Polyphenolic extracts of walnut (Juglans regia) green husk containing juglone inhibit the growth of HL-60 cells and induce apoptosis

BACKGROUND: Juglone is a naphthoquinone currently obtained by chemical synthesis with biological activities including antitumor activity. Additionally, juglone is present in the green husk of walnut, which suggests evaluating the effect of GH extracts on carcinogenic cell lines. RESULTS: Walnut green husk ethanolic extract was obtained as 169.1 mg juglone/100 g Green Husk and antioxidant activity (ORAC) of 44,920 µmol Trolox Equivalent/100 g DW Green Husk. At 1 µM juglone in HL-60 cell culture, green husk extract showed an antiproliferative effect, but pure juglone did not; under these conditions, normal fibroblast cells were not affected. A dose-dependent effect on mitochondrial membrane potential loss was observed. Apoptosis of HL-60 was detected at 10 µM juglone. Despite high ORAC values, neither purified juglone nor the extract showed protective effects on HL-60 cells under oxidative conditions. CONCLUSIONS: Green husk extract generates an antiproliferative effect in HL-60 cells, which is related to an induction of the early stages of apoptosis and a loss of mitochondrial membrane potential. The normal cells were not affected when juglone is present at concentrations of 1 µM, while at higher concentrations, there is loss of viability of both cancerous and healthy cells.

Study on chemical constituents from green husk of Juglans sigillata / 中草药

Objective: To investigate the chemical constituents in the green husk of Juglans sigillate. Methods: The chemical constituents were isolated by silica gel, RP-18, MCI column chromatographies and so on. The structures were identified on the basis of spectroscopic analysis (MS, 13C-NMR, 1H-NMR). Results: Eleven compounds were isolated from the extract of green husk of J. sigillate. And their structures were characterized as: sinapaldehyde (1), (Z)-10-eicosenoic acid (2), 5α, 8α-epidioxyergosta-6, 22E-diene-3β-ol (3), 5, 8-dihydroxy-4-methoxy-α-tetralone (4), regiolone (5), 4, 5-dihydroxy-α-tetralone (6), 4, 5, 8-trihydroxy-α-tetralone (7), 5-hydroxy-4-methoxy-α-tetralone (8), 5-hydroxy-2-methoxy-1, 4-naphthoquinone (9), naringenin (10), and β-sitosterol (11). Conclusion: Compounds 1-2 are isolated from the plants of Juglans Linn. for the first time.