Isoquercitrin (IQ), a major flavonol present in Prunus mume fruit, has gained much attention in recent studies because of its superior bioavailability and physiological effects. In this study, the anti-cancer mechanism of IQ against human melanoma, particularly its effect on the mitochondria-mediated apoptosis, was investigated. Treatment with IQ at 25 μM concentration effectively inhibited the proliferation of SK-MEL-2 skin cancer cells while the same concentration did not exhibit cytotoxicity against human keratinocytes HaCaT. Morphological analysis and clonogenic assay also showed that IQ can alter the growth and long-term survival of SK-MEL-2 cells. IQ also induced apoptosis in the melanoma cells as manifested in the nuclear morphology changes, DNA fragmentation, increase in the apoptosis rate (17.69% at 25 μM) and accumulation of sub-G1 cell cycle phase population (19.55% at 25 μM). Western blot analysis revealed the involvement of the mitochondrial apoptosis signaling pathway in the anti-cancer property of IQ. Treatment with IQ resulted in the decrease in the levels of procaspase-8 and -9, and Bcl-2 protein, and an increase in the expression of cleaved PARP and Bax. Moreover, AIF and Endo G protein expression increased, indicating a caspase-independent mitochondrial-mediated apoptosis. The anti-proliferative activity of IQ against SK-MEL-2 can also be attributed to the downregulation of the PI3K/AktmTOR signaling pathway. These findings showed that IQ can be developed into a chemopreventive therapeutic agent against the melanoma cells.

BACKGROUND Lactic acid fermentation has been widely used to improve the nutritional and functional properties of food products. Cherry silverberry (Elaeagnus multiflora Thunb.) is considered as an invasive plant species with known medicinal and functional properties. In this study, improvement of the biological activity and health benefits of cherry silverberry fruit through lactic acid fermentation was investigated. RESULTS Extracts of cherry silverberry fruits fermented by pure cultures of Lactobacillus plantarum KCTC 33131 and L. casei KCTC 13086 exhibited favorable physicochemical properties and enhanced phytochemical content, antioxidant properties (DPPH radical scavenging activity, reducing power, superoxide dismutase‐like property and hydrogen peroxide scavenging activity) and α‐glucosidase and tyrosinase enzyme inhibitory activity as compared with unfermented fruits. Despite a decrease in the specific phenolic acid contents among the fermented samples, the cherry silverberry fruit fermented by mixed cultures of L. plantarum and L. casei contained superior total polyphenols (3.78 ± 0.22 mg GAE g−1) and total (0.66 ± 0.12 mg QE g−1) and individual flavonoid contents in comparison with fruits fermented by single cultures and unfermented ones. Multivariate analysis also showed strong association among total phytochemical contents and biological activities. CONCLUSIONS This work has elucidated the effect of fermentation with L. plantarum KCTC 33131 and L. casei KCTC 13086 on the improvement of the physicochemical properties and biological activity of cherry silverberry fruit. It also revealed the potential application of fermented cherry silverberry in the production of food materials beneficial for health. © 2020 Society of Chemical Industry

Elaeagnus multiflora Thunb. (cherry silverberry, CS) is an underutilized fruit with notable phytochemical profile and biological activities. However, there are few studies on cancer inhibitory effect using fermented CS fruits. This study aimed to develop fermented CS fruits using lactic acid bacteria and investigate its anticolorectal cancer (CRC) property and phenolic composition. SW480 CRC cells were treated with aqueous extracts of CS fermented by single and coculture of Lactobacillus plantarum and L. casei. The extracts of fermented CS exhibited greater antiproliferative activity and anticlonogenicity in comparison with the unfermented extract and the control. Among the extracts of CS fruits, the ones fermented by the coculture (LPLC) showed the most potent tumor suppression property, at 25 to 50 µg/mL, by induction of cell cycle arrest at the S and G2/M phases, downregulating cyclins and its dependent kinases while increasing tumor suppressor proteins p27 and p53. LPLC also exerted its tumor suppression effect by inhibiting the chemotactic motility and invasiveness of SW480 cells, downregulating matrix metalloproteinase‐9, and PI3K/AKT/mTOR pathways and upregulating TIMP‐9, and E‐cadherin. HPLC‐PDA analysis revealed that the levels of major flavonoids in CS extracts, namely, catechin, epigallocatechin, epicatechin, epigallocatechin gallate, rutin, naringin, and quercetin, were enhanced by fermentation with L. plantarum and L. casei in coculture. Overall, this study showed that the extracts of fermented CS have augmented and multifaceted anticancer property and can be utilized in the development of functional food or ingredient for the prevention of CRC. Practical Application Elaeagnus multiflora, commonly known as cherry silverberry, has been proven to contain bioactive components and possesses high functionality. However, due to limited shelf‐life as a fresh commodity, development of novel product is essential. Fermentation is a beneficial process employed in the food industry to enhance the shelf stability, nutritional, sensory, and functional properties of food products. The present study has explored the possibility of adding value to an underutilized fruit, cherry silverberry, through the process of fermentation, making it as a potential source of functional food and ingredient for the prevention of colorectal cancer.