3. Extraction and preliminary phytochemical analyses 1 Introduction
4.5 Conclusion
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acetone and methanol as extracts both had lower content in phenolic, tannin and flavonoid; hence, they have the lower antioxidant activity. The absorbance of DPPH radical decreases as the concentration increases. This is because of the reaction between antioxidant and radical molecules, which results in the radical being scavenged by hydrogen donation (Bhalodia et al., 2013). Antioxidants offer an alternative method for both treating and preventing chronic disorders. Due to their oxidative activity, phenolic compounds have the potential to prevent and treat a wide range of oxidative stress-related disorders (Sofowora et al., 2013). Phytochemicals with antioxidant properties are needed so that plant products can be effective in treating human diseases such TB (Kumar et al., 2021).
The quantification of antioxidants was done using the ferric reducing power assay and the ascorbic acid was used as control. The assay was based on the reduction of Fe3+/ ferricyanide complex to the Fe2+/ ferrous form, which acts as a potential indicator of antioxidant activity. In the plant extract, hexane had the highest reducing capacity while acetone had the least due to their hydrogen donating ability (Figure 4.3). The hexane extract acts as an electron donor which reacts with free radicals to convert them into more stable molecules and end the free radical chain reactions (Irshad et al., 2012). The absorbance increases with an increase in concentrations which indicate the antioxidant activity; so, the reducing power of the plant extracts and ascorbic acid increase as the concentration increases. There is a relationship between the phenolic content and the antioxidant activity; hence, the extract that had the highest phenolic content had the highest reducing capacity, which indicated the antioxidant activity. Kudumela and Masoko (2018) evaluated antioxidant activity using the same method, where D rotundifolia had the highest reducing power when compared to other plants. The antioxidant activity was due to the flavonoids and phenolics that had been identified from the leaves.
64 4.6 References
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67 Chapter 5
5. Antimycobacterial activity and antibiofilm assays