High Value-Added Application of Two Renewable Sources as Healthy Food: The Nutritional Properties, Chemical Compositions, Antioxidant, and Antiinflammatory Activities of the Stalks of Rheum officinale Baill. and Rheum tanguticum Maxim. ex Regel

Abstract

Rhubarb plants (Rheum officinale and R. tanguticum) have edible stalks. In this work, we aimed to compare the nutritional properties, chemical compositions, and bioactivities of R. officinale (SRO) and R. tanguticum (SRT) stalks and to analyze the composition–function relationship. Results showed that the two stalks were good sources of fiber, as well as minerals. They contained abundant essential amino acids and essential fatty acids to regulate the immunity and prevent some chronic diseases; the contents of polyunsaturated fatty acids were 2,244.32 mg/100 g and 2,844.69 mg/100 g, respectively. The antioxidant activity were also proved. Metabolomics showed that SRO and SRT contained abundant phenolic acids. Due to the higher concentrations of flavones, SRT has better antiinflammatory activities than SRO by inhibiting NF-κB signaling pathway. Rhubarb stalks exhibited good safety in acute toxicity and cytotoxicity tests. This work indicated that the two stalks have nutritional value, safety, and bioactivities, and could be used as sources of nutritional ingredients for regulating the immunity of body in food industry.

Changes in the nutrients, phytochemical profile and antioxidant activity of Rheum officinale Baill. leaf blades during different growth periods

“…The content of total phenolic compounds (TPCs) in LRO harvested in the different seasons was determined using the Folin–Ciocalteu method, and the results are expressed as mg of gallic acid equivalent/100 g of fresh sample (mg GAE/100 g). The content of flavonoids (TF) in LRO was measured according to the aluminum chloride colorimetric method, and the result was expressed as mg of quecertin/100 g of fresh sample (mg QE/100 g) ( 3 ). The absorbance was measured at a wavelength of 760 nm to determine the TPC and 510 nm to measure the TF.…”

“…The in vitro antioxidant activity of LRO was investigated according to a previously described method ( 3 ). For the DPPH radical scavenging activity assay, LRO (50–1,000 μg/mL) was added to 96-well plates with a methanol solution of DPPH (100 μL, 0.2 mM) and then incubated at 37°C for 30 min in the dark.…”

“…For determining the cellular antioxidant activity, when the supernatants of RAW 264.7 cells (2 × 10 5 cells/well) were discarded after incubating for 24 h, 2 mL of LRO (400 μg/mL) was added and cultured for 1 h. Dexamethasone (Dex,10 μg/mL) was used as the positive control. H 2 O 2 (0.5 mM) was added to stimulate oxidant stress for 24 h. Finally, the activity of SOD (superoxide dismutase) in cells was detected using the assay kits (Solarbio, China) ( 3 ).…”

“…As an important herb in this genus, R. officinale is widely distributed in some Asian countries. In China, this species is cultivated in northwestern regions, such as Gansu, Qinghai, Inner Mongolia and Sichuan provinces ( 3 ). Approximately 5,500 tons of dried rhizomes and roots are produced annually ( 8 ), and these products are used in folk medicine to treat diarrhea, constipation, abdominal pain and jaundice.…”

“…The fresh aerial parts, including stalks, stems and leaves, produce a sour taste and are eaten as vegetables by local people and animals in some regions; however, many raw materials are discarded. To further develop the production and use of the aerial parts as a functional food, we previously performed investigations and revealed that R. officinale stalks exhibit good safety; contain an abundance of essential amino acids, essential fatty acids, fiber, and minerals; and can be used as sources of nutrients in the food industry to regulate the body’s immunity ( 3 ). Further study revealed that more nutrients and chemical components are present in the leaves than stalks, which contain abundant pectin that can be used as dietary fiber ( 9 ).…”