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PubMed2006

Limonoids: overview of significant bioactive triterpenes distributed in plants kingdom.

The search for limonoids started long back when scientists started looking for the factor responsible for bitterness in citrus which has negative impact on citrus fruit and juice industry worldwide. The term limonoids was derived from limonin, the first tetranortriterpenoid obtained from citrus bitter principles. Compounds belonging to this group have exhibited a range of biological activities like insecticidal, insect antifeedant and growth regulating activity on insects as well as antibacterial, antifungal, antimalarial, anticancer, antiviral and a number of other pharmacological activities on humans. Although hundreds of limonoids have been isolated from various plants but, their occurrence in the plant kingdom is confined to only plant families of order Rutales and that too more abundantly in Meliaceae and Rutaceae, and less frequently in Cneoraceae and Harrisonia sp. of Simaroubaceae. Limonoids are highly oxygenated, modified terpenoids with a prototypical structure either containing or derived from a precursor with a 4,4,8-trimethyl-17-furanylsteroid skeleton. All naturally occurring citrus limonoids contain a furan ring attached to the D-ring, at C-17, as well as oxygen containing functional groups at C-3, C-4, C-7, C-16 and C-17. The structural variations of limonoids found in Rutaceae are less than in Meliaceae and are generally limited to the modification of A and B rings, the limonoids of Meliaceae are more complex with very high degree of oxidation and rearrangement exhibited in the parent limonoid structure. To counter the problem of bitterness in citrus juice and products genetic engineering of citrus to maximize the formation of limonoid glucosides for reducing limonoid bitterness is the focus of recent and future research. Regarding the biological activities of limonoids the investigations are to be directed towards detailed characterization, quantification, and designing a simple as well as versatile synthetic route of apparently important limonoids. Extraction methods too should be optimized; evaluation and establishment of pharmaco-dynamic and kinetic principles, and structure activity relationships should be a key goal associated with limonoids so that they can be safely introduced in our arsenal of pharmaceuticals to safeguard the humanity from the wrath of disease and its discomfort.

Anti-Infective Agents↗
PubMed2004

Deterrent effects of four neem-based formulations on gravid female boll weevil (Coleoptera: Curculionidae) feeding and oviposition on cotton squares.

Three commercial neem-based insecticides, Agroneem, Ecozin, and Neemix, and a neem seed extract formulation, bitters, containing 1,036, 16,506, 471, and 223 microg/ml azadirachtin, respectively, were assessed for feeding and oviposition deterrence against gravid female boll weevils, Anthonomus grandis grandis Boheman, in the laboratory. In choice assays, excised cotton squares dipped in the separate formulations were first physically contacted by the weevils' tarsi or antennae fewer times than nontreated control squares. In choice and no-choice assays, each formulation repelled the weevils for > or = 90 min. After 24 h in the choice assays, feeding punctures on the squares treated with Agroneem, Ecozin, or bitters were significantly fewer compared with controls. Egg punctures on the Ecozin- and the bitters-treated squares were significantly fewer than on control squares after 24 h. In the no-choice assay, no significant difference was detected. Aging the formulations under outdoor conditions for 24 h before weevils were exposed resulted in 46-60% and 62-82% reductions in feeding and oviposition punctures, respectively, compared with controls. Agroneem- and bitters-treated squares had > 37% fewer feeding punctures after being aged for 48 h. No significant difference was detected after 72 h of aging. Because the deterrence of the gravid female boll weevils was not correlated with amounts of azadirachtin, azadirachtin does not seem to be the only, or the most influential, component of neem that induced the observed deterrence.

Animals↗
PubMed1997

Effects of debittering on grapefruit juice acceptance.

This study was conducted to assess the acceptance of grapefruit juice which has undergone a debittering process. The sensory effect of debittering and the sensory attributes of sourness, sweetness, bitterness, and aftertaste were appraised, and the correlation between chemical and sensory analyses of the debittered juice were identified. The effect of added grapefruit flavor on perception of sweetness and sourness was statistically significant. Both the level of bitterness and storage duration of grapefruit were shown to influence the way judges perceived bitterness and sweetness. Storage study showed no difference in aftertaste, which may increase consumers buying interest in debittered juice with a high level of bitterness (450 ppm).

