Pechay is an erect, biennial herb, growing about 15 to 30 centimeters tall in vegetative state. Leaves are ovate, spreading, and arranged spirally. Petioles are enlarged, growing upright forming a subcylindrical bundle. Inflorescence is a raceme with pale yellow flowers. Seeds are 1 millimeter in diameter, reddish to blackish brown in color.
- An ancient vegetable, cultivated over 4000 years.
- Cultivated in the Philippines, grown from low to mid elevations throughout the year.
- Each 100 g of fresh edible portion yields: water, 93.0 g; protein, 1.7 g; fat, 0.2 g; carbohydrates, 3.1 g; fiber, 0.7 g; ash, 0.8 g; beta-carotene, 2.3 g; vitamin C, 53.0 mg; calcium 102.0 mg; phosphorus, 46.0 mg; iron, 2.6 mg; energy value 86.0 kJ. (2)
- Vitamin content of a cup of shredded pechay: vitamin C, 20.5 mg; folate, 60 mcg; vitamin K, 32.6 mcg; with small amounts of vitamins A, niacin and B6. (4)
- Nutrient value per 100 g yielded:
(Principle) energy 16 kcal, carbohydrates 3.23 g, protein 1.2 g, total fat 0.2 g, cholesterol 0, dietary fiber 1.2 mg; (Vitamins) folates 79 µg, niacin 0.4 mg, pantothenic acid 0.105 mg, pyridoxine 0.05 mg, thiamin 0.04 mg, vitamin A 318 IU, vitamin C 27 mg, vitamin K 42.9 µg; (Electrolytes) sodium 8 mg, potassium 238 mg; (Minerals) calcium 77 mg, iron 0.31 mg, magnesium 13 mg, manganese 0.19 mg, phosphorus 29 mg, zinc 0.23 mg. (USDA National Nutrient Database) (15)
Studies have suggested anti-tumor, immunomodulating, antioxidant, phytoremediating properties.
Leaves, stems, seeds.
- Used primarily for its immature, fully expanded and tender leaves. Succulent petioles are preferred parts.
- Ingredient for soups and stir-fried dishes.
- In Chinese cuisine, green leaves are used as garnish. (2)
- Roots eaten raw or cooked as vegetable.
- Tops used as potherb like spinach.
- No reported folkloric use in the Philippines.
- Elsewhere, stems, leaves, and powdered seed used as cancer remedy. Boiled roots used for breast tumors. (9)
- Livestock: Roots used as livestock feed.
- Occasionally suspected of poisoning bovines, sheep, and pigs.
• Phytoremedition of Arsenic and Lead: Phytoremediation is a process of absorption of contamination, such as heavy metals, from the soil. Study evaluated B. rapa;s ability to absorb arsenic and lead from the soil. Results showed all plants contaminated with arsenic absorbed some of it. Only two of nine samples absorbed any lead. Under specific conditions, Brassica rapa is able to absorb arsenic but not lead. (3)
• Immunomodulating: Study evaluated the effects of various extracts of Brassica rapa on cell mediated immune response in mice. In both innate and acquired immunity models, chloroform, ethyl acetate and methanolic extracts of B. rapa glands significantly and dose-dependently reduced paw thickness. Study assumes glucosinolates contributed in the more pronounced effects of the ethyl acetate extract and suggests further studies to identify the constituents and immunomodulating mechanisms. (5)
• Glucosinolates / Anti-Cancer: Glucosinolates are S- and N-containing secondary metabolites found in abundance in plants belonging to the Brassicaceae genus. Study evaluated the mutagenic and/or anti-mutagenic properties of crude B. rapa chinensis extracts by comparing it against Mitomycin-C, a known mutagenic drug. Results showed glucosinates in the crude Petchay extract are potential antimutagenic compounds in human lymphocytes, and suggests glucosinates may potentially prevent cancer from proliferating in the human body. (6)
• Effects on Fructose-Induced Metabolic Syndrome: Study evaluated the role of Brassica rapa on fructose-induced metabolic syndrome in rats. Results showed BR attenuated most of the changes associated with metabolic syndrome: reduced weight gain and blood glucose, MDA, nitric oxide, total triglycerides and total cholesterol, also elevating blood GSH and liver glycogen. (7)
• Antioxidant: Study evaluated the antioxidant potential of crude extract and fractions from Brassica rapa for glutathione peroxidase (GPx), superoxide dismutase (SOD) enzymes and total antioxidant status in blood samples. Results showed concentration dependent effects of GPx, SOD, and TAS, suggesting potential applications for pharmaceutical usage due to its antioxidant properties. (8)
• Thrombolytic / Membrane Stabilizing: Study evaluated the in vitro thrombolytic and membrane stabilizing properties of B. rapa subsp. chinensis. The carbon tetrachloride soluble fraction exhibited the highest clot lysis. A crude methanol extract along with other extractives showed inhibition of hemolysis of erythrocyte membrane in hypotonic solution and heat-induced conditions. (11)
• Chemopreventive / Antiproliferative: Study evaluated the mutagenic and/or antimutagenic properties of crude Brassica rapa chinensis extracts for possible cancer chemopreventive potentials. Glucosinates in crude Petchay extracts are potential antimutagenic compounds in human lymphocytes and may potentially prevent proliferation of cancer in the human body. (12)
• Effect of Blanching on Vitamin C in Leafy Vegetables: Study evaluated the percentage (%) loss of vitamin C due to effects of different blanching times and physical forms. The effect of the vegetable's physical form on vitamin C loss was significant (p<0.05)—cut leaves lose more vitamin C than intact ones. While blanching vegetables makes leafy vegetables more palatable, it reduces their antioxidant properties drastically. Results suggest shorter blanching times of vegetables may reduce the loss of vitamin C. (13)
• Hypoglycemic Effect / Hypolipidemic / Leaves:Study showed an AETL has dose-dependent decrease in blood glucose of alloxan induced diabetic rats. There was also a decrease (p<0.05) in total plasma cholesterol and LDL-c, while also significantly decreasing (p<0.05) HDL-c and increased triglycerides and AST in a dose dependent manner. (14)
• Nanoparticles / Ant-Tumor Effect / Dalton's Lymphoma Ascites (DLA) / Leaves: Krishnaswamy studied the anti-tumor effect of methanolic extract and nanoparticles of of Brassica rapa chinensis. Results showed strong effect against Dalton's ascites lymphoma (DLA) cells in a mice model. The DLA tumor induced mice might have survived longer because of important secondary metabolites. The extract also enhanced in a dose dependent manner (16) (17)
• Effect of Moist Cooking Blanching on Phenolic and Glucosinolate Contents: Study evaluated the effects of traditional blanching methods on changes of color properties, phenolic metabolites, glucosinolates and antioxidant properties on Brassica rapa chinensis leaves. Blanching at 95°C in 10% lemon solution significantly increased the glucosinolate sinigrin content. Overall blanching at 95°C in 5% lemon juice solution can be recommended to preserve the functional compounds in Nightshade leaves. (18)