Transcellular transport of genistein, a soybean-derived isoflavone, across human colon carcinoma cell line (Caco-2)

A Single-Center, Randomized, Double-Blind, Placebo-Controlled Clinical Trial of the Effectiveness of ANT1 Soybean Extract Cream on Skin Recovery After Nd: YAG Laser Treatment

Nd:YAG laser has been used extensively for its versatility in treating many common aesthetic problems, but numerous adverse effects are often complained by recipients of Nd:YAG laser. This study introduces the ANT1 soybean extract cream, which was formulated to alleviate adverse effects after laser therapy. This study explores whether ANT1 enhances the repair mechanism of the postlaser skin, decreases laser-induced complication, and shortens recovery time. The study also aims to pinpoint the ANT1 concentration that is most effective in improving the skin condition after Nd-YAG laser therapy.

MATERIALS AND METHODS

This study was a single-center, randomized, double-blind, placebo-controlled trial. Patients eligible for the study were Asian women, aged 25 to 40 years, who were free of dermatological diseases and allergic reaction. There were a total of 45 subjects. Each subject received a session of Nd-YAG laser therapy every 2 weeks, totaling 3 sessions. Facial skin assessment was achieved via VISIA complexion analysis. VISIA complexion analysis quantitatively assessed the skin condition and tracked the recovery progress of each subject at baseline, immediately after all 3 laser sessions, and a week after the final laser treatment.

RESULTS

Skin condition was evaluated by VISIA complexion analysis. Skin condition was recorded in aspects of pigmented spots, wrinkles, texture, pores, and red area. After Nd-YAG laser therapy, postlaser inflammation was observed in all subjects. Throughout the laser sessions and the outpatient follow-up clinic, the adverse effects of laser therapy, such as redness, spots, wrinkles, pores, and textures, decreased with the use of ANT1 cream. There has been a marked effect in wrinkle reduction in the patients who received a higher concentration of ANT1 cream (P ≤ 0.05). Statistically significant improvement in spots and pores is also seen (P ≤ 0.05).

CONCLUSIONS

Through this study, the results suggest that the application of ANT1 soybean extract cream ameliorates the complications and enhances the cosmetic effects of Nd-YAG laser therapy. A higher concentration of the ANT1 cream significantly reduces wrinkles and redness after laser. All in all, this study proves that the ANT1 soy extract cream may be a useful addition to postlaser care for an overall enhancement in skin condition and recovery.

Single- and multiple-dose pharmacokinetics of genistein capsules in healthy chinese subjects: A phase I, randomized, open-label study

BACKGROUND

Genistein capsules are currently being developed to treat osteoporosis in China. Genistein is extracted from the fruit of Sophora japonica Leguminosae.

OBJECTIVE

The objective of this study was to assess the pharmacokinetics of genistein capsules after single and multiple oral doses in healthy Chinese subjects.

METHODS

This was a Phase I, randomized, open-label, single- and multiple- dose study in healthy Chinese adults (aged 19-40 years). In the single-dose study, subjects were randomly assigned in a 1:1:1 ratio to receive genistein 50, 100, or 300 mg (in 50-mg capsules). To assess the effect of food on the pharmacokinetics, subjects in the 50-mg group were equally randomized again into fasting and postprandial (genistein was administered after a high-fat breakfast) groups according to a 2-way cross-over design. A separate equal-sized group of subjects were administered genistein 50 mg on day 1 (single dose), received no treatment on days 2 and 3, and were administered genistein 50 mg QD for 6 days (days 4-9) to obtain a multiple-dose pharmacokinetic profile. Because genistein is converted so rapidly and completely to glucuronidated genistein after administration, plasma concentrations of glucuronidated genistein were determined using a validated high-performance liquid chromatography/ tandem mass spectrometry method. Drug tolerability was assessed by monitoring adverse events (AEs) and laboratory parameters.

