Abstract
Abelmoschus esculentus (AE) (okra), is an edible plant used in many food applications.
This study explored whether sulfated AE (SAE) has promising cancer chemopreventive activities that may recommend it as a functional food supplement instead of (or in addition to) AE for the population at risk of cancer and in the health food industry.
Cytochrome P450-1A (CYP1A) was estimated by fluorescence enzymatic reaction, using β-naphthoflavone-treated cells (CYP1A inducer). Peroxyl and hydroxyl radical scavenging was assayed by oxygen radical absorbance capacity assay. Flow cytometry was used to analyze apoptosis/necrosis in MCF-7 cells, cell cycle phases in MCF-7 cells, and macrophage binding to fluorescein isothiocyanate-lipopolysaccharide (FITC-LPS). Nitric oxide was determined by Griess assay in LPS-stimulated macrophages, and cytotoxicity was determined by MTT assay. Diethylnitrosamine (DEN) was used to induce hepatic tumor initiation in rats. Placental glutathione-S-transferase (GSTP; an initiation marker) was stained in a fluorescence immunohistochemical analysis of liver sections, and histopathological changes were examined.
SAE exhibited strong antitumor initiation and antitumor promotion activities. It suppressed CYP1A, scavenged peroxyl and hydroxyl radicals, induced macrophage proliferation, suppressed macrophage binding to FITC-LPS, inhibited nitric oxide generation, showed specific cytotoxicity to human breast MCF-7 adenocarcinoma cells, and disturbed the cell cycle phases (S and G2/M phases) in association with an increased percentage of apoptotic/necrotic MCF-7 cells. Over a short time period, DEN stimulated liver cancer initiation, but SAE treatment reduced the DEN-induced histopathological alterations and inhibited CYP1A and GSTP.
SAE extract has the potential for use as an alternative to AE in health foods to provide cancer chemoprevention in populations at risk for cancer.