BERRY FRUITS AS A SOURCE OF BIOLOGICALLY ACTIVE COMPOUNDS: THE CASE OF LONICERA CAERULEA

BACKGROUND
Lonicera caerulea L. (blueberry honeysuckle, Caprifoliaceae) is a traditional crop in northern Russia, China, and Japan. Its fruits are little known as edible berries in North America and Europe. This review deals with the botany and chemical composition of L. caerulea and the biological activity of its main constituents, focusing on the potential health benefits of the berries.


METHODS AND RESULTS
PubMed, Science Direct and ISI Web of Knowledge databases were used for this paper. Literature sources include the period 1935-2007. L. caerulea berries a are rich source of phenolic compounds such as phenolic acids as well as anthocyanins, proanthocyanidins and other flavonoids, which display potential health promoting effects. Chemopreventive, antimicrobial, anti-adherence and antioxidant benefits, among others are described for these compounds.


CONCLUSIONS
The potential of L. caerulea berries to prevent chronic diseases such as diabetes mellitus, cardiovascular diseases and cancer seems to be related above all to their phenolic content.


INTRODUCTION
Lonicera caerulea L. (blue berry honeysuckle, Caprifoliaceae) is a traditional crop used in folk medicine in northern Russia, China, and Japan but its fruits are little known as edible berries in North America and Europe 1 .In recent years a large number of studies have investigated the therapeutic eff ects of various fruits and vegetables in the prevention of a range of diseases and there is increasing interest in herbal medicine products.Berries constitute one of the most important sources of potential health supporting phytochemicals in the human diet 2 .They are a rich source of ascorbic acid and phenolic compounds, particularly phenolic acids, anthocyanins, proanthocyanidins and other fl avonoids.These compounds provide the pigmentation of fruits and prove benefi cial to human health 3,4 .Their biological activities include: protection against the incidence and mortality rates of cancer 5 , protection against ischemic heart disease mortality 6 and as well as they have antitumorigenic 7 , antimicrobial 8 , antiinlammatory-allergic 9 and antimutagenic properties 10 .The aim of this paper was to review the current literature on berry-derived biologically active compounds, with the focus on L. caerulea.

BOTANICAL DESCRIPTION
The genus Lonicera, which includes almost 180 species of deciduous or evergreen shrubs, belongs to the Caprifoliaceae family and is native to the Northern Hemisphere (Fig. 1) (ref. 1 ).The nomenclature of honeysuckles is complicated; a lot of species are sometimes classifi ed as varieties and have many synonyms.Large genetic variation is common among the Lonicera genus.For example 10 common species of L. involucrata are only hybrids of one known origin 11 .Many species of Caprifoliaceae family have non-edible fruits and are cultivated only as decorative shrubs or rambling plants 12 , especially for their glorious blooms and ornamental fruits 1 .The fruit colour, which ranges from white or yellow to scarlet or navy blue, is used as an indicator of plant maturity 1 .Honeysuckles are also favoured because of their extreme hardiness to the cold 13 .A few species are used in indigenous medicine as antipyretic, stomachic, diuretic and antidysenteric in India 14 .
L. caerulea L., also known as blue honeysuckle, honeyberry, edible honeysuckle or sweet berry honeysuckle 15 is native to the northern temperate zone, especially Russia (Kamchatka Peninsula, Siberia), North Eastern Asia, and Japan 15,16 .In Europe, it occurs rarely in the Alps and Scandinavia 3 .L. caerulea is currently commercially produced in Russia and Japan, but this species was unknown as an edible berry in North America until very recently 17 .
Native L. caerulea plants grow from 0.8 to 3.0 m tall, but under cultivation the shrubs reach 1.0 m wide to 1.8 m tall 17 .They do not require special soil type; even wet sandy or loamy soil is suitable, pH can range from 5 to 7 and the organic proportion can be higher 12 .Plants have strong tolerance to severe low-temperature conditions.They can survive a temperature of -46 °C without damage 17,18 .The freezing tolerance of perennial plants increases in fall and winter to prevent injury under cold conditions.It is known as cold acclimation and seems to be connected with the content and accumulation of specifi c type of carbohydrates and proteins (see below).The raffi nose family of oligosaccharides have been shown to be potential cryoprotectants because of their capacity to modify the freezing behaviour of aqueous solutions 18,19 .Also the presence of galactose-containing oligosaccharides strongly correlates with increases in freezing, as well as desiccation tolerance 18 .Blue honeysuckle shrubs are long-lived and can survive 25 to 30 years 12 .
Blue honeysuckles are not self-pollinating so at least two single plants are required.Fruits become ripe very early in May or June in European conditions.The plants can begin fruiting within one year after planting and after three years almost 500 g of fruits can be acquired from one plant 12 .Fruit shapes are oval to long and dark navy blue to purple in color 15 with blue waxy coating according to the genotype 12 .They can grow up to more than 2 cm long and weigh more than 1.5 g 17 .Their fl avour is similar to that of bilberries or black currants and it can vary from bitter to sweet 15 .

