Free Volatile Compounds of Veronica austriaca ssp. jacquinii (Baumg.) Eb. Fisch. and Their Biological Activity

The composition of free volatile compounds of essential oils (EO) and hydrosols (Hy) from four different localities of the species Veronica austriaca ssp. jacquinii (Baumg.) Eb. Fisch. were analyzed by gas chromatography coupled with mass spectrometry. In the EOs, the most abundant compounds identified were hexahydrofarnesyl acetone (23.34–52.56%), hexadecanoic acid (palmitic acid, 26.71–58.91%) and octadecanol acetate (0–6.24%). The hydrosols were characterized by high abundance of methyl eugenol (23.35–57.93%), trans-p-mentha-1(7),8-dien-2-ol (5.24–7.69%) and thymol (3.48–9.45%). Glandular trichomes were analyzed using SEM (Scanning Electron Microscopy), as they are the sites of synthesis of free volatile compounds. We have detected glandular trichomes, consisting of a one stalk cell and two elliptically shaped head cells, and non-glandular (unbranched, bi-cellular to multicellular) trichomes on stems, leaves and the sepals. Data for volatile compounds from EOs and hydrosols were analyzed using Principal Component Analyses (PCA) to demonstrate variations in the composition of the volatile compounds identified. Isolated samples of EO and hydrosols were analyzed for their antioxidant activity using two methods, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ORAC (Oxygen Radical Absorbance Capacity). The essential oils showed higher antioxidant activity than the hydrosols in ORAC method, but lower activity by the DPPH method. The isolates were also tested for their antiproliferative activity on different types of cancer cells and also on two lines of healthy cells, and the results showed that the extracts were not toxic to the cell lines tested. Total polyphenols, total tannins, total flavonoids and total phenolic acids were also analyzed and determined spectrophotometrically. The free volatile compounds of Veronica austriaca ssp. jacquinii can be considered as a safe natural product.

Comparative Chemical Profiles and Phytotoxic Activity of Essential Oils of Two Ecospecies of Pulicaria undulata (L.) C.A.Mey

The Asteraceae (Compositae) family is one of the largest angiosperm families that has a large number of aromatic species. Pulicaria undulata is a well-known medicinal plant that is used in the treatment of various diseases due to its essential oil (EO). The EO of both Saudi and Egyptian ecospecies were extracted via hydrodistillation, and the chemical compounds were identified by GC–MS analysis. The composition of the EOs of Saudi and Egyptian ecospecies, as well as other reported ecospecies, were chemometrically analyzed. Additionally, the phytotoxic activity of the extracted EOs was tested against the weeds Dactyloctenium aegyptium and Bidens pilosa. In total, 80 compounds were identified from both ecospecies, of which 61 were Saudi ecospecies, with a preponderance of β-pinene, isoshyobunone, 6-epi-shyobunol, α-pinene, and α-terpinolene. However, the Egyptian ecospecies attained a lower number (34 compounds), with spathulenol, hexahydrofarnesyl acetone, α-bisabolol, and τ--cadinol as the main compounds. The chemometric analysis revealed that the studied ecospecies and other reported species were different in their composition. This variation could be attributed to the difference in the environmental and climatic conditions. The EO of the Egyptian ecospecies showed more phytotoxic activity against D. aegyptium and B. pilosa than the Saudi ecospecies. This variation might be ascribed to the difference in their major constituents. Therefore, further study is recommended for the characterization of authentic materials of these compounds as allelochemicals against various weeds, either singular or in combination.

Chemical Composition, Allelopathic, Antioxidant, and Anti-Inflammatory Activities of Sesquiterpenes Rich Essential Oil of Cleome amblyocarpa Barratte & Murb.

