Four flavonols from the seed of Hibiscus sabdariffa. Linn. growing in Binh Thuan Province

Huy Thuc Duong,Huynh Bui Linh Chi,Nguyen Kim Phi Phung,Nguyen Thi Hoa,Nguyen Thi Hoai Thu,Pham Nguyen Kim Tuyen,Tran The Anh Huy,Truong Van Tien

doi:10.32508/stdj.v22i4.1690

Abstract

Introduction: Hibiscus sabdariffa Linn. (Malvaceae) is a medicinal plant popularly distributed in Asian countries. As of 2019, no chemical investigations from the Vietnamese plant were found. This paper reported the isolation and elucidation of compounds isolated from the seeds of Hibiscus sabdariffa Linn. (Malvaceae) growing in Binh Thuan province. Method: The maceration was applied to the seeds of the plant to afford the crude extract which was then fractionated by liquid-liquid extraction to obtain the ethyl acetate extract. The extract was carried out by using normal phase silica gel column chromatography and thin-layer chromatography. Analysis of spectroscopic data including HR-ESI-MS, 1D and 2D-NMR and a comparison of the NMR data with that in the literature led to the structural elucidation of isolated compounds. Results: Four flavonols comprising quercetin 3-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside (1), quercetin 3-O-β-D-glucopyranoside (2), quercetin (3) and kaempferol (4) were isolated from the ethyl acetate extract. Conclusions: This is the first time the isolated compounds were found from the seeds of this plant.

Highlights

Hibiscussabdariffa Linn. (Malvaceae) is a medicinal plant popularly distributed in Asian countries
This paper reported the isolation and elucidation of compounds isolated from the seeds of Hibiscus sabdariffa Linn. (Malvaceae) growing in Binh Thuan province
Analysis of spectroscopic data including HR-ESI-MS, 1D and 2D-Proton nuclear magnetic resonance C NMR (NMR) and a comparison of the NMR data with that in the literature led to the structural elucidation of isolated compounds

Summary

INTRODUCTION

Hibiscus is one of the largest Malvaceae genera and comprises about 300 species widely distributed in Central and West Africa, and South East Asia 1,2. Leaves and powdered seeds of H. sabdariffa are used as foods in West Africa 2. Various chemical investigations on flowers, calyces, and leaves of H. sabdariffa were reported so far, providing a number of organic compounds such as phenolic acid, pectin, polysaccharides, anthocyanin and flavonoids. The phytochemical data on Vietnamese H. sabdariffa plants have not been studied while the chemical constituents of the seeds of H. sabdariffa are scarce with the reports of fatty acids, proteins, lipids 4. Four compounds have been afforded, including quercetin 3-O-α-Lrhamnopyranosyl-(1→6)-β -D-glucopyranoside (1), quercetin 3-O-β -D-glucopyranoside (2), quercetin (3) and kaempferol (4). This is the first time the isolated compounds found from the seed of this plant

MATERIALS AND METHODS

RESULTS AND DISCUSSION

CONCLUSION

CONFLICTS OF INTEREST