CONSTITUENTS AND THEIR BIOLOGICAL ACTIVITY
L. caerulea berries and their juice contain saccharides, lipids, proteins, organic acids and polyphenols as major components and also ascorbic acid (45-93 mg • 100 g -1 )(ref. 15), vitamin B, magnesium, phosphorus, calcium and potassium as minor compounds 20 .

Saccharides
L. caerulea fruit contain 7.20 % saccharides.Free saccharides include 3.2 % glucose and 2.9 % fructose, bound saccharides are 0.8 % glucose, 0.2 % galactose and 0.1 % arabinose 21 .Five kinds of saccharides have been identifi ed in L. caerulea shoot apices according to Imanishi et al 18 .The content of fructose, glucose, saccharose, raffi nose and stachyose varies depending on climatic conditions and season.The highest level of sugars has been measured in January, and then the saccharide content decreased to May and after that increased again.According to the literature 18 the dominant sugar is saccharose with 50-90 % of total saccharides.The content of stachyose and raffinose changes dramatically during the year.While it is negligible from April to November, it increases rapidly from November to March.Fructose and glucose constitute only small proportion of total sugars and their content does not change over the year.Accumulation of raffi nose and/or stachyose has strong relationship to the freezing tolerance and desiccation 18 .L. caerulea leaves comprise three glucosides, named caerulosides A, B (Fig. 2) and C.These compounds are formed from secologanin attached through acetal bonds to C-4'and C-6' of the saccharide part of loganin and sweroside, respectively.Caerulosides are the fi rst bis-iridoids, that are composed of two units of iridoids bound by acetal linkages 22,23 .
H Berry fruits as a source of biologically active compounds: the case of Lonicera caerulea

