Bing Ling

Antifeedant Activity and Active Ingredients against Plutella xylostella from Momordica charantia Leaves

With the bioguided fractionation of the ethanol extracts from the leaves of Momordica charantia, we obtained two most active compounds against the feeding of the diamondback moth, Plutella xylostella larvae. The antifeedant activity of momordicine I and momordicine II against the second and the third instar larvae of Plutella xylostella were tested using leaf discs of cabbage in the laboratory. The results showed that momordicin I and momordicin II had significant antifeedant activity on the larvae of P. xylostella were tested using leaf discs of cabbage in the laboratory. The results showed that momordicin Ⅰ and momordicin Ⅱ had significant antifeedant activity on the larvae of P. xylostella, and momordicin Ⅱ was more active than momordicin Ⅰ. The concentrations for 50% antifeedant effects (AFC50) of momordicin Ⅱ against the second and the third instar larvae of P. xylostella were 76.69 and 116.24 μg L^(-1) whereas that of momordicin Ⅰ was 144.08 and 168.42 μg mL^(-1), respectively. In addition, momordicin Ⅰ and momordicin Ⅱ had significant inhibitive effect on the rate of weight gain and survival of P. xylostella larvae.

REPELLENT AND OVIPOSITION DETERRENT ACTIVITIES OF THE ESSENTIAL OIL FROM MIKANIA MICRANTHA AND ITS COMPOUNDS ON PLUTELLA XYLOSTELLA

Abstract  Repellent and oviposition deterrent activities of the essential oil from Mikania micrantha and five volatile compounds including limonene, α‐terpinene, linalool, β‐caryophylene and verbenone on the diamondback moth (DBM), Plutella xylostella, was investigated in door and in net‐house. The results showed that the essential oil of the M. micrantha had significant repellant effect (at flow 100–180 mL/min) and oviposition deterrent activity at dose 10–20 μL/seedling for the DBM. In five volatile compounds, α‐terpinene, limonene and linalool had significant effect on repellent and oviposition deterrent of the DBM moths, but verbenone and β‐caryophylene, no significantly effect was observed in repellent and oviposition deterrent.

Cucurbitane-type triterpenoids from the leaves of Momordica charantia

Phytochemical investigation of the ethanol extract from the leaves of Momordica charantia L. led to the isolation of two new (1, 2) and four known (3–6) cucurbitane-type triterpenoids. Their structures were elucidated on the basis of extensive analyses of spectroscopic data including IR, UV, MS, 1D, and 2D NMR. Also the absolute configurations of momordicines I (3) and II (4) were determined for the first time by application of the modified Moshers method, acid hydrolysis, and GC analysis.

The cytotoxicology of momordicins I and II on Spodoptera litura cultured cell line SL-1

Momordicin I and II are secondary metabolites from bitter melon (Momordica charantia L.) that are toxic to the Spodoptera litura ovary cell line (SL-1 cell). Both momordicin I and II significantly inhibited SL-1 cells proliferation. IC50 values after 24 h were 8.35 and 82.31 µg/mL, 6.11 and 77.49 µg/mL for 36 h, 4.93 and 49.42 µg/mL for 48 h for cells treated by momordicin I and II, respectively. IC50 values of the azadirachtin A control were 149.63, 54.54 and 23.66 µg/mL at 24, 36 and 48 h respectively, indicating that the cytotoxicity of momordicin I was significantly higher than that of momordicin II and azadirachtin A. Using inverted phase contrast microscopy we found that after 24 h exposure to momordicin I and II, cell shapes changed to circular, swelling increased, adherence ability declined and the cellular membrane bubbled. After 48 h exposure to momordicin I, most cells were suspended and dead; vacuole deformation and cytoplasm leakage indicated that momordicin I was more toxic to the cytoskeleton than momordicin II. Cells treated with momordicin I and II inhibited glucose absorption by 23.04 and 13.38% after 48 h and 47.60 and 20.92% after 60 h. Flow cytometry analysis suggested that SL-1 cells treated with momordicin I and II dramatically accumulated during the G2/M phase of the cell cycle, and total cell protein content increased by 56.93 and 35.81% respectively after 48 h treatment. Following treatment with momordicin I and II the karyotheca dissolved, the chromatin condensed abnormally and the nucleoli were damaged, migrated, or disappeared. The PI fluorescent value by FCM showed that the relative fluorescent intensity of SL-1 cells induced by momordicin I and II increased to 521.45 and 370.17, higher than 135.04 induced by control group treatment for 48 h. This indicated significant damage to the cytomembrane. Overall, the results demonstrate that suppression of cytoskeletal function, interference of mitotic figures and destruction of nuclear structure are effects of momordicin I and II exposure. These effects play major roles in momordicin I and II inhibition of SL-1 cells growth. The mode of action by which momordicins inhibit insect cell growth and development may be useful in the development of novel pest control formulations containing cucurbitane-type triterpene glycosides.