Isolation of Natural Compounds from Tradescantia Spathacea Sw. Leaves and Evaluation of its Antioxidant and Antibacterial Properties

Keng, Xin Yi (2023) Isolation of Natural Compounds from Tradescantia Spathacea Sw. Leaves and Evaluation of its Antioxidant and Antibacterial Properties. Masters thesis, Tunku Abdul Rahman University of Management and Technology.

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Abstract

Tradescantia spathacea Sw. is a tropical plant known for its medicinal properties. Only a few phytochemical studies have been performed on T. spathacea to date. The objectives of this study was to obtain hexane and ethyl acetate extracts from T. spathacea leaves, which were then subjected for isolation, purification, and characterization processes. Both the crude extracts and isolated compounds were evaluated for their antioxidant and antibacterial properties. Chromatographic techniques such as CC, TLC, and PTLC were used for isolation and purification, while spectroscopic techniques, including 1D (1H, 13C, and DEPT) and 2D (COSY, NOESY, HMQC, HMBC) NMR, IR, UV, and LC-MS were used for structure elucidation. Seven compounds were isolated from the leaves of T. spathacea leaves, two of which (T2 and T3) were newly identified. Seven isolated compounds comprising three chlorophylls, pheophytin a (T1), 131-hydroxy-132-carboxy-173-phytyl ester chlorin a (T2), and 131-ethoxy-132-methyl ester-173-phytyl ester chlorin a (T3); two steroids, β-sitostenone (T4), β-sitosterol (T5); along with two other compounds, 2,4-di-tert-butylphenol (T6) and 1,1'-oxybis(2,4-di-tert-butylbenzene) (T7). All isolated compounds exhibited moderate antioxidant activities, with DPPH scavenging activities ranging from 9 to 36%, and FRAP values ranging from 30 to 34 mM of Fe2+/g DW. Among the compounds, compound T6 showed the most potent antioxidant activity with 35.2 ± 0.7% of DPPH scavenging activity and a FRAP value of 34.0 ± 0.6 mM of Fe2+/g DW. Antibacterial assay results revealed that only pheophytin a T1, exhibited a weak inhibition effect against S. aureus (MIC value of 200 μg/mL) and E. coli (MIC value of 200 μg/mL). The other compounds (T2-T7) did not exhibit weak inhibitory effects (MIC value ≥ 200 μg/mL) against all selected bacteria strains, such as S. aureus, E. faecium, E. coli, and A. baumannii. None of the isolated compounds demonstrated cytotoxicity against human MRC-5 cells. These results contribute to the understanding of the medicinal properties of this plant and its potential as a source for developing novel therapeutic agents. The information and results on isolated compounds acquired from this work can be a useful resource and reference for future drug development and discovery