A purified lectin with larvicidal activity from a woodland mushroom, Agaricus semotus Fr.

This study investigated the larvicidal activity on Culex quinquefasciatus of lectin purified from fresh fruiting bodies of woodland mushroom, Agaricus semotus. A. semotus lectin (ASL) was purified via ion-exchange chromatography on DEAE-cellulose A-25 and size exclusion chromatography on Sephadex G-100 matrix. Molecular weight (16.6 kDa) was estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The effects of temperature, pH, metal chelation- and larvicidal activity of ASL were also investigated. The ASL indifferently agglutinated the erythrocytes of the human ABO blood system and was stable at acidic pH and below 50 °C whereas 66% of its activity was lost at 60 °C with complete inactivation at 70 °C. ASL is a metalloprotein requiring barium ion as chelation of metals by 50 mM EDTA rendered the lectin inactive, while the addition of BaCl2, among other metal salts, restored the activity. ASL showed larvicidal activity against C. quinquefasciatus larvae after 24 h with a mortality of 5 and 95% at 5 and 25 mg/mL respectively, and LC50 of 13.80 mg/mL. This study concluded that purified A. semotus lectin showed impressive larvicidal activity, which could be exploited in its development as an insecticidal agent

MOLLUSCIDIAL, INSECTICIDAL AND PISCICIDAL ACTIVITIES OF BARRINGTONIA RACEMOSA

The aqueous, methanol, chloroform, ethyl acetate, petroleum ether extracts of Barringtonia racemosa Blume pericarp and seed were evaluated for molluscicidal, larvicial and pisicidal activity against Biomphalaria glabrata, larvae of Aedes aegypti and fish (Clarias lazera and Tilapia nilotica) respectively. The mollusciicidal, larvicidal and piscicidal assays involved incubation of B. glabrata snails, larvae of A. aegypti and fish with extracts of the fruit and seed of B. racemosa compared with niclosamide and T. tetraptera. The pericarp extracts contain more potent molluscicidal components (LC 50 =367.3 — 625.0 ppm) than the seed extracts of the fruit (LC50= 530.53 - 704.27 ppm). The rank order of toxicity for the pericarp extracts tested was for the snails: CHCl3 extract 367.3 ppm >Ethyl acetate extract 390.3 ppm. > methanol extract 530.4 ppm > petroleum ether extract 704.27 ppm. The larvicidal active agents are higher in the seed extracts (LC50 = 588.44 — 1,604.2 ppm) than in the pericarp extracts of the fruit (LC50 = 1,507.0 — 4,000.0 ppm). The rank order of toxicity of the seed extract for the larvae of A. aegypti was: CHCl3 extract 588.44 ppm > MeOH extract 762.5 ppm > petroleum ether extract 1,244.2 ppm > Ethyl acetate extract 1,604.2 ppm. The C. lazera was more resistant to Niclosamide, aqueous extracts of the pericarp and Tetrapleura tetraptera than T. nilotica. These biological activities suggest possible role for B. racemosa in the control of snail intermediate hosts of schistosomiasis and dengue fever. Key Words: Barringtonia racemosa, Leeythidaceae, Aedes aegypti, Dengue, Biomphalaria glabrata, mollusicides, schistosomiasis, piscicides Nig. J. Nat Prod. And Med. Vol.5 2001: 56-5