Antioxidant Activities in Kenaf (Hibiscus cannabinus) Shoots during Growth Stages and Destination of Chlorogenic Acid and Kaempferol Glycosides.

Apart from being utilized as a commercial fiber at maturity, kenaf shoots have potential as a food and feed source because of their diverse bioactivities. Previous studies have focused on mature stems because of their high biomass, whereas the antioxidant activities (AA) and the destination of AA contributors of kenaf stems and their high-yielding byproduct leaves during the growth stage have rarely been studied. Therefore, we investigated changes in AA and its relative components in kenaf leaves and stems during the four vital growth stages. Higher ABTS radical cation and DPPH radical scavenging abilities and ferric reducing antioxidant power, total phenolic content, total flavonoid content, and total polysaccharide content were observed at all leaf stages and in the late stem stages. Chlorogenic acid (CGA) and kaempferol glycosides, especially kaempferitrin (Kfr), were identified as representative phenolic acids and flavonoids in both kenaf leaves and stems. The content of CGA in both leaves and stems increased corresponding to the plant's growth stage, whereas kaempferol glycosides were enhanced in leaves but declined in stems. The highest correlation was observed between TPC and AA in all organs. Further evaluation of CGA and Kfr verified that CGA was the predominant contributor to AA, surpassing Kfr. These findings suggest that kenaf leaves increase antioxidant levels as they grow and can be a useful source of stem harvesting byproducts.

Light-Induced Antioxidant Phenolic Changes among the Sprouts of Lentil Cultivar.

Lentil is a leguminous crop with a high content of health-beneficial polyphenols. Lentil sprouts are popularly consumed in fresh vegetable markets, although their phytochemical qualities are not well understood. In this study, we investigated the accumulation of phenolics in lentil sprouts in response to photosynthetic and stress light qualities, including fluorescent light (FL), red LED (RL), blue LED (BL), ultraviolet A (UV-A), and ultraviolet B (UV-B). Three lentil cultivars, Lentil Green (LG), French Green (FG), and Lentil Red (LR), were used to evaluate sprouts grown under each light condition. The adequate light intensities for enhancing the antioxidant activity of lentil sprouts were found to be 11 W/m2 under photosynthetic lights (FL, RL, BL), and 1 W/m2 under stress lights (UV-A, UV-B). Subsequently, HPLC-ESI/Q-TOF MS analysis was conducted for the quantitative analysis of the individual phenolics that were accumulated in response to light quality. Four main phenolic compounds were identified: ferulic acid, tricetin, luteolin, and kaempferol. Notably, tricetin accumulation was significantly enhanced under BL across all three lentil cultivars examined. Furthermore, the study revealed that the other phenolic compounds were highly dependent on FL, BL, or UV-B exposure, exhibiting cultivar-specific variations. Additionally, the antioxidant activities of lentil extracts indicated that BL was most effective for LG and FG cultivars, whereas FL was most effective for enhancing antioxidant activity of LR cultivars as the sprouts grew.

Tissue-Specific Antioxidant Activities of Germinated Seeds in Lentil Cultivars during Thermal Processing.

Nongerminated seeds (NGS) and germinated seeds (GS) of lentils are regularly eaten after thermal processing. However, the effect of these high temperatures on the beneficial antioxidants present in seeds is unknown. This study examined the effects of thermal processing on the color, polyphenol content, and antioxidant activity (AA) of the seeds of three different cultivars of lentils, including two with seed coats, French green (FG) and Lentil green (LG), and one without a seed coat, Lentil red (LR). Regardless of the cultivars and processing temperatures, the GS tended to be clearer and less yellow than the NGS. The GS of the FG and LG showed lower levels of total phenolic content, major flavonoid content (kaempferol, luteolin, and myricetin), and AA than the NGS. On the other hand, the LR displayed the opposite trend, with the above indicators being higher in the GS than in the NGS. As the values in the germinated endosperm tended to increase, it was concluded that the decrease in AA in the FG and LG was caused by the reduction in antioxidants in the seed coat. Although the temperature had nonsignificant effects on the majority of the antioxidants in the NGS and GS of different lentil cultivars, an 80 °C treatment yielded the highest value of AA in the GS of FG and LG. The results of a correlation coefficient analysis demonstrated the significance of the content of kaempferol, total flavonoids, and total phenolics examined for this experiment as contributors to AA in lentil tissues.