Phytochemical and biological investigations on two Nepeta species: Nepeta heliotropifolia and N. congesta subsp. cryptantha

In vitro micropropagation and conservation of endangered medicinal plant Nepeta asterotricha Rech.f. (Lamiaceae): genetic fidelity, phytochemical and biological assessment

An efficient in vitro protocol was introduced for the conservation of Nepeta asterotricha, a vulnerable and endangered medicinal species found in the central of Iran for the first time. Growth, phytochemical, and biological traits of in vitro regenerated plant (RP) and acclimated plant (AP) were compared to the mother plant (MP). In addition, the genetic stability of AP was assessed by using inter-simple sequence repeats (ISSR) markers. The highest number of lateral branches (4.25) was obtained from the medium with 3 mg/mL kinetin (KIN), while the highest length of lateral branches (13.25 cm) was achieved on the medium culture fortified with 3 mg/mL thidiazuron (TDZ) and 6-benzylaminopurine (BAP). The highest number of leaves (20.25) and main branch length (12.25 cm) were obtained from the medium containing 3 mg/mL TDZ. The highest number of roots (46.25) and root length (2.25 cm) was measured from the medium fortified with 1 mg/mL indole-3-butyric acid (IBA) and 0.6 mg/mL indole-3-acetic acid (IAA), respectively. RP was successfully acclimated (85%) in vivo. Molecular analysis showed that the AP was true to the type of the MP. cis-Sabinene hydrate (26.8-57.7), 1,8-cineole (6.2-24.1), 4aα,7β,7aα-nepetalactone (4.1-12.3), and terpinene-4-ol (3.2-15.0) were the major essential oils compounds. The studied samples contained rosmarinic acid (2.55-5.97 mg/g DW), cichoric acid (1.68-12.7 mg/g DW), chlorogenic acid (1.91-64.21 mg/g DW), rutin (0.59-1.09 mg/g DW), apigenin (0.52-0.72 mg/g DW), betulinic acid (0.17-2.20 mg g DW), oleanolic acid (0.84-5.37 mg/g DW) and ursolic acid (3.46-15.70 mg/g DW). Acclimated plant exhibited the highest antioxidant activity (IC50 = 196.4 μg/mL), while the methanolic extract of MP displayed the highest antibacterial activity (MIC = 8 mg/mL) against Staphylococcus aureus.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01416-x.

Leaves micromorphology, chemical profile, and bioactivity of in vitro-propagated Nepeta cyrenaica (Lamiaceae)

INTRODUCTION

The endemic species Nepeta cyrenaica Quézel & Zaffran, native to northeastern Libya, is valued as an important honey-bearing plant.

OBJECTIVES

This study was aimed to examine the micromorphology, phytochemistry, and bioactivity of in vitro-propagated N. cyrenaica for the first time.

MATERIALS AND METHODS

The leaf indumentum was examined using light and scanning electron microscopy and further characterised for histochemistry. The chemical composition of essential oil (EO) was performed using GC-MS analysis, while dichloromethane (DCM), methanol (ME), ethanol (ET), and aqueous (AQ) extracts were analysed using qualitative and quantitative LC/MS analyses. The antioxidant activities of EO and extracts were assessed using three parallel assays, while enzyme-inhibiting effects were evaluated against four enzymes.

RESULTS

The leaves bear various types of glandular trichomes, with lipophilic secretion predominating. The main EO component of EO was 1,8-cineole. A considerable number of phenolics and iridoids were tentatively identified in the ME extract. Quantitative LC/MS analysis confirmed that ferulic acid, rosmarinic acid, and epigallocatechin gallate were present in the highest amount in the extracts, in which three iridoids were also quantified. Although the ME extract contained the highest amount of polyphenolics and iridoids, the DCM extract showed the best overall biological potential. Additionally, EO exerted the strongest acetylcholinesterase and tyrosinase inhibition.

CONCLUSION

This study demonstrated that the endemic N. cyrenaica can be efficiently grown under in vitro conditions, where it develops various glandular trichomes that are thought to secrete and/or accumulate bioactive compounds with valuable medicinal potential.

Comparison of antibacterial and antioxidant potentials of pure and nanoemulsified Nepeta pogonosperma essential oil

