Essential Oil of Piper Purusanum C.DC (Piperaceae) and Its Main Sesquiterpenes: Biodefensives Against Malaria and Dengue Vectors, Without Lethal Effect on Non-target Aquatic Fauna

The mosquitoes vectors of the genus Aedes and Anopheles present resistance to several commercial insecticides, which are also toxic to non-predators targets. On the other hand, essential oils are a promising source of insecticides. Thus, in this work, the essential oil from the leaves of Piper purusanum was characterized by gas chromatography based approaches and evaluated as biodefensive against malaria and dengue vectors. The main compounds of P. purusanum essential oil were β-caryophyllene (57.05%), α-humulene (14.50%) and germacrene D (8.20%). The essential oil inhibited egg hatching (7.6 ± 1.5 to 95.6 ± 4.5%) caused larval death (LC50 from 49.84 to 51.60 ppm) and inhibited the action of acetylcholinesterase (IC50 of 2.29 µg/mL), which can be related to the mechanisms of action. On the other hand, the biological activity of β-caryophyllene, α-humulene and germacrene D were higher than the essential oil. In addition, these sesquiterpenes and essential oil did not show a lethal effect on Toxorhynchites splendens, Anisops bouvieri, Gambusia affinis and Diplonychus indicus (LC50 from 2098.80 to 7707.13 ppm), although D. indicus is more sensible (SI/PSF from 48.56 to 252.02 ppm) to essential oil, representing a natural alternative against these relevant vectors.

Phytochemical Investigation and Reproductive Capacity of the Bulgarian Endemic Plant Species Marrubium friwaldskyanum Boiss. (Lamiaceae)

Marrubium friwaldskyanum Boiss (Lamiaceae) is a Bulgarian endemic species. Overall, the essential oil (EO) composition of M. friwaldskyanum was different from that of the other Marrubium species reported in the literature. The main EO constituents of M. friwaldskyanum were (E)-caryophyllene, germacrene D, and caryophyllene oxide. The effect of the harvest stage was significant only on α-copaene, (E)-caryophyllene, caryophyllene oxide, and τ-muurolol. The concentration of α-copaene (1.26–1.83% range of the total oil), (E)-caryophyllene (31–41%), caryophyllene oxide (6.4–11.8%), and τ-muurolol (1.3–2.8%) were the highest at 2–3 pair of leaves or before flowering and lower at flowering. The harvest stage did not significantly affect the concentrations of the other six identified EO compounds β-bourbonene (1.1%), α-humulene (2.8%), germacrene D (23.3%), bicyclogermacrene (2.85%), δ-cadinene (1.1%), and spathulenol (2.8%). In a separate experiment, grinding of the biomass prior to EO extraction had a significant effect only on the concentrations of D-limonene (0.24–3.3%) and bicyclogermacrene (3.6–9.1%). Grinding in water or without water, maceration, and addition of Tween®20 had rather small effects on the EO profile. The identified EO constituents and their mean concentrations in this experiment were (E)-caryophyllene (25.4%), germacrene D (17.6%), caryophyllene oxide (9.1%), spathulenol (6.5%), τ-muurolol (5.0%), carvacrol (3.9%), α-copaene (2.5%), β-bourbonene (2.5%), δ-cadinene (2.4%), α-humulene (1.8%), and Z-β-farnesene (1.3%). Embryological studies observed anther and the development of the male gametophyte and ovule and development of the female gametophyte of M. friwaldskyanum. Furthermore, pollen and seed viability assays were conducted, and mass spectrometry-based metabolomics analysis of an extract from shoots revealed the presence of 45 natural products, identified as flavonoids, phenolic acids, and (tri)terpenoids. Overall, the phytochemistry and some of the microscopic analyses distinguished this endemic species from other species in Marrubium.

Lemongrass Essential Oil Components with Antimicrobial and Anticancer Activities

The prominent cultivation of lemongrass (Cymbopogon spp.) relies on the pharmacological incentives of its essential oil. Lemongrass essential oil (LEO) carries a significant amount of numerous bioactive compounds, such as citral (mixture of geranial and neral), isoneral, isogeranial, geraniol, geranyl acetate, citronellal, citronellol, germacrene-D, and elemol, in addition to other bioactive compounds. These components confer various pharmacological actions to LEO, including antifungal, antibacterial, antiviral, anticancer, and antioxidant properties. These LEO attributes are commercially exploited in the pharmaceutical, cosmetics, and food preservations industries. Furthermore, the application of LEO in the treatment of cancer opens a new vista in the field of therapeutics. Although different LEO components have shown promising anticancer activities in vitro, their effects have not yet been assessed in the human system. Hence, further studies on the anticancer mechanisms conferred by LEO components are required. The present review intends to provide a timely discussion on the relevance of LEO in combating cancer and sustaining human healthcare, as well as in food industry applications.

