Wayne C. Liao

Antioxidative activity of water extract of sweet potato leaves in Taiwan

This study reports the preparation of four varieties of water extract from sweet potato leaves from Taiwan, including TNG10, TNG57, TNG66 and YSP, and evaluates their antioxidative activity. The EC50 values (scavenging DPPH radicals) of TNG10, TNG57, TNG66 and YSP were 0.27±0.01, 0.19±0.01, 0.41±0.02, and 0.31±0.02mg/ml, respectively, on a freeze-dry weight basis. The total phenolic contents of these water extracts were in the order: TNG57>TNG10>TNG66>YSP. The TNG10 and TNG57 extracts exhibited better reducing power and scavenging effects of superoxide radicals than did TNG66 and YSP. At a concentration of 1mg/ml, TNG10 and TNG57 significantly protected HaCaT cells from H2O2-induced cytotoxicity. The water extracts of YSP had more flavonoids than had those of TNG66 which may have contributed to their higher activity in many antioxidative assays. These results suggest that the water extracts of all four varieties of sweet potato leaves, and especially TNG10 and TNG57, display potent antioxidative effects.

Changes in sugar composition during baking and their effects on sensory attributes of baked sweet potatoes

The objective of this study was to evaluate the influence of sugar composition on the sensory attributes of seven baked sweet potatoes. The sugar composition was analyzed using high performance liquid chromatography. Results showed that the total sugar content of baked sweet potatoes increased significantly because of the formation of maltose. The maltose content dramatically increased after baking, and became the major sugar component of baked sweet potatoes. On the other hand, baked sweet potatoes were evaluated on a 7-point hedonic scale for sensory analysis. Overall acceptability results showed that the panelists preferred baked CYY95-26 and TNG66 over the other baked varieties. Because the correlation between overall acceptability and sweetness was the highest (r = 0.69, p < 0.01), sweetness was determined as the most important factor determining the overall acceptability of baked sweet potatoes. Although sugar composition changed on baking, the overall acceptability of baked sweet potatoes was highly associated with the sucrose content.

Ultrasound-Assisted Anthocyanin Extraction of Purple Sweet Potato Variety TNG73, Ipomoea batatas, L

The acidic-ethanol anthocyanin extraction process of TNG73 sweet potatoes was improved with introducing the sonication treatment. The linear terms of sonication time and extraction temperature were determined to be significant factors. Response surface methodology (RSM) models were successfully established to perform the extraction study and energy requirement analysis. After calculating the required energy for collected anthocyanins (J/µg), the process with higher extraction temperature became less effective. Based on the combined results of extraction study and energy requirement analysis, the recommended operating condition of anthocyanin extraction process was at 25°C with 22 min sonication.

Studies of Carotene Extraction from Sweet Potato Variety CYY95-26, Ipomoea batatas, L

The goal of this study was to extract β-carotene from CYY95-26 sweet potatoes. Acetone was used as the solvent to successfully extract β-carotene. To achieve better extraction results, acetone concentration was required to be higher than 75%. Two extraction parameters, including acetone concentration and extraction time, were evaluated with the response surface methodology. The process was optimized, and optimal extraction conditions were determined to be 91.1% of acetone and 19.6 min extraction. Acetone concentration was a significant factor of the β-carotene extraction. The multiple extraction improved the extraction performance. After the third extraction, 278.1 mg/kg of β-carotene was extracted. The major carotene of CYY95-26 sweet potatoes was all-trans-β-carotene. CYY95-26 also contained small amount of 9-cis-β-carotene and 13-cis-β-carotene which were carotene isomers.

