STRUCTURAL ELUCIDATION OF TWO NEW b-CARBOLINETOXINS FROM THE DROPLETS OF Nephila clavipes WEB

MARQUES, M.R.(1), SALLES, H.C.(1), MENDES, M.A.(1), SOUZA, B.M.(1), CESAR, L.M.M.(1), KONNO, K.(1), TORMENA, C. F.(2), RITTNER, R.(2), PALMA, M.S.(1)

(1)Department of Biology,CEIS, IBRC, UNESP, CAT, (CEPID-FAPESP), Rio Claro, SP, Brazil, (2)Physical Organic Chemistry Laboratory, Chemistry Institute, UNICAMP, Campinas, Brazil.

The orb-web spiders are polyphagous animals in which the web localized compounds play a very important role in the capture of prey, specifically aqueous droplets that cover the capture threads of these webs. In our field observations, we have noted that immediately after web entrapment, prey present toxicity signs, prior to venom inoculation by the spider. This fact suggests the existence of toxins in the web of Nephila clavipes. The objectives of this research are to investigate the presence of toxins in the aqueous droplets of Nephila clavipes webs, characterize these toxins biochemically, elucidate their structures and reveal the ultra-structure of the droplets. The ultra-structure of the droplets was analyzed by transmission electron microscopy and scanning electron microscopy. The droplets present regular shape, varying among oval and elliptic shape, keeping a standard organization for whole thread extension. The sections of the droplets show that them present three deferent layers surrounding of two axial fibers. The crude extract of Nephila clavipes web was chromatographed under RP-HPLC. The chromatographic profile of the crude extract presented 6 fractions. Fraction 6 was one of the major peaks. This fraction was rechromatographed, resulting in more 5 subfractions. The subfraction 6.5 was submitted to mass spectrometry (ESI-MS and ESI-MS/MS) and H¹-NMR analysis. We have found two compounds of low molecular weight: 287 Daand 315 Da. The two new compounds were denominated of (I) 1-2-guanidinoethyl-6-hydroximethyl-1,2,3,4-tetrahydro-b-carbolineand (II) 1-4-guanidinobuthyl-6-hydroximethyl-1,2,3,4-tetrahydro-b-carboline. These compounds are natural analogous of the trypargine, a b-carbolinetoxin isolated from skin frog. Cesar (2001) found out three b-carbolinetoxins in the venom of the social spider Parawixia bistriata, which showed significative evidence of stimulation in regions of the diencephalon of Wistars rat. Taken to gather, these data indicate that these newly toxins are involved with the process of prey paralysis or death in the Nephila clavipes web.

Supported by FAPESP and CAPES

CORRESPONDENCE TO:

SOUZA, B. M., CEIS, Department of Biology, IBRC, UNESP, CAT (CEPID/FAPESP), Institute of Immunological Investigation (Millennium Institute/CNPq), Rio Claro, SP, Brasil, Email: bmsouza@hotmail.com