Rhodojaponin III

Arch Insect Biochem Physiol. 2014 Jun;86(2):122-36.

Contacting is essential for oviposition deterrence of Rhodojaponin-III in Spodoptera litura.[Pubmed: 24782249]

In Lepidoptera, choosing the right site for egg laying is particularly important, because the small larvae cannot forage for alternate host plants easily. Some secondary compounds of plants have the ability to deter oviposition behaviors of insects.
METHODS AND RESULTS:
Rhodojaponin III, a botanical compound, has been reported to have intense deterring-oviposition activity against many insects, which have important implications for agricultural pest management. This study provided evidence for elucidating the perception mechanism underlying Rhodojaponin III as oviposition deterrent. In this study, the antennas of moths could not elicit notable electroantennogram responses to Rhodojaponin III, which suggested the Rhodojaponin III could not exert effects like those volatile compounds. The results of physiological experiments confirmed the Rhodojaponin III could produce the oviposition deterrence effect against moths without depending on antennas, while the physical contact was essential for perceiving the compound, which suggested that the sensilla on tarsus and ovipositor could be chemoreceptor for Rhodojaponin III. Therefore, these sensilla were investigated by scanning electron microscopy to explore their potential functions in detecting Rhodojaponin III.
CONCLUSIONS:
This study highlighted the contacting mechanism in deterring oviposition behaviors of moths by Rhodojaponin III and provided new insight for development of contact-based pest management.

PLoS One. 2013 Jul 5;8(7):e67723.

Proteomic and properties analysis of botanical insecticide rhodojaponin III-induced response of the diamondback moth, Plutella xyllostella (L.).[Pubmed: 23861792]

Rhodojaponin III, as a botanical insecticide, affects a wide variety of biological processes in insects, including reduction of feeding, suspension of development, and oviposition deterring of adults in a dose-dependent manner. However, the mode of these actions remains obscure.
METHODS AND RESULTS:
In this study, a comparative proteomic approach was adopted to examine the effect of Rhodojaponin III on the Plutella xyllostella (L.). Following treating 48 hours, newly emergence moths were collected and protein samples were prepared. The proteins were separated by 2-DE, and total 31 proteins were significantly affected by Rhodojaponin III compared to the control identified by MALDI-TOF/TOF-MS/MS. These differentially expressed proteins act in the nervous transduction, odorant degradation and metabolic change pathways. Further, gene expression patterns in treated and untreated moths were confirmed by qRT-PCR and western blot analysis. RNAi of the chemosensory protein (PxCSP) gene resulted in oviposition significantly increased on cabbage plants treated with Rhodojaponin III.
CONCLUSIONS:
These Rhodojaponin III-induced proteins and gene properties analysis would be essential for a better understanding of the potential molecular mechanism of the response to Rhodojaponin III from moths of P. xylostella.

PLoS One. 2013 Oct 14;8(10):e77295.

BdorCSP2 is important for antifeed and oviposition-deterring activities induced by Rhodojaponin-III against Bactrocera dorsalis.[Pubmed: 24155937]

Rhodojaponin III is a nonvolatile botanical grayanoid diterpene compound, which has antifeedant and oviposition deterrence effects against many kinds of insects. However, the molecular mechanism of the chemoreception process remains unknown.
METHODS AND RESULTS:
In this study, the important role of BdorCSP2 in the recognition of Rhodojaponin III was identified. The full length cDNA encoding BdorCSP2 was cloned from legs of Bactrocera dorsalis. The results of expression pattern revealed that BdorCSP2 was abundantly expressed in the legs of adult B. dorsalis. Moreover, the expression of BdorCSP2 could be up-regulated by Rhodojaponin III. In order to gain comprehensive understanding of the recognition process, the binding affinity between BdorCSP2 and Rhodojaponin III was measured by fluorescence binding assay. Silencing the expression of BdorCSP2 through the ingestion of dsRNA could weaken the effect of oviposition deterrence and antifeedant of Rhodojaponin III.
CONCLUSIONS:
These results suggested that BdorCSP2 of B. dorsalis could be involved in chemoreception of Rhodojaponin III and played a critical role in antifeedant and oviposition behaviors induced by Rhodojaponin III.

Molecules. 2011 Apr 15;16(4):3179-96.

Induction of intracellular Ca2+ and pH changes in Sf9 insect cells by rhodojaponin-III, a natural botanic insecticide isolated from Rhododendron molle.[Pubmed: 21499219]

The purpose of the present study was to characterize the effect of Rhodojaponin III (R-III) on [Ca2+](i) and pH(i) and the proliferation of Sf9 cells.
METHODS AND RESULTS:
Rhodojaponin III strongly inhibited Sf9 cells proliferation with a time- and dose-dependent manner. Flow cytometry established that Rhodojaponin III interfered with Sf9 cells division and arrested them in G2/M. By using confocal scanning technique, effects of Rhodojaponin III on intracellular free calcium ([Ca2+](i)) and intracellular pH (pH(i)) in Sf9 cells were determined. Rhodojaponin III induced a significant dose-dependent (1, 10, 100, 200 μg/mL) increase in [Ca2+](i) and pH(i) of Sf9 cells in presence of Ca2+-containing solution (Hanks) and an irreversible decrease in the absence of extra cellular Ca2+. We also found that both extra cellular Ca2+ and intracellular Ca2+ stores contributed to the increase of [Ca2+](i), because completely treating Sf9 cells with CdCl(2) (5 mM), a Ca2+ channels blocker, Rhodojaponin III (100 μg/mL) induced a transient elevation of [Ca2+](i) in case of cells either in presence of Ca2+ containing or Ca2+ free solution. In these conditions, pH(i) showed similar changes with that of [Ca2+](i) on the whole.
CONCLUSIONS:
Accordingly, we supposed that there was a certain linkage for change of [Ca2+](i), cell cycle arrest, proliferation inhibition in Sf9 cells induced by Rhodojaponin III.