Beverages↗
PubMed1990

Practical debittering using model peptides and related compounds.

In order to develop a practical debittering method for amino acids and peptides, several debittering methods were studied. The authors found that hooking acidic amino acids to and acetylation of bitter amino acids is very effective to remove the bitterness from their concentrated solution. For debittering by mixing with additives, skin milk and other peptide compounds were effective. Acidic amino acids were also effective to reduce the bitterness. Gelatinized starch was found to be useful for debittering because it takes bitter substances into its net structure.

Amino Acid Sequence↗
PubMed2002

Effects of Maitake mushroom fractions on blood pressure of Zucker fatty rats.

A link exists between insulin resistance and many chronic disorders of aging including advancing-age. A safer means to prevent or, at least, slow the erosion of insulin sensitivity would provide a novel approach to better health. We compared the ability of a specific extract labeled fraction SX, as well as whole Maitake powder, fraction ES and fraction D of Maitake to influence SBP and various pertinent biochemical parameters when given orally to Zucker Fatty rats, a model of insulin resistance and type 2 diabetes mellitus. A secondary gain was the ability to ascertain the effects of bitter melon, olive oil, and sesame oil alone and combined with fraction SX to influence SBP. We found that a water-soluble fraction obtained from Maitake mushroom (SX) lowers SBP and fasting blood glucose significantly over the three to six weeks of study. While whole Maitake fraction lowered SBP effectively, the effects on fasting blood sugar were not apparent under the conditions of study. In contrast to fraction SX and fraction D, developed primarily to enhance immunity and suppress tumor development and growth, has essentially no effect on SBP under the conditions examined. An ether soluble fraction designated ES lowers SBP significantly. Interestingly, olive oil, unlike sesame oil, also lowers SBP. Finally, bitter melon and a combination of SX plus bitter melon also lower SBP. We conclude that fraction SX of Maitake mushroom may be useful to treat insulin resistance alone or combined with other natural products such as bitter melon and niacin-bound chromium.

Agaricales↗
PubMed2005

[Effect of sour TCM compound recipe on insulin resistance in experimental rats with diabetes mellitus type 2].

OBJECTIVE: To study the effect of sour TCM compound Recipe (SCCR) on insulin resistance in experimental rats with diabetes mellitus type 2 (DM2), under the guidance of TCM doctrine of "sour restrains sweet". METHODS: Model rats of DM2 were established by 8 weeks' feeding with high calorie forage combined with intraperitoneal injection of small dose of streptozotocin, and treated with SCCR (15 g/kg of crude drug/day). Levels of fasting blood glucose (FBG), serum insulin, free fatty acids (FFA), tumor necrosis factor a (TNF-alpha), combining capacity and constant of insulin receptor in liver were determined before treatment and 4, 8 and 12 weeks after treatment, and the insulin sensitive index was calculated. The data were compared with those in the model group (untreated), sweet TCM compound recipe group and bitter TCM compound group (treated with sweet and bitter Chinese drugs respectively) and the control group (treated with dimethyldiguanide). RESULTS: SCCR could markedly reduce the FBG, serum FFA and TNF-alpha levels in rat model of DM2, stimulate the secretion of insulin, raise the combining capacity and constant of insulin receptor in liver and improve the insulin sensitivity, as compared with the effect of sweet or bitter Chinese compound recipe, the difference was significant (P < 0.05). CONCLUSION: SCCR could improve the glucose metabolic disorder and ameliorate the degree of insulin resistance in DM2 model rats, with the effect superior to those with sweet or bitter taste, which illustrates primarily that the therapeutic principle of "sour restrains sweet" of TCM is true of science in a certain degree and having its guiding significance in clinical practice.

Animals↗
PubMed2006

[Assessment of taste development in 62 newborn infants].

