Effects of drying on caffeoylquinic acid derivative content and antioxidant capacity of sweet potato leaves.

Caffeoylquinic acid (CQA) derivatives are known to possess antioxidative potential and have many beneficial effects on human health. The present study compared the CQA contents and antioxidant activities of aerial parts of sweet potato plants. The effects of drying methods (freeze drying, and drying at 30°C, 70°C, and 100°C) on these two parameters of the first fully expanded leaves were also assessed. The results indicated that the CQA derivatives were detectable in leaves, stem, and flowers of sweet potato plants (varied from 39.34 mg/g dry weight to 154.05 mg/g dry weight), with the leaves (particularly expanding and first fully expanded leaves) containing more CQA derivatives than other aerial plant parts. The expanding and first fully expanded leaves also exhibited greater antioxidant activities than other aerial plant parts, possibly due to their higher contents of CQA derivatives. Drying method significantly affected the content of CQA derivatives in dried sweet potato leaf tissues. Drying treatments at both 70°C and 100°C significantly reduced the CQA derivative content and antioxidant activity in the first fully expanded leaves. Among the tested drying methods, the freeze-drying method demonstrated the preservation of the highest amount of CQA derivatives (147.84 mg/g) and antioxidant property. However, 30°C cool air drying was also a desirable choice (total CQA derivative content was reduced to only 129.52 mg/g), compared to 70°C and 100°C hot air drying, for commercial-scale processing of sweet potato leaves, if the higher operation cost of freeze drying was a major concern.

Sweet potato leaf extract inhibits the simulated in vitro gastrointestinal digestion of native starch.

Several studies have reported the therapeutic use of caffeoylquinic acid (CQA) derivatives in the management of hyperglycemia. This study used a simulated in vitro gastrointestinal digestion model to assess the inhibitory effects of CQA derivatives-rich sweet potato leaf extract (SPLE) and a commercially produced green coffee bean extract (GCBE), each with total polyphenols contents of 452 mg g-1 and 278 mg g-1, respectively, against starch digestion. The changes in the amounts of total polyphenols and total CQA derivatives during in vitro gastrointestinal digestion were also examined. The results indicated that both extracts contained substantial levels of CQA derivatives (136 mg g-1 and 83.5 mg g-1 of extract for SPLE and GCBE, respectively). The amounts of total polyphenols and total CQA derivatives in 20 mg of SPLE and GCBE samples decreased from 9.04 mg to 0.58 mg and from 5.56 mg to 0.58 mg, and from 2.72 mg to 0.16 mg and from 1.67 mg to 0.10 mg, respectively, following in vitro gastrointestinal digestion and subsequent dialysis. When SPLE and GCBE were accompanied with starch for in vitro digestion test, they both exhibited inhibitory effect against starch digestion during simulated intestinal digestion, with estimated half maximal inhibitory concentration (IC50) values of 4.91 mg and 6.06 mg polyphenols, respectively. The amount of glucose permeated through dialysis membrane also decreased significantly in comparison with the extract-negative control. Thus, both SPLE and GCBE were capable of modulating the release of glucose from starch digestion in simulated intestinal tract. The observed inhibitory effects against glucose release were presumably due in part to the presence of CQA derivatives in the tested extracts. The SPLE had higher inhibitory effect against in vitro starch digestion than the commercially prepared reference GCBE. Therefore, the SPLE might be used to manage hyperglycemia over the long term.

γ-Oryzanol, tocol and mineral compositions in different grain fractions of giant embryo rice mutants.

BACKGROUND: Rice embryo is concentrated with lipid, protein and some bioactive chemicals. Two rice mutants IR64-GE and TNG71-GE (M7 generation) were characterised by an enlarged embryo compared with their wild types. In the present study, distributions of protein, lipid, total phenolics, γ-oryzanol, tocols and some essential minerals in these two giant embryo mutants and their respective normal embryo wild types IR64 and TNG71 were compared. RESULTS: The embryo dry weights of giant embryo mutants IR64-GE and TNG71-GE were 0.92 and 1.32 mg per seed respectively. These values were higher than those of their respective normal embryo genotypes (0.50 and 0.62 mg per seed). Large variations in protein, lipid, phenolic, γ-oryzanol, tocol and minerals levels were found between mutant and wild-type pairs. The brown rice of TNG71-GE had higher total γ-oryzanol (average of 24% increase) and total tocol (average of 75% increase) levels than TNG71, IR64 and IR64-GE. CONCLUSION: The embryo and bran parts of giant embryo mutant TNG71-GE were found to be good sources of vitamin E and γ-oryzanol. Therefore it could be used to produce high-value by-products from milled embryo and bran parts and as a genetic resource for rice improvement programmes. TNG71-GE can also be used as a nutrient-fortified rice cultivar.

A comparison between adipose tissue and dental pulp as sources of MSCs for tooth regeneration.

In this study, several in vivo and in vitro comparisons were performed to test the possibility of using adipose-derived stem cells (ADSCs), a more convenient cell source than dental pulp stem cells (DPSCs), in tooth regeneration. Using an efficient, non-engineering implantation method, we first demonstrated that both implants of ADSCs and DPSCs were able to grow self-assembled new teeth in adult rabbit extraction sockets with high success rate. The stem cells were necessary because the implants grew no tooth without them. A stepwise comparison showed that the regenerated teeth from these two types of adult stem cells were living with nerves and vascular system and remarkably similar to a normal tooth in many details. Further strictly controlled, side-by-side comparisons between the two types of stem cells also showed that the expression patterns of gene markers and the broad differentiation potentials induced by specific methods in vitro were very similar. Although a few differences were found, they did not affect the tested tooth regeneration in vivo or differentiation in vitro. Furthermore, rabbit ADSCs had a higher growth rate and a better senescence resistance in culture. All these findings suggest that ADSCs, one of the richest adult stem cells in mammals, are very similar and useful as DPSCs for regenerative dentistry.

Comparisons of protein, lipid, phenolics, γ-oryzanol, vitamin E, and mineral contents in bran layer of sodium azide-induced red rice mutants.

BACKGROUND: The bran part of red rice grain is concentrated with many phytochemicals, including proanthocyanidins, oryzanol and vitamin E, that exert beneficial effects on human health, but it contains low levels of essential minerals such as Fe and Zn. In the present study, the protein, lipid, phytochemicals and mineral contents in bran samples were compared among red rice SA-586 and its NaN3-induced mutants. RESULTS: The plant heights of NaN3-induced mutants were decreased. The contents of protein, lipid, total phenolics, total flavonoids, total anthocyanins, total proanthocyanidins, total γ-oryzanol, total tocopherols and total tocotrienols also varied among the tested mutants. The brans of mutants M-18, M-56 and M-50 contained more proanthocyanidins, γ-oryzanol, vitamin E than that of SA-586, respectively. M-54 accumulated more Fe content (588.7 mg kg⁻¹ bran dry weight) than SA-586 (100.1 mg kg⁻¹ bran dry weight). CONCLUSIONS: The brans of M-18, M-50 and M-56 are good sources of proanthocyanidins, vitamin E and γ-oryzanol, respectively, while the bran of M-54 is rich in Fe. Thus these mutants could be used to produce high-value phytochemicals or Fe byproducts from bran during rice grain milling or as genetic resources for rice improvement programs.