Possible Mechanisms Behind the Differential Effects of Soy Protein and Casein Feedings on Colon Cancer Biomarkers in the Rat

Evaluation of the spermicidal and contraceptive activity of Platycodin D, a Saponin from Platycodon grandiflorum

BACKGROUND

The extract of Platycodon grandiflorum has been reported to have effective spermicidal activity. This study was designed to evaluate the spermicidal and contraceptive activity, as well as the safety, of Platycodin D (PD), a major saponin in Platycodon grandiflorum.

METHODS

Using the computer-aided sperm analysis (CASA) test criteria, the sperm-immobilizing activity of PD was studied using highly motile human sperm. The sperm viability was assessed by fluorescent staining using SYBR-14 (living sperm) and propidium iodide (dead sperm). The sperm membrane integrity was assessed by evaluating the hypo-osmotic swelling (HOS) and examinations by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The in vivo contraceptive efficacy was evaluated in rats using post-intrauterine PD application. The comet assay was employed to determine whether PD caused DNA damage in the sperm. Vaginal biopsies were also performed to determine whether the PD gel induced vaginal inflammation.

RESULTS

A dose-dependent effect of PD on the sperm motility and viability was observed. The maximum spermicidal effect was observed with a 0.25 mM concentration of PD. More than 70% of the PD-treated sperm lost their HOS responsiveness at a concentration of 0.20 mM PD, indicating that PD caused injury to the sperm plasma membrane. TEM and SEM revealed significant damage to both the head and tail membranes of the sperm. PD decreased the fertility to zero in rats, was non-DNA damaging and was not harmful to the vaginal tissue in the rats.

CONCLUSION

PD has significant spermicidal activity that should be explored in further studies.

Flavonoids and cancer prevention: a review of the evidence

The objective of this work is to review data from epidemiological and preclinical studies addressing the potential benefits of diets based on flavonoids for cancer prevention. Flavonoids are subdivided into subclasses including flavonols, flavones, flavanones, flavan-3-ols, anthocyanidins, and isoflavones. Epidemiological studies suggest dietary intake of flavonoids may reduce the risk of tumors of the breast, colon, lung, prostate, and pancreas. However, some studies have reported inconclusive or even harmful associations. A major challenge in the interpretation of epidemiological studies is that most of the data originate from case-control studies and retrospective acquisition of flavonoid intake. Differences in agricultural, sociodemographics, and lifestyle factors contribute to the heterogeneity in the intake of flavonoids among populations residing in the United States, Europe, and Asia. Dose and timing of exposure may influence the anticancer response to flavonoid-rich diets. A limited number of intervention trials of flavonoids have documented cancer preventative effects. Proposed anticancer mechanisms for flavonoids are inhibition of proliferation, inflammation, invasion, metastasis, and activation of apoptosis. Prospective studies with larger sample sizes are needed to develop biomarkers of flavonoid intake and effect. Mechanistic studies are needed to ascertain how flavonoid-rich diets influence gene regulation for cancer prevention.

Relevance of protein fermentation to gut health

It is generally accepted that carbohydrate fermentation results in beneficial effects for the host because of the generation of short chain fatty acids, whereas protein fermentation is considered detrimental for the host's health. Protein fermentation mainly occurs in the distal colon, when carbohydrates get depleted and results in the production of potentially toxic metabolites such as ammonia, amines, phenols and sulfides. However, the effectivity of these metabolites has been established mainly in in vitro studies. In addition, some important bowel diseases such as colorectal cancer (CRC) and ulcerative colitis appear most often in the distal colon, which is the primary site of protein fermentation. Finally, epidemiological studies revealed that diets rich in meat are associated with the prevalence of CRC, as is the case in Western society. Importantly, meat intake not only increases fermentation of proteins but also induces increased intake of fat, heme and heterocyclic amines, which may also play a role in the development of CRC. Despite these indications, the relationship between gut health and protein fermentation has not been thoroughly investigated. In this review, the existing evidence about the potential toxicity of protein fermentation from in vitro animal and human studies will be summarized.

Studies on the viability and membrane integrity of human spermatozoa treated with essential oil of Trachyspermum ammi (L.) Sprague ex Turrill fruit

The present study aimed at investigating the effects of essential oil of Trachyspermum ammi fruits, an oil-bearing plant of Apiaceae family, on human sperm viability and membrane integrity. Chemical compositions of the oil were analysed by GC-MS. Thirty compounds representing 91.39% of the total oil were identified. The viability and membrane integrity of human spermatozoa were assessed using minimum effective dose (MED) concentration (125 μg ml(-1)) of the oil. Sperm treated with essential oil showed a significant decrease (P < 0.05) in viability assessed by eosin-nigrosin and fluorescence dual staining. Moreover, the treated sperm also showed a significant loss (P < 0.05) of functional mitochondria and antioxidant enzyme, catalase (EC 1.11.1.6, CAT), when compared to control. The cholesterol:phospholipid ratio was also increased (P < 0.05) in treated sperm when compared to control, which is an indicator of loss of binding ability of human spermatozoa to the zona pellucida. The scanning electron microscopic studies demonstrated the loss of membrane integrity in essential oil-treated human spermatozoa, which showed vacuolation, swelling of acrosomal cap, detachment of head portion and tail coiling. Present observations indicate the spermicidal property of essential oil of T. ammi fruits, which could be helpful to develop medicinal preparations as a male contraceptive.

In vitro determination of the contraceptive spermicidal activity of essential oil of Trachyspermum ammi (L.) Sprague ex Turrill fruits

This study was conducted to determine the spermicidal and contraceptive efficacy of essential oil of Trachyspermum ammi on human sperm in vitro. Chemical compositions of the oil were analyzed by GC-MS. Nearly 30 compounds representing 91.39% of the total oil were identified. The minimum effective dose (MED) of essential oil of T. ammi that induced instant immobilization of human spermatozoa in vitro was 125 μg/mL. The motility was also irreversible. All of the human sperms were found to be non viable within 10 min at this concentration. The activity of acrosomal enzyme was reduced and a significant releases of 5'-nucleotidase into the surrounding medium was noted after treatment with MED concentration of essential oil, indicating the plasma membrane degradation of the sperm. The maximum number of human sperm failed to decondense when treated with MED concentration of essential oil. The morphological deformities of sperm plasma membrane were evidenced by SEM, which showed vaculation, detachment of heads and tail coiling. The present research indicates that essential oil of T. ammi possesses appreciable spermicidal potential, which may be explored as an effective constituent of vaginal contraceptive.

[Sperm immobilizing effect of leaves extracts of Cestrum parqui]

OBJECTIVE

The leaves extracts of Cestrum parqui were reported to have spermicidal activity. The current investigation identified the spermicidal component of the extracts and evaluated its spermicidal potential in vitro, particularly the effects on sperm motility and vitality.

METHODS

Sperms were prepared by discontinuous buoyant density gradient centrifugation and incubated with varying concentrations of extract