Antioxidant indices of some green leafy vegetables

Changes in antinutrients, phenolics, antioxidant activities and in vitro α-glucosidase inhibitory activity in pumpkin leaves (Cucurbita moschata) during different domestic cooking methods

Pumpkin leaves (Cucurbita moschata) were subjected to different household cooking methods (boiling, microwaving, steaming, and stir-frying) to evaluate their effect on antinutrients, phenolic compounds, antioxidant properties (ABTS, and DPPH) and in vitro α-glucosidase activity. All cooking methods studied significantly reduced the antinutrients and antioxidant activities, whilst phenolic compounds p-coumaric and ferulic acids significantly increased. The cooking methods reduced the oxalates by more than 50%, tannins by 47% and phytates by 79.22%. Steaming and boiling resulted in highest concentrations of p-coumaric (195.40 mg kg^-1) and ferulic acids (103.90 mg kg^-1) compared to other methods. Overall, boiled leaves retained the highest total phenolic compounds, whilst steamed leaves retained the highest antioxidant capacity. Raw pumpkin leaf extracts showed higher in vitro α-glucosidase inhibitory effects than the cooked leaves. Thus, cooking affected the inhibitory effect of in vitro α-glucosidase activity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-00916-w.

Induction of NAD(P)H-quinone oxidoreductase 1 by antioxidants in female ACI rats is associated with decrease in oxidative DNA damage and inhibition of estrogen-induced breast cancer

Exact mechanisms underlying the initiation and progression of estrogen-related cancers are not clear. Literature, evidence and our studies strongly support the role of estrogen metabolism-mediated oxidative stress in estrogen-induced breast carcinogenesis. We have recently demonstrated that antioxidants vitamin C and butylated hydroxyanisole (BHA) or estrogen metabolism inhibitor α-naphthoflavone (ANF) inhibit 17β-estradiol (E2)-induced mammary tumorigenesis in female ACI rats. The objective of the current study was to identify the mechanism of antioxidant-mediated protection against E2-induced DNA damage and mammary tumorigenesis. Female ACI rats were treated with E2 in the presence or absence of vitamin C or BHA or ANF for up to 240 days. Nuclear factor erythroid 2-related factor 2 (NRF2) and NAD(P)H-quinone oxidoreductase 1 (NQO1) were suppressed in E2-exposed mammary tissue and in mammary tumors after treatment of rats with E2 for 240 days. This suppression was overcome by co-treatment of rats with E2 and vitamin C or BHA. Time course studies indicate that NQO1 levels tend to increase after 4 months of E2 treatment but decrease on chronic exposure to E2 for 8 months. Vitamin C and BHA significantly increased NQO1 levels after 120 days. 8-Hydroxydeoxyguanosine (8-OHdG) levels were higher in E2-exposed mammary tissue and in mammary tumors compared with age-matched controls. Vitamin C or BHA treatment significantly decreased E2-mediated increase in 8-OHdG levels in the mammary tissue. In vitro studies using silencer RNA confirmed the role of NQO1 in prevention of oxidative DNA damage. Our studies further demonstrate that NQO1 upregulation by antioxidants is mediated through NRF2.

Protective effect of some tropical vegetables against CCl4-induced hepatic damage

In the present study, ethanolic extracts of some tropical vegetables were investigated for their hepatoprotective effect against CCl4-induced liver damage in rats. CCl4 at a dose of 0.5 mL/kg of body weight produced liver damage in rats as manifested by the rise in the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total protein in serum (40.60 +/- 3.50 IU/L, 80.60 +/- 5.10 IU/L, and 73.20 +/- 1.87 g/L, respectively) and in liver homogenate (1,300.00 +/- 7.38 IU/L, 1,660.00 +/- 13.69 IU/L, and 250.00 +/- 7.51 g/L, respectively) compared to the control. The extracts at doses of 250 and 500 mg/kg of body weight were administered to the CCl4-treated rats. The vegetables at a dose of 250 mg/kg of body weight produced a significant hepatoprotective effect by decreasing the serum levels of ALT, AST, and total protein to values in the range of 11.21 +/- 1.90-16.22 +/- 1.00 IU/L, 29.00 +/- 2.70-48.00 +/- 2.10 IU/L, and 62.10 +/- 2.40-70.13 +/- 2.00 g/L and at a dose of 500 mg/kg of body weight to 13.00 +/- 1.20-21.00 +/- 1.30 IU/L, 40.00 +/- 2.5-59.00 +/- 2.20 IU/L, and 68.00 +/- 2.40-72.00 +/- 2.10 g/L, respectively. Similar results were obtained for liver homogenate levels of ALT, AST, and total protein with decreasing values compared with the CCl4-treated rats: 900.00 +/- 3.05-1,020.00 +/- 4.25 IU/L, 1,150.00 +/- 5.57-1,530.00 +/- 4.99 IU/L, and 150.00 +/- 3.12-185.00 +/- 3.00 g/L and 900.00 +/- 3.05-1,030.00 +/- 8.80 IU/L, 1,400.00 +/- 6.95-1,530.00 +/- 8.50 IU/L, and 165.0 +/- 5.50-210.00 +/- 4.41 g/L, respectively, at doses of 250 and 500 mg/kg of body weight, respectively. Furthermore, the effect of the extracts on lipid peroxidation, measured as malondialdehyde (MDA), was estimated on the liver homogenate. A significant hepatoprotective effect was also noticed with a decreased value of the MDA levels: 46.00 +/- 0.08-52.00 +/- 0.06 and 47.00 +/- 0.07-60.00 +/- 0.10 nmol of thiobarbituric acid-reactive substances/g of liver protein at doses of 250 and 500 mg/kg of body weight, respectively. It could be concluded that all the evaluated vegetables exhibit good hepatoprotective activities, though to varying degrees.