Chemical constituents from the leaves and stem barks of Macaranga hypoleuca (Rchb.f. & Zoll.) Müll.arg / Hamizah Muhamad Nazeri

• Main Author: Muhamad Nazeri, Hamizah
• Format: Thesis
• Language: English
• Published: 2020
• Subjects: Biochemistry; Medical botany (General)
• Online Access: https://ir.uitm.edu.my/id/eprint/59085/1/59085.pdf; https://ir.uitm.edu.my/id/eprint/59085/

The stem barks and leaves of Macaranga hypoleuca (Rchb.f. & Zoll.) Müll.Arg from the family Euphorbiaceae were investigated for their phytochemical and biological properties. The objectives of this study are to isolate chemical compounds from the plant, to elucidate the structure of the isolated compounds, to propose plausible biogenetic pathway of the new compound and to discuss the biosynthetic pathway of the isolated flavonoids, and to evaluate DPPH radical scavenging activity of crude extracts and purified flavonoids. Several chromatographic techniques were used to separate the compounds including vacuum liquid chromatography (VLC), column chromatography (CC), radial chromatography (RC), and high performance liquid chromatography (HPLC). Malayhypoleucin A (new compound-HS1) and scopoletin (HS2) were purified from the stem barks of M. hypoleuca, while five flavanones, known as 5,4’-dihydroxy-7-methoxyflavanone (HL1), 7-O-methyleriodictyol (HL2), 8- prenylnaringenin (HL3), 6-(3-hydroxy-3-methyl)naringenin (HL4), and tomentosanol D (HL5), two flavonols, quercetin (HL6) and kaempferol (HL7), and one phenolic compound known as 3,4-dihydroxybenzoic acid (HL8) were isolated from the leaves of M. hypoleuca. The structure of the compounds was elucidated based on several spectroscopic methods such as mass spectroscopy (MS), 1D and 2D NMR data, UVVis, ATR-IR and comparison with the reported data. Biosynthesis of malayhypoleucin A (new compound) was proposed from the acetate pathway, while flavonoids were derived from shikimate and phenylpropanoid pathways. Crude extracts (hexane, ethyl acetate and acetone), and five flavonoids, HL1, HL3, HL5, HL6, and HL7 were evaluated for DPPH radical scavenging activity. Hexane and ethyl acetate extracts, along with HL6 and HL7 showed strong activity with percent inhibition more than 90% at 100 μg/ml. Hexane extract and HL5 displayed moderate activity with percent inhibition of 60.5% and 50.3% respectively at 100 μg/ml, while HL1 and HL3 have weak activity with percent inhibition of 20% and 25% at 100 μg/ml.