The integration of green natural chemical resources in agricultural, industrial, and pharmaceutical applications allures researchers and scientistic worldwide. Cleome amblyocarpa has been reported as an important medicinal plant. However, its essential oil (EO) has not been well studied; therefore, the present study aimed to characterize the chemical composition of the C. amblyocarpa, collected from Egypt, and assess the allelopathic, antioxidant, and anti-inflammatory activities of its EO. The EO of C. amblyocarpa was extracted by hydrodistillation and characterized via gas chromatography–mass spectrometry (GC-MS). The chemometric analysis of the EO composition of the present studied ecospecies and the other reported ecospecies was studied. The allelopathic activity of the EO was evaluated against the weed Dactyloctenium aegyptium. Additionally, antioxidant and anti-inflammatory activities were determined. Forty-eight compounds, with a prespondence of sesquiterpenes, were recorded. The major compounds were caryophyllene oxide (36.01%), hexahydrofarnesyl acetone (7.92%), alloaromadendrene epoxide (6.17%), myrtenyl acetate (5.73%), isoshyobunone (4.52%), shyobunol (4.19%), and trans-caryophyllene (3.45%). The chemometric analysis revealed inconsistency in the EO composition among various studied ecospecies, where it could be ascribed to the environmental and climatic conditions. The EO showed substantial allelopathic inhibitory activity against the germination, seedling root, and shoot growth of D. aegyptium, with IC50 values of 54.78, 57.10, and 74.07 mg L−1. Additionally, the EO showed strong antioxidant potentiality based on the IC50 values of 4.52 mg mL−1 compared to 2.11 mg mL−1 of the ascorbic acid as standard. Moreover, this oil showed significant anti-inflammation via the suppression of lipoxygenase (LOX) and cyclooxygenases (COX1, and COX2), along with membrane stabilization. Further study is recommended for analysis of the activity of pure authentic materials of the major compounds either singularly or in combination, as well as for evaluation of their mechanism(s) and modes of action as antioxidants or allelochemicals.

Generalized olfactory detection of floral volatiles in the highly specialized Greya-Lithophragma nursery pollination system

Volatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.

Phytotoxic Effects of Plant Essential Oils: A Systematic Review and Structure-Activity Relationship Based on Chemometric Analyses

Herbicides are natural or synthetic chemicals used to control unwanted plants (weeds). To avoid the harmful effects of synthetic herbicides, considerable effort has been devoted to finding alternative products derived from natural sources. Essential oils (EOs) from aromatic plants are auspicious source of bioherbicides. This review discusses phytotoxic EOs and their chemical compositions as reported from 1972 to 2020. Using chemometric analysis, we attempt to build a structure-activity relationship between phytotoxicity and EO chemical composition. Data analysis reveals that oxygenated terpenes, and mono- and sesquiterpenes, in particular, play principal roles in the phytotoxicity of EOs. Pinene, 1,8 cineole, linalool, and carvacrol are the most effective monoterpenes, with significant phytotoxicity evident in the EOs of many plants. Caryophyllene and its derivatives, including germacrene, spathulenol, and hexahydrofarnesyl acetone, are the most effective sesquiterpenes. EOs rich in iridoids (non-terpene compounds) also exhibit allelopathic activity. Further studies are recommended to evaluate the phytotoxic activity of these compounds in pure forms, determine their activity in the field, evaluate their safety, and assess their modes of action.

Endemic Veronica saturejoides Vis. ssp. saturejoides–Chemical Composition and Antioxidant Activity of Free Volatile Compounds

Chemical profile and antioxidant activity of the species Veronica saturejoides Vis. ssp. saturejoides (Plantaginaceae)—which is endemic to Croatia, Bosnia and Herzegovina and Montenegro —were investigated. Volatile compounds produced by glandular trichomes (composed of one stalk cell and two elliptically formed head cells according to scanning electron microscope investigation) were isolated from the plants collected in two locations. Additionally, as a part of specialized metabolites, total polyphenols, total tannins, total flavonoids and total phenolic acids were determined spectrophotometrically. In the lipophilic volatile fractions-essential oils, the most abundant compounds identified were hexahydrofarnesyl acetone, caryophyllene oxide and hexadecanoic acid. In total, the class of oxygenated sesquiterpenes and the group of fatty aldehydes, acids and alcoholic compounds dominated in the essential oils. In the hydrophilic volatile fractions-hydrosols, the most abundant compounds identified were trans-p-mentha-1(7),8-dien-2-ol, allo-aromadendrene and (E)-caryophyllene. A group of oxygenated monoterpenes and the sesquiterpene hydrocarbons dominated in the hydrosols. Antioxidant activity of essential oils and hydrosols was tested with two methods: 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC). Essential oils showed higher antioxidant activity than hydrosols and showed similar antioxidant activity to Rosmarinus officinalis essential oil. Obtained results demonstrate that this genus is a potential source of volatiles with antioxidant activity.

