title: Nor-hopanes from Zanha africana root bark with toxicity to bruchid beetles.
abstract: Zanha africana (Radlk.) Exell (Sapindaceae) root bark is used by farmers throughout sub-Saharan Africa to protect stored grain from bruchid beetles, such as Callosobruchus maculatus. Chloroform, methanol and water extracts of Z. africana root bark inhibited oviposition and caused significantly higher mortality of C. maculatus at a rate of application equivalent to that applied by farmers compared to control insects. The chloroform extract contained nor-hopanes rarely found in plants of which seven were isolated, one of which was previously known. Two of the most abundant nor-hopanes 3β,6β-dihydroxy-7β-[(4-hydroxybenzoyl)oxy]-21αH-24-norhopa-4(23),22(29)-diene and 3β,6β-dihydroxy-7β-[(4-hydroxybenzoyl)oxy]-24-norhopa-4(23),17(21)-diene were toxic to and reduced oviposition of C. maculatus in a dose dependent manner. Z. africana root bark is rich in insecticidal compounds that account for its effective use by smallholder farmers as an alternative to conventional insecticides.
authors.affiliation: Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK; Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK. Electronic address: p.stevenson@kew.org.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Stevenson
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Paul W C
authors.initials: PW
authors.lastname: Green
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Nigel C
authors.initials: NC
authors.lastname: Veitch
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Iain W
authors.initials: IW
authors.lastname: Farrell
authors.affiliation: Faculty of Agriculture, Sokoine University of Agriculture, Box 3005, Morogoro, Tanzania.
authors.forename: Paul
authors.initials: P
authors.lastname: Kusolwa
authors.affiliation: Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Belmain
mesh_terms: D017954:Africa South of the Sahara; D000818:Animals; D001517:Coleoptera / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007306:Insecticides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D010058:Oviposition / Q000187:drug effects; D024301:Plant Bark / Q000737:chemistry; D029631:Sapindaceae / Q000737:chemistry*; D014315:Triterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D014315:Triterpenes; C025206:hopane
keywords: Botanicals; Bruchid beetles; Callosobruchus maculatus; Cowpea; Fabaceae; Pesticidal plants; Post-harvest pest management; Sapindaceae; Stored product pests; Vigna unguiculata; Zanha africana