Biological effects of essential oils - A review

In recent years, the use of essential oils (EOs) derived from aromatic plants as low-risk insecticides has increased considerably owing to their popularity with organic growers and environmentally conscious consumers. EOs are easily produced by steam distillation of plant material and contain many volatile, low-molecular-weight terpenes and phenolics. The major plant families from which EOs are extracted include Myrtaceae, Lauraceae, Lamiaceae, and Asteraceae. EOs have repellent, insecticidal, and growth-reducing effects on a variety of insects. They have been used effectively to control preharvest and postharvest phytophagous insects and as insect repellents for biting flies and for home and garden insects. The compounds exert their activities on insects through neurotoxic effects involving several mechanisms, notably through GABA, octopamine synapses, and the inhibition of acetylcholinesterase. With a few exceptions, their mammalian toxicity is low and environmental persistence is short. Registration has been the main bottleneck in putting new products on the market, but more EOs have been approved for use in the United States than elsewhere owing to reduced-risk processes for these materials.

Essential oils in insect control: low-risk products in a high-stakes world.

The essential oil extracted from the dried flower buds of clove, Eugenia caryophyllata L. Merr. & Perry (Myrtaceae), is used as a topical application to relieve pain and to promote healing and also finds use in the fragrance and flavouring industries. The main constituents of the essential oil are phenylpropanoids such as carvacrol, thymol, eugenol and cinnamaldehyde. The biological activity of Eugenia caryophyllata has been investigated on several microorganisms and parasites, including pathogenic bacteria, Herpes simplex and hepatitis C viruses. In addition to its antimicrobial, antioxidant, antifungal and antiviral activity, clove essential oil possesses antiinflammatory, cytotoxic, insect repellent and anaesthetic properties. This short review addresses the chemical composition and biological effects of clove essential oil, and includes new results from GC/MS analysis and a study of its antimicrobial activity against a large number of multi-resistant Staphylococcus epidermidis isolated from dialysis biomaterials.

The chemical composition and biological activity of clove essential oil, Eugenia caryophyllata (Syzigium aromaticum L. Myrtaceae): a short review.

Eucalyptus essential oil as a natural pesticide

A review of botanical phytochemicals with mosquitocidal potential.

The insecticidal activity of materials derived from the fruits of Piper nigrum against third instar larvae of Culex pipiens pallens, Aedes aegypti, and A. togoi was examined and compared with that of commercially available piperine, a known insecticidal compound from Piper species. The biologically active constituents of P. nigrum fruits were characterized as the isobutylamide alkaloids pellitorine, guineensine, pipercide, and retrofractamide A by spectroscopic analysis. Retrofractamide A was isolated from P. nigrum fruits as a new insecticidal principle. On the basis of 48-h LC(50) values, the compound most toxic to C. pipiens pallens larvae was pipercide (0.004 ppm) followed by retrofractamide A (0.028 ppm), guineensine (0.17 ppm), and pellitorine (0.86 ppm). Piperine (3.21 ppm) was least toxic. Against A. aegypti larvae, larvicidal activity was more pronounced in retrofractamide A (0.039 ppm) than in pipercide (0.1 ppm), guineensine (0.89 ppm), and pellitorine (0.92 ppm). Piperine (5.1 ppm) was relatively ineffective. Against A. togoi larvae, retrofractamide A (0.01 ppm) was much more effective, compared with pipercide (0.26 ppm), pellitorine (0.71 ppm), and guineensine (0.75 ppm). Again, very low activity was observed with piperine (4.6 ppm). Structure-activity relationships indicate that the N-isobutylamine moiety might play a crucial role in the larvicidal activity, but the methylenedioxyphenyl moiety does not appear essential for toxicity. Naturally occurring Piper fruit-derived compounds merit further study as potential mosquito larval control agents or as lead compounds.

Larvicidal activity of isobutylamides identified in Piper nigrum fruits against three mosquito species

Commercial plant essential oils obtained from 11 Myrtaceae plant species were tested for their antifungal activity against Phytophthora cactorum, Cryponectria parasitica and Fusarium circinatum. Good antifungal activity against Phytophthora cactorum was achieved with the essential oil derived from Leptospermumpetersonii at 28 × 10−3 mg/ml air concentration. Inhibition rates of Eucalyptus citriodora and Melaleuca quinquenervia were 35.4% and 33.6% at 28 × 10−3 mg/ml air concentration, respectively. In a test with C. parasitica, inhibition rates of E. citriodora and L. petersonii were 29.4% and 38.5%, respectively. Only L. petersonii essential oil showed antifungal activity against F. circinatum. Analysis by gas chromatography–mass spectrometry led to identification of 16, 15 and 12 compounds, respectively, in the oils of L. petersonii, M. quinquenervia and E. citriodora. The antifungal activity of the identified compounds was tested individually using standard or synthesized compounds. The inhibition rates of citronellol, neral, geraniol and geranial were 100% against P. cactorum at 28 × 10−3 mg/ml air concentration. In a test with C. parasitica, the inhibition rates of neral and geranial were 61.7% and 68.9% at 28 × 10−3 mg/ml air concentration. Copyright © 2008 John Wiley & Sons, Ltd.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/ffj.1850

