Phytochemical Studies of Bornean Myristicaceae and Clusiaceae Species and Evaluation of their Antibacterial and Anticancer Activities

Valmiki, Maya Dawn (2025) Phytochemical Studies of Bornean Myristicaceae and Clusiaceae Species and Evaluation of their Antibacterial and Anticancer Activities. Doctoral thesis, University of East Anglia.

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Abstract

Bacterial antimicrobial resistance has emerged as one of the most pressing global health threats. The inappropriate use of antibiotics has led to the growing ineffectiveness of many frontline treatments, escalating the need for novel therapeutic agents. Amongst the most promising, yet underexplored, sources of such agents are plant natural products, particularly those derived from biodiverse ecosystems, like the tropical rainforests of Borneo. These rainforests host a wealth of ethnomedicinal plants, traditionally used to treat infections and cancers, inferring a potential source for bioactive compounds. However, despite their cultural and medicinal significance, their phytochemical and pharmacological profiles remain largely uncharacterised.

This thesis presents the isolation, structural elucidation and biological evaluation of secondary metabolites from three previously unexplored Bornean plant species: Knema membranifolia, Gymnacranthera contracta (Myristicaceae) and Garcinia caudiculata (Clusiaceae). Here, chromatographic separation and spectroscopic techniques (MS, 1D/2D NMR) were used to characterise one previously undescribed salicylic acid derivative, and twelve known phytochemicals, including seven additional salicylic acid-related compounds, two acetophenones, a resorcinol, a tocopherol derivative, and a fatty acid from the Myristicaceae family. From the Clusiaceae family, one previously undescribed hydroquinone methyl ester and five known metabolites were identified: a benzofuranone lactone, a flavonoid glycoside, a polyphenol, and two tocopherol derivatives. Several isolated compounds exhibited promising antibacterial effects, with compound 2.4 showing the most potent bactericidal activity against methicillin-resistant Staphylococcus aureus with an MIC of 2 μg/mL. In addition, compounds were assessed for their in vitro antifungal and anticancer activities.

In summary, this research identifies nineteen metabolites, including two new natural products (a salicylic acid derivative and a meroterpene named caudiquinol), from three chemically unresearched rainforest species, including Knema membranifolia, Gymnacranthera contracta and Garcinia caudiculata. Several compounds demonstrated significant antibacterial activity, particularly against drug-resistant bacteria, evidencing the therapeutic potential of these plant species and their genera in modern medicine, particularly in the age of antimicrobial resistance.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Chemistry, Pharmacy and Pharmacology
Depositing User:	Chris White
Date Deposited:	10 Nov 2025 14:29
Last Modified:	10 Nov 2025 14:29
URI:	https://ueaeprints.uea.ac.uk/id/eprint/100940
DOI:

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