Comparison of the Phytochemical Properties, Antioxidant Activity and Cytotoxic Effect on HepG2 Cells in Mongolian and Taiwanese Rhubarb Species

Abstract

The Mongolian rhubarb—Rheum undulatum L. (RU)—and Rumex crispus L. (RC)—a Taiwanese local rhubarb belonging to the family of Polygonaceae—are principal therapeutic materials in integrative medicine due to their rich quantities of bioactive compounds; however, their phytochemical and antioxidant properties, and anti-cancer activity is poorly investigated. Furthermore, the phytochemical characteristics of both species may be affected by their different geographical distribution and climatic variance. The current study aimed to compare RU with RC extracts in different polarity solvents (n-hexane, ethyl acetate, acetone, ethanol, and water) for their phytochemical contents including the total phenolic content (TPC), total anthraquinone content (TAC), total flavonoid content (TFC), antioxidant and free radical scavenging capacities, and anticancer ability on the HepG2 cell. Except for the n-hexane extract, all of the RU extracts had considerably higher TPCs than RC extracts, ranging from 8.39 to 11.16 mg gallic acid equivalent (GAE) per gram of dry weight, and the TPCs of each extract were also significantly correlated with their antioxidant capacities by ABTS, DPPH, and FRAP assays (p < 0.05). Moreover, there was no remarkable association between the antioxidant capacities and either TACs or TFCs in both the RU and RC extracts. Besides, high-performance liquid chromatography (HPLC) analysis revealed that both the RU and RC extracts contained chrysophanol, emodin, and physcion, and those bioactive compounds were relatively higher in the n-hexane solvent extracts. Additionally, we observed different levels of dose-dependent cytotoxic effects in all the extracts by cell viability assay. Notably, the ethanol extract of RU had a compelling cytotoxic effect with the lowest half-maximum inhibition concentration (IC50-171.94 ± 6.56 µg/mL at 48 h) among the RU extracts than the ethanol extract of RC. Interestingly, the ethanol extract of RU but not RC significantly induced apoptosis in the human liver cancer cell line, HepG2, with a distinct pattern in caspase-3 activation, resulting in increased PARP cleavage and DNA damage. In summary, Mongolian Rhubarb, RU, showed more phytochemical contents, as well as a higher antioxidant capacity and apoptotic effect to HepG2 than RC; thus, it can be exploited for the proper source of natural antioxidants and liver cancer treatment in further investigation.

Phytochemical Profile and Pharmacological Activity of Vernonia amygdalina Delile Stem Bark Extracts Using Different Solvent Extraction

“…The cytotoxic activity of ethyl acetate extract against PANC-1 cell was in correlation with phytochemical content (−0.994). This is indicating that phytochemical content could play a key role against these cancer cell line due to their ability to remove reactive oxygen species which cause cell damage [38], [39], [40]. According to these results, the varied cytotoxic activity of extracts may be attributed to the difference in the concentration of phenolic and flavonoid compounds in each extracts.…”

Rhei Undulati Rhizoma attenuates memory decline and reduces amyloid-β induced neuritic dystrophy in 5xFAD mouse

“…Rhei Undulati Rhizoma (RUR), an herbal medicine belonging to the family Polygonaceae, have traditionally been used to treat constipation, ulcers, and jaundice in the East Asia [ 18 ]. Furthermore, recent studies have reported that RUR has various pharmacological activities such as anti-inflammatory, antioxidant, and anti-neuroinflammatory effects [ 19 – 21 ]. Furthermore, rhapontigenin in stilbene glucosides isolated from RUR has a neuroprotective effect against Aβ-induced neurotoxicity [ 22 ].…”

Exploration of plant metabolomics variation and absorption characteristics of water‐extracted Rheum tanguticum and ethanol‐extracted Rheum tanguticum by UHPLC‐Q‐TOF‐MS/MS

“…2,3 In the clinical treatment of Chinese medicine, the main extraction method of RT was water decoction, but modern pharmacological activity studies have reported that some extraction of RT with ethanol has a better effect than water decoction. [4][5][6] In the research model of plant metabolomics, based on a multivariate statistical analysis platform, high-throughput screening of components with significant differences provides a robust technology for studying the material basis between different extraction methods of RT.…”