Red Mexican Grapefruit: A Novel Source for Bioactive Limonoids and their Antioxidant Activity

Abstract

Citrus limonoids have shown to inhibit the growth of cancer in colon, lung, mouth, stomach and breast in animal and cell culture studies. For the first time in the present study, an attempt has been made to isolate antioxidant fractions and five limonoids from red Mexican grapefruit seeds. Defatted seed powder was successively extracted with hexane, ethyl acetate (EtOAc), acetone, methanol (MeOH) and MeOH/water and the extracts were concentrated under vacuum. Radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and total phenolic content were also measured for comparison with the antioxidant capacity in the phosphomolybdenum method for the above extracts. Acetone and MeOH extracts, respectively, showed the highest (85.7%) and lowest (53.3%) radical scavenging activity, at 500 ppm. The total phenolic contents were found to be highest in the acetone extract (15.94%) followed by the MeOH extract (5.92%), ethyl acetate extract (5.54%) and water extract (5.26%). Antioxidant capacity of the extracts as equivalents to ascorbic acid (μmol/g of the extract) was in the order, EtOAc extract Ͼ acetone extract Ͼ water extract Ͼ methanol extract. Furthermore, the EtOAC and acetone extracts were loaded onto silica gel columns to obtain four limonoid aglycons. MeOH fraction was loaded onto a dowex-50 and sepabeads resin column to obtain a limonoid glucoside. The purity of the isolated five compounds was analyzed by HPLC using a C 18 column and UV detection at 210 nm. Finally, the structures of the compounds were identified as obacunone, nomilin, limonin, deacetylnomilin (DAN) and limonin-17--d-glucopyranoside (LG) using 1 H and 13 C NMR studies.

Neuroprotective effects of constituents of the root bark of Dictamnus dasycarpus in mouse hippocampal cells

“…of three independent experiments. *p < 0.05. pharmacological active natural occurring compound such as antimalarial, antioxidant, antiproliferative and neuroprotective agent (Poulose et al, 2006;Mandadi et al, 2007;Lee et al, 2008;Yoon et al, 2008). In the previous study, obacunone (4) especially showed protective effects against glutamate-induced neurotoxicity in primary cultures of rat cortical cells (Yoon et al, 2008).…”

Antioxidant capacity of pummelo and navel oranges: Extraction efficiency of solvents in sequence

“…The difference in antioxidant capacity of different extracts may be attributed to differences in their chemical composition such as phenolics, ascorbic acid, limonoids and carotenoids. Recent results from our group and others indicated that certain citrus limonoids are found to posses moderate antioxidant activity (Mandadi, Jayaprakasha, Narayan Bhat, & Patil, 2007;Poulose et al, 2005;Sun, Chen, Chen, & Chen, 2005). The antioxidant activity shown by the citrus fruit extracts may be due to the presence of flavonoids, carotenoids and ascorbic acid (Goristein et al, 2004).…”

Limonin 7-methoxime interferes with Escherichia coli biofilm formation and attachment in type 1 pili and antigen 43 dependent manner

“…1) were determined by spectrometric studies. Chemical shifts of limonin, LG, DFL and LM were recorded and compared with previously reported data (Mandadi et al, 2007;Perez et al, 2009;Poulose, Jayaprakasha, Mayer, Girennavar, & Patil, 2007). The 1 H and 13 C spectra of L7OX with assignments of various signals are presented in Table 3.…”

“…Limonin and limonin 17-b-D-glucoside were purified as reported earlier (Mandadi, Jayaprakasha, Bhat, & Patil, 2007;. LM and DFL were prepared as described (Perez et al, 2009).…”