RESULTS

The study enrolled 40 healthy subjects (24 men, 16 women; 10 each in the 50-, 100-, and 300-mg single-dose groups and 10 in the multiple-dose group). Three subjects voluntarily withdrew (2 in the 100-mg group and 1 in the 300-mg group) before study drug administration. Thirty-seven subjects (24 men, 13 women) completed the study and were included in the analysis. The mean (SD) values of the single-dose genistein 50-, 100-, and 300-mg groups were as follows: Tmax, 6.0 (2.4), 7.4 (2.4), and 5.6 (1.2) hours, respectively; tl/2, 13.0 (4.0), 12.6 (5.8), and 9.4 (1.1) hours; AUC0-t, 3344 (1635), 8389 (5164), and 9361 (2428) ng/mL · h(-1); and Cmax , 218.7 (68.6), 435.7 (202.1), and 553.4 (152.8) ng/mL. The plasma glucuronidated genistein concentrations were directly proportional to the administered dose over the range of 50 to 100 mg and increased nonproportionately with the 300-mg dose. No statistically significant differences in pharmacokinetic parameters were found in the fasting group compared with the postprandial group. In the multiple-dose group, the mean (SD) steady-state pharmacokinetic parameters on day 9 were similar to those following a single dose of genistein on day 1 (Tmax, 6.0 [1.0] vs 5.9 [1.5] hours, respectively; tl/2, 9.5 [1.5] vs 9.1 [1.5] hours; AUC0-t, 2830 [1541] vs 2078 [1308] ng/mL · h(-1); Cmax, 203.1 [130.9] vs 168.4 [105.7] ng/mL). All AEs were assessed as mild or moderate and resolved without treatment, with the exception of elevated alanine aminotransferase and aspartate aminotransferase activities in one subject that resolved with treatment.

CONCLUSIONS

The pharmacokinetics of glucuronidated genistein appeared to fit the linear-dose range of genistein 50 to 100 mg, but not the 300-mg dose in these healthy Chinese volunteers. Food consumption did not significantly affect the pharmacokinetic properties. No significant differences were observed in the pharmacokinetic parameters after multiple doses of genistein compared with a single dose, suggesting that the drug did not accumulate after multiple doses.

Analytical and compositional aspects of isoflavones in food and their biological effects

This paper provides an overview of analytical techniques used to determine isoflavones (IFs) in foods and biological fluids with main emphasis on sample preparation methods. Factors influencing the content of IFs in food including processing and natural variability are summarized and an insight into IF databases is given. Comparisons of dietary intake of IFs in Asian and Western populations, in special subgroups like vegetarians, vegans, and infants are made and our knowledge on their absorption, distribution, metabolism, and excretion by the human body is presented. The influences of the gut microflora, age, gender, background diet, food matrix, and the chemical nature of the IFs on the metabolism of IFs are described. Potential mechanisms by which IFs may exert their actions are reviewed, and genetic polymorphism as determinants of biological response to soy IFs is discussed. The effects of IFs on a range of health outcomes including atherosclerosis, breast, intestinal, and prostate cancers, menopausal symptoms, bone health, and cognition are reviewed on the basis of the available in vitro, in vivo animal and human data.

Absorption, Conjugation and Efflux of the Flavonoids, Kaempferol and Galangin, Using the Intestinal CACO-2/TC7 Cell Model

