The Anti-oxidative/Anti-inflammatory Activities and the Active components of Lotus Leaf Extracts, and its Lipid Modulating/Anti-obesity Effect
Date Issued
2010
Date
2010
Author(s)
Lin, Hong-Yu
Abstract
Hypertension and cardiovascular diseases based on atherosclerosis are the leading cause of death in Taiwan. There are many reports about the healthy function of lotus leaf in old Chinese traditional herb book, especially for the function of regulating blood lipid. Therefore, this project aims to conduct bioassay-guided separation and identification of the effective constituents on the anti-oxidative and anti-immflamatory activities, and to understand its functional property. Furthermore, the high fat diet model was used to investigate the blood lipid modulatory effect of ethanolic extract of local lotus leaf in hamsters. Moreover, the high energy diet model was used to estimate anti-obesity effect of n-butanol fraction of local lotus leaf in SD rats.We expect to understand its functional property and to enhance the value of local lotus leaf.
The DPPH scavenging effect, the inhibition of human low-density lipoprotein oxidation and antioxidative contents were employed for the activity-guided purification to identify the antioxidant components of lotus leaves (leaves of Nelumbo nucifera Gaertn.). The methanolic extract of lotus leaves (LLM) was separated into ethyl acetate (LLME), n-butanol (LLMB), and water (LLMW) fractions. LLME and LLMB exhibited greater capacity to scavenge DPPH radical, delayed LDL oxidation and had higher antioxidative contents than LLMW. Seven flavonoids were isolated from both fractions by column chromatography. On the basis of 1D- and 2D-NMR experiments, and MS data analyses, these compounds were identified as catechin (1), quercetin (2), quercetin-3-O-glucopyranoside (3), quercetin-3-O-glucuronide (4), quercetin-3-O-galactopyranoside (5), kaempferol-3-O-glucopyranoside (6), myricetin-3-O-glucopyranoside (7). Quercetin and its glycosides (compound 2-5) exerted potent inhibition of LDL oxidation, whereas myricetin-3-O-glucopyranoside (7) showed stronger DPPH scavenging activity. These results indicated that the antioxidant capacity of lotus leaves partially relevant to its flavonoids. However, We have identified twelve compounds from the ethyl acetate effective subfraction. They included 5 apocarotenoids, 4 phenolics, 1 flavonoids and 2 others.
The alkaloid extracts from leaves of lotus, including total alkaloids (TAs), non-phenolic alkaloids (NPAs), and phenolic alkaloids (PAs) revealed inhibitory effects on nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. The direct scavenging effects on NO and DPPH radicals by TAs were respectively attributed to NPAs and PAs. Five alkaloids were isolated from both fractions by column chromatography and identified as asimilobine (1), roemerine (2), lysicamine (3), nuciferine (4), and N-methylcoclaurine (5). Asimilobine (1) and roemerine (2) exhibited potency as direct NO scavengers while N-methylcoclaurine (5) exerted the highest DPPH radical-scavenging effect. N-Methylcoclaurine (5) also inhibited NO production with an EC50 value of 6±1μM through suppression of inducible NO synthase expression in a concentration-dependent manner in LPS-induced RAW 264.7 macrophages. However, roemerine (2) and lysicamine (3) inhibited NO production (EC50 values of 21±4 and 25±5μM) as well as iNOS and COX-2 expressions.
In the lipid modulatory model, the results showed that diets contained Dahan-lien and Kien-lien extract can reduce adipose tissue and increase fecal excretive cholesterol. Moreover, the diet contained Dahan-lien extract can increase fecal excretive triglyceride. Furthermore, the medium dose of diet contained Dahan-lien planted in Taoyuan can effectively decrease the AI value, and the high dose one can reduce total plasma cholesterol. In anti-obesity model, the results revealed that a high energy diet to SD rats for 10 weeks led to significant increases of body and adipose tissue weight. Ingestion of 2.0% LLEB inhibited the development of increased blood glucose, insulin concentration and abdominal fat mass, while plasma and hepatic triglyceride concentrations were significantly lower in the 2.0% LLEB group than in the HE group. The microarray analysis of hepatic mRNA indicated that 2.0% LLEB up-regulated the expression of gene related to fatty acid oxidation, probably resulting in the suppression of the elevating of triglyceride concentration and abdominal fat mass. Gene expression of glycolysis and insulin signaling was also up-regulated in the 2.0% LLEB group suggesting that administration of LLEB could ameliorate obesity-induced hyperinsulinemia as well as the decrease of blood glucose.
Subjects
lotus leaves
anti-inflammatory effect
antioxidative effect
flavonoid
alkaloid
obesity
SDGs
Type
thesis
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