Phenolic compounds
Small berries are one of the most important sources of phenolic compounds with potential health promoting eff ects.L. caerulea contain a huge amount of these compounds.The phenolic content is dependent on the degree of maturity, genetic diversity, preharvest climatic, postharvest storage conditions and processing 20 .We prepared a phenolic fraction from L. caerulea var.kamtschatica (4 % of fresh fruits) containing 33.5 % of phenolics, including anthocyanins (18.5 %), fl avonoids and phenolic acids 21 .
The polyphenols comprise a range of chemical classes of secondary plant metabolites that they all share the ability to act as chain breaking antioxidants 28 .Phenolic compounds are essential for the growth and reproduction of plants and are produced as a response to plant injury by pathogens.At low concentrations they also protect food from oxidative deterioration.At high concentrations they or their oxidation products may interact with proteins, carbohydrates and minerals 29 .The health benefi ts of polyphenols are usually linked to two properties: (i) inhibition of certain enzymes such as xanthine oxidase, aldose reductase, and (ii) antioxidant activity 30 .Polyphenols can protect other food components such as carotenoids and vitamin C and also digestive enzymes and gut epithelial cells from oxidation due to free radicals generated in stomach 31,32 .
Little is known about the bioavailability, absorption and metabolism of polyphenols in humans and it is likely that single groups of fl avonoids have diff erent pharmacokinetic properties 33 .Phenolics are powerful antioxidants in in vitro models, but there is lack of information about whether they can remain a suffi cient time in effi cient chemical forms in the human body 29 .A large proportion of the ingested polyphenols from berries are not taken up into the circulation and pass through the upper GIT into the large intestine where they may be transformed or broken down by the indigenous microfl ora 34 .Phenolic compounds are metabolized by deconjugation and reconjugation reactions.They are hydrolyzed to their free aglycones, and then they are conjugated by methylation, sulphation, glucuronidation or their combination.The subsequent metabolic pathway is similar to that of drug metabolism.Since drugs are usually administrated in hundreds of milligrams in one dose while dietary phenolics are presented in much lower concentration, drugs usually saturate these pathways.When food phenolics are administrated at pharmacological doses, they are found in free forms in the blood 35 .Large doses are metabolized primarily in the liver.Small doses may be metabolized in the intestinal mucosa, the liver has a secondary role in their metabolism 35 .Hollman et al. 36 proposed, based on indirect evidence, that fl avonoid glycosides actually may be absorbed intact in the small intestine, using sodium-dependent glucose transporter 1 (SGLT1).On the one hand this postulate has been confi rmed 37 .On the other hand it has been demonstrated that the effi ciency of such absorption