Antifungal activity of Myrtaceae essential oils and their components against three phytopathogenic fungi

The insecticidal and fumigant activities of Cinnamomum cassia (Blume) bark-derived materials against the oak nut weevil (Mechoris ursulus Roelofs) were examined using filter paper diffusion and fumigation methods and compared to those of the commercially available Cinnamomum bark-derived compounds (eugenol, salicylaldehyde, trans-cinnamic acid, and cinnamyl alcohol) The biologically active constituent of the Cinnamomum bark was characterized as trans-cinnamaldehyde by spectroscopic analysis In a test with the filter paper diffusion method, trans-cinnamaldehyde showed 100 and 833% mortality at rates of 25 and 10 mg/filter paper, respectively At 25 mg/paper, strong insecticidal activity was produced from eugenol (900% mortality) and salicylaldehyde (88 9%), whereas trans-cinnamic acid revealed moderate activity (733%) At 5 mg/paper, weak insecticidal activity (500%) was produced from cinnamyl alcohol In a fumigation test, the Cinnamomum bark-derived compounds were much more effective against M ursulus larvae in closed cups than in open ones These results indicate that the insecticidal activity of test compounds was attributable to fumigant action, although there is also significant contact toxicity As a naturally occurring insect-control agent, the Cinnamomum bark-derived materials described could be useful as a new preventive agent against damage caused by M ursulus

Insecticidal and fumigant activities of Cinnamomum cassia bark-derived materials against Mechoris ursulus (Coleoptera: attelabidae).

Plant essential oils from 20 plant species were tested for their insecticidal activity against larvae of Lycoriella ingenua (Dufour) (Diptera: Sciaridae) by using a fumigation bioassay. Good insecticidal activity (>90%) against larvae of L. ingenua was achieved with essential oils of caraway seed Carum carvi (L.)], lemongrass [Cymbopogon citratus (D.C.) Stapf.], mandarine (Citrus reticulate Blanco), nutmeg (Myristica fragrans Houtt), cade (Juniperus oxycedrus L.), spearmint (Mentha spicata L.), cumin (Cuminum cyminum L.), and thyme red [Thymus vulgaris (L.)] oils at 30 X 10-3 mg/1 air. Among them, caraway seed, spearmint, cumin, and thyme red essential oils were highly effective against L. ingenua at 20 x 10(-3) mg/ml air. Analysis by gas chromatography-mass spectrometry led to identification of 4, 9, 8, and 17 compounds from caraway seed, spearmint, cumin, and thyme red oils, respectively. These compounds were tested individually for their insecticidal activities against larvae of L. ingenua, and compared with the toxicity of dichlorvos. Carvacrol, thymol, linalool, cuminaldehyde, p-cymen, terpinen-4-ol, and carvone was effective at 10 x 10(-3) mg/l. The insecticidal activity of dichlorvos was 60% at 10 x 10(-3) mg/ml. Effects of four selected plant essential oils on growth of oyster mushroom, Pleurotus ostreatus, also were investigated.

https://bioone.org/journals/journal-of-economic-entomology/volume-101/issue-1/0022-0493(2008)101[139:TOPEOA]2.0.CO;2/Toxicity-of-Plant-Essential-Oils-and-Their-Components-Against-Lycoriella/10.1603/0022-0493(2008)101[139:TOPEOA]2.0.CO;2.pdf

Il-Kwon Park

Papers

Larvicidal activity of isobutylamides identified in Piper nigrum fruits against three mosquito species

Antifungal activity of Myrtaceae essential oils and their components against three phytopathogenic fungi

Insecticidal and fumigant activities of Cinnamomum cassia bark-derived materials against Mechoris ursulus (Coleoptera: attelabidae).

Toxicity of Plant Essential Oils and Their Components Against Lycoriella ingenua (Diptera: Sciaridae)

Nematicidal activity of monoterpenoids against the pine wood nematode (Bursaphelenchus xylophilus)