Cytotoxicity effects of various Juglans regia (walnut) leaf extracts in human cancer cell lines

Currently, natural products have been shown to present interesting biological and pharmacological activities and are used as chemotherapeutic agents. Plants have historically been used in treating cancer and are recognized for their ability to produce secondary metabolites. Juglans regia L. (Juglandaceae) has medicinal applications to treat a wide range of diseases such as cancer.

The current study was designed to evaluate the antiproliferative activity of total extract as well as several fractions from the leaves of J. regia.The total phenolics, flavonoids, and condensed tannins content of these extracts were also determined to obtain further information on the correlation between the contents of phenolic compounds and antiproliferative effects as well as the leaf developmental stages.

Antiproliferative activity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and flow cytometry methods against human oral cancer, breast adenocarcinoma and colon adenocarcinoma cell lines. The total phenolics, flavonoids, and condensed tannins were determined by Folin-Ciocalteu, aluminum chloride and butanol-HCl colorimetric methods.

Our present study has shown that chloroform fraction has the lowest IC(50) values (0.36-0.81 mg/mL) and also induces cell cycle arrest (G0\G1 phase) after a 24 h treatment. The colorimetric methods showed the highest amount of total phenolics, flavonoids, and condensed tannins in the methanol fraction (120.28 ± 2.32, 59.44 ± 0.87, 227.00 ± 4.91 mg/g of dry weight of extract).

The results obtained herein indicate that walnut chloroform fraction may contain effective compounds which can be used as a chemotherapeutic agent.