is dramatically suppressed by effl ux of at least some fl avonoid glycosides by the apical transporter multidrug resistance-associated protein 2 (MRP2) (ref. 38).Some fl avonoid glycosides could be hydrolyzed in the small intestine 39 .If the fl avonoid glycosides are able to enter the intestinal epithelial cells (enterocytes), which may include shredded cells, they may be hydrolyzed by broadspecifi c β-glucosidase (BSβG) (ref. 40).For some fl avonoid glycosides, lactase phloridzin hydrolase (LPH), located in the brush border of the mammalian small intestine, could perform this hydrolysis 41 .It has also been shown, that phenolics, which have rhamnose in their molecule, cannot be absorbed through the small intestine.They are degraded by the action of rhamnosidases produced by the colonic microfl ora 29 .

Phenolic acids
Phenolic acids form approximately one third of the total intake of plant polyphenols in the human diet 42 .Daily consumption of phenolic acids has been estimated as 25 to 1000 mg (ref. 43).They are present in free and bound forms in plant material.Bound phenolic acids may be linked through ester, ether, acetyl or other bonds 42 .Simple phenolic acids may also be formed by colonic microfl ora from ingested fl avonoids 44 .
Free phenolic acids stand for only a minor portion of phenolic acids.Their amounts ranged from 1.7 to 4.2 % for all berries.Caff eic, ferulic and p-coumaric acids predominate.Free phenolic acids levels do not exceed taste threshold and they do not infl uence the taste of the berries 45 .
Chlorogenic acid is formed by the esterifi cation of caffeic acid with quinic acid.It can be also degraded to caffeic and quinic acid by esterases produced by the colonic microfl ora 47 .Caff eic acid is known as an antioxidant both in vitro and in vivo 48 .While both caff eic and chlorogenic acid have been reported to be absorbed in humans 49 , caffeic acid absorption is nevertheless hampered when it is esterifi ed with quinic acid.Caff eic acid is still listed under older Hazard Data sheets as a potential carcinogen because of two early experiments on rats and mice.More recent data show that bacteria in the rat's guts may alter the formation of caff eic acid metabolites.There have been no known adverse eff ect of caff eic acid in humans 50,51 .Ferulic acid could be absorbed by passive diff usion or by facilitated transport that appears not be saturated even at a luminal concentration of 50 μmol/l (ref. 52).The absorption of ferulic acid and also free cinnamic acid are controlled by the Na + /dependent carrier-mediated transport process in rat jejunal segments 53 .Some food products also contain oxidatively coupled product of the ferulic acid, the diferulic acid 54 .Coumaric acid is a hydroxy derivative of cinnamic acid.There are three isomers, o-coumaric, m-coumaric and p-coumaric acid, that diff er by the position of the hydroxy substitution of the phenyl group.p-Coumaric acid is the most abundant isomer in nature, has antioxidant properties 55 and is believed to reduce the risk of stomach cancer 56 .

