Sweet potato (Ipomoea batatas) is one of the most important food crops worldwide and its leaves provide a dietary source of nutrients and various bioactive compounds. These constituents of sweet potato leaves (SPL) vary among varieties and play important roles in treating and preventing various diseases. Recently, more attentions in health-promoting benefits have led to several in vitro and in vivo investigations, as well as the identification and quantification of bioactive compounds in SPL. Among them, many new compounds have been reported as the first identified compounds from SPL with their dominant bioactivities. This review summarizes the current knowledge of the bioactive compositions of SPL and their health benefits. Since SPL serve as a potential source of micronutrients and functional compounds, they can be further developed as a sustainable crop for food and medicinal industries.

The objectives of this study were to identify the antioxidants and antioxidant axtivity in 27 of Taiwan’s indigenous vegetables. Lycium chinense (Lc), Lactuca indica (Li), and Perilla ocymoides (Po) contained abundant quercetin (Que), while Artemisia lactiflora (Al) and Gynura bicolor (Gb) were rich in morin and kaempferol, respectively. Additionally, Nymphoides cristata (Nc) and Sechium edule (Se)-yellow had significantly higher levels of myricetin (Myr) than other tested samples. Cyanidin (Cyan) and malvidin (Mal) were abundant in Gb, Abelmoschus esculentus Moench (Abe), Po, Anisogonium esculentum (Retz.) Presl (Ane), Ipomoea batatas (Ib)-purple, and Hemerocallis fulva (Hf)-bright orange. Relatively high levels of Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorption capacity (ORAC), and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenger were generated from extracts of Toona sinensis (Ts) and Po. Significant and positive correlations between antioxidant activity and polyphenols, anthocyanidins, Que, Myr, and morin were observed, indicating that these phytochemicals were some of the main components responsible for the antioxidant activity of tested plants. The much higher antioxidant activity of Po, Ts, and Ib (purple leaf) may be related to their higher Cyan, Que, and polyphenol content.

This study investigated the effects of purple sweet potato leaf extract (PSPLE) and its components, cyanidin and quercetin, on human aortic endothelial cells (HAECs) during the inflammatory process. HAECs were pretreated with 100 μg/mL PSPLE or 10 μM quercetin, cyanidin or aspirin for 18 h followed by TNF-α (2 ng/mL) for 6 h, and U937 cell adhesion was determined. Adhesion molecule expression and CD40 were evaluated; NFκB p65 protein localization and DNA binding were assessed. PSPLE, aspirin, cyanidin and quercetin significantly inhibited TNF-α-induced monocyte-endothelial cell adhesion (p < 0.05). Cyanidin, quercetin and PSPLE also significantly attenuated VCAM-1, IL-8 and CD40 expression, and quercetin significantly attenuated ICAM-1 and E-selectin expression (p < 0.05). Significant reductions in NFκB expression and DNA binding by aspirin, cyanidin and quercetin were also observed in addition to decreased expression of ERK1, ERK2 and p38 MAPK (p < 0.05). Thus, PSPLE and its components, cyanidin and quercetin, have anti-inflammatory effects through modulation of NFκB and MAPK signaling. Further in vivo studies are necessary to explore the possible therapeutic effects of PSPLE on atherosclerosis.

