Rhus taitensis

Abstract: Tuberculosis has become a major health problem, in particular with the emergence of extremely drug resistant tuberculosis (XDRTB). In our search for new therapeutic leads against TB, we isolated a new triterpene (1) from the plant Rhus taitensis collected in Papua New Guinea. Tetrahydroxysqualene (1) was isolated using bioassay-guided fractionation of the methanolic extract of R. taitensis leaves and twigs. The structure of tetrahydroxysqualene (1) was elucidated on the basis of HRESIMS and 1D and 2D NMR spectra. Tetrahydroxysqualene (1) exhibited antituberculosis activity with an MIC of 10.0 μg/mL, while showing only modest cytotoxicity.

Abstract: Two new triterpenoids were isolated from the leaves and twigs of Rhus taitensis. Their structures were elucidated by 1D and 2D NMR spectroscopic studies as 1,10,24,25,30-pentahydroxysqualene and dammar-20(22),24-diene-3 β,26,27-triol. Both compounds exhibited moderate antimycobacterial activities with an MIC of 45 µg/mL.

Abstract: Polynesian Lowland Rain Forest Human habitations or agricultural crops such as coconut groves, banana patches or breadfruit trees, have largely replaced most of these forests. However, a few valley forests exist. On Moorea (Society Islands) they are dominated by Inocarpus (mape) trees, which typically have large fluted trunks and intricate buttresses. Hibiscus tiliaceus is also an important component, and in less disturbed areas there are understory shrubs comprising Canthium barbatum and the endemic Ixora mooreaensis (Rubiaceae). There is a rich terrestrial and epiphytic flora with many ferns. The largest of these is the curious Angiopteris erecta, which has a huge barrel-like, erect rhizomes or corms covered in fleshy stipules and giant fronds reaching 4.5 m in length. On the valley sides there are dense tangled shrubs of Aleurites moluccana, Hibiscus tiliaceus and the endemic Rhus taitensis (Anacardiaceae). Other indigenous species on these slopes include the remarkable but rare endemic Lepinia taitensis (Apocynaceae) with it large, hanging, basket-like fruits. Inocarpus-Hibiscus forest is also characteristic of the valleys on Huahina (Society Islands), but just above this zone are stands of huge pandans together with indigenous trees such as Crossostylis biflora, Neonauclea forsteri and the endemic Xylosma suaveolens (Salicaceae).