Flavonoids
Flavonoids are polyphenolic compounds, whose structure is formed by the diphenyl propane skeleton (C 6 -C 3 -C 6 ).The diff erences within each group fl ow from variation in numbering and order of the hydroxyl groups, as well as the nature and extent of alkylation and glycosylation of these groups.The degree of hydroxylation is a determinant for their tendency to degradation in the colon and products formed by colonic microfl ora.The absence of hydroxyl group in the molecule prevents the degradation of the ring structure; the degree of hydroxylation magnifi es the tendency to degradation.The absence of the methyl group causes a decrease in the tendency to degradation 57 .Food fl avonoids are usually glycosylated mostly with glucose or rhamnose, but galactose, arabinose, xylose; glucuronic acid and other sugars can also be found.The number of sugar molecules can be one, two or three in diff erent possible positions of the ring substitution.The glycosylation infl uences chemical, physical and biological properties of these compounds 35 .
The extent of absorption and bioavailability of drugs has long been known to be aff ected by membrane transporters, mainly effl ux transporters, in addition to metabolism.The traditional effl ux transporter for drugs, e.g.P-glycoprotein, does not seem to be involved in the transport of fl avonoids.Other transporters have been found to play a role, e.g. the absorptive transporter SGLT1 (ref. 38), the absorptive monocarboxylate transporter (MCT), MRP2, but probably also other MRP isoforms, for glucuronide and sulphate conjugates 38,58 .
The metabolism of fl avonoids was initially described to be mediated by cytochrome P450 (CYP) enzymes 59 in liver microsomes from induced rats and from humans, but it has never been shown to be important in vivo or in intact cells, where conjugative metabolism may be expected to compete with oxidation 60 .Glucuronic acid conjugates of fl avonoids have been well-documented with respect to both the molecular site of glucuronidation and the UD P-glucuronyltransferase (UGT) isoforms involved 61 .One of the tea fl avonoids, epicatechin gallate (ECG), showed only sulphate conjugation 62 .Other metabolic pathways include O-methylation by soluble catechol-O-methyltransferase (COMT) (ref. 63) or by bacterial enzymes.Bacteria Berry fruits as a source of biologically active compounds: the case of Lonicera caerulea from faecal fl ora may be responsible for the hydrolysis of fl avonoids glycosides as well as fl avonoid glucuronides and sulphates.The reaction proceeds via degradation of the fl avonoid backbone into numerous phenolic and carboxylic acid products 64 , as well as carbon dioxide 65 .Many of these products are absorbed and can be detected in human urine 64 .Other types of metabolites are those resulting from oxidation by reactive oxygen species (ROS) 66 .
Covalent binding of oxidized quercetin to DNA and cellular protein has been demonstrated in human cells 67 .
Quercetin is one of the most extensively studied fl avonoids apropos its anticancer activity because of its prevalence among fruits and vegetables (Fig. 3) (ref. 68).Quercetin glucosides are resistant to hydrolysis by HCl in stomach 69 and the absorption occurs in the small intestine into enterocytes probably via active transport 70,71 .They can be methylated into isorhamnetin immediately after absorption in the human body.Quercetin rutinosides are absorbed from the colon following the deglycosylation 71 .After intravenous dose, quercetin can be detected in urine, in particular after hydrolysis with β-glucuronidase/aryl sulphatase 72 .The main route of quercetin excretion is as carbon dioxide, 23 -81 % of the dose, measured by trapping exhaled air 73 .Apigenin is a nontoxic dietary fl avonoid that has been shown to have anti-tumour and anti-infl ammatory activities (Fig. 3).Apigenin can block the formation of uric acid leading to benefi cial eff ects in gout 74 .Catechin and epicatechin are epimers, with (-)-epicatechin and (+)-catechin being the most common optical isomers found in nature (Fig. 3) (ref. 75).Epicatechin can reduce the risk of four of the major health problems: stroke, heart failure, cancer and diabetes 76 .Acylated fl avonoids, such as epicatechin are reported to be absorbed without deconjugation and hydrolysis 77 .