OBJECTIVE: To study the differential facial responses to four basic tastes of the newborns and the gender-related different taste sensitivity. METHODS: Sixty-two newborns (31 females and 31 males) born in the Department of Obstetrics, First Hospital of the Chongqing University of Medical Sciences were tested for responses to four solutions, including 25% sucrose (sweet), 5% sodium chloride (salt), 1.43% citric acid (sour), and 0.025% berberine (bitter) 90 minutes after birth. The inclusion criteria were: (1) medically uncomplicated full-term pregnancy; (2) medically uncomplicated spontaneous vaginal delivery; (3) Apgar score of at least 8 at 1 and 5 min. All the infants were found to be normal and healthy on pediatric examination. The facial responses of the newborns were recorded by video. The facial responses were divided into nine facial action units and expressions from A1 to C3, which are also expressed as the 1 - 9 grades of intensity, crying was included as grade 9 and nausea was defined as grade 10 intensity. The distinctions of the facial responses were analyzed by chi-square test. The distinctions of sex in the facial responses were analyzed by the Wilcoxon test. RESULTS: All the newborns were full term, excluding the medical conditions. The average birth weight of the newborns was 3324.3 g. The data from the study indicated that absence of distinctive mouth action or sucking was the major facial response of the infants to sucrose solution (P < 0.01). There were no special expressions when the newborns were given the salt solution (P > 0.01). The lip pursing with negative brow and middle face actions were major response of the infants to the sour solution (citric acid) (P < 0.01). The expressions in response to the bitter solution of the infants were the mouth gaping with negative brow and middle face actions (P < 0.01). The facial responses to the sweet and bitter solutions in the boys were more sensitive than those in the girls (P < 0.01). There was no sex difference in the intensities of the facial responses to the salt and sour solutions (P > 0.05). CONCLUSIONS: The newborns had distinct responses to the four solutions shortly after birth. The facial expression to sweet and bitter solutions in the boys were more sensitive than in the girls.

Berberine↗
PubMed1991

Taste disorder in hypo and hyperthyroidism.

Gustatory responses to the basic taste substances (sweet, salty, sour and bitter) were studied in hypothyroid and hyperthyroid subjects. The intensity and hedonic responses were evaluated using "category scaling" for 7 concentrations of glucose, sodium chloride, citric acid and quinine sulphate. The intensity and hedonic values decrease in hyperthyroidism for salt and bitter solution, and sourness is perceived as more unpleasant. In hypothyroid subjects intensity and hedonic value decreases for sweetness, the pleasant responses to salt and bitter increase, though intensity perception decreases for bitter solutions.

Adult↗
PubMed1988

Differential facial responses to four basic tastes in newborns.

The distinctiveness and recognizability of taste-elicited facial expressions in newborns were examined in 2 studies. Sucrose, sodium chloride, citric acid, and quinine hydrochloride solutions were presented to 12 infants at 2 hours of age. In Study 1, the anatomically based Facial Action Coding System adapted for infants (Baby FACS) was used to obtain detailed, objective descriptions of the infants' videotaped facial responses to each solution. Facial responses to sucrose were characterized primarily by facial relaxation and sucking. The responses to salty, sour, and bitter solutions shared the same hedonically negative upper- and midface components but differed in the accompanying lower-face actions: lip pursing in response to sour and mouth gaping in response to bitter. There was no distinctive facial expression for sodium chloride. These findings demonstrate that newborns differentiate sour and bitter from each other and from salt, as well as discriminating sweet versus nonsweet tastes. In Study 2, untrained adults viewing videotapes of the infants' facial reactions made forced-choice judgments identifying the stimuli presented and rated the hedonic tone of the infants' responses. While the judges accurately identified the newborns' responses to sucrose, there were systematic errors in their judgments of the 3 nonsweet stimuli. The judges' hedonic ratings, on the other hand, clearly differentiated between the infants' responses to the bitter stimulus and the other 3 tastes. The findings are discussed in terms of the possible functional origins and communicative value of taste-elicited facial expressions in infants.

Discrimination Learning↗
PubMed1997

Differential expression of alpha-gustducin in taste bud populations of the rat and hamster.

