Chul-Sa Kim

Cucurbitane glucosides from Momordica charantia leaves as oviposition deterrents to the leafminer, Liriomyza trifolii.

Abstract The American serpentine leaf mining fly, Liriomyza trifolii, whose larva feeds on more than 120 plant species is well characterized by its high degree of polyphagy. Observations on the oviposition behavior by L. trifolii demonstrated that among cucurbitaceous plants, Momordica charantia is rarely attacked by L. trifolii. The methanol extract of M. charantia leaves strongly deterred the females from ovipositing on kidney bean leaves treated at a concentration of 1 g leaf equivalent extract/ml. Analysis of the polar fraction of the methanol extract of M. charantia leaves resulted in the isolation of a novel cucurbitane glucoside, 7-O- β-ᴅ-glucopyranosyl-3,23-dihydroxycucurbita-5,24-dien-19-al, named momordicine IV, along with another known compound, momordicine II. Momordicine II and IV deterred oviposition by L. trifolii significantly when bioassays were carried out on kidney bean leaves treated at 75.6 and 20.3 μg/cm2 leaf surface, respectively. There was no synergistic effect on oviposition deterrent when the two compounds were combined in their natural abundance

Probing stimulants from the rice plant towards the smaller brown planthopper, Laodelphax striatellus (Fallén) (Homoptera: Delphacidae).

When adult males of the smaller brown planthopper, Laodelphax striatellus were fed on 2% crude rice (leaf and stem ) extract containing 15% sucrose there were characteristic stylet sheaths deposited on parafilm membrane. Further bioassays with the butanol-soluble fr. of the extract revealed that it is highly effective for the insects. When the butanol fr. was charged on an ODS open column and eluted in sequence with 20, 40 and 100% m ethanol in w ater, the ODS-40% m ethanol fr. was shown as the most effective one. F urther separation of the ODS-40% methanol fr. resulted in six effective components. These components acted to stimulate very high probing response on L. striatellus only when they are combined. This activity was found to be similar to those of the ODS-40% methanol fr. and the original crude rice plant extract. Two of the active components were identified as tricin 5-O-glucoside and tricin 7-O-glucoside, respectively, through spectroscopic analyses.

A new oviposition deterrent to the leafminer, Liriomyza trifolii: cucurbitane glucoside from Momordica charantia.

A new cucurbitane glucoside, 23-O-β-D-glucopyranosyl-7-hydroxy-3-O-malonylcucurbita-5,24-dien-19-al, named momordicine V, has been isolated from Momordica charantia leaves, along with the previously reported compounds, momordicines I, II, IV and 3-O-malonylmomordicine I. The structure of the new compound was established on the basis of spectral analysis, as well as by its conversion to momordicine II by alkaline catalyzed hydrolysis. Momordicine V deterred significantly the oviposition by L. trifolii on host plant leaves treated at 26.16 μg/cm2 leaf surface

Ovipositional deterrent on mature stage of sweet pepper, Capsicum annuum, against Liriomyza trifolii (Burgess).

Abstract Liriomyza trifolii (Burgess), the American serpentine leafminer fly, is a well-known serious pest in the world. This insect species attacks plants of more than 21 families including Solanaceae plants. A sweet pepper, Capsicum annuum (Solanaceae), on mature stage, however, shows resistance to this leafminer fly. This resistance is based on the ovipositional deterrent in the sweet pepper leaf against the fly species. Based on the bioassay guided fractionation, phytol [(2E)-3,7,11,15-tetramethyl-2-hexadecen-1-ol] was isolated and identified as an ovipositional deterrent against this insect species. The yield of this compound was 815 μg/g fresh leaf of C. annuum. This compound completely deterred the females from laying their eggs on host plant leaves treated at 35.2 μg/cm2.

Antifeedants of Indian Barnyard Millet, Echinochloa frumentacea Link, against Brown Planthopper, Nilaparvata lugens (Stål)

Eight compounds isolated from Indian barnyard millet have been identified as l-malic acid, trans-aconitic acid, (+)-isocitric acid, 5-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, isocarlinoside, 2″-O-rhamnosylisoorientin, and 7-O-(2″-O-glucuronosyl)glucuronosyltricin, respectively. These compounds showed high antifeeding activity against brown planthopper only when they were combined.

Feeding Stimulants Eliciting the Probing Behavior for Peregrinator biannulipes Montrouzier et Signore (Hemiptera: Ruduviidae) from Tribolium confusum (Jacquelin du Val)

Four fatty acid methyl esters identified in the solvent extract of Tribolium confusum (Jacquelin du Val) larvae as kairomones were individually and collectively tested for probing behavior of Peregrinator biannulipes Montrouzier et Signoret. All identified fatty acid methyl eaters, methyl palmitate, methyl linolate, methyl oleate and methyl stearate, exhibited characterisitic kairomonal probing behavior of P. biannulipe toward the lure. These fatty acid methyl ester were active at 0.2 μg/lure but a synergistic effect was not observed among them. Commercially available C8-C14 even-numbered fatty acid methyl esters that were not detected in the extract of T. confusum larvae also elicited a probing behavior but their activities were weaker than those of four fatty acid methyl ester (C16:0, C18:0, C18:1 and C18:2) identified in the extract. On the other hand, C17 and C19 odd-numbered fatty acid methyl esters did not show any activity at all.

Feeding stimulant in Cinnamomum camphora for the common bluebottle, Graphium sarpedon nipponum (Lepidoptera: Papilionidae).

The acceptance of camphor tree (Cinnamomum camphora) as a host plant for the larvae of common bluebottle (Graphium sarpedon nipponum) was explained by the presence of feeding stimulants in the leaves. When the active methanol extract of C. camphora leaves was separated into hexane and water layers, both layers showed high feeding activities for the larvae of G. sarpedon nipponum. Bioassay-guided fractionation of the hexane layer resulted in the isolation of a highly active compound, which was identified as α-linolenic acid by nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry.

The evaluation of the synergistic effect of 3-(2,4-dihydroxyphenyl)propionic acid and l-ascorbic acid on tyrosinase inhibition.

Abstract 3-(2,4-Dihydroxyphenyl)propionic acid (DDPA) and l-ascorbic acid (vitamin C) show tyrosinase inhibition activity. A synergistic effect on tyrosinase inhibition was observed when the two compounds were mixed. The effect significantly decreased the IC50 value of both compounds.

Feeding stimulants for larvae of Graphium sarpedon nipponum (Lepidoptera: Papilionidae) from Cinnamomum camphora.

Abstract The feeding response of larvae of the swallowtail butterfly, Graphium sarpedon nipponum (Lepidoptera: Papilionidae), is elicited by a methanolic extract from camphor tree (Cinnamomum camphora) leaves. Based on bioassay-guided fractionation, three compounds, isolated from the methanolic extract of fresh leaves of the camphor tree, were revealed to be involved in a multi-component system of feeding stimulants. Structures of these feeding stimulants were identified as sucrose, 5-O-caffeoylquinic acid and quercetin 3-O-β-glucopyranoside by NMR and LC-MS.