Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva, Granada, Spain.
Mol Nutr Food Res. 2012 Oct;56(10):1590-5. doi: 10.1002/mnfr.201200091. Epub 2012 Aug 15.
The aqueous extracts of Hibiscus sabdariffa have been commonly used in folk medicine. Nevertheless, the compounds or metabolites responsible for its healthy effects have not yet been identified. The major metabolites present in rat plasma after acute ingestion of a polyphenol-enriched Hibiscus sabdariffa extract were characterized and quantified in order to study their bioavailability. The antioxidant status of the plasma samples was also measured through several complementary antioxidant techniques. High-performance liquid chromatography coupled to time-of-flight mass spectrometry (HPLC-ESI-TOF-MS) was used for the bioavailability study. The antioxidant status was measured by ferric reducing ability of plasma method, thiobarbituric acid reactive substances assay, and superoxide dismutase activity assay. Seventeen polyphenols and metabolites have been detected and quantified. Eleven of these compounds were metabolites. Although phenolic acids were found in plasma without any modification in their structures, most flavonols were found as quercetin or kaempferol glucuronide conjugates. Flavonol glucuronide conjugates, which show longer half-life elimination values, are proposed to contribute to the observed lipid peroxidation inhibitory activity in the cellular membranes. By contrast, phenolic acids appear to exert their antioxidant activity through ferric ion reduction and superoxide scavenging at shorter times. We propose that flavonol-conjugated forms (quercetin and kaempferol) may be the compounds responsible for the observed antioxidant effects and contribute to the healthy effects of H. sabdariffa polyphenolic extract.
洛神花的水提物在民间医学中被广泛应用。然而，其具有健康功效的化合物或代谢物尚未被确定。为了研究其生物利用度，我们对大鼠急性摄入富含多酚的洛神花提取物后血浆中的主要代谢物进行了鉴定和定量。通过几种互补的抗氧化技术，还测量了血浆样品的抗氧化状态。采用高效液相色谱-飞行时间质谱联用（HPLC-ESI-TOF-MS）进行生物利用度研究。通过血浆铁还原能力测定法、硫代巴比妥酸反应物质测定法和超氧化物歧化酶活性测定法来测量抗氧化状态。检测和定量了 17 种多酚和代谢物。其中 11 种为代谢物。尽管在结构上没有任何修饰的情况下在血浆中发现了酚酸，但大多数类黄酮被发现为槲皮素或山柰酚葡萄糖醛酸缀合物。类黄酮葡萄糖醛酸缀合物的半衰期消除值较长，被认为有助于观察到的细胞膜脂质过氧化抑制活性。相比之下，酚酸似乎通过铁离子还原和短时间内清除超氧化物来发挥其抗氧化活性。我们提出，类黄酮结合形式（槲皮素和山柰酚）可能是引起观察到的抗氧化作用的化合物，并有助于洛神花多酚提取物的健康作用。