Anthocyanins
Anthocyanins are secondary plant metabolites, derivatives of 2-phenylbenzopyrylium, generally found in glycosidic forms [78][79][80] .The aglycones (anthocyanidins) are rarely found in fresh plants.They occur as 3-glycosides and 3,5diglycosides linked with glucose, galactose, rhamnose or arabinose 78 .Anthocyanins represent the most important group of water-soluble pigments, responsible for the blue, purple and red colour of many plant tissues due to their ability to associate into complexes characterized by higher absorbance of light lengths, co-pigmentation and formation of complexes with metals.In aqueous solution, anthocyanins exist in a number of diff erent molecular forms that are in dynamic equilibrium depending mostly on pH (Fig. 4).The red fl avylium cation is the most abundant molecular form at pH < 2. As the pH increases, there is rapid loss of a proton to generate the blue quinonoidal structure.At the same time, much slower hydration of the fl avylium cation occurs to yield the colourless hemiketal form that further tautomerises to generate the chalcone form 81 .The positively-charged oxonium anthocyanin form may not be aff ected by MRP2 effl ux, which seriously limits the absorption of other fl avonoid glycosides 38 .Anthocyanins seem to be able to be absorbed intact as glycosides 82 .However, the proportion of anthocyanins absorbed and excreted in the urine appears to be quite small, perhaps much less than 0.1 % of the intake 83 .The clearance of anthocyanins from the circulation is rapid; very little is generally detected in the plasma 6 h after administration 82 .Some anthocyanins can be metabolized to colourless forms, oxidized, or degraded into other compounds.Researchers have also found that no glycoside hydrolysis takes place during digestion 84 .The absorption of anthocyanins without removal of glycoside has also been demonstrated 85 .
Anthocyanins and proanthocyanidins have antibacterial properties as well as the ability to inhibit adhesion of bacteria to mucosal membrane of urinary tract 86 .Anthocyanins also act as anti-infl ammatory and anti-mutagenic agents and provide cardioprotection by maintaining vascular permeability 4 .The ability to regulate the perme- ability of capillary vessels has become the basis for their defi nition as vitamin P.They show protection against hepatitis A and B and also against paracetamol hepatotoxicity 87 .Berry extracts rich in anthocyanins have been linked to protective eff ects including the modulation of age-related neurological dysfunctions and improved resistance of red blood cells against oxidative stress in vitro 88 .
Anthocyanins are very good antioxidants due to the presence of hydroxyl groups in position 3 of the C ring, which can chelate metal ions (Fe, Cu), and 3' and 4' of the B ring.Antioxidant activity is also increased by acylation of sugar residues with aromatic hydroxy acids 89 .These compounds have higher antioxidative activities than vitamin E, ascorbic acid or β-carotene 79 .
The major anthocyanins in L. caerulea fruit are the glucosides and rutinosides of cyanidin, peonidin, dephinidin and pelargonidin 21 (Fig. 5).Quantities of these compounds vary depending on a number of the factors 46 .Table 2 shows a comparison of L. caerulea phenolic fraction anthocyanin content with those of Vaccinium macrocarpon 90 and Vitis vinifera 91 .
Cyanidin is the most common anthocyanidin, with a 3', 4'-dihydroxylation of the B ring, present in 90 % of fruits 92 .Wu et al. 83 detected the methylated form of anthocyanins in human urine after consumption of elderberries and blueberries.The cyanidin glycosides tend to have higher antioxidant capacity than peonidin or malvidin glycosides likely due to the free hydroxyl groups on the 3' and 4' positions of cyanidin 93 .The key diff erence compared to other fl avonoid glucosides, is that cyanidin-3-glucoside appears to be absorbed after oral ingestion, although to a limited extent 38 .Cyanidin-3-rutinoside from sweet cherry exhibited cyclooxygenase I and II inhibitory activities 94 .It showed potential in the treatment of diabetes, obesity, hyperlipidemia 95 and B and C type viral hepatitis 96 .Delphinidin may preserve endothelium integrity and protect against endothelial cell apoptosis 97 .Delphinidin, malvidin and petunidin are metabolized in the liver through the catechol-O-methyltransferase reaction in the 3' position 83 .Pelargonidin itself displays an orange red color.Pelargonidin-3-monoglucoside, isolated from frozen strawberries, protected the amino acid tyrosine from the highly reactive oxidant peroxynitrite, inhibited the growth  of Escherichia coli and Staphylococcus aureus, and exerted both a stimulatory and inhibitory eff ect on Lactobacillus casei culture.The stimulation may be due to a decrease in the oxidation-reduction potential of the media aff ected by the pigment, and/or the ability of the organism to split the β-glycosyl bond and use the glucose moiety 98 .Peonidin has been patented for use as food colouring agent 99 .

