Phenolic compounds in plants and agri-industrial by-products: Antioxidant activity, occurrence, and potential uses

The antioxidant activity of pomegranate juices was evaluated by four different methods (ABTS, DPPH, DMPD, and FRAP) and compared to those of red wine and a green tea infusion. Commercial pomegranate juices showed an antioxidant activity (18-20 TEAC) three times higher than those of red wine and green tea (6-8 TEAC). The activity was higher in commercial juices extracted from whole pomegranates than in experimental juices obtained from the arils only (12-14 TEAC). HPLC-DAD and HPLC-MS analyses of the juices revealed that commercial juices contained the pomegranate tannin punicalagin (1500-1900 mg/L) while only traces of this compound were detected in the experimental juice obtained from arils in the laboratory. This shows that pomegranate industrial processing extracts some of the hydrolyzable tannins present in the fruit rind. This could account for the higher antioxidant activity of commercial juices compared to the experimental ones. In addition, anthocyanins, ellagic acid derivatives, and hydrolyzable tannins were detected and quantified in the pomegranate juices.

http://ucce.ucdavis.edu/files/datastore/234-60.pdf

Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing

Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods. They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals. Therefore, foods rich in tannins are considered to be of low nutritional value. However, recent findings indicate that the major effect of tannins was not due to their inhibition on food consumption or digestion but rather the decreased efficiency in converting the absorbed nutrients to new body substances. Incidences of certain cancers, such as esophageal cancer, have been reported to be related to consumption of tannins-rich foods such as betel nuts and herbal teas, suggesting that tannins might be carcinogenic. However, other reports indicated that the carcinogenic activity of tannins might be related to components associated with tannins rather than tannins themselves. Interestingly, many reports indicated negative association between tea consumption and incidences of cancers. Tea polyphenols and many tannin components were suggested to be anticarcinogenic. Many tannin molecules have also been shown to reduce the mutagenic activity of a number of mutagens. Many carcinogens and/or mutagens produce oxygen-free radicals for interaction with cellular macromolecules. The anticarcinogenic and antimutagenic potentials of tannins may be related to their antioxidative property, which is important in protecting cellular oxidative damage, including lipid peroxidation. The generation of superoxide radicals was reported to be inhibited by tannins and related compounds. The antimicrobial activities of tannins are well documented. The growth of many fungi, yeasts, bacteria, and viruses was inhibited by tannins. We have also found that tannic acid and propyl gallate, but not gallic acid, were inhibitory to foodborne bacteria, aquatic bacteria, and off-flavor-producing microorganisms. Their antimicrobial properties seemed to be associated with the hydrolysis of ester linkage between gallic acid and polyols hydrolyzed after ripening of many edible fruits. Tannins in these fruits thus serve as a natural defense mechanism against microbial infections. The antimicrobial property of tannic acid can also be used in food processing to increase the shelf-life of certain foods, such as catfish fillets. Tannins have also been reported to exert other physiological effects, such as to accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, produce liver necrosis, and modulate immunoresponses. The dosage and kind of tannins are critical to these effects. The aim of this review is to summarize and analyze the vast and sometimes conflicting literature on tannins and to provide as accurately as possible the needed information for assessment of the overall effects of tannins on human health.