THE CHEMICAL CONSTITUENTS' OF THE LEAVE ESSENTIAL OIL OF ALTERNANTHERA PUNGENS (KUNTH)

Alternanthera pungens Kunth commonly called khaki weed is from the family Amaranthaceae. It is a herbaceous perennial plant that has stems prostrate, rarely rising and about 10-50 cm long. The work was carried out due to the scarcity of information on the volatile constituents from the plant leaves despite works on the flower and other parts. The extraction of the essential oils from the dried leaves was carried out by the hydro distillation method using an all-glass Clevenger apparatus. The extracted oils were then analyzed using gas chromatography-mass spectrometry (GC-MS). A total of twelve constituents' representing 93.39% of A. Pungens oil with a yield of 0.4% (v/w) was obtained. The analysis of the GC-MS results of the leaf oil showed that it was dominated by â-ionone (42.18%) and hexahydrofarnesyl acetone (15.53%), others in trace amounts include; methyl palmitate (6.13%), 1octadecyne (4.72%), undecane (3.73%), para-mentha-1, 3, 8-triene (3.65%), isophytol (3.21%), ?cadinene (3.06%), 1, 2-dimethyl cyclooctene (3.05%), para-cymene (2.96%), phytol (2.67%) and neophytadiene (2.50%). The common classes of compounds present in the leaves oil are aceto monocyclic monoterpenoid (42.18%), sesquiterpenoids (18.59%), hydrocarbons (11.50%), diterpenoids (8.38%), monoterpenes (6.61%) and fatty acids (6.13%).The constituents and the compositional pattern of essential oil identified from the leaves of Alternanthera pungens grown in Nigeria differ quantitatively and qualitatively from previously reported member of the genus and the presence of sesquiterpenoid as one of the major components of the oils justify the traditional use of the plants in treating pains, headaches and inflammations.

THE CHEMICAL CONSTITUENTS' OF THE LEAVE ESSENTIAL OIL OF ALTERNANTHERA PUNGENS (KUNTH)

Alternanthera pungens Kunth commonly called khaki weed is from the family Amaranthaceae. It is a herbaceous perennial plant that has stems prostrate, rarely rising and about 10-50 cm long. The work was carried out due to the scarcity of information on the volatile constituents from the plant leaves despite works on the flower and other parts. The extraction of the essential oils from the dried leaves was carried out by the hydro distillation method using an all-glass Clevenger apparatus. The extracted oils were then analyzed using gas chromatography-mass spectrometry (GC-MS). A total of twelve constituents' representing 93.39% of A. Pungens oil with a yield of 0.4% (v/w) was obtained. The analysis of the GC-MS results of the leaf oil showed that it was dominated by â-ionone (42.18%) and hexahydrofarnesyl acetone (15.53%), others in trace amounts include; methyl palmitate (6.13%), 1octadecyne (4.72%), undecane (3.73%), para-mentha-1, 3, 8-triene (3.65%), isophytol (3.21%), ?cadinene (3.06%), 1, 2-dimethyl cyclooctene (3.05%), para-cymene (2.96%), phytol (2.67%) and neophytadiene (2.50%). The common classes of compounds present in the leaves oil are aceto monocyclic monoterpenoid (42.18%), sesquiterpenoids (18.59%), hydrocarbons (11.50%), diterpenoids (8.38%), monoterpenes (6.61%) and fatty acids (6.13%).The constituents and the compositional pattern of essential oil identified from the leaves of Alternanthera pungens grown in Nigeria differ quantitatively and qualitatively from previously reported member of the genus and the presence of sesquiterpenoid as one of the major components of the oils justify the traditional use of the plants in treating pains, headaches and inflammations.

GC and GC-–MS Analysis of Volatile Compounds From Ballota nigra subsp. uncinata Collected in Aeolian Islands, Sicily (Southern Italy)

In the present study, the chemical composition of the essential oils from aerial parts of Ballota nigra subsp. uncinata (Bég.) Patzak collected in Sicily was evaluated by gas chromatography (GC) and GC-mass spectrometry. The main components of the oil were ( E)-phytol (20.0%), α-pinene (9.0%), hexahydrofarnesyl acetone (5.7%), and α-selinene (5.1%). Cluster analysis of the essential oil compositions of all the taxa belonging to B. nigra s.l. group was performed.

Medicinal and pesticidal potentials of the constituents of the essential oil from Adenia cissampeloides leaves

Adenia cissampeloides (Planch. ex Hook.) Harms is used in alternative medicine primarily for the management of hypertension and several other diseases. Isolation and GC-MS analysis of five essential oils collected fractionally and over 4 h by hydrodistillation from the dried leaves were carried out. The constituents included phytol, α-linolenic acid, n-hexadecanoic acid, hexahydrofarnesyl acetone, (13S)-8,13-epoxy-labd-14-ene, kaur-16-ene, guaiol, α-gurjunene, and α-elemene. Several bioactivities of the constituents as well as their potential applications in medicine and the pharmaceutical and pesticidal industries are discussed. Essential oils from some other plants have several constituents in common with those isolated from A. cissampeloides. The bioactivities of such plants are used to suggest other possible applications of A. cissampeloides.