-MB 231 tumor cells lines (IC50 values of 23.9-34.4 μg/ml).

Reassessment of Melittis melissophyllum L. subsp. melissophyllum iridoidic fraction

“…Compounds 1, 2, 3, 4 and 5 had been already evidenced in this species (Scarpati et al 1965;Scarpati & Esposito 1967a, 1967b, Guiso et al 1974 and their presence was also confirmed in this study. Actually, these compounds and in particular harpagide (3) and its acetyl derivative (4) are considered chemotaxonomic markers for this genus and also for other related genera in the Lamiaceae family such as Ajuga (Assaad & Lahloub 1988;Breschi et al 1992), Stachys (Kotsos et al 2001;Munoz et al 2001;Háznagy-Radnai et al 2006;Venditti et al 2013aVenditti et al , 2013cVenditti et al , 2014 and Galeopsis (Wieffering & Fikenscher 1974;Venditti et al 2013b). Moreover, their occurrence may substantiate the traditional use of the plant as an anti-inflammatory agent (Guarrera 2005).…”

Essential Oil from Flowers and Leaves of Elaeagnus Angustifolia (Elaeagnaceae): Composition, Radical Scavenging and General Toxicity Activities

“…The presence of a hydroxyl moiety on a hydrocarbon skeleton causes that the compound easily oxidizes and shows antioxidant properties; therefore, the possibility that the higher radical scavenging activity by the essential oil of leaves would be due to the presence of higher amount of phytol in leaves (12.08%) could not be excluded. Previous investigations demonstrated that phytol, as a natural linear diterpene alcohol, showed antioxidant activity in different assays 36,37 as well as it is utilized in manufactoring synthetic vitamins E and K. 38 The general toxicity of essential oils was assessed by brine shrimp lethality test which represent a quick, inexpensive and efficient method for evaluating extracts and essential oils toxicity and most of the time correlates fairly well with anti-proliferative and antitumor activities. 34,35 In this assay, compared with the positive control (Podophyllotoxin, LD 50 = 2.69 ± 0.30 µg/ml) , the essential oils of flowers and leaves showed potent toxicity against brine shrimps with LD 50 values of 2.25 ± 0.60 and 11.00 ± 5.19 µg/ml, respectively.…”

Reassessment of the polar fraction of Stachys alopecuros (L.) Benth. subsp. divulsa (Ten.) Grande (Lamiaceae) from the Monti Sibillini National Park and its potential pharmacologic uses.

“…Chlorogenic acid (8) has been isolated for the first time from S. alopecuros subsp divulsa , although it has been already found in several Stachys species as S. tymphaea [8], S. lanata [30], S. officinalis [31], S. recta [32], S. byzantina , S. iberica subsp. iberica var.…”

“…The eluting system was a mixture of n -BuOH/H 2 O (82:18 v/v). From this chromatographic separation (Scheme 1) 11 compounds were isolated and identified by comparison with data reported in literature and/or by comparison with pure compounds available in our laboratory: Verbascoside (10, 12.4 mg) [14] from the assembly of fractions 8-15; stachysoside A (11, 11.2 mg) [8,15] in mixture with verbascoside (1:2) in the assembly of fractions 17-24; b-arbutin (9, 3.2 mg) [16] from the assembly of fractions 30-32; reptoside (6) [17] and 6-O-acetyl-ajugol (7) [18] in mixture in ratio 1:1.5 (25.0 mg) from the assembly of fractions 43-45; ajugoside (1, 113.7 mg) [17,19] as pure compound from the assembly of fractions 53-54; 8-O-acetyl-harpagide (2, 1.0 g) [20] from the assembly of fractions 70-88; chlorogenic acid (8) [21] in mixture with 8-O-acetyl-harpagide (2) in ratio 1:2 (109.4 mg) from the assembly of fractions 95-112; harpagide (3) [22] and chlorogenic acid (8) in mixture 3:1 (48.3 mg) from the assembly of fractions 118-122; allobetonicoside (4) and chlorogenic acid (8) in mixture 10:1 (29.1 mg) from the assembly of fractions 133-135; allobetonicoside (4, 100.7 mg) [23] as a pure compound from the assembly of fractions 144-163; 4¢-O-galactopyranosyl-teuhircoside (5) [6] in mixture with allobetonicoside (4) in ratio 3:1 (24.7 mg) from the assembly of fractions 166-169.…”

“…The genus Stachys is represented by annual or perennial herbs known for their interesting biological activities, i.e., anti-inflammatory [2], antispasmodic, sedative, and diuretic [3-5]. Several phytochemical components, which may be responsible of the biological activities, have been isolated from Stachys species, i.e., iridoids [6,7], phenylethanoid glycosides, flavonoids [8,9], acidic metabolites, polysaccharides, and terpenoids [10]. …”