Flavonoids are biologically active compounds in food with potential health effects. We have used the Caco-2 cell monolayer model to study the absorption and metabolism of two flavonols, a class of flavonoids, specifically kaempferol and galangin. Metabolism experiments allowed identification of 5 kaempferol conjugates: 3-, 7- and 4'-glucuronide, a sulphate and a glucurono-sulphate; and 4 galangin conjugates: 3-, 5- and 7-glucuronides, and a sulphate, using specific enzyme hydrolysis, HPLC-MS, and HPLC with post column metal complexation/tandem MS. Transport studies showed that the flavonols were conjugated inside the cells then transported across the monolayer or effluxed back to the apical side. Sulphated conjugates were preferentially effluxed back to the apical side, whereas glucuronides were mostly transported to the basolateral side. For kaempferol, a small amount of the unconjugated aglycone permeated in both directions, indicating some passive diffusion. When kaempferol-3-glucuronide and quercetin7-sulphate were applied to either side of the cells, no permeation in either direction was observed, indicating that conjugates cannot re-cross the cell monolayer. Formation of apical kaempferol-7- and 4'-glucuronides was readily saturated, whereas formation of other conjugates at the apical side and all at the basolateral side increased with increasing concentration of kaempferol, implying different transporters are responsible at the apical and basolateral sides. The results highlight the important but complex metabolic changes occurring in flavonoids during absorption.

Dose-dependent absorption, metabolism, and excretion of genistein in rats

Genistein (4',5,7-trihydroxyisoflavone), a naturally occurring phenolic compound, possesses well-known preventive activity in breast and prostate cancer, cardiovascular diseases, and postmenopausal problems. The aim of this study is to investigate the distribution and dose-dependent absorption, metabolism, and excretion of genistein in rats. Genistein was orally administered to rats at different doses. At various time intervals, blood, bile, and urine samples were collected and incubated with glucuronidase to hydrolyze the glucuronidated genistein. Genistein was detected by HPLC. High levels of glucuronidated genistein were detected in the plasma, bile, and urine after genistein administration. When genistein was administered to rats at 6.25, 12.5, and 50 mg x kg (-1) doses, the AUC (0- t) values for genistein were 23.5, 80.9, and 177.9 mg x min x L (-1); the oral absolute bioavailabilities were 21.9, 33.5, and 19.0%; the AUC (0- t) values of glucuronidated genistein were 173.8, 470.7, and 1721.2 mg x min x L (-1), respectively. The cumulative biliary excretion of genistein respective to each dose was 42.6 +/- 6.5, 75.2 +/- 18.9, and 126.6 +/- 34.8 microg; the cumulative biliary excretion of glucuronidated genistein was 108.5 +/- 35.2, 423.5 +/- 158.3, and 853.7 +/- 320.8 microg for each dose, respectively. The cumulative urinary excretion of genistein was 34.8 +/- 10.8, 187.3 +/- 67.0 and 213.6 +/- 30.6 microg for each dose, respectively; the cumulative levels of glucuronidated genistein excreted in the urine were 217.8 +/- 52.1, 583.1 +/- 106.9, and 1108.4 +/- 88.1 microg, respectively. These results indicated that at high doses absorption, biotransformation, and excretion of genistein occurred in a nonlinear dose-dependent manner. Therefore, the results of these pharmacokinetic studies raise important questions about the therapeutic significance of consuming large quantities of genistein, genistein analogues, or soy-based neutraceuticals.

Pharmacokinetics of the soybean isoflavone daidzein in its aglycone and glucoside form: a randomized, double-blind, crossover study

BACKGROUND

There are conflicting results in the literature on the bioavailability of isoflavones in the aglycone and the glucoside forms.

OBJECTIVE

The objective was to investigate the pharmacokinetics of the soy isoflavone daidzein (DAI) on oral administration of both the aglycone and glucoside form in a human intervention study. In addition, the pharmacokinetics of the bacterial and oxidative metabolites of DAI was assessed.

DESIGN

Seven German men aged 22-30 y participated in a randomized, double-blind study in a crossover design. After ingestion of pure DAI or pure daidzein-7-O-beta-d-glucoside (DG) (1 mg DAI aglycone equivalent/kg body weight), blood samples were drawn before isoflavone administration and 1, 2, 3, 4.5, 6, 8, 10, 12, 24, and 48 h after the dose. Urine was collected before and 0-6, 6-12, and 12-24 h after the intake of the isoflavones. The concentrations of DAI and its major bacterial and oxidative metabolites in plasma and urine were measured with isotope dilution capillary gas chromatography-mass spectrometry.