Background: Herbaceous plants containing antioxidants can protect against DNA damage. Thepurpose of this study was to evaluate the antioxidant substances,antioxidant activity, and protection of DNA from oxidative damage in humanlymphocytes induced by hydrogen peroxide (H₂O₂). Ourmethods used acidic methanol and water extractions from six herbaceousplants, including Bidens alba (BA), Lycium chinense (LC),Mentha arvensis (MA), Plantago asiatica (PA),Houttuynia cordata (HC), and Centella asiatica(CA). Methods: Antioxidant compounds such as flavonol and polyphenol were analyzed.Antioxidant activity was determined by the inhibition percentage ofconjugated diene formation in a linoleic acid emulsion system and bytrolox-equivalent antioxidant capacity (TEAC) assay. Their antioxidativecapacities for protecting human lymphocyte DNA fromH₂O₂-induced strand breaks was evaluated by cometassay. Results: The studied plants were found to be rich in flavonols, especially myricetinin BA, morin in MA, quercetin in HC, and kaemperol in CA. In addition,polyphenol abounded in BA and CA. The best conjugated diene formationinhibition percentage was found in the acidic methanolic extract of PA.Regarding TEAC, the best antioxidant activity was generated from the acidicmethanolic extract of HC. Water and acidic methanolic extracts of MA and HCboth had better inhibition percentages of tail DNA% and tail moment ascompared to the rest of the tested extracts, and significantly suppressedoxidative damage to lymphocyte DNA. Conclusion: Quercetin and morin are important for preventing peroxidation and oxidativedamage to DNA, and the leaves of MA and HC extracts may have excellentpotential as functional ingredients representing potential sources ofnatural antioxidants.

Effects of mulberry leaf-related extracts (MLREs) on hydrogen peroxide-induced DNA damage in human lymphocytes and on inflammatory signaling pathways in human aortic endothelial cells (HAECs) were studied. The tested MLREs were rich in flavonols, especially bombyx faces tea (BT) in quercetin and kaempferol. Polyphenols, flavonoids, and anthocyanidin also abounded in BT. The best trolox equivalent antioxidant capacity (TEAC) was generated from the acidic methanolic extracts of BT. Acidic methanolic and water extracts of mulberry leaf tea (MT), mulberry leaf (M), and BT significantly inhibited DNA oxidative damage to lymphocytes based on the comet assay as compared to the H₂O₂-treated group. TNF-α-induced monocyte-endothelial cell adhesion was significantly suppressed by MLREs. Additionally, nuclear factor kappa B (NF-κB) expression was significantly reduced by BT and MT. Significant reductions were also observed in both NF-κB and activator protein (AP)-1 DNA binding by MLREs. Significant increases in peroxisome proliferator-activated receptor (PPAR)αandγDNA binding by MLREs were also detected in M and MT extracts, but no evidence for PPARαDNA binding in 50 μg/mL MT extract was found. Apparently, MLREs can provide distinct cytoprotective mechanisms that may contribute to its putative beneficial effects on suppressing endothelial responses to cytokines during inflammation.

The objectives of this study were to investigate the effects of chlorophyll-related compounds (CRCs) and chlorophyll (Chl) a+b on inflammation in human aortic endothelial cells. Adhesion molecule expression and interleukin (IL)-8, nuclear factor (NF)-κB p65 protein, and NF-κB and activator protein (AP)-1 DNA binding were assessed. The effects of CRCs on inflammatory signaling pathways of signal transducers and activators of transcription 3 (STAT3) and mothers against decapentaplegic homolog 4, respectively induced by IL-6 and transforming growth factor (TGF)-β, in human aortic smooth muscle cells cultured in vitro were also investigated. HAECs were pretreated with 10 μM of CRCs, Chl a+b, and aspirin (Asp) for 18 h followed by tumor necrosis factor (TNF)-α (2 ng/mL) for 6 h, and U937 cell adhesion was determined. TNF-α–induced monocyte-endothelial cell adhesion was significantly inhibited by CRCs. Moreover, CRCs and Chl a+b significantly attenuated vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and IL-8 expressions. Treatments also significantly decreased in NF-κB expression, DNA binding, and AP-1 DNA binding by CRCs and Asp. Thus, CRCs exert anti-inflammatory effects through modulation of NF-κB and AP-1 signaling. Ten micromoles of CRCs and Asp upregulated the expression of mothers against decapentaplegic homolog 4 (Drosophila) (SMAD4) in the TGF-β receptor signaling pathway, and SMAD3/4 transcription activity was also increased. Ten micromoles of CRCs were able to potently inhibit STAT3-binding activity by repressing IL-6–induced STAT3 expression. Our results provide a potential mechanism that explains the anti-inflammatory activities of these CRCs.