Monoacetalization of Unprotected Sucrose with Citral And Ionones1

Mite color alteration and acaricidal activity of 3,7-dimethyl-2,6-octadienal and its structural analogues against the stored food pest mite Tyrophagus putrescentiae

Acaricidal activities of the active component isolated from Melissa officinalis oil and its structural analogues against Tyrophagus putrescentiae were evaluated using fumigant and contact bioassays. The structure of 3,7-dimethyl-2,6-octadienal purified from M. officinalis oil was elucidated with EI-MS, ¹H- and ¹³C-NMR, ¹H-¹H COSY, and DEPT-NMR. Based on the LD₅₀ values of 3,7-dimethyl-2,6-octadienal analogues in fumigant and contact bioassays, respectively, 2,4-octadienal showed the highest activity (LD₅₀ = 2.09 µg/cm³ and 11.08 µg/cm²), followed by 3,7-dimethyl-6-octenal (3.60 µg/cm³ and 29.34 µg/cm²), 3,7-dimethyl-2,6-octadienal (6.18 µg/cm³ and 36.17 µg/cm²), 2-octenal (7.45 µg/cm³ and 47.36 µg/cm²) and M. officinalis oil (8.89 µg/cm³ and 23.83 µg/cm²). Comparing the acaricidal activities of the aldehyde group based on the degree of unsaturation, 2,4-octadienal containing two double bonds was more potent than 2-octenal with a single double bond. Based on the acaricidal activities of the methyl group, on the other hand, 3,7-dimethyl-6-octenal containing a single double bond was more acaricidal than 3,7-dimethyl-2,6-octadienal with two double bonds. These results indicate that 3,7-dimethyl-2,6-octadienal analogues are useful to control food mites.

Acaricidal target and mite indicator as color alteration using 3,7-dimethyl-2,6-octadienal and its derivatives derived from Melissa officinalis leaves

Toxicities and color deformation were evaluated of essential oils of Melissa officinalis cultivated in France, Ireland, and Serbia and their constituents, along with the control efficacy of spray formulations (0.25, 0.5, and 1%) containing M. officinalis oils cultivated in France and its main compound against Dermatophagoides farinae and D. pteronyssinus adults. In a contact + fumigant bioassay, M. officinalis oil (France) was more active against D. farinae and D. pteronyssinus, compared to M. officinalis oils (Ireland and Serbia). Interestingly, color alteration of D. farinae and D. pteronyssinus was exhibited, changing from colorless to golden brown through the treatment with M. officinalis oils. The acaricidal and color alteration principle of three M. officinalis oils was determined to be 3,7-dimethyl-2,6-octadienal. M. officinalis oil (France) and 3,7-dimethyl-2,6-octadienal were significantly more effective in closed containers than in open containers, indicating that their acaricidal route of action was largely a result of vapor action. Sprays (0.5 and 1%) containing 3,7-dimethyl-2,6-octadienal and 1% spray containing M. officinalis oil (France) resulted in 100% mortality and color alteration against D. farinae and D. pteronyssinus. These results indicated that M. officinalis oil and 3,7-dimethyl-2,6-octadienal could be developed as a suitable acaricidal and mite indicator ingredient for the control of dust mites.

Synthesis of alpha-lactosyl-(1-->3)-L-glycero-alpha-D-manno-heptopyranoside, a partial oligosaccharide structure expressed within the lipooligosaccharide produced by Neisseria gonorrhoeae strain 15253

The glycosyl donor, hepta-O-benzyl-beta-lactosyl trichloroacetimidate (4) was prepared by treating hepta-O-benzyl-lactose with trichloroacetonitrile in the presence of potassium carbonate. The acceptor, methyl 2-O-benzyl-4,6-O-benzylidene-7,8-dideoxy-alpha-D-manno-oct-7-enopyranoside (8) was synthesized by hydrolysis of a 3,4-butane diacetal of methyl L-glycero-alpha-D-manno-oct-enopyranoside and subsequent benzylidenation. Glycosidation of the donor 4 with the acceptor 8 in 1,4-dioxane using Me(3)SiOTf as a promoter for 1 h at room temperature gave methyl (2,3,4,6-tetra-O-benzyl-beta-D-galactopyranosyl)-(1-->4)-(2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl)-(1-->3)-2-O-benzyl-4,6-O-benzylidene-7,8-dideoxy-alpha-D-manno-oct-7-enopyranoside (9) as a major product (59%). The oct-enopyranoside moiety of the trisaccharide 9 was converted to a heptopyranoside (80%) by oxidative cleavage with OsO(4)-NaIO(4) and subsequent reduction. Hydrogenolysis of the resulting trisaccharide and subsequent acetylation gave the peracetate of alpha-lactosyl-(1-->3)-Hep. Deacetylation of the peracetate afforded the title trisaccharide.