Terpenoids from the Oleo-Gum-Resin of Boswellia serrata and Their Antiplasmodial Effects In Vitro

Planta Med. 2017 Oct;83(14-15):1214-1226. doi: 10.1055/s-0043-116943. Epub 2017 Jul 24.

Abstract

In the course of our ongoing search for new natural products as leads against protozoal diseases, the dichloromethane extract of Indian frankincense, the oleo-gum-resin obtained from Boswellia serrata, showed in vitro activity against Plasmodium falciparum. Bioactivity-guided fractionation led to the isolation of eight diterpenes: (1S,3E,7E,11R)-verticilla-3,7,12(18)-triene (1), cembrene A (2), serratol (3), 1S,3E,7R,8R,11E-7,8-epoxy-cembra-3,11-dien-1-ol (4), incensole oxide (5), rel (1S,3R,7E,11S,12R)-1,12-epoxy-4-methylenecembr-7-ene-3, 11-diol (6), isoincensole oxide (7), and isodecaryiol (8). Furthermore, 10 triterpenes, namely, oleanolic acid (9), 11-keto-β-boswellic acid (10), 3-epi-neoilexonol (11), uvaol (12), β-boswellic aldehyde (13), 5α-tirucalla-8,24-dien-3α-ol (14), isoflindissone lactone (15), isoflindissol lactone (16), rel (8R,9S,20R)-tirucall-24-ene-3β,20-diol (17), and rel (3α,8R, 9S,20R,24S)-20,24-epoxytirucalla-3,25-diol (18) as well as the sesquiterpene β-bourbonene (19), the monoterpene carvacrol (20) and the phenyl propanoids methyleugenol (21), and p-methoxycinnamaldehyde (22) were isolated. All compounds were identified by mass spectrometry and nuclear magnetic resonance spectroscopic measurements. Compounds 6, 11, and 16-18 are described for the first time. Compounds 13 - 15 are isolated as natural products for the first time, compound 8 for the first time from a plant. Antiplasmodial IC50 values and cytotoxicity against L6 rat skeletal myoblasts were determined. Isoflindissone lactone (15) was the most active compound with an IC50 of 2.2 µM against P. falciparum and a selectivity index of 18.

MeSH terms

  • Antimalarials / chemistry
  • Antimalarials / isolation & purification
  • Antimalarials / pharmacology*
  • Boswellia / chemistry*
  • Diterpenes / chemistry
  • Diterpenes / isolation & purification
  • Diterpenes / pharmacology*
  • Plasmodium falciparum / drug effects*
  • Resins, Plant / chemistry*
  • Terpenes / chemistry
  • Terpenes / isolation & purification
  • Terpenes / pharmacology*

Substances

  • Antimalarials
  • Diterpenes
  • Resins, Plant
  • Terpenes