Asma Nisar (2020) Antioxidant activity of plant and honey extract and effect of extraction process parameter. Doctoral thesis, Universiti Malaysia Sabah.
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Abstract
The identification of antioxidant compounds and their different activities from the single natural product is very common practice but the combination of two natural products and identification of their activity was very rare. Scholars have acknowledged that activities of antioxidant compounds were enhanced by the combination of natural products but there is lack of significant scientific reports about the combination of natural products. Therefore, it is necessary to assess their activity by combining different natural products. So, the foremost objective of this research is to identify the antioxidant compounds from medicinal plants namely Rhizophora apiculata {R. apiculataJ C/inacanthus nutans {C nutansJ Carica papaya {C papaya) and stingless bee honey (SBH) extract separately by HPLC, and to assess the antioxidant activity of these medicinal plants individually and with the combination of SBH by UV spectrophotometer and quite important to examine the effect of extraction condition (extraction temperature and extraction time) of combination of above plants and SBH. For this purpose, the response surface methodology (RSM) software with the central composite design (CCD) was employed and identified the relationship between the two process variables and their response variable (antioxidant activity by UV spectrophotometer and the identification of quercetin by HPLC). According to the results, gallic acid, rutin and quercetin were present in all extracts. However, the antioxidant compound, ascorbic acid was not identified in the extract of R. apiculata and C nutans but found in the C papaya leaves and SBH extract. Whereas, R. apiculata, C nutans leaves and SBH extract have kaempferol but this compound was not identified in the leaf extract of C papaya. In addition, the antioxidant activity of selected plants individually and with the combination of SBH was assessed. Based on the obtained results of this research, it has been concluded that the antioxidant activity of plants was enhanced with a combination of SBH and they exhibited low ICso values. The combination of R. apiculata and SBH had lowest ICso value which means that this combination had the highest antioxidant activity as compared to the other two combinations. Furthermore, the validation of the RSM model coefficients was performed by the analysis of the variance (ANOVA). A high R2 coefficient and low p-values ensure a satisfactory adjustment of the quadratic model to the experimental data. Moreover, the antioxidant activity and % yield of quercetin was increased with the increase in time and temperature but gradually reduced when the duration extraction time and temperature were extended above 40min and 60 °C. Based on the outcomes of these results, it has been concluded that the C nutans, R. apiculata and C papaya leaves and SBH extract have an antioxidant compound and the combination of SBH with the medicinal plants increases the antioxidant activity of plants.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Keyword: | Stingless bee honey, Clinacanthus nutans, Rhizophora apiculata, Carica papaya, Antioxidant compounds, HPLC, UV Spectrophotometer, Response surface methodology |
| Subjects: | Q Science > QD Chemistry > QD1-999 Chemistry > QD241-441 Organic chemistry > QD415-436 Biochemistry |
| Department: | FACULTY > Faculty of Engineering |
| Depositing User: | DG MASNIAH AHMAD - |
| Date Deposited: | 17 Mar 2025 11:09 |
| Last Modified: | 17 Mar 2025 11:09 |
| URI: | https://eprints.ums.edu.my/id/eprint/43228 |
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