Proanthocyanidins
Proanthocyanidins (condensed tannins) are oligomeric and polymeric end products of the fl avonoid biosynthetic pathway and are metabolized to anthocyanidins 79 .They can be considered as the fi fth class of plant biopolymers besides polynucleotides, proteins, lignins and polysaccharides.As a class, proanthocyanidins can be complex in structure and composition, featuring various fl avan-3-ols (most commonly catechin, epicatechin, and galloylated catechins) linked together in diff erent ways.Berry proanthocyanidins are primarily dimers, trimers and other oligomers 100 .These molecules may contain two types of linkages between epicatechin units.The B-type (4β → 8) is widely found in apples and grapes and A-type (4β → 8 and L. caerulea phenolics, as secondary plant metabolites, have been shown to provide defence against oxidative stress from endogenous ROS and free radicals 111 .Tumor inhibition by the berries is likely to involve synergic activities between its phytochemicals, including fl avonols (quercetin), proanthocyanidins and others and to be primarily based on reducing oxidation of lipoproteins, improving antioxidant status and lipid levels and mitigating the eff ect of oxidative stress and infl ammation on the vascular system 112 .Phenolics protect cardiomyocytes after ischemic episodes by inhibition of free radical formation in the process of reperfusion 113 .These compounds are able to reduce nitric oxide synthase activity and nitric oxide (NO) level 114 .They inhibit the cyclooxygenase activity, adhesion and reaction of leukocytes with endothelial cells, degranulation of mast cells and decrease in the level of interleukin (IL)-2, interferon (INF)-γ and tumor necrosis factor (TNF)-α (ref. 115).Polyphenolics have been regarded as a potential novel, safe and nontoxic strategy for the modulation of infl ammation dependent on the nuclear factor (NF)-κB pathway 27 .An extract of L. caerulea showed signifi cant anti-infl ammatory eff ects on endotoxin-induced uveitis in rat.The possible mechanisms for this eff ect may depend especially on its ability to inhibit activation of NF-κB and the subsequent production of proinfl ammatory mediators such as TNF-α, prostaglandin (PG)-E 2 and NO (ref. 27).
Berry anthocyanins act as novel cardioprotectants by maintaining vascular permeability, reducing infl ammatory responses and platelet aggregation, and off er superior vascular protection compared to other cardioprotective drugs 116,117 .Bioactive compounds from L. caerulea have been also demonstrated in in vitro models to inhibit the oxidation of lipoproteins.A recent study of ours showed inhibition of copper-induced lipoprotein oxidation by a phenolic fraction of L. caerulea var.kamtschatica 118 .Reduction of atherosclerotic plaques by polyphenolics has been found in animal models; reduction of carcinogenesis was observed in vitro.Epicatechin 76 and anthocyanins, especially delphinidin, may preserve endothelium integrity whose damage can lead to the development of atherosclerosis and also cancer 97 .Some L. caerulea compounds can block mutagenesis by chemical carcinogens and endogenous mutagens and have been shown to modify the process of uncontrolled cell proliferation and apoptosis in vitro 119 .These phytochemicals may exert their anticarcinogenic eff ect by modulating the enzyme systems that metabolize carcinogens or procarcinogens to genotoxins.For example CYP activity can be induced or inhibited by fl avonoids.Ellagic acid inhibits mutagenesis and carcinogenesis by acting on both CYP xenobiotic metabolism and several phase 2 detoxifying enzymes 120 .Berry extracts can protect against carcinogenesis also in animal models 121 .Numerous reports shows quercetin ability to inhibit proliferation of cancer cell lines in vitro, including breast, colon, pancreas cancer, and leukemia 122 .Its mechanism of action includes induction of apoptosis 123 , inhibition of epidermal growth factor receptor expression and associated tyrosine kinase activity 122 , reduced expression of Ras protein in colon cancer cells and primary colorectal tumors 124 , increased expression of endogenous inhibitors 2β → O →7) found in cranberries can inhibit adherence of uropathogenic P-fi mbriated Escherichia coli (Fig. 6) (ref. 101,102 .The stereochemistry of the linkage at C4 may be α or β 103 .The major function of proanthocyanidins in plants is to provide protection against microbial pathogens, insect pests and larger herbivores.Their deposition in the endothelial layer of the seed coat appear to be an example of a pre-formed protective barrier 104 .Salmonella, Staphylococcus, Helicobacter and Bacillus are the most sensitive bacteria to the berry phenolics.In addition, the growth of Escherichia, Clostridium and Campylobacter species but not Lactobacillus and Listeria species are inhibited 105 .The main mechanisms of action are destabilization of cytoplasmic membrane, permeabilization of plasma membrane, inhibition of extracellular microbial enzymes, direct actions on microbial metabolism and deprivation of the substrates required for microbial growth 106 .

