Influence of different extraction temperatures and methanol concentractions on flavonoid content af Acacia auriculiformis and its antifungal and antioxidant activities

• Main Author: Tham, Mun Wai
• Format: Thesis
• Language: English; English
• Published: 2014
• Subjects: QK710-899 Plant physiology
• Online Access: https://eprints.ums.edu.my/id/eprint/38938/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/38938/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/38938/

Acacia auriculiformis is a fast growing tree species widely grown in plantations. It contains an abundance of natural products including flavonoids possessing antioxidant, antifungal and other biological activities. These flavonoids can only be fully utilized after it is extracted optimally. With this in mind, the main objectives of this study were to determine the optimum extraction temperatures and methanol solvent concentrations on the A. auriculiformis heartwood (HW) and bark (B) flavonoids extraction yield and its antioxidant and antifungal activity. The wood samples were collected, air dried under shelter for 2 weeks, flaked, grinded and sieved to a pulverized form. These pulverized wood samples were extracted in a ratio of 1:20 [pulverized samples (g): methanol solvent (mL)] at 50 rpm for 3 hours in a water bath shaker with different extraction temperatures (35ᵒC, 55ᵒC and 75ᵒC) and methanol solvent concentrations [55% (v/v), 65% (v/v) and 75% (v/v)]. The extraction yields [total extractives (TE), total phenolics (TP) and total flavonoids (TFlav)], antioxidant (DPPH free radical scavenging activity) and antifungal (mycelia growth inhibition) activities of these extracts were then evaluated. The antifungal activity of the extracts were done against the following wood rotting fungi; Coniophora puteana (CP), Stereum ostrea (SA), Pycnoporus sanguineus (PS),Trametes spp (M) and Microporus xanthopus (MX). The results showed that an increase in the extraction temperatures and methanol solvent concentrations increases the A. auriculiformis heartwood and bark extraction yields where the optimum extraction yields [HW (TE–9.81%, TP–75.44% and TFlav–36.64%) and B (TE–18.89%, TP–87.18% and TFlav–99.10%)] were achieved at an extraction temperature of 75ᵒC with a 75% methanol solvent concentration. Statistical analysis using Pearson correlation coefficient also indicated that there is a positive correlation between the extraction temperatures and methanol solvent concentrations with the extraction yields. The extracts extracted at an extraction temperature of 75ᵒC with a 75% methanol solvent concentration also exhibited the highest antioxidant [HW (IC50 value–2.23 mg/mL) and B (IC50 value–1.79 mg/mL)] and antifungal [HW (CP–31.40%, PS–12.80%, M–17.01%, MX–0.00% and SA–49.55%) and B (CP–41.60%, PS–21.27%, M–27.55%, MX–0.00% and SA–48.65%)] activity which increases with an increase in the extraction temperatures and methanol solvent concentrations. This increase in the antioxidant and antifungal activity were influenced by the increase in the extraction yields of the extracts tested which was further supported by the statistical analysis using Pearson coefficient correlation indicating that there is a positive correlation between the extraction yields with the antioxidant and antifungal activity exhibited by the extracts. These results show that A. auriculiformis heartwood and bark flavonoids extracts to be an invaluable source when incorporated into the development of an environmental friendly wood preservatives.