Nat Prod Sci.  2020 Sep;26(3):214-220. 10.20307/nps.2020.26.3.214.

Isolation and Identification of Bioactive Compounds from the Tuber of Brassica oleracea var. gongylodes

• Prajapati R
• Seong SH
• Kim HR
• Jung HA
• Choi JS

• KMID: 2507454
• DOI: http://doi.org/10.20307/nps.2020.26.3.214

Abstract

Brassica oleracea var. gongylodes (red kohlrabi) is a biennial herbaceous vegetable whose edible bulbotuber-like stem and leaves are consumed globally. Sliced red kohlrabi tubers were extracted using methanol and the concentrated extract was partitioned successively with dichloromethane (CH ₂ Cl ₂), ethyl acetate (EtOAc), n-butanol (n-BuOH) and water (H ₂ O). Repeated column chromatography of EtOAc fraction through silica, sephadex LH-20 and RP-18 gel led to isolation of eleven compounds of which compound 1 was a new glycosylated indole alkaloid derivative, 1-methoxyindole 3-carboxylic acid 6-O-β-D-glucopyranoside. Others were known compounds namely, β-sitosterol glucoside (4), 5-hydroxymethyl-2-furaldehyde (5), methyl-1-thio-βD-glucopyranosyl disulfide (6), 5-hydroxy-2-pyridinemethanol (7), (3S,4R)-2-deoxyribonolactone (8), n-butyl-βD-fructopyranoside (9), uridine (10) and three fructose derivatives, D-tagatose (11), β-D-fructofuranose (12) and β-D-fructopyranose (13). Similarly, isolation from CH ₂Cl ₂ fraction gave two known indole alkaloids, indole 3-acetonitrile (2) and N-methoxyindole 3-acetonitrile (3). The structure elucidation and identification of these compounds were conducted with the help of ¹³ C and ¹ H NMR, HMBC, HMQC, EIMS, HR-ESIMS and IR spectroscopic data, and TLC plate spots visualization. Compounds 2, 3, 4, 5, 6, 7, 8 and 9 are noted to occur in kohlrabi for the first time. Different bioactivities of these isolated compounds have been reported in literature.

Keyword

Brassica oleracea var. gongylodes; 1-methoxyindole 3-carboxylic acid 6-O-β-D-glucopyranoside; bioactive compounds