TRADITIONAL USE AND PUTATIVE HEALTH BENEFITS
L. caerulea berries have long been harvested from wild plants in regions of Russia, China and Japan where superior edible forms are native.Recently, research in Russia and Japan has resulted in cultivars being selected for commercial production because of its very early maturity, unique fl avour and health benefi ts that have long been acknowledged in Russia 16 .Recent research has supported some of the folkloric claims for the therapeutic uses of blue honeysuckle berries in atherosclerosis, hypertension, gastrointestinal disorders and bacterial infection.The main benefi cial eff ect is due to the presence of vitamin C and high levels of polyphenolics 16,[107][108][109][110] .Berry fruits as a source of biologically active compounds: the case of Lonicera caerulea of matrix metalloproteinases 125 and phytoestrogenic activity involving interaction with the estrogen α-and β-receptors of human breast cancer MCF-7 cells 68 .Cyanidin and its 3-glycoside reduce oxidant-induced DNA strand breakage in normal human lymphocytes ex vivo and are as potent chemoprotectants as the fl avonols, quercetin and myricetin.Cyanidin-3-rutinoside and cyanidin-3-glucoside suppress cancer cell metastasis by inhibiting the motility adhesiveness and invasiveness of metastatic human lung cancer cell lines A579 (ref. 126).Cyanidin and a mixture of several of its glycosides dose-dependently inhibited HCT 116 and HT 29 colon cancer cell growth 127 .Delphinidin, malvidin and petunidin also inhibited proliferation of cancer cells derived from various tissues including colon, breast, blood and lung at high micromolar concentrations 128 .Peonidin has shown potent inhibitory and pro-apoptotic eff ects on cancer cells in vitro, notably human metastatic breast cancer cells 99 .p-Coumaric acid is believed to reduce the risk of stomach cancer by reducing the formation of carcinogenic nitrosamines 56 .Also caff eic acid and epicatechin have been shown to act as an inhibitor of carcinogenesis 48,76 .Wild and cultivated berry proanthocyanidin fractions demonstrated antiproliferative eff ects on two models of prostate cancer: an androgen-sensitive (LNCaP) and more aggressive androgen-insensitive cell line (DU145) (ref. 129).
Several berry derivatives have also potent anti-angiogenesis properties in vitro by altering vascular endothelial growth factor (VEGF) expression and invasiveness.Berry extracts can inhibit hydrogen peroxide and TNF-α induced VEGF expression in these cells and also inhibit angiogenesis in animals 130 .For example apigenin inhibits expression of VEGF in human ovarian cancer cells 74 .
Polyphenolic fractions from plants can display insulin-like eff ects by reducing blood glucose levels after food intake 131 .The main eff ect may be due to inhibition of starch degradation within the gastrointestinal tract (GIT) by inhibiting α-glucosidase/maltase activity 132 .It has been shown, that anthocyanins, especially diacylated forms owing to intestinal pH, inhibit α-glucosidase activity and can reduce blood glucose levels after starch-rich meals, a proven clinical treatment for controlling diabetes mellitus type II (ref. 132,133 .Anthocyanins can directly induce insulin secretion from pancreatic cells in ex vivo models, but this eff ect may be disregarded because of its low serum bioavailability 31,134 .Cyanidin-3-glucoside, quercetin, ferulic acid, peonidin-3-glucoside and tocopherol, in this order, showed signifi cant inhibitory activity against aldose reductase activity 135 .Cyanidin-3-rutinoside inhibited α-glucosidase from baker's yeast in a dose-dependent manner 136 .It can lead to a reduction in glucose absorption and therefore the rise of postprandial hyperglycemia can be attenuated 94 .Berry anthocyanins appear to benefi t vision in several ways in diabetes, including improving night vision by enhanced generation of retinal pigment, increasing circulation within the capillaries of the retina, decreasing macular degeneration and diabetic retinopathy, and improving or preventing glaucoma and cataracts 137 .
A range of berry polyphenols can inhibit protease activities at levels which may aff ect protein digestion in the GIT.Soluble proanthocyanidins can inhibit pancreatic and gastric lipase activity and therefore would be a target in the treatment of obesity 133 .Berries have also been shown to reverse age-related and oxidative stress-induced decline in brain function in rats 138 .

CONCLUSION
Lonicera caerulea berries contain 7.20 % saccharides, 1.52 % lipids, 14.62 % dry matter, 12.2 % organic acids and 4 % phenolics, containing 33.5 % of phenolics, including anthocyanins (18.5 %), fl avonoids and phenolic acids.The major anthocyanins in L. caerulea fruit are glucosides and rutinosides of cyanidin, peonidin, dephinidin and pelargonidin.These berries seem to be prospective sources of health supporting phytochemicals that exhibit benefi cial activities such as anti-adherence, antioxidant and chemoprotective, thus they may provide protection against a number of chronic conditions, e.g.cancer, diabetes mellitus, tumor growth or cardiovascular diseases.These plants can be cultivated in European climatic conditions and therefore are a suitable source of economically accessible nutraceutical preparations.

Table 2 .
Structures of main anthocyanidins.Berry fruits as a source of biologically active compounds: the case of Lonicera caerulea Content of anthocyanins in Lonicera caerulea, Vaccinium macrocarpon and Vitis vinifera extracts.