The current study aimed to investigate the antiradical and antibacterial potential of pure and its nanoemulsified (NNE) Nepeta pogonosperma essential oil (PNE). Antimicrobial activity of the essential oil against two Gram-positive (E. faecalis and B. cereus) and two Gram-negative (M. catarrhalis and K. pneumonia) food-related pathogens during 60-day storage was investigated based on disc diffusion, minimum inhibition concentration (MIC), and minimum bactericidal concentration (MBC). The chemical compounds of Nepeta essential oil were estimated by GC/MS. The physical properties of the nanoemulsion including polydispersity index (PDI), mean particle diameter, and viscosity were also determined. 4aα,7α,7aβ-Nepetalactone (46.31%), 1,8-cineole (23.13%), and (Z)-α-bisabolene (4.01%) were the main compounds of this essential oil. The Nepeta nanoemulsion had a mean droplet diameter of 254.07 nm, PDI of 0.281, and viscosity of 0.887 cP. NNE had stability for up to 60 days. The PNE showed a higher IC50 value than NNE (p < .05). During storage, the antiradical performance of both PNE and NNE was decreased (p < .05). However, emulsification was successful to control this decreasing trend. E. faecalis was the most susceptible bacteria to PNE and NNE, while the lowest inhibition zone was obtained for K. pneumoniae. At the first time, the antibacterial effect of PNE was more than NNE. However, over time nanoemulsion became more successful in maintaining its antibacterial effect. Overall, the incorporation of Nepeta pogonosperma essential oil into a nanoemulsion system can be a promising system to maintain the bioactivity of the essential oil for a longer time.

Essential Oil, Aroma, and Fatty Acid Profiles of Five Endemic Salvia Taxa from Turkey with Chemometric Analysis

The essential oil, aroma, and fatty acid compositions of Salvia cerino-pruinosa var. cerino-pruinosa, S. cerino-pruinosa var. elazigensis, S. pseudeuphratica, S. rosifolia, and S. kurdica collected in 2015, 2016, and 2017 were analysed by GC-FID, GC/MS/Head Space and GC/MS. The results were evaluated chemometrically for principal component analyses and hierarchical clustering analyses using Minitab program. The main components of their essential oils have been determined as germacrene-D (41.79 % highest for these species), camphor (55.80 %), linalool (33.38 %), caryophyllene oxide (32.99 %), 1,8-cineole (26.30 %) and geraniol acetate (31.63 %), while for aroma 1,8-cineole (45.95 % highest for these species), camphor (58.54 %), D-limonene (40.83 %), linalool (27.67 %) and cis-linalool oxide (25.87 %). Oleic (72.65 % highest for these species), erucic (44.61 %), 2-palmitoleic (42.17 %) and nervonic (32.61 %) acids were determined as major components of their fatty acids. According to the PCA and HCA, the essential oil components of these Salvia taxa unaffected by the years, and accordingly, the Salvia taxa grouped among themselves.

A GC-MS method validation for quantitative investigation of some chemical markers in Salvia hypargeia Fisch. & C.A. Mey. of Turkey: Enzyme inhibitory potential of ferruginol

In the present study, a GC-MS method used for quantitative screening of 26 compounds (sclareolide, sclareol, ferruginol, cryptanol, 6,7-dehydroroyleanone, suginal, 9,10-dihydro-7,8-dimethyl-2-(1-methylethyl) phenanthren-3-ol, sugiol, inuroyleanone, 12-demethylmulticauline, 7α-hydroxy-β-sitosterol, stigmasterol, sitosterol, salvigenin, sinensetin, α-amyrin, lupeol, lupenone, 3-acetyl lupeol, 1α,21α-dihydroxy-2,3-(1'1'-dimethyl-dioxymethylene) urs-9(11),12-dien, uvaol, betulin, pyxinol, lup-(20),29-ene-2α-hydroxy-3β-acetate, betulin 3β, 28β-diacetate, 21α-hydroxy,2α,3β-diacetoxy urs-9(11),12-dien) specific to Turkish Salvia species was developed and validated. According to the GC-MS analysis results, Salvia hypargeia Fisch. & C.A. Mey. roots were found to be rich in ferruginol (30787.97 µg/g extract) and lupenone (23276.21 µg/g extract), and leaves in lupeol (20625.92 µg/g extract). Additionally, the essential oil and aroma contents of this species were identified by GC-MS technique. According to the LC-MS/MS results, especially S. hypargeia leaf extract was rich in rosmarinic acid (38035.7 µg/g extract) and isoquercitrin (4136.91 µg/g extract). Furthermore, anticholinesterase, antiurease, antityrosinase and antielastase inhibitory, antioxidant, cytotoxic activities of the ethanol extracts, essential oil, and major components of the species were evaluated. Antioxidant potentials of all extracts of this species were quite high in all studied antioxidant methods. Moreover, butyrylcholinesterase and elastase inhibitory capacities of ferruginol, the major component of S. hypargeia roots, were notable. For these reasons, this species has a high potential for food and pharmaceutical industries. PRACTICAL APPLICATIONS: This new GC-MS method was applied to S. hypargeia Fisch. & C.A. Mey. and it indicated that this species possessed high amount of ferruginol and lupeol, and that this species could be used for their natural sources. According to the results of the activity studies (antioxidant, anticholinesterase, tyrosinase, elastase, and cytotoxic), this method was used to exhibit which compound may be responsible for the activities. This developed and validated method could be easily applied to determine major/active/toxic secondary metabolites of Salvia species which are used and/or could be used in pharmaceutical, cosmetic, and food industries.