The G-protein subunit alpha-gustducin, which is similar to rod transducin, has been implicated in the transduction of both sweet- and bitter-tasting substances. In rodents, there are differences in sensitivity to sweet and bitter stimuli in different populations of taste buds. Rat fungiform taste buds are more responsive to salts than to sweet stimuli, whereas those on the palate respond predominantly to sweet substances. In contrast, hamster fungiform taste buds are more sensitive to sweet-tasting stimuli. Taste buds in the vallate and foliate papillae of both species are sensitive to bitter compounds. These differences in sensitivity should be reflected in the numbers of gustducin-containing cells in different taste bud populations. We examined taste buds in the rat and hamster for immunoreactivity to an antibody against alpha-gustducin. Immunofluorescence of labeled taste cells was examined by confocal microscopy, and the cells were counted. Gustducin-positive cells were seen in all taste bud regions; they were spindle-shaped, with circular cross-sections and apical processes that extended to the taste pore. Cells with this characteristic shape in rat vallate taste buds are Type II (light) cells. In the rat, taste buds of the fungiform papillae had fewer gustducin-positive cells (3.1/taste bud) than those of other regions, including the posterior tongue and palate (>8.9/taste bud). Hamster fungiform taste buds contained twice as many gustducin-expressing cells (6.8/taste bud) as those of the rat. These data support the hypothesis that alpha-gustducin is involved in the transduction of both sweet- and bitter-tasting stimuli by mammalian taste receptor cells.

Animals↗
PubMed1997

[Studies on the taste perceptive threshold for 4 basic taste qualities at various sites of lingual surface].

Using filter-paper-disk method for 20 approximately 23 year-old 60 healthy females, taste perceptive thresholds for 4 basic taste qualities (sweetness, saltiness, sourness and bitterness) were measured detailedly at various sites of the lingual surface (lingual apex, lingual center, lingual margin, lingual radix). Sucrose, sodium chloride, sodium tartarate and quinine hydrochloride as taste-producing substances were used for the sweetness, saltiness, sourness and bitterness, respectively. The results revealed the apical site to be most sensitive to all of the sweetness, saltiness and sourness (and especially to the saltiness) and to be followed by marginal and radical sites in sensitiveness. The radical site was revealed to be most sensitive only to the bitterness, and the central site was remarkably hyposensitive to all of these taste qualities. These experimental results differ, in many respects, from those results of study which have been published by Kiesow in 1894 and are already established today (lingual sensitivity to taste qualities is found separately by site: sweetness, sourness and bitterness and highly perceptible at apical, marginal and radical sites, respectively, and saltiness is not very differently perceptible by site), indicating that further detailed reexamination will be needed to know how taste perceptive thresholds for 4 basic taste qualities are distributed in the lingual surface.

Adult↗
PubMed1993

Gustducin and transducin: a tale of two G proteins.

In the vertebrate taste cell, heterotrimeric guanine nucleotide-binding proteins (G proteins) are involved in the transduction of both bitter and sweet taste stimulants. The bitter compound denatonium raises the intracellular Ca2+ concentration in rat taste cells, apparently via G protein-mediated increases in inositol trisphosphate. Sucrose causes a G protein-dependent generation of cAMP in rat taste bud membranes; elevation of cAMP levels leads to taste cell depolarization. To identify and characterize those proteins involved in the taste transduction process, we have cloned G protein alpha subunit (G alpha) cDNAs from rat taste cells. Using degenerate primers corresponding to conserved regions of G proteins, we used the polymerase chain reaction to amplify and clone taste cell G alpha cDNAs. Eight distinct G alpha cDNAs were isolated, cloned and sequenced from a taste cell library. Among these clones was alpha gustducin, a novel taste G alpha closely related to the transducins. In addition to alpha gustducin, we cloned rod and cone transducins from taste cells. This is the first identification of transducin expression outside photoreceptor cells. The primary sequence of alpha gustducin shows similarities to the transducins in the receptor interaction domain and the phosphodiesterase activation site. These sequence similarities suggest that gustducin and transducin regulate taste cell phosphodiesterase, probably in bitter taste transduction.