Tannins and Human Health: A Review

Essential oils are aromatic and volatile liquids extracted from plants. The chemicals in essential oils are secondary metabolites, which play an important role in plant defense as they often possess antimicrobial properties. The interest in essential oils and their application in food preservation has been amplified in recent years by an increasingly negative consumer perception of synthetic preservatives. Furthermore, food-borne diseases are a growing public health problem worldwide, calling for more effective preservation strategies. The antibacterial properties of essential oils and their constituents have been documented extensively. Pioneering work has also elucidated the mode of action of a few essential oil constituents, but detailed knowledge about most of the compounds’ mode of action is still lacking. This knowledge is particularly important to predict their effect on different microorganisms, how they interact with food matrix components, and how they work in combination with other antimicrobial compounds. The main obstacle for using essential oil constituents as food preservatives is that they are most often not potent enough as single components, and they cause negative organoleptic effects when added in sufficient amounts to provide an antimicrobial effect. Exploiting synergies between several compounds has been suggested as a solution to this problem. However, little is known about which interactions lead to synergistic, additive, or antagonistic effects. Such knowledge could contribute to design of new and more potent antimicrobial blends, and to understand the interplay between the constituents of crude essential oils. The purpose of this review is to provide an overview of current knowledge about the antibacterial properties and antibacterial mode of action of essential oils and their constituents, and to identify research avenues that can facilitate implementation of essential oils as natural preservatives in foods.

/pdf/essential-oils-in-food-preservation-mode-of-action-synergies-26gwz54pww.pdf

Essential oils in food preservation: mode of action, synergies, and interactions with food matrix components.

Effects of gamma -irradiation on the amimo-carbonyl reaction were investigated with the medel system of various sugar-glycine solutions. The mixed solutions of sugar and glycine were irradiatnd at 20 deg C with gamma rays from a /sup 60/Co source under the presence and absence of oxygen. The browning, the increase in absorbance at 420 nm of this solution with heating, was enhanced by irradiation, especially at the initial stage of browning reaction, but the extent of browning depended on the kinds of sugars, and fructose, sorbose, and sucrose were more remarkable than other sugars. Their browning was more enhanced in the basic solution than the case of neutml and acidic solution, and they were also increased with irradiation doses. The browning between irradiated sugar and unirradiated glycine solution was similar to that of irradiated sugar-glycine solution, and therefore, it was assumed that this browning reaction was due to some fraction in the irradiated sugar. On the browning in the system of the irradiated fructose-other amino acid, the cases of histidine and tryptophane were more noticeable. Glycolaldehyde, glyceraldehyde and glucosone, which are known to be produced by gamma -radiolysis of sugars, showed the browning on reaction with glycine, and the lastmore » one was also detected in the irradiated fructose solution by paper chromatography. (auth)« less

/pdf/effects-of-gamma-irradiation-on-the-amino-carbonyl-reaction-4rq315cujm.pdf

Effects of gamma-irradiation on the amino-carbonyl reaction

各種ゴマ種子および脱脂粉末に，各種微生物を培養したものについて，抗血栓効果を調べるため，試料の50％エタノール抽出物について，ヒト血液を用いた血流改善，血小板凝集抑制，活性酸素消去の各試験を行った．（1）中米産ゴマ脱脂ゴマ粉末（セサミフラワー）は殆ど効果を示さないが，これにAsp. niger（NRIC 1222株）を7日間以上培養したものは，いずれの試験においても強い効果を示した．Asp. awamoriとAsp. oryzaeの場合は弱い効果がみられたが，B. nattoでは殆ど効果がみられなかった．（2）各試料の抽出物のリグナン含量の変化を調べた結果，このセサミフラワーには，セサミン，セサモリンは含有されているが，遊離セサミノールは全くない．Asp. nigerを培養した場合，セサミン，セサモリンは殆ど変化しないが，著量の遊離セサミノールが生成し，Asp. awamori, Asp. oryzaeの場合にもセサミノールは生成するが，比較的少なかった．（3）原料のフラワーを完全脱脂した試料に，Asp. niger培養，および加水分解酵素処理したものは，いずれの場合にも強い血液機能改善効果がみられ，セサミノールが著量に存在していた．またその脱脂フラワーを70％アルコールで抽出し，配糖体を除去後にAsp. nigerを培養した物では，改善効果はみられなかった．（4）タイ産黒ゴマ，パラグアイ産白ゴマ，高リグナンゴマのいずれの試料において，血流改善効果は種子において僅かにみられただけであったが，Asp. nigerの培養で増大した．発芽による影響はあまり見られなかった．血小板凝集抑制効果は種子でみられ，培養，発芽処理により効果はあまり変わらなかった．これらゴマ種子の場合，セサミン，セサモリンは高濃度に存在するが，セサミノールは遊離のものはなく，配糖体も殆どないと推定された．ただ発芽後微生物培養したものに少量の生成がみられた．（5）Asp. nigerまたは複数の酵素作用により発現する血流改善効果などの抗血栓機能には，それらの処理により，配糖体から生成したセサミノールが主に関与することを強く示唆するものである．（6）標品のセサミン，セサミノール，セサモールについて同様な血液試験をした結果，セサミノールにはいずれも有効で，とくに血流改善効果では非常に強い効果がみられた．セサミンは血小板凝集阻害のみに効果が見られ，セサモールには，いずれも弱い効果がみられるだけであった．（7）Asp. niger培養で著量（3～5％）に生成するクエン酸は，このような高濃度においては，培養抽出物の血栓予防効果に多少寄与しているものと思われた．（8）本研究により，セサミノール配糖体を多く含むゴマ試料に，その配糖体を有効に遊離セサミノールにする作用を持つ微生物の培養は，酵素作用を用いて加工することにより，強い抗血栓効果を持つ新しい機能性食品素材を作成する可能性が示された．

