Mosquito larvicidal activity of Cassia tora seed extract and its key anthraquinones aurantio-obtusin and obtusin

Abstract

BackgroundThe edible and medicinal leguminous plant Cassia tora L. (Fabaceae) is known to possess insecticidal properties against a wide range of plant-feeding insects. However, the bioactivity of extracts of this plant and their constituents against vectors of medical importance has been largely unexplored. We investigated the mosquito larvicidal activity of the seed extract and its major anthraquinones against larvae of the African malaria vector Anopheles gambiae (s.s.).MethodsThird-fourth instar larval mortality was observed after 24, 48, 72 and 96 h of exposure to varying doses of the extracts, and two anthraquinones isolates identified using liquid chromatography- quadrupole time of flight mass spectrometry (LC-QtoF-MS). The mosquito larval mortality was evaluated relative to the natural insecticide azadirachtin.ResultsFractionation of the crude extract decreased mosquito larvicidal activity, however, larvicidal activity increased with increasing dose of the treatment and exposure time. The known anthraquinones aurantio-obtusin and obtusin were identified as key larvicidal compounds. Aurantio-obtusin and obtusin, exhibited similar toxicity to larvae of A. gambiae (s.s.) with LD50 values of 10 and 10.2 ppm, respectively. However, the two anthraquinones were four- and ~ six-fold less potent than that of the crude seed extract and azadirachtin, which had comparable LD50 values of 2.5 and 1.7 ppm, respectively.ConclusionBoth aurantio-obtusin and obtusin showed mosquito larvicidal activity which were comparable to their respective fractions although they were less potent relative to the crude extract and azadirachtin. Further studies need to be conducted on C. tora for its exploitation as a potential eco-friendly tool in mosquito larval source reduction.

In Vitro Study of Antiamoebic Activity of Methanol Extracts ofArgemone mexicanaon Trophozoites ofEntamoeba histolyticaHM1-IMSS

“…Although there are no reports on the use of extracts of A. mexicana against E histolytica , some studies have evaluated extracts of this plant against other parasites, such as nematodes [ 23 ]. The aqueous extract of leaves of A. mexicana exhibits significant anthelmintic activity against Ascaridia galli at a concentration of 100 μ g/mL, and this aqueous extract has also been used as an anthelmintic against the earthworm Pheritima posthuma [ 20 ].…”

Full-Length Transcriptome Survey and Expression Analysis of Cassia obtusifolia to Discover Putative Genes Related to Aurantio-Obtusin Biosynthesis, Seed Formation and Development, and Stress Response

“…With an aim to understand the genes leading to the aurantio-obtusin biosynthesis, we carried out a short-read NGS transcriptome of the C. obtusifolia seed previously [ 81 ]. Meanwhile, a few NGS transcriptome databases have been obtained from Cassia angustifolia [ 82 , 83 ] and Cassia biscapsularis [ 84 ] in the Caesalpiniaceae family, which belong to the Cassia genus. However, this short-read NGS study was limited by either number and/or length of the generated sequence information.…”

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“…[136] Cassia tora seed extract contains anthraquinones aurantio-obtusin and obtusin which showed much potent mosquito larvicidal activity. [137] Rotenoids from Cassia tora L are also reported strong larvicidal agents. [138] Cassia siamea ethanolic leaf extracts larvicidal and repellent activities against Anopheles stephensi (An.…”