Interspecific variability of 1,8-cineole content, phenolics and bioactivity among nine Eucalyptus taxa growing under the sub-humid bioclimate stage.

Background Eucalyptus essential oils and extracts are used since the ancient times in alternative medicine. The 1,8-cineole is the most significant constituent of Eucalyptus essential oil, while phenolic contents define the value of eucalyptus extracts. Based on the last considerations, interspecific variability of 1,8-cineole content, phenolics and antioxidant potentials among nine Eucalyptus taxa growing under the sub-humid bioclimate stage of Tunisia was investigated. Methods Essential oil profiling was assessed based on gas chromatography-mass spectrometry analysis. Total phenolic and flavonoid contents were assessed using Folin-Ciocalteau and aluminium chloride colorimetric methods, respectively. The antioxidant ability of Eucalyptus volatile metabolites and extracts was achieved based on two test systems namely DPPH and FRAP assays. Results Qualitative and quantitative variations in the composition of essential oils according to the studied taxon were shown. The total phenolic and flavonoid contents varied also significantly among the investigated samples. Based on the obtained results, the species Eucalyptus sideroxylon exhibits the highest 1,8-cineole content (76.24 ± 0.86), total phenolics and flavonoids contents (38.5 ± 1.4 mg GAE /g DW and 18.6 ± 0.3 mg RE /g DW, respectively). Moreover this species highlighted the highest free radical-scavenging ability and ferric reducing power for both essential oil and methanolic extracts. Chemometric multivariate analysis showed the classification of the nine studied taxa to three clusters. Conclusions The pattern of 1,8-cineole concentration, phenolic and flavonoid contents for the studied nine Eucalyptus species and hybrid showed E. sideroxylon species as the potential candidate for further improvement strategies regarding the production of eucalyptus essential oils and phenolics with high quality for pharmaceutical industry.

Chemical composition of Rosmarinus and Lavandula essential oils and their insecticidal effects on Orgyia trigotephras (Lepidoptera, Lymantriidae)

OBJECTIVE@#To evaluate toxic activities of essential oils obtained from Rosmarinus officinalis and Lavandula stoechas against the fourth larval instars of Orgyia trigotephras.@*METHODS@#A total of 1 200 larvae were divided into three groups I II III. Group I was to investigate the effect of extracted essential oils from these aromatic plants as gastric disturbance. Bacillus thuringiensis and ethanol were used as control group. Group II was used as contact action and Group III was used as fumigant action. Decis and ethanol were used as control group. During the three experiments, the effect of essential oils on larvae was assessed.@*RESULTS@#The chemical composition of essential oils from two medicinal plants was determined and, their insecticidal effects on the fourth larval state of Orgyia trigotephras were assessed. The two simples presented an insecticidal activity, nevertheless Rosmarinus officinalis essential oil was less efficient compared to Lavandula stoechas one are discussed.@*CONCLUSIONS@#The relationship between the chemical composition and the biological activities is confirmed by the present findings. Therefore the potential uses of these essential oils as bioinsecticides can be considered as an alternative to the use of synthetic products.

Chemical composition of Rosmarinus and Lavandula essential oils and their insecticidal effects on Orgyia trigotephras (Lepidoptera, Lymantriidae)

Objective: To evaluate toxic activities of essential oils obtained from Rosmarinus officinalis and Lavandula stoechas against the fourth larval instars of Orgyia trigotephras. Methods: A total of 1 200 larvae were divided into three groups I II III. Group I was to investigate the effect of extracted essential oils from these aromatic plants as gastric disturbance. Bacillus thuringiensis and ethanol were used as control group. Group II was used as contact action and Group III was used as fumigant action. Decis and ethanol were used as control group. During the three experiments, the effect of essential oils on larvae was assessed. Results: The chemical composition of essential oils from two medicinal plants was determined and, their insecticidal effects on the fourth larval state of Orgyia trigotephras were assessed. The two simples presented an insecticidal activity, nevertheless Rosmarinus officinalis essential oil was less efficient compared to Lavandula stoechas one are discussed. Conclusions: The relationship between the chemical composition and the biological activities is confirmed by the present findings. Therefore the potential uses of these essential oils as bioinsecticides can be considered as an alternative to the use of synthetic products.