Antithrombosis effect of sesame seeds and flour cultured with microorganisms.

ゴマ種子を37℃,暗所で発芽させ,抗酸化性について検討し,次の結果を得た。(1) ゴマ種子は,24時間で幼根が現われ,7日目で全長が約11cm(平均)となり,発芽2日目から4日目にかけて,長さ,生鮮物重量,クロロホルム・メタノール抽出量に大きな変化が認められた。(2) メタノール抽出区分の抗酸化性は,発芽により著して増大し,4日目にピークがみられた。(3) メタノール抽出区分の全フェノール量も発芽に伴い増加した。(4) セザモリン,セザミンは発芽2日目には著しく減少した。セザモリンの減少にもかかわらず,セザモールの生成は認められなかった。またγ-トコフェノールは,種子では,約200μg/g seed存在していたが,発芽に伴い急激に減少し,発芽7日目には40μg/g seedとなった。アスコルビン酸は,発芽に伴い著しく増加し,4日目で約10mg%(生鮮物重量当り)になり,以後減少した。(5) (2)で増えた抗酸化力は,(4)よりセザモール,γ-トコフェロール,アスコルビン酸ではないことが明らかとなった。(6) 全フェノール量,280nmに紫外部吸収をもつ物質の増大,TLC上のフェノール呈色反応から,未知の抗酸化性物質は,フェノール性物質の可能性が強い。

Studies on the Enhancement in Antioxidative Activity of Sesame Seed Induced by Germination

NEW MATERIAL:(6Z, 8E, 10E)-N,N-Dimethyl-5,12-dihydroxyeicosa-6,8,10- trieneamide shown by formula I. USE:An anti-inflammatory drug and auti-rheumatic agent having excellent leukotriene B3 antagonism and immune modulating action. PREPARATION:A compound shown by formula II is reduced to give a compound shown by formula I. The compound shown by formula II is partially hydrolyzed by hydrolyzing the compound in a solvent such as ethanol or methanol at -20 deg.C-60 deg.C in the presence of a metallic catalyst such as Pd-BaCO3. The compound shown by formula I is administered by oral administration such as tablets or capsules, or by parenteral administration such as intravenous, hypodermic or intramuscular injection or by inhalation by aerosol or by percutaneous administration.

Mitsuo Namiki

Papers

Effects of gamma-irradiation on the amino-carbonyl reaction

Antithrombosis effect of sesame seeds and flour cultured with microorganisms.

Studies on the Enhancement in Antioxidative Activity of Sesame Seed Induced by Germination

Leukotriene b3 dimethylamide

Green Pigment Formed by the Reaction of Chlorogenic Acid (or Caffeic Acid Esters) with a Primary Amino Compound during Food Processing