BIOPESTICIDE POTENTIAL OF (7R)-TRANS, TRANS-NEPETALACTONE AND CIS-LACHNOPHYLLUM ESTER IN CONTROL OF MUSTARD APHID, LIPAPHIS ERYSIMI (KALT.)

(7R)-trans, trans-nepetalactone; a monoterpene iridoid (1) and acetylenic compound named cis-lachnophyllum ester (2) were isolated from the essential oils of Nepeta elliptica and Erigeron annuus, respectively and characterized using a combination of their spectral data (1D-and 2D-NMR, MS, IR). Compound 1 and 2 were tested for biopesticide activity against mustard aphid, Lipaphis erysimi (Kalt.). Compound 1 exhibited high insecticidal activity towards L. erysimi with LC50 values of 2.18 and 2.73 mg/mL; LT50 values of 15.24 and 17.18 h. Compound 2 also displayed significant insecticidal activity having LC50 values of 0.85 and 4.70 mg/mL; LT50 values of 13.25 and 26.2 h. The activity of compounds 1 and 2 were comparable with synthetic pesticide, monocrotophos used as positive control and thus has potential as natural pesticides for use in economically important crops.

Diastereoselective Synthesis of N-Protected β-Amino-α-hydroxyacids (Norstatines) from Urethane N-Carboxyanhydrides (UNCAs)

β-Amino-α-hydroxyacids (norstatines) are prepared from urethane N-protected carboxyanhydrides (UNCAs); the key step is the diastereoselective reduction of a keto-acetylenic compound, which lead is, with syn diastereoselectivity, to the corresponding propargylic alcohol.

Chemical Structure-Odor Correlation in a Series of Synthetic n-Nonen-1-ols

In order to elucidate chemical structure-odor correlation in the all isomers of n-nonen-1- ols, an entire series of these alcohols were synthesized stereo-selectively in high purity. For unequivocal syntheses of them, geometrically selective hydrogenation of the respective acetylenic compound was adopted. The synthesized alcohols were converted to their 3,5-dinitrobenzoate derivatives with 3,5-dinitrobenzoyl chloride, and then purified by repeated recrystallization. Chemical structure-odor correlations in all the isomers of n-nonen-1-ols were elucidated by introducing a novel method to evaluate odor characteristics and by treating the obtained data statistically with the principal component analysis method (Cramer et al., 1988). The odor profiles of the tested compounds were attributable largely to the positions of the carbon- double bond. The geometries of compounds had only a little effect. With the principal component analysis, the odor profiles of the series of compounds were successfully integrated into the first and the second principal components. The first component (PC-1) consisted of combined characteristics of fruity, fresh, sweet, herbal and oily-fatty, in which herbal and oily-fatty were conversely correlated each other to the position of double-bond of the tested compounds. Of these, only (6Z)-nonen-1-ol deviated markedly from the correlation, indicative of some special interaction between the spatial structure of this compound and the sensory machinery of human.

Reactions of glutamate semialdehyde aminotransferase (glutamate-1-semialdehyde 2,1 aminomutase) with vinyl and acetylenic substrate analogues analysed by rapid scanning spectrophotometry

The reactions occurring when glutamate-1-semialdehyde amino-transferase (glutamate-1-semialdehyde 2,1 aminomutase, EC 5.4.3.8) was treated with two potential mechanism-based inactivators, namely 4-aminohex-5-enoate and 4-aminohex-5-ynoate, have been investigated by monitoring rapid transient changes in the absorption spectrum of the enzyme's prosthetic group, pyridoxal 5′-phosphate. In both cases a short-lived chromophore absorbing maximally at about 500 nm was formed in a few milliseconds. In the case of the vinyl analogue (4-aminohex-5-enoate) this chromophore, considered to be a quinonoid intermediate, converted rapidly into the pyridoxamine phosphate form of the co-enzyme in a single turnover which was accompanied by negligible inactivation. However, slow inactivation of the enzyme by this compound was observed when the enzyme was made to undergo multiple turnovers by including the efficient aldehyde substrate, succinic semialdehyde. The acetylenic compound, aminohexynoate, produced more complex spectral changes with the consecutive formation of compounds absorbing maximally at 496 nm, 450 nm, 564 nm and 330 nm. The enzyme was 90% inactivated by aminohexynoate within 10 s and thereafter lost no further activity unless aldehyde substrate was added. Mechanisms and kinetic constants consistent with the observations are proposed for each compound. The observation that the acetylenic compound is a much more potent inactivator than its vinyl analogue is attributed to the occurrence of a conjugated allene as intermediate.