Naturally occurring flavoring agents

Flatheaded borers (FHB; Chrysobothris spp.), are woodboring-beetles that lay their eggs in the bark and cambium of deciduous trees in North America. Females often target stressed host-plants for oviposition. The reason why is unknown; however, stressed plants often suffer various induced phytochemical changes that may enhance larval infestation success depending on the stressor such as induced upregulation of defenses, reallocation of nutrients, and changes to volatile organic compound (VOC) emissions. To understand attraction of FHB to specific stress-induced changes, we analyzed phytochemical changes associated with stress treatments and attractiveness maple trees to FHB. Trees were stressed by: (1) chemical stress (pelargonic acid herbicide), (2) physical stress (physically removing leaves), and (3) physical stress (removing portions of bark near the root crown). After reflush of defoliated trees, bark tissues where FHB larvae feed were analyzed for nutritional changes (carbon and nitrogen), anti-nutritive changes (polyphenols and tannins) and emissions of foliar VOCs. At the end of the growing season, trees were assessed for FHB larval presence and oviposition attempts. There were more larvae and oviposition attempts on trees stressed by herbicide application. Compared to other treatments, herbicide-stressed trees had greater nitrogen and total polyphenol concentrations. Greater nitrogen may play a role in the fitness of feeding larvae, and the greater polyphenol concentration may stimulate female oviposition in the herbicide stressed trees. Females may be able to locate the herbicide-stressed trees by using volatile cues such as increases in limonene, α-farnesene, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) and hexenyl acetate. [1]

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Several volatile organic compounds were only present in either control or herbicided treatments, but many of these compounds were not statistically significant, including DMNT and sabinene. Despite not being significant, DMNT contributed to much of the variation that was found between the treatments (Table 3). Because several VOCs or the ratio of the VOCs could be important for host selection, compounds that were not statistically significant in the ANOVA cannot be excluded from host selection importance if they were important to the overall plume of the tree. From the study findings, we can imagine three possible scenarios about the role these compounds might play in host selection by Chrysobothris. (1) The presence of specific compounds may act as a susceptible host cue (α-thujene, α-farnesene, bornyl chloride, methyl salicylate, caprolactam, caryophyllene, and DMNT). (2) The absence of specific compounds may act as a susceptible host cue (sabinene, 3-carene, and β-ocimene). (3) Changes in the percentages of specific VOC compounds may act as a susceptible host cue (α-pinene, β-ocimene, hexenyl acetate, limonene, and linalool).
These three assumptions offer directions for future experiment to test the responsiveness of FHB to specific compounds. Physiological methods such as electroantennography can be used to narrow down the list of compounds that these borers can detect before attraction assays. However, to date, it has been difficult to collect the quantity of beetles necessary to sacrifice for this method of analysis. The GC-EAD analysis performed on a different buprestid, emerald ash borer, revealed at least 16 antennally-active compounds from their host plant, Fraxinus mandshurica Rupr., including: hexanal, (E)-2-hexenal, (Z)-3-hexen-1-ol, 3-methyl-butylaldoxime, 2-methyl-butylaldoxime, (Z)-3-hexen-1-yl acetate, hexyl acetate, (E)-β-ocimene, linalool, 4,8-dimethyl-1,3,7-nonatriene (DMNT), and E,E-α-farnesene (Rodriguez-Saona et al. 2006). Some of the compounds are also present in the herbicide stressed maple emissions such as (Z)-3-hexen-1-yl acetate, (E)-β-ocimene, linalool, 4,8-dimethyl-1,3,7-nonatriene (DMNT), and E, E-α-farnesene, and could potentially be signals for FHB if the olfactory receptors are conserved within Buprestidae [1].

[1]. Herbicide Stress Induces beetle Oviposition on Red Maples. J Chem Ecol. 2024 Aug 26;50(9-10):515–528.

(E)-beta-ocimene is a beta-ocimene that consists of octa-1,3,6-triene bearing two methyl substituents at positions 3 and 7 (the 3E-isomer). It has a role as a plant metabolite.
beta-Ocimene has been reported in Camellia sinensis, Salvia rosmarinus, and other organisms with data available.
See also: Cannabis sativa subsp. indica top (part of).

C10H16

136.23

136.125

3779-61-1

13877-91-3

5281553

Colorless to light yellow liquid

0.776g/cm3

175.2ºC at 760mmHg

46.9ºC

1.458

3.475

0

0

3

10

155

0

CC(=CC/C=C(\C)/C=C)C

IHPKGUQCSIINRJ-CSKARUKUSA-N

InChI=1S/C10H16/c1-5-10(4)8-6-7-9(2)3/h5,7-8H,1,6H2,2-4H3/b10-8+

(3E)-3,7-dimethylocta-1,3,6-triene

(E)-beta-ocimene; 3779-61-1; (3E)-3,7-dimethylocta-1,3,6-triene; trans-beta-Ocimene; Ocimene trans-beta-form; 3,7-dimethyl-1,3E,6-octatriene; 1,3,6-Octatriene, 3,7-dimethyl-, (E)-; UNII-38BQ4UYY06;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Typically soluble in DMSO (e.g. 10 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)