Animals↗
PubMed2004

Morphologic characterization of rat taste receptor cells that express components of the phospholipase C signaling pathway.

Rat taste buds contain three morphologically distinct cell types that are candidates for taste transduction. The physiologic roles of these cells are, however, not clear. Inositol 1,4,5-triphosphate (IP(3)) has been implicated as an important second messenger in bitter, sweet, and umami taste transductions. Previously, we identified the type III IP(3) receptor (IP(3)R3) as the dominant isoform in taste receptor cells. In addition, a recent study showed that phospholipase Cbeta(2) (PLCbeta(2)) is essential for the transduction of bitter, sweet, and umami stimuli. IP(3)R3 and PLCbeta(2) are expressed in the same subset of cells. To identify the taste cell types that express proteins involved in PLC signal transduction, we used 3,3'diaminobenzidine tetrahydrochloride immunoelectron microscopy and fluorescence microscopy to identify cells with IP(3)R3. Confocal microscopy was used to compare IP(3)R3 or PLCbeta(2) immunoreactivity with that of some known cell type markers such as serotonin, protein gene-regulated product 9.5, and neural cell adhesion molecule. Here we show that a large subset of type II cells and a small subset of type III cells display IP(3)R3 immunoreactivity within their cytoplasm. These data suggest that type II cells are the principal transducers of bitter, sweet, and umami taste transduction. However, we did not observe synapses between type II taste cells and nerve fibers. Interestingly, we observed subsurface cisternae of smooth endoplasmic reticulum at the close appositions between the plasma membrane of type II taste cells and nerve processes. We speculate that some type II cells may communicate to the nervous system via subsurface cisternae of smooth endoplasmic reticulum in lieu of conventional synapses.

Animals↗
PubMed2002

Genetic taste sensitivity to 6-n-propylthiouracil influences food preference and reported intake in preschool children.

Adult tasters of 6-n-propylthiouracil (PROP) are more sensitive to bitter taste and fattiness in foods, and often show lower acceptance of foods that are high in these taste qualities. This study hypothesized that PROP taster children would show lower acceptance of these same foods. Sixty-seven preschool children were classified as PROP tasters (N = 43) or nontasters (N = 24) using a suprathreshold screening solution. Children rated acceptance of 10 bitter and/or fat-containing foods using a 5-pt. facial scale. Parents completed a food frequency questionnaire to estimate their child's intake. Taster children showed lower acceptance of raw broccoli and American cheese (p < or = 0 x 05). Taster-girls showed lower acceptance of full-fat milk than nontaster-girls (p < or = 0 x 05). This effect was not seen in boys. Nontasters reported more daily intake of discretionary fats than tasters (p < or = 0 x 05), an effect largely due to nontaster-girls, in whom reported intake was 2--3 more servings per day than taster-girls, and boys of both groups. These data suggest that PROP taste sensitivity plays a role in acceptance of certain bitter cruciferous vegetables and cheese by young children. In addition, taster group differences in acceptance of full-fat milk and intake of discretionary fats seen in girls, suggest that gender-specific environmental factors might interact with genetics to influence fat preferences.

Analysis of Variance↗
PubMed2002

Relation between PROP (6-n-propylthiouracil) taster status, taste anatomy and dietary intake measures for young men and women.

Previous studies have related 6-n-propylthiouracil (PROP) taster status to preference for, and consumption of various (bitter-tasting) foods recognized for their cancer-preventive properties. The aim of this study was to examine PROP taster status in relation to general measures of dietary intake as well as the consumption of specific food groups. College students (n=183) were classified as non-tasters (n=49), medium tasters (n=89) and supertasters (n=45) of PROP based on intensity ratings of NaCl and PROP solutions. Dietary intake measures were derived from a food frequency questionnaire and body mass indices (BMI) were derived from self-reported height and weight. Supertasters had higher fungiform papillae counts on the anterior tongue than tasters and non-tasters, yet the distributions of papillae counts overlapped across PROP taster groups. No significant differences were found for BMI values and energy intake among taster groups. PROP-tasting women derived a greater percentage of their dietary energy from fat, and consumed less fruit than non-tasters. PROP supertasters did not differ from tasters and non-tasters in intake of bitter fruits, vegetables or beverages except for a lesser intake of green salad. The hypothesis that PROP supertasters, through heightened sensitivity to, and avoidance of, bitter-tasting fruits, vegetables and other foods with antioxidant properties, may therefore be at increased risk for diet-linked diseases such as cancer, is not supported by these findings.

Adolescent↗
PubMed1996

Effects of debittering methods on the proximate composition, organoleptic and functional properties of sesame (Sesamum indicum L.) seed flour.

Sesame seeds were boiled and allowed to sprout under ambient condition (30 +/- 2 degrees C) with an objective to reduce or eliminate the bitter taste associated with them. The untreated seeds were used as a control. The proximate composition, functional and organoleptic properties of defatted sesame flour were assessed at room temperature. There was slight increase (about 10%) in protein content of sprouted seeds. The foaming capacity of flours from untreated, sprouted and boiled seeds were 34.6, 38.5 and 11.5%, respectively. The flour from the boiled seeds had the highest foam stability. Flours from untreated or sprouted seeds, gelation started at the least concentration of 6% whereas that from boiled seed was 11%. The emulsion capacity of flours from the untreated or sprouted seeds was the same (27.6 g oil/g sample) while that from boiled seeds was 12.9 g oil/g sample. Emulsion stability with prolonged storage appeared to be more with flours from the sprouted or boiled seeds than that from the untreated ones. The water absorption properties of flours from the untreated, sprouted and boiled seeds were 8.0, 5.9 and 6.5 g H2O/g sample, respectively whereas the oil absorption capacity same (5.9 g oil/g sample). The bitter taste in flours from the untreated or sprouted was high. The bitter taste was not detected in flour from boiled seeds and the functional properties of the flour were not deleteriously affected except foaming and emulsion capacity. Therefore, this boiling method of debittering sesame seed could be practised. The quality of sesame flour obtained with this boiling method could still serve its role in traditional dishes and in the formulation of some other conventional food products.

Absorption↗
PubMed1977

Enzymatic oxydation of linoleic acid: formation of bittertasting fatty acids.

Linoleic acid was oxidized with a protein fraction from soya beans (25 degrees C; 2h), in which lipoxygenase and peroxydase activities occurred. The fatty acids formed were isolated and, after emulsification with a sugar ester, were evaluated for bitter taste. The main components of the bitter-tasting fractions was a mixture of 9.12.13-trihydroxyoctadec-10- and 9.10.13-trihydroxyoctadec-11-enoic acids. The taste threshold lies in the range 0.6-0.9 mumol/ml. Two further trihydroxy-acids and two oxodihydroxy-acids were also identified in the bitter-tasting fraction.

Fatty Acids↗
PubMed1981

Unconventional protein sources: apricot seed kernels.

Hamawy apricot seed kernels (sweet), Amar apricot seed kernels (bitter) and treated Amar apricot kernels (bitterness removed) were evaluated biochemically. All kernels were found to be high in fat (42.2--50.91%), protein (23.74--25.70%) and fiber (15.08--18.02%). Phosphorus, calcium, and iron were determined in all experimental samples. The three different apricot seed kernels were used for extensive study including the qualitative determination of the amino acid constituents by acid hydrolysis, quantitative determination of some amino acids, and biological evaluation of the kernel proteins in order to use them as new protein sources. Weanling albino rats failed to grow on diets containing the Amar apricot seed kernels due to low food consumption because of its bitterness. There was no loss in weight in that case. The Protein Efficiency Ratio data and blood analysis results showed the Hamawy apricot seed kernels to be higher in biological value than treated apricot seed kernels. The Net Protein Ratio data which accounts for both weight, maintenance and growth showed the treated apricot seed kernels to be higher in biological value than both Hamawy and Amar kernels. The Net Protein Ratio for the last two kernels were nearly equal.

Fruit↗