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Research Project: Biobased Pesticide Discovery and Product Optimization and Enhancement from Medicinal and Aromatic Crops

Location: Natural Products Utilization Research

Title: A new gnidiflavanone-flavonol dimer and other constituents from Gnidia apiculata

item KAMAU, RAHAB - Masinde Muliro University Of Science And Technology
item MIDIWO, JACOB - University Of Nairobi
item MGANI, QUINTINO - University Of Dar Es Salaam
item MASILA, VERONICA - University Of Nairobi
item KUMARIHAMY, MALIKA - University Of Mississippi
item Wang, Mei
item ZHAO, JIANPING - University Of Mississippi
item MUHAMMA, ILIAS - University Of Mississippi

Submitted to: Natural Product Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2022
Publication Date: 4/8/2022
Citation: Kamau, R.W., Midiwo, J.O., Mgani, Q.A., Masila, V.M., Kumarihamy, M., Wang, M., Zhao, J., Muhamma, I. 2022. A new gnidiflavanone-flavonol dimer and other constituents from Gnidia apiculata. Natural Product Research.

Interpretive Summary: Gnidia apiculata Gilg. belongs to the genus Gnidia in the family Thymelaeaceae. It has been used in folk medicine to treat fever, cancer, snake bites, pulmonary tuberculosis and tooth-ache, among others. Prior to the current study, there were very limited reports about the phytochemical constituents and biological potential of G. apiculata. In order to unravel its chemical constituents and also establish its biological potential, an in-depth investigation was performed. The chromatographic separation of root extract led to isolation of a previously un-described biflavonoid (1), four primula-type flavones, along with five other known compounds In addition, the antimicrobial and anti-plasmodial activities of crude extract, isolated and structurally modified compounds of the plant are reported. The findings of this study could enrich the chemical diversity of genus Gnidia.

Technical Abstract: A previously un-described, (2R,3S)-3'',3''',4',4''',5,5'',5''',7,7''-nonahydroxy-3,8''-biflavonol (1), together with four unique Primula-type flavones (2-5) and five other known compounds (6-10) were isolated from the roots of Gnidia apiculata. Their chemical structures were determined using spectroscopic analyses and literature review. The structure and absolute configuration of compound 1 was established by 2D NMR HMBC, HMQC, NOESY and circular dichroism (CD) spectra. This appears to be the first report of compounds 2-5 and 7 in the plant Family Thymelaeceae, and 6-methoxyflavone (2) as a new natural product. The crude extract and isolated compounds were evaluated for antimicrobial and antiplasmodial activities. Among the isolated compounds, only 6-hydroxyflavone (3), together with its acetylated product 3a, showed weak anti plasmodial activities against chloroquine sensitive (D6) and -resistant (W2) strains of Plasmodium falciparum.