Manami Monobe

Immunostimulating activity of a crude polysaccharide derived from green tea (Camellia sinensis) extract.

Green tea extract is well-known to reduce the risk of a variety of diseases. Here, we investigated the immunostimulating activity of tea polysaccharide (TPS), one of the main components in green tea extract. The water extracts from mature or immature tea leaves were precipitated by using ethanol at room temperature. The sediment was washed with ethanol and acetone alternately and then dried. We used the phagocytic activity of macrophage-like cells as an indicator of immune function activation. Chemical components were analyzed by HPLC. The immunostimulating activity of TPS from immature leaves extract was higher than that of TPS from mature leaves, and its activities were dependent on the content of strictinin in the leaf extract. Futhermore, a mixture of catechin and TPS that removed polyphenols did not increase the immunostimulating activity. These results suggest that the catechin-polysaccharide complex is a very important molecule in the immunomodulating activity of tea extracts.

Enhancement of phagocytic activity of macrophage-like cells by pyrogallol-type green tea polyphenols through caspase signaling pathways

We investigated the phagocytosis-enhancing activity of green tea polyphenols, such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), epicatechin (EC) catechin (+C) and strictinin, using VD3-differentiated HL60 cells. EGCG, EGC, ECG and strictinin, but not EC and +C, increased the phagocytic activity of macrophage-like cells, and a caspase inhibitor significantly inhibited phagocytic activities. These results suggest that the pyrogallol-type structure in green tea polyphenols may be important for enhancement of the phagocytic activity through caspase signaling pathways.

Effect on the Epigallocatechin Gallate/Epigallocatechin Ratio in a Green Tea (Camellia sinensis L.) Extract of Different Extraction Temperatures and Its Effect on IgA Production in Mice

We found that the epigallocatechin gallate (EGCG)/epigallocatechin (EGC) ratio in a green tea (Camellia sinensis L.) extract was affected by the extraction temperature. The EGCG/EGC ratio in the 4 °C extract was around 1:3-4, whereas in the 100 °C extract, it was around 1:0.7. Oral administration of the mixture with a high EGC ratio (1:2-3 = EGCG/EGC) resulted in greater IgA production by murine Peyer’s patch cells.

Increased plasma concentration of epigallocatechin in mice after orally administering a green tea (Camellia sinensis L.) extract supplemented by steamed rice.

We attempted to improve the bioavailability of green tea catechins by using food ingredients. The catechin bioavailability of a green tea extract administered to mice was significantly (p<0.05) increased by supplementing with steamed rice. This enhanced bioavailability was due to the increased concentration of plasma non-gallated catechins, especially epigallocatechin (EGC).

Enhancement of the Phagocytic Activity of Macrophage-Like Cells with a Crude Polysaccharide Derived from Green Tea (Camellia sinensis) Extract

To identify the immunostimulants included in green tea extract, we investigated a crude tea polysaccharide related to increases in phagocytic activity using macrophage-like cells, and found that the crude tea polysaccharide from immature tea leaves included many RNAs as compared with that from mature tea leaves. Furthermore, the crude tea polysaccharide increased phagocytosis through toll-like receptor 7.

Enhancement of Phagocytic Activity by a Crude Polysaccharide from Tea (Camellia sinensis) Extract

We investigated the immunostimulating activity of tea polysaccharide (TPS), one of the main components in tea extract. The water extracts from mature or immature tea leaves were precipitated by using ethanol at room temperature. The sediment was washed with ethanol and acetone alternately and then dried. We used the phagocytic activity of macrophage-like cells as an indicator of immune function activation. The immunostimulating activity of TPS from immature leaves extract was higher than that of TPS from mature leaves, and its activities were dependent on the content of total catechin in the leaf extract. Furthermore, a mixture of catechin and TPS that removed polyphenols did not increase the immunostimulating activity. These results suggest that the tannin-polysaccharide complex is a very important molecule in the immunomodulating activity of tea extracts.

