Evaluation of Antioxidant and Antibacterial Activities, Cytotoxicity of Acacia seyal Del Bark Extracts and Isolated Compounds

• Published in: Molecules (Basel, Switzerland) Vol. 25; no. 10; p. 2392
• Main Authors: Elmi, Abdirahman, Spina, Rosella, Risler, Arnaud, Philippot, Stéphanie, Mérito, Ali, Duval, Raphaël E, Abdoul-Latif, Fatouma Mohamed, Laurain-Mattar, Dominique
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 21.05.2020; MDPI
• Subjects: Acacia - chemistry; Acacia seyal; Acacia seyal bark; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; antioxidant activity; Antioxidants; Antioxidants - chemistry; Antioxidants - pharmacology; Ascorbic acid; Bark; Benzothiazoles - chemistry; Biphenyl Compounds - chemistry; Catechin; Chemical precipitation; Chemical Sciences; Cholesterol - analogs & derivatives; Cholesterol - chemistry; Cholesterol - isolation & purification; Corynebacterium - drug effects; Cytotoxicity; Epicatechin; Flavanols; Flavonoids; Fractionation; Fruits; in vitro antibacterial properties; Ionization; Life Sciences; MALDI-TOF; Mass spectrometry; Mass spectroscopy; Microbiology and Parasitology; Minimum inhibitory concentration; Morphology; Oleamide; Oleic Acids - chemistry; Oleic Acids - isolation & purification; Phytosterols - chemistry; Phytosterols - isolation & purification; Picrates - chemistry; Plant Bark - chemistry; Plant extracts; Plant Extracts - chemistry; Plant Extracts - pharmacology; Polyphenols; Polyphenols - chemistry; Polyphenols - pharmacology; Sitosterols - chemistry; Sitosterols - isolation & purification; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Steroid hormones; Steroids; Stigmasterol - chemistry; Stigmasterol - isolation & purification; Sulfonic Acids - chemistry; Tannins; Tannins - chemistry; Water pollution effects; Djibouti; Africa; Acacia seyal bark; polyphenols; in vitro antibacterial properties; tannins; MALDI-TOF; antioxidant activity
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules25102392

Water extract of bark is used traditionally by the population in Djibouti for its anti-infectious activity. The evaluation of in vitro antibacterial, antioxidant activities and cytotoxicity as well as chemical characterization of bark water and methanolic extracts were presented. The water extract has a toxicity against the MRC-5 cells at 256 μg/mL while the methanolic extract has a weak toxicity at the same concentration. The methanolic extract has a strong antioxidant activity with half maximal inhibitory concentration (IC ) of 150 ± 2.2 μg/mL using 1-diphenyl-2-picrylhydrazyl (DPPH) and IC of 27 ± 1.3 μg/mL using 2,2'-azino-bis 3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical methods. For ferric reducing/antioxidant power (FRAP) assay, the result is 45.74 ± 5.96 μg Vitamin C Equivalent (VCE)/g of dry weight (DW). The precipitation of tannins from methanol crude extract decreases the MIC from 64 µg/mL to 32 µg/mL against and . However, the antioxidant activity is higher before tannins precipitation than after (IC = 150 µg/mL for methanolic crude extract and 250 µg/mL after tannins precipitation determined by DPPH method). By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, the results showed that the condensed tannins consist of two types of catechin and gallocatechin-based oligomers. The fractionation led to the identification of three pure compounds: two flavanols catechin and epicatechin; one triterpene as lupeol; and a mixture of three steroids and one fatty acid: campesterol, stigmasterol, clionasterol, and oleamide.