Document Type : Research Paper

Authors

• Fatemeh Nejad-Alimoradi ¹
• Mansoureh Khodashenas ²
• Farkhondeh Rezanejad ³

¹ Department of Biology, Payame Noor University, Tehran, Iran

² Department of Natural Resources, Agriculture and Natural Resources Research Center, Kerman, Iran

³ Department of Biology, Shahid Bahonar University, Kerman, Iran

Abstract

Background and objectives: Nepeta, with 300 species, is one of the largest genera in the Lamiaceae family. Seventy-five species of this genus are distributed in Iran, many of which are endemic. Due to the medicinal importance and traditional uses of its various species, much research has been conducted to identify their secondary metabolites. Nepetalactone, cineole, and phenolic compounds have been reported as their main compounds, and most have medicinal, antimicrobial, and industrial properties. The amount of these compounds varies in different parts of the plant and different species and populations. Nepeta bornmulleriHausskn. ex Bornm. is endemic to Iran and is a type specimen from Kerman province. Although secondary metabolites have been studied in many species of this genus, more research is needed on N. bornmulleri. Therefore, the morphology, quantity, and quality of antioxidant compounds and essential oils were investigated in the plant's two vegetative and generative parts.
Methodology: Vegetative (stem and leaf) and generative (flower and fruit) parts of N. bornmulleri were collected in May 2023 from Rayen city (Kerman province) at an altitude of 2450 meters. The used generative parts were 80% flowers and 20% unripe fruits. The size of the plant, its vegetative form, and the structure of the inflorescence and flower were examined and photographed with the naked eye or stereomicroscope so that researchers could identify them quickly. Biochemical compounds, including phenolic compounds and essential oil, were studied in vegetative and generative parts. Total phenolic compounds, including total phenols, flavonoids, and anthocyanins from fresh samples, were studied by spectrophotometric method. The phenolic compounds and anthocyanins profile were investigated using dried samples with HPLC. The analysis of essential oil was done using dry samples with gas chromatography (GC) and gas chromatography coupled to a mass spectrometer (GC/MS). Essential oil extraction was done by distillation with water using Clevenger. The experiment was conducted in a completely random design, including two types of vegetative (stem and leaf) and generative (flower and fruit) organs with three replications.
Results: Morphological studies of N. bornmulleri showed that in the studied area, the height of the species is about 10-25 cm with hairy basal (rosette) leaves, apical and dense head-like inflorescence, purple-blue synpetal corolla with bilobate apex, synsepal calyx. The Androecium comprises four purple stamens of equal length (didynamous stamens) and an upper pistil with tetra-achene schizocarp fruit surrounded by persistent sepals. The total content of phenols, flavonoids, and anthocyanins in flowering branches (generative) was significantly higher than in leaves and stems (vegetative parts). The profile of phenolic and anthocyanin compounds by HPLC showed that ten phenolic compounds and three anthocyanin compounds were identified in the generative part, and six phenolic compounds and two anthocyanin compounds were identified in the vegetative part. The most phenolic compound observed in both vegetative and generative parts was luteolin, while malvidin-glucoside was recorded as the most anthocyanin compound. The amount of malvidin-glucoside in the generative part was twice that of the vegetative part. The percentage of essential oil in vegetative and generative parts was observed at 0.2 and 0.1, respectively. In the essential oils of vegetative and reproductive parts, respectively, 10 (69.41%) and 16 (89.29%) identified compounds and 9 (14.59%) and 4 (6.21%) unidentified compounds were reported, which in total 84% and 95.5% constituted the essential oil.The main components of the essential oil of the vegetative part include spatholenol (31.2%), 1,8-cineole (14.5%), hexadecanoic acid (10.6%), myrtenol (9.7%), caryophyllene oxide (6.4%). ) and trans-pinocarveol (4.4%). In the generative part, 1,8-cineole (31.7%), spatholenol (16.2%), myrtenol (14.14%), dihydro nepetalactone (6.92%), trans-pinocarveol (6.7%), pinocarovone (5.2%) and caryophyllene oxide (4.5%) were the main components of the essential oil.
Conclusion: Based on the results, the quantity and quality of phenolic compounds, anthocyanin, and essential oil in the generative part were higher than in the vegetative part of the studied species. So, it is suggested that the generative parts of the plant be used to obtain antioxidant compounds. The amount of nepetalactone, which is significant in most species of Nepeta, was relatively low in this species, while spatholenol and 1, 8-cineole were the main compounds. Considering the numerous medicinal and industrial applications of the two dominant species combinations on the one hand and the exclusivity and limited distribution of the species on the other hand, it is essential to preserve its different populations.

Keywords

• Essential oil
• phenolic compounds
• Nepeta bornmulleri Hausskn. ex Bornm
• 1
• 8-cineole
• nepetalactone

Main Subjects

• Phytochemistry (extraction, identification and measurement of active components)