Triterpenoids from Acacia ataxacantha DC: antimicrobial and antioxidant activities

Abstract

BackgroundAcacia ataxacantha is a medicinal specie used extensively in traditional medicine of Benin republic to treat infectious diseases. Our previous study showed interesting antibacterial and antifungal activities against six strains of bacteria and six strains of fungi. The aim of this study was to investigate the antimicrobial and antioxidant activities of compounds isolated from A. ataxacantha.MethodsChromatographic and spectroscopic methods were used to isolate and identify three compounds (1–3) from the bark of A. ataxacantha. Phytochemical investigation of A. ataxacantha (Fabaceae) led to the isolation of three triterpenoids (1–3). The structure of isolated compounds was established by differents spectroscopic methods such as UV, 1H NMR, 13C NMR, 2D NMR and Mass. All isolated compounds were tested for antimicrobial activity using agar disc-diffusion and microdilution methods. The radical scavenging activity of isolated compounds was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method.ResultsPhytochemical investigation led to the isolation and identification of lupeol (1), betulinic acid (2) and betulinic acid-3-trans-caffeate (3). Moderate antimicrobial activity was obtained with compound 3 against methicillin-resitant Staphylococcus aureus, Enterococcus feacalis and Pseudomonas aeruginosa with MIC value of 25 μg/ml and Staphylococcus aureus (MIC of 50 μg/ml). Compounds 3 was more active against Staphylococcus epidermidis and Candida albicans with a MIC value of 12.5 μg/ml in boths cases. Compounds 3 had also interesting antioxidant activity with an IC50 of 3.57 μg/ml compared to quercetin (1.04 μg/ml).ConclusionThe overall results of this study provide evidence that the compound 3, isolated from A. ataxacantha, exhibit antimicrobial activity against Gram-positive and Gram-negative bacteria and yeast, especially against C. albicans.

Review of Ethnopharmacology and phytochemistry of <i>Acacia ataxacantha</i>

“…The strongest ferric reducing ability was found in ethyl acetate extract with value of 1273.6 µmol AAE g -1 , followed by methanol (849.1 µmol AAE g -1 ), hydroalcoholic (816.7 µmol AAE g -1 ), dichloromethane (489.4 µmol AAE g -1 ) and nhexane (120.3 µmol AAE g -1 ) [25]. Similarly, Amoussa et al [29] evaluated antioxidant activities of betulinic acid-3-trans-caffeate 1, betulinic acid 2 and lupeol 3 compounds isolated from the bark extracts of A. ataxacantha using DPPH assay with quercetin as the standard reference. The compound, betulinic acid-3-transcaffeate 3 demonstrated significant antioxidant activities with half maximal inhibitory concentration (IC 50 ) of 3.6 μg/mL compared to value of 1.0 μg/mL exhibited against the control.…”

“…Amoussa et al [24,29] isolated betulinic acid-3trans-caffeate 1, betulinic acid 2 and lupeol 3, while Amoussa et al [30] The nutritional composition of A. ataxacantha leaves is shown in Table 2. Results from literature search focusing on the FAO or WHO dietary reference intake (DRI), recommended dietary allowance (RDA) and tolerable upper levels (UL) of the chemical elements identified from A. ataxacantha leaves is shown in Table 2.…”

“…Some major elements such as Ca, Fe, K, Mg, Mn, P, Na and Zn as determined by Daden et al [31] are within the permissible values defined by the FAO/WHO dietary limits. [24,26,29,30], antifungal [24,26,29,30], antidiabetic [23,28], anti-inflammatory [27], antioxidant [25,29,30], laxative [32] and ulceroprotective [20] activities.…”

“…Similarly, Amoussa et al [30] In another experiment, Amoussa et al [29] evaluated antifungal activities of betulinic acid-3trans-caffeate 1 isolated from the bark extracts of A. ataxacantha against Candida albicans using the microdilution method and disc diffusion assay with DMSO and fluconazole as negative and positive controls, respectively. The compound 3 exhibited some activities with MIC value of 12.5 µg/mL compared to 0.8 µg/mL exhibited against the control, and MFC value of 25 µg/mL compared to 1.6 µg/mL exhibited against the control [29].…”

Chemical constituents of the Stem Bark of Acacia ataxacantha (Fabaceae)

“…11,12 Phytochemically, triterpenoids and a new chromone have been reported. 13,14 We have previously reported the protein kinase inhibitory activity of two new Peltogynoids isolated from the chloroform extract of the stem bark of Acacia nilotica, 15 while the…”