A crude extract from immature green tea ( Camellia sinensis ) leaves promotes Toll-like receptor 7-mediated interferon-α production in human macrophage-like cells

Toll-like receptor 7 (TLR7) senses viral single-stranded RNA (ssRNA), induces the production of type I interferons (IFNs), IFN-α and -β, in macrophages such as dendritic cells (DCs), and its immune system protects the host from virus infection. Here, we found that a crude extract from immature green tea leaves (iTPS) containing a macromolecule with ssRNA fragments, induces IFN-α production in human macrophage-like cells. In addition IFN-α production was inhibited by treatment with TLR7 inhibitors or a phagocytosis inhibitor.

Effects of flavonol-rich green tea cultivar (Camellia sinensis L.) on plasma oxidized LDL levels in hypercholesterolemic mice

To examine the possible benefits of tea flavonols, we compared anti-atherogenic effects between common and flavonol-rich tea cultivars. The tea infusion made from a flavonol-rich cultivar, but not a common cultivar, significantly decreased the plasma oxidized low-density lipoprotein level in mice fed a high-cholesterol diet. The result suggests that tea flavonols have the potential to protect against cardiovascular diseases.

A randomized, placebo-controlled study on the safety and efficacy of daily ingestion of green tea (Camellia sinensis l.) cv. “Yabukita” and “Sunrouge” on eyestrain and blood pressure in healthy adults

The green tea (Camellia sinensis L.) cultivar “Sunrouge” contains anthocyanins, catechins and flavonols. To determine whether ingesting green tea containing anthocyanins improves visual function and blood pressure (BP) in healthy adults, a randomized, double-blind, placebo-controlled study was performed. A total of 120 healthy subjects, aged between 20 and 60 years and with a systolic BP (SBP) value of ≤125 and <155 and a diastolic BP (DBP) value <95, or a DBP of ≤75 mmHg and <95 mmHg and a SBP <155 mmHg, were randomly assigned to one of three groups. For 12 weeks, the placebo group received barley extract without catechin; another group received “Sunrouge” extract containing 11.2 mg anthocyanin and 323.6 mg epigallocatechin-3-O-gallate (EGCG); and a third group received “Yabukita” extract containing 322.2 mg EGCG. Home BP, accommodation ability, visual analog scale questionnaires for eyestrain, and metabolic-associated markers were analyzed at weeks 0, 4, 8, and 12 of the intake period. The ingestion of “Sunrouge” tea significantly improved accommodation ability and eyestrain in subjects younger than 45 years and in subjects who operated visual display terminals every day. It also elevated BP. “Yabukita” tea ingestion significantly increased serum adiponectin levels. No adverse effects were observed. We conclude that long-term intake of “Sunrouge” tea containing anthocyanins and flavonols might improve visual function.

Comparing the Nutritional Values of Tea and Vegetables

現在の日本茶の摂取形態は,煎茶に代表されるように 浸出液を飲用する形態が主体であるが,近年,食品素材 としての抹茶や粉末茶の盛んな利用にみられるように, 茶を野菜や香草のように調理するレシピが数多く紹介さ れるなど,全量を摂取する形態が一段と定着しつつあ る。茶を丸ごと食べることによって,茶浸出液の飲用で は得られない不溶性の成分も摂取できる。このような現 状から,食べ物としての茶の栄養成分に関する問い合わ せが数多く寄せられている。そこで本資料では,文部科 学省による「日本食品標準成分表」から茶と野菜の成分 分析値を抜粋し,ビタミン類やミネラル類,食物繊維の 摂取源として有望とされる野菜と茶を比較することによ って,茶の栄養学的特徴を明らかにした。さらに,現在 の我々の食生活がこれらの成分の摂取基準をどれほど満 たしているか,厚生労働省による「日本人の食事摂取基 準」に加えて,「国民健康・栄養調査」に掲載されてい るデータに基づき現状を推測した。 2 「日本食品標準成分表」と栄養素