Combined Effect of Altitude, Season and Light on the Accumulation of Extractable Terpenes in Norway Spruce Needles

Plants produce specific terpenes, secondary metabolites conferring tolerance to biotic and abiotic stresses. Our study aims to investigate the effects of altitude, light intensity and season on contents of mono- and sesquiterpenes in needles of coniferous Norway spruce (Picea abies). Needles of current shoots representing upper and lower canopy were collected from adult trees growing along an altitudinal gradient (400–1100 m a.s.l.) in summer and autumn. After the extraction in cold heptane, the content of extractable terpenes was determined by gas chromatography coupled with mass spectrometry. Our results show that the total content of terpenes decreases with increasing altitude regardless of canopy position and season. Needles of the upper canopy have a higher total content of terpenes than lower canopy needles, but this difference decreases with increasing altitude in summer. Total content of extractable terpenes increases in autumn when compared to summer particularly in upper canopy needles of trees from high altitudes. Limonene, camphene, α-pinene and myrcene are the most abundant monoterpenes in spruce needles forming up to 85% of total monoterpenes, while germacrene D-4-ol is the most abundant sesquiterpene. Altitude, canopy position and season have a significant interactive effect on most monoterpenes, but not on sesquiterpenes. Terpenoid biosynthesis is thus tightly linked to growth conditions and likely plays a crucial role in the constitution of stress tolerance in evergreen conifers.

Chemical Composition of the Essential Oil and Antimicrobial Properties of Crude Extract From Tanacetum Corymbosum (L.) Shi. Bip.

The GC-MS analysis of the essential oil from Tanacetum corymbosum revealed the presence of 38 compounds, including terpenes - germacrene D, (Z)-β-farnesene, g-elemene, β-caryophyllene, aliphatic - palmitic and linoleic fatty acids, fatty alcohol n-octadecanol, higher alkane n-heneicosane as the major constituents. The in vitro antimicrobial assessment of the ethanolic extract showed promising antibacterial/antifungal activities against five Gram-(+), Gram-(-) and phytopathogenic bacteria species and two fungi strains. The data obtained in this study may be useful both for researchers and for producers interested in new or less studied species of medicinal plants in healthcare and their biological activities.

Effects of Phytophthora Inoculations on Photosynthetic Behaviour and Induced Defence Responses of Plant Volatiles in Field-Grown Hybrid Poplar Tolerant to Bark Canker Disease

Bark cankers accompanied by symptoms of decline and dieback are the result of a destructive disease caused by Phytophthora infections in woody plants. Pathogenicity, gas exchange, chlorophyll a fluorescence, and volatile responses to P. cactorum and P. plurivora inoculations were studied in field-grown 10-year-old hybrid poplar plants. The most stressful effects of P. cactorum on photosynthetic behaviour were found at days 30 and 38 post-inoculation (p.-i.), whereas major disturbances induced by P. plurivora were identified at day 30 p.-i. and also belatedly at day 52 p.-i. The spectrum of volatile organic compounds emitted at day 98 p.-i. was richer than that at day 9 p.-i, and the emissions of both sesquiterpenes α-cubebene and germacrene D were induced solely by the Phytophthora inoculations. Significant positive relationships were found between both the axial and the tangential development of bark cankers and the emissions of α-cubebene and β-caryophyllene, respectively. These results show that both α-cubebene and germacrene D are signal molecules for the suppression of Phytophthora hyphae spread from necrotic sites of the bark to healthy living tissues. Four years following inoculations, for the majority of the inoculated plants, the callus tissue had already closed over the bark cankers.

ANALYSIS OF ESSENTIAL OIL CONSTITUENTS OF THREE ANNONA SPECIES GROWING IN KERALA, INDIA

The volatile chemical composition of leaf essential oils of three Annona species (Annona cherimola, Annona muricata and Annona squamosa) from the different regions of Kerala, South Indian was determined using gas chromatography-mass spectrometry analysis. A total of 41 constituents belonging to monoterpenoids, sesquiterpenoids and diterpenoids were identified. Monoterpenes and sesquiterpenoids were the major class of volatile compounds in most of the Annona species examined. The study led to the identification of major compounds as germacrene D (23.5%), bicyclogermacrene (14.6%) and β-caryophyllene (11.7%) in A. cherimola, α-pinene (13.3%), β-caryophyllene (11.2%) and β-pinene (10.1%) in A. muricata, and β-caryophyllene (11.9%) and α-pinene (8.2%) in A. squamosa respectively. The examined essential oils showed that β-caryophyllene is the common constituent identified in all the three species and other constituents are more specific for each species under study. Present investigation reports, a comparison of essential oil compositions of three Annona species from Kerala. Results of this study prove that essential oils examined have considerable dissimilarity in chemical composition with previously reported leaf essential oil compositions from other regions. A chemotaxonomic analysis of these essential oils based on the distribution of compounds has revealed an efficient method to differentiate Annona species unambiguously.