Essential oils from two Eucalyptus from Tunisia and their insecticidal action on Orgyia trigotephras (Lepidotera, Lymantriidae).

BACKGROUND: Essential oils extracted from aromatic and medicinal plants have many biological properties and are therefore an alternative to the use of synthetic products. The chemical composition of essential oils from two medicinal plants (Eucalyptus globulus and E. lehmannii) was determined and, their insecticidal effects on the third and fourth larval stages of Orgyia trigotephras were assessed. RESULTS: Larvae were collected from Jebel Abderrahmane (North-East of Tunisia), conserved in groups of 50/box (21 × 10 × 10 cm) at a temperature of 25°C. Larvae were tested for larvicidal activities of essential oils. Each oil was diluted in ethanol (96%) to prepare 3 test solutions (S1 = 0.05%, S2 = 0.10% and S3 = 0.50%). Essential oils were used for contact, ingestion and Olfactory actions and compared to reference products (Bacillus thuringiensis and Decis). Olfactory action of essential oils shows that larvae mortality is higher than contact action, lower than ingestion action. MTM and FTM of S3 of E. lehmannii were respectively 1 h 32 min and 1 h 39 min are higher than those of E. globulus (MTM = 51 min and FTM = 1 h 22 min 34 sec). Contact action of E. lehmannii oil shows low insecticidal activity compared to E. globulus. MTM are respectively (1 min 52 sec and 1 min 7 sec), FTM are (2 min 38 sec, 1 min 39 sec), are the shortest recorded for S3, on the third stage of larvae. The fourth stage of larvae, MTM are (2 min 20 sec and 2 min 9 sec), FTM are (3 min 25 sec, 3 min 19 sec). Ingestion action of essential oils is longer than the contact action, since the time of death exceeds 60 minutes for all species. CONCLUSION: Results shows that essential oils have a toxic action on nerves leading to a disruption of vital system of insects. High toxic properties make these plant-derived compounds suitable for incorporation in integrated pest management programs.

Essential oils from two Eucalyptus from Tunisia and their insecticidal action on Orgyia trigotephras (Lepidotera, Lymantriidae)

BACKGROUND: Essential oils extracted from aromatic and medicinal plants have many biological properties and are therefore an alternative to the use of synthetic products. The chemical composition of essential oils from two medicinal plants (Eucalyptus globulus and E. lehmannii) was determined and, their insecticidal effects on the third and fourth larval stages of Orgyia trigotephras were assessed. RESULTS: Larvae were collected from Jebel Abderrahmane (North-East of Tunisia), conserved in groups of 50/box (21 × 10 × 10 cm) at a temperature of 25°C. Larvae were tested for larvicidal activities of essential oils. Each oil was diluted in ethanol (96%) to prepare 3 test solutions (S1 = 0.05%, S2 = 0.10% and S3 = 0.50%). Essential oils were used for contact, ingestion and Olfactory actions and compared to reference products (Bacillus thuringiensis and Decis). Olfactory action of essential oils shows that larvae mortality is higher than contact action, lower than ingestion action. MTM and FTM of S3 of E. lehmannii were respectively 1 h 32 min and 1 h 39 min are higher than those of E. globulus (MTM = 51 min and FTM = 1 h 22 min 34 sec). Contact action of E. lehmannii oil shows low insecticidal activity compared to E. globulus. MTM are respectively (1 min 52 sec and 1 min 7 sec), FTM are (2 min 38 sec, 1 min 39 sec), are the shortest recorded for S3, on the third stage of larvae. The fourth stage of larvae, MTM are (2 min 20 sec and 2 min 9 sec), FTM are (3 min 25 sec, 3 min 19 sec). Ingestion action of essential oils is longer than the contact action, since the time of death exceeds 60 minutes for all species. CONCLUSION: Results shows that essential oils have a toxic action on nerves leading to a disruption of vital system of insects. High toxic properties make these plant-derived compounds suitable for incorporation in integrated pest management programs.