Tetranortriterpenes from Turraea robusta

Abstract

Anew limonoid, mzikonol [2], in addition to the known limonoids mzikonone [1], azadirone [3], 1,2-dihydroazadirone [4], and nimbolinin B [6], was isolated from the root bark of Turraea robusta. In addition, a new tetranortriterpene lactone, turranolide [51, and the known triterpene, butyrospermol [7], both possible protolimonoids, were isolated.Compounds were identified by chemical and spectroscopic methods.Turraea robusta Guerke (Meliaceae) is a small tree found in East Africa. The Zaramo tribe of Tanzania utilizes a tea prepared from the root bark of this tree, called mzikoziko in the Zaramo language, as a traditional medicine for the treatment of stomach pains and diarrhea. The leaves are used as an antidote for poisoning (1). We reported earlier the isolation and identification of a new compound, mzikonone [1], as the major tetranortriterpene (limonoid) from the MeOH extract of the root bark (2). Limonoids from two other members of this genus, Turrea floribunda and Turrea obtusifolia, have been reported (3). The latter plant was shown to contain prieurianin, while the former con-

Novel and Neuroprotective Tetranortriterpenoids from Chinese Mangrove Xylocarpus granatum Koenig

“…1,2-dihydro-3α-hydroxy-turranolide ( 8 ) was isolated as a colorless gum. Its molecular formula, C 28 H 42 O 5 , was deduced by HREIMS at m / z 481.2892, a plus of two mass units to that of turranolide ( 17 ), previously isolated from the root bark of Turraea robusta collected from Awasi, Kisumu District, Kenya 21 . The NMR spectra of 8 were similar to those of 17 , except for the presence of oxymethine signal at C-3 ( δ H 3.42, t, J = 2.8 Hz) in 1 H NMR.…”

Antiplasmodial and cytotoxic activities of the constituents of Turraea robusta and Turraea nilotica

“…Various classes of limonoids were reported from the genus Turraea with each species synthesizing more than one class of limonoids. Ring intact limonoids were reported from eight Turraea species, namely T. robusta , T. nilotica, T. cornucopia , T. parvifolia , T. floribunda , T. holstii , T. wakefieldii and T. pubescens ( Bentley et al, 1992 , Ndung’u et al, 2004 , Owino et al, 2008 , Yuan et al, 2013 ). So far, ring A seco limonoids have only been isolated from T. wakefieldii ( Ndung'u et al, 2003 ), whereas ring B seco limonoids were reported in T. floribunda, T. holstii and T. pubescens ( Mulholland et al, 1998 , McFarland et al, 2004 , Yuan et al, 2013 ).…”

“…The methanolic root bark extract of T. robusta was previously reported to possess antiplasmodial and antimalarial activities, with negligible toxicity (mice oral LD 50 >5000 mg/kg body weight) ( Irungu et al, 2007 , Gathirwa et al, 2008 ). Previous phytochemical investigations of the root bark of T. robusta led to the isolation of triterpenoids which included five limonoids ( Rajab et al, 1988 , Bentley et al, 1992 ). There are no phytochemical and antiplasmodial reports on the stem bark of T. robusta .…”

Identification of limonoids and steroids from the leaves of Turraea heterophylla (Smith) by HPLC‐ESI‐QTOF‐MS/MS methods

“…This fragmentation pathway matches the chemical structure of 1,2-dihydroazadirone (Figure 3); what structure was found in the databases Reaxys and Dictionary of Natural Products (DNP). This molecule is also a known limonoid previously isolated from the roots bark and stem bark of Turraea robusta [Rajab et al, 1988;Bentley et al, 1992] [18,19] .…”