Chemical Variability and In Vitro Anti-Inflammatory Activity of Leaf Essential Oil from Ivorian Isolona dewevrei (De Wild. & T. Durand) Engl. & Diels

The chemical variability and the in vitro anti-inflammatory activity of the leaf essential oil from Ivorian Isolona dewevrei were investigated for the first time. Forty-seven oil samples were analyzed using a combination of CC, GC(RI), GC-MS and 13C-NMR, thus leading to the identification of 113 constituents (90.8–98.9%). As the main components varied drastically from sample to sample, the 47 oil compositions were submitted to hierarchical cluster and principal components analyses. Three distinct groups, each divided into two subgroups, were evidenced. Subgroup I−A was dominated by (Z)-β-ocimene, β-eudesmol, germacrene D and (E)-β-ocimene, while (10βH)-1β,8β-oxido-cadina-4-ene, santalenone, trans-α-bergamotene and trans-β-bergamotene were the main compounds of Subgroup I−B. The prevalent constituents of Subgroup II−A were germacrene B, (E)-β-caryophyllene, (5αH,10βMe)-6,12-oxido-elema-1,3,6,11(12)-tetraene and γ-elemene. Subgroup II−B displayed germacrene B, germacrene D and (Z)-β-ocimene as the majority compounds. Germacrene D was the most abundant constituent of Group III, followed in Subgroup III−A by (E)-β-caryophyllene, (10βH)-1β,8β-oxido-cadina-4-ene, germacrene D-8-one, and then in Subgroup III−B by (Z)-β-ocimene and (E)-β-ocimene. The observed qualitative and quantitative chemical variability was probably due to combined factors, mostly phenology and season, then harvest site to a lesser extent. The lipoxygenase inhibition by a leaf oil sample was also evaluated. The oil IC50 (0.020 ± 0.005 mg/mL) was slightly higher than the non-competitive lipoxygenase inhibitor NDGA IC50 (0.013 ± 0.003 mg/mL), suggesting a significant in vitro anti-inflammatory potential.

Phytochemical Traits and Biological Activity of Eryngium amethystinum and E. alpinum (Apiaceae)

Eryngium amethystinum L. is a wild vegetable used in Croatia. Both E. amethystinum and E. alpinum L. are decorative plants that can also be used in horticulture. To find out the hidden qualities of these two species, the following biological activities were studied: essential oil (EO) composition, analyzed by gas chromatography and gas chromatography with mass spectrometry (GC, GC–MS); phenolic compound content (PC), analyzed by high performance liquid chromatography (HPLC); total phenols as well as total flavonoids, analyzed by ultraviolet–visible spectrophotometry (UV/Vis); antioxidants, analyzed by 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity (DPPH), b-carotene-linoleic acid assay, chelating activity and reducing power of the extracts; and antimicrobial evaluation by micro-dilution assay and inhibition of Candida albicans blastospore germination. The major constituents of EO were β-caryophyllene (15.2%), α-pinene (10.2%) and 2,3,6-trimethylbenzaldehyde (9.3%) for E. amethystinum and caryophyllene oxide (27.9%), bicyclogermacrene (13.2%) and germacrene D (8.2%) for E. alpinum. The methanol extracts of both species showed a broad spectrum of antibacterial and antifungal activity with minimum inhibitory concentrations (MIC) less than or equal to 1.944 and 1.11 mg/mL, respectively.

Potential insecticidal activity of four essential oils against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

Oils extracted from Cymbopogon citratus, Lantana camara, Artemisia camphorata, and Imperata cylindrica plants were used as potential insecticides against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae). The phytochemical composition of the isolated oils was identified by gas chromatograph-mass spectrometry (GC-MS). Oil contact toxicities were evaluated against the adults of S. oryzae. The activities of acetylcholinesterase (AChE), alkaline phosphatase (ALP), and transaminases enzymes (AST) were measured. L. camara oil (LC50 = 9.81 mg/cm2) demonstrated the highest effect, followed by C. citratus oil (LC50 = 10.89 mg/cm2), A. camphorata EO (LC50 = 16.12 mg/cm2), and I. cylindrica oil (LC50= 36.85 mg/cm2) against the adults of S. oryzae. The inhibition percentages of AChE were 38.8, 41.7, 35.0, and 27.2%; ALP were 42.4, 49.3, 28.1, and 18.7%; AST were 33.9, 38.7, 20.8, and 11.8%; and ALT were 22.7, 30.5, 14.6, and 9.6% after treated S. oryzae with oils from C. citratus, L. camara, A. camphorata and I. cylindrica, respectively. The highest abundant compounds in C. citratus were geranial (25.95%), nerylacetal (8.85%), and neral (8.45%), in L. camara were caryophyllene (12.2%), and 3-elemene (8.89%), in A. camphorata were germacrene D-4-ol (20.83%), and borneol (19.47%), and in I. cylindrica were 5-phenylundecane (10.68%), and 6-phenyldodecane (8.70%).