Extraction Parameter Studies for Anthocyanin Extraction from Purple Sweet Potato Variety TNG73, Ipomoea Batatas, L

Anthocyanins were successfully extracted from TNG73 purple sweet potatoes (PSP), which were provided by Agricultural Research Institute (ARI), Chia-Yi Agricultural Experiment Station, Taiwan. An acidic-ethanol extraction method was used, and the extraction parameters were carefully evaluated. The experimental design and process data for anthocyanin extraction were analyzed by statistical software. The HCl concentration, extraction time, and extraction temperature were significant factors in the extraction of anthocyanins from PSP. Using 15% HCl (1.5N HCl in ethanol) with a 9 g/100mL PSP solid/solvent ratio at 25°C for 30 min was adequate for PSP anthocyanin extraction. The extraction performance was increased 15~25% by running a second extraction. Under the same process conditions, the performance was improved about 80% when sonication was applied. The difference caused by the sonication treatment was more significant for the high solid/solvent ratio system. Ultrasound-assisted extraction was a useful tool for PSP anthocyanin extraction. The goals of this study were to collect detailed process data for further process scaling-up and to develop an ultrasound-assisted anthocyanin extraction process.

Cell line studies of glioblastoma and malignant glioma using a newly discovered prenylated chalcone

Context: A newly discovered geranyl prenylated chalcone, semisynthesized from naturally occurring nymphaeol C, has the ability to inhibit the growth of CNS1 (glioblastoma) and 13-06 (malignant glioma) cells. A second-order regression model was established to predict the normalized cell viability of CNS1 and 13-06 cells. Objective: The goal of this study is to evaluate the influence of prenylated chalcone on the glioblastoma and malignant glioma cell lines. For the first time, response surface methodology (RSM) has been introduced to perform a cell line study. Materials and methods: A newly discovered prenylated chalcone was used. This compound is a member of the flavonoid family and possesses a common phenylbenzopyrone structure. Two independent factors, including prenylated chalcone concentration and uptake time, were carefully evaluated by a 22 factorial design. RSM was introduced as a new method for CNS1 and 13-06 cell line studies. Results: For CNS1 cells, the least inhibition uptake time was 20.7 h, and the least inhibition dose was 12.4 μg/ml. For 13-06 cells, the best inhibition uptake time was 26.2 h, and the least inhibition dose was 12.0 μg/ml. Discussion and conclusion: The RSM model successfully predicted the normalized cell viability of CNS1 and 13-06 cells through the use of prenylated chalcone. The results obtained in this study will be useful for further studies on the use of prenylated chalcone.

Induction of apoptosis of malignant gliomas cells by a prenylated chalcone

Abstract Context: Malignant gliomas are the most commonly diagnosed brain tumors in adults. Chalcone and its derivatives have shown potential against glioblastoma and malignant gliomas. Objective: The inhibitory activity of geranyl prenylated chalcone was investigated in four glioma cell lines: C6, U87 MB, CNS-1 and 13-06 MB. Cell death caused by the prenylated chalcone was determined to be necrosis or apoptosis. Materials and methods: The inhibitory activity of geranyl prenylated chalcone with 5, 10, 15, 20, 25, 30 and 40 μg/ml (treatment time: 24, 48 and 72 h) was investigated in C6, U87 MB, CNS-1 and 13-06 MB. Cell cycle distribution, DNA fragmentation, chromatin condensation and protein expression were used as indicators of apoptosis. The migration ability of glioma cells with 30 μg/ml prenylated chalcone after 24 and 36 h incubation was also studied by the scratch wound assay. Results: After 24 h, treatment with 20 μg/ml prenylated chalcone reduced the proliferation (approximately 50%) of all four glioma cell lines (half maximal inhibitory concentration (IC50) = 20 μg/ml). Glioma cell death was verified by the fluorescence-activated cell sorter as prenylated chalcone-induced apoptosis. After running the analysis of protein expression, apoptotic activity induced by the prenylated chalcone was caspase independent for the C6 and U87 MB cell lines, but caspase dependent for the 13-06 MB and CNS-1 cell lines. In addition, prenylated chalcone treatment (30 μg/ml) resulted in the inhibition of glioma cell migration after 24 and 36 h treatment. Discussion and conclusion: Because prenylated chalcone-induced apoptosis inhibited the proliferation and reduced the invasiveness of glioma cells, the prenylated chalcone has potential as a new chemotherapeutic reagent in the treatment of malignant gliomas. The ultimate goal was to develop a novel potential multi-therapy for treating gliomas.