RESULTS

The systemic bioavailability (area under the curve; AUC(inf)), the maximal plasma concentration (C(max)), and the cumulative recovery of DAI in urine after administration of DG were 3-6 times greater than after the ingestion of DAI. Except for equol, which was formed by only one volunteer, all other quantified metabolites exhibited 2-12 times greater AUC(inf), C(max), and urinary recoveries after consumption of DG.

CONCLUSION

Our results show that DG exhibits a greater bioavailability than its aglycone when ingested in an isolated form.

Effect of lectins on the transport of food factors in caco-2 cell monolayers

The effect of three plant lectins, soybean lectin (SBA), Japanese jack bean lectin (CGA), and wheat germ lectin (WGA), on the transport of various food factors, such as isoflavones, quercetin, dipeptides, and calcium ions, were investigated by use of an intestinal tract model, Caco-2 cell monolayers. The lectins increased the isoflavone transport but had no effect on aglycon transport. SBA increased the transport of quercetin glycosides, whereas CGA and WGA had no effect. The lectins increased the transport of calcium ions but showed no effect on the transport of dipeptides, carnosine, and anserine. Although SBA did not change the transepithelial electrical resistance (TER) value of the Caco-2 cell monolayers, CGA and WGA decreased the TER value. These results indicate that plant lectins affect the transport of food factors in different manners, presumably due to their specific sugar binding activity.

Dietary polyphenols decrease glucose uptake by human intestinal Caco-2 cells

The effect of different classes of dietary polyphenols on intestinal glucose uptake was investigated using polarised Caco-2 intestinal cells. Glucose uptake into cells under sodium-dependent conditions was inhibited by flavonoid glycosides and non-glycosylated polyphenols whereas aglycones and phenolic acids were without effect. Under sodium-free conditions, aglycones and non-glycosylated polyphenols inhibited glucose uptake whereas glycosides and phenolic acids were ineffective. These data suggest that aglycones inhibit facilitated glucose uptake whereas glycosides inhibit the active transport of glucose. The non-glycosylated dietary polyphenols appear to exert their effects via steric hindrance, and (-)-epigallochatechingallate, (-)-epichatechingallate and (-)-epigallochatechin are effective against both transporters.

Phytoestrogens and colorectal cancer prevention

Because colorectal cancer (CRC) is a leading cause of cancer mortality in the Western industrialized world, future chemopreventive strategies will be of high socioeconomic importance. Lower CRC incidences in Far Eastern countries in part may be attributed to high nutritional intake of soy and its abundance in phytoestrogens. Phytoestrogens are plant-derived substances which, due to molecular similarities to endogenous estrogens, distinctly interact with estrogen receptors ERalpha and ERbeta. Both genomic and nongenomic mechanisms have been shown to be responsible for possible anticarcinogenic properties of phytoestrogens, such as induction of apoptosis and inhibition of tyrosine kinases and DNA topoisomerases. This chapter provides a comprehensive review of a variety of studies exploring possible relations between phytoestrogen uptake and CRC risk. While in vitro and animal studies in general are somewhat supportive of a protective role of phytoestrogens against CRC, epidemiological work so far performed does not allow any conclusion on this issue. Studies about mechanisms of phytoestrogenic action against CRC development have been evaluated as well. Because estrogens, vitamin D, and calcium are frequently suggested to be important in CRC prevention, studies concentrating on interactions of phytoestrogens with these substances have been performed. Although support in evidence for a protective effect of phytoestrogens against CRC has increased over the last decade, it is still too early to give a definite recommendation, especially in view of enduring inconsistencies about concentrations most likely to be effective. Further experimental, and particularly epidemiological, studies are required to advance our understanding of the role of phytoestrogens against colon carcinogenesis.

Soyasaponin I and sapongenol B have limited absorption by Caco-2 intestinal cells and limited bioavailability in women

A human study was conducted to evaluate soyasaponin bioavailability in humans. Eight healthy women ingested a single dose of concentrated soy extract containing 434 micromol of group B soyasaponins, the predominant form of soyasaponins in soybeans. Neither soyasaponins nor their metabolites were detected in a 24-h urine collection. Soyasapogenol B, a major metabolite of group B soyasaponins, was found (36.3 +/- 10.2 micromol) in a 5-d fecal collection but no group B soyasaponins were detected. A human colon cancer Caco-2 cell model was used to evaluate the absorbability of soyasaponins at the mucosal level. The mucosal transfers of soyasaponin I and soyasapogenol B were 0.5-2.9 and 0.2-0.8%, respectively, after 4-h incubation on the Caco-2 monolayer. The apical to basolateral absorptions of soyasaponin I and soyasapogenol B were low with P(app) of 0.9 to 3.6 x 10(-6) and 0.3 to 0.6 x 10(-6) cm/s, respectively. The transport rate and cell uptake of soyasaponin I were saturable and concentration-independent. In contrast, soyasapogenol B was taken up by Caco-2 cells in a concentration-dependent manner. Soyasaponin I had no apparent cytotoxic effect on Caco-2 cells at concentrations up to 3 mmol/L, whereas soyasapogenol B at 1 mmol/L or more significantly reduced cell viability. Therefore, ingested soyasaponins have low absorbability in human intestinal cells and seem to be metabolized to soyasapogenol B by human intestinal microorganisms in vivo and excreted in the feces.

Permeability characteristics and membrane affinity of flavonoids and alkyl gallates in Caco-2 cells and in phospholipid vesicles

Biomembrane interactions of flavonoids and alkyl gallates were investigated using transport studies on Caco-2 cells and membrane affinity experiments in phospholipid vesicles. Flavone was rapidly absorbed across the cell monolayer (P(app),380 x 10(-6) cm/s), whereas efficient uptake but no apical to basolateral transport was observed with the flavonoids with higher degree of hydroxylation (e.g., quercetin and luteolin). The transport of alkyl gallates was governed by the length of the alkyl chain, i.e., methyl and propyl gallate were absorbed while octyl gallate showed cellular uptake but no transport. Flavonoids with several hydroxyl groups exhibited highest affinity for vesicle membranes, partition coefficients being 7.1 and 7.5 microM for luteolin and quercetin, respectively. In conclusion, the degree of hydroxylation, molecular configuration, and length of the side chain of flavonoids and alkyl gallates seem to have a highly important impact on their membrane affinity as well as on their permeability characteristics in Caco-2 cells.

Genistein at a concentration present in soy infant formula inhibits Caco-2BBe cell proliferation by causing G2/M cell cycle arrest

Fifteen percent of all U.S. infants are fed soy formulas containing up to 47 mg/L of isoflavones (>65% as genistin + genistein); thus, these infants' intestines are exposed to a high dose of genistein, a phytoestrogen and tyrosine kinase inhibitor. Little attention has been focused on genistein's impact on the developing intestine. We hypothesized that a high dose of genistein would inhibit intestinal cell growth. Caco-2BBe human intestinal cells were exposed to 0, 3.7, and 111 micro mol/L (0, 1, and 30 mg/L) genistein in DMEM + 0.5% fetal bovine serum for 24-48 h. Cell number, thymidine incorporation, apoptosis, and cell cycle analyses were performed. The low genistein concentration increased intestinal cell proliferation by 28% (P = 0.001), but did not affect cell number or caspase-3 activity compared to the control. Furthermore, the addition of ICI, an estrogen receptor antagonist, negated the proliferative effect of the low genistein. In contrast, the high genistein concentration reduced cell number by 40%, proliferation by 94%, and caspase-3 activity by 50% compared to the control (P < 0.05). Cell cycle analysis after 48 h exposure to high genistein revealed 37% of cells in G0/G1 and 35% in G2/M vs. 71% in G0/G1 and 17% in G2/M for the control and low genistein groups. Thus, a biphasic effect of genistein was seen with a low dose stimulating intestinal cell proliferation through the estrogen receptor, whereas a high dose of genistein inhibited intestinal cell proliferation and altered cell cycle dynamics. A high dose of genistein may potentially compromise intestinal growth.

Antioxidative bioavailability of artepillin C in Brazilian propolis

Propolis has strong antioxidative activity. We investigated here whether this activity was available in intestinal Caco-2 and hepatic HepG2 cells. Phenolics in Brazilian propolis, extracted with ethyl acetate after the removal of resin and wax with 90% methanol, included artepillin C at 21 mmol/100 g, p-coumaric acid and cinnamic acid relatives 24mmol, kaempferol and its derivatives 9.4 mmol, naringenin 2.8 mmol, isosakuranetin 0.9 mmol, chrysin at 0.8 mmol/100 g, and several minor components. When the extract was added to the apical side of Caco-2 monolayers, artepillin C was specifically incorporated into the cells and released to the basolateral side mostly without conjugation. Then, artepillin C was added to HepG2 cells and exposed to reactive oxygens. Artepillin C prevented oxidative damage dose-dependently, and suppressed lipid peroxidation evaluated with thiobarbituric acid reactive substances by 16% and the formation of 8-hydroxy-2'-deoxyguanosine in DNA by 36% at a concentration of 20microM. Artepillin C is a bioavailable antioxidant.

Comparison of Caco-2, IEC-18 and HCEC cell lines as a model for intestinal absorption of genistein, daidzein and their glycosides

Genistein and daidzein receive much attention because of their potential to prevent hormone-related cancer and cardiovascular diseases. Limited information is available on the pharmacokinetics of these compounds like, for instance, intestinal uptake by humans and systematic bioavailability. In this study the transport and metabolism of genistein, daidzein and their glycosides has been compared in various cellular models for intestinal absorption such as human colonic Caco-2, rat small intestinal IEC-18 and human immortalized colon HCEC cell lines. Genistein and daidzein were taken up by Caco-2, IEC-18 and HCEC cells and transported to almost same rate and extents. Glycosides were transported across IEC-18 and HCEC monolayers, but not across Caco-2 cells. In Caco-2 and IEC-18 cells, the glycosides were metabolized to their respective aglycones. Furthermore, it was shown that genistein and daidzein were glucuronidated and sulfated in Caco-2 cells, to glucuronidated forms in IEC-18 cells and to sulfated conjugates in HCEC cells. The results of this study compared with reported in vivo data indicate that Caco-2 cells are a valuable model for studying intestinal transport and metabolism of isoflavones.

The splanchnic metabolism of flavonoids highly differed according to the nature of the compound

The absorption and splanchnic metabolism of different flavonoids (namely quercetin, kaempferol, luteolin, eriodictyol, genistein, and catechin) were investigated in rats after an in situ perfusion of jejunum plus ileum (14 nmol/min). Net transfer across the brush border ranged widely according to the perfused compound (from 78% for kaempferol to 35% for catechin). This variation seems linked to the lipophilicity of a given flavonoid rather than to its three-dimensional structure. Except for catechin, conjugated forms of perfused flavonoids were also detected in the intestinal lumen, but the extent of this secretion depended on the nature of the perfused compounds (52% for quercetin to 11% for genistein). For some of the perfused aglycones, biliary secretion was an important excretion route: 30% of the perfused dose for genistein but only 1% for catechin. Thus the splanchnic metabolism of flavonoid is controlled by several factors: 1) the efficiency of their transfer through the brush border, 2) the intensity of the intestinal secretion of conjugates toward the mucosal and serosal sides, respectively, and 3) the biliary secretion of conjugates. These data suggested that the splanchnic metabolism of perfused flavonoids depends on the nature of the compound considered, which in turn influences their availability for peripheral tissues.