Abstract
Gynura bicolor (Compositae) which is widely used by the locals as natural remedies in folk medicine has limited scientific studies to ensure its efficacy and nontoxicity. The current study reports the total phenolic content, antioxidant capacity, cytotoxicity, and acute oral toxicity of crude methanol and its fractionated extracts (hexane, ethyl acetate, and water) of G. bicolor leaves. Five human colon cancer cell lines (HT-29, HCT-15, SW480, Caco-2, and HCT 116), one human breast adenocarcinoma cell line (MCF7), and one human normal colon cell line (CCD-18Co) were used to evaluate the cytotoxicity of G. bicolor. The present findings had clearly demonstrated that ethyl acetate extract of G. bicolor with the highest total phenolic content among the extracts showed the strongest antioxidant activity (DPPH radical scavenging assay and metal chelating assay), possessed cytotoxicity, and induced apoptotic and necrotic cell death, especially towards the HCT 116 and HCT-15 colon cancer cells. The acute oral toxicity study indicated that methanol extract of G. bicolor has negligible level of toxicity when administered orally and has been regarded as safe in experimental rats. The findings of the current study clearly established the chemoprevention potential of G. bicolor and thus provide scientific validation on the therapeutic claims of G. bicolor.
Highlights
Plants have been used to maintain human health for a very long time
Hexane extract usually contains high level of oil, wax, and chlorophyll, while water extract contains high sugar content. This could be the reason for lower phenolic content in both of the extracts. Phenolic compounds such as quercetin, kaempferol, quercitrin, isoquercitrin, rutin, and three poly-acylated anthocyanins had been identified in G. bicolor leaves in previous studies reported by Lu et al [3] and Shimizu et al [9]
These phenolic compounds may be present in the ethyl acetate extract and contribute to the high phenolic content of ethyl acetate extract in the current study
Summary
It is well known that some of the plant species possess interesting bioactivities with potential therapeutic applications which can benefit us. Locally known as “Hong Feng Cai” (Chinese) and “Sambung Nyawa Ungu” (Malay), belongs to the botanical family of Compositae. The leaves of G. bicolor distinctively show reddish purple color on the abaxial side and green color on the adaxial side. The native geographic distribution of G. bicolor occurs in China, Taiwan, Myanmar, and Thailand. The G. bicolor is consumed as a culinary cooked vegetable and believed to confer a wide range of benefits such as anticancer, anti-inflammatory, and possibly antihypertensive effects. G. bicolor is used for post-labor recovery, blood circulation improvement, treatment of dysmenorrhea, hemoptysis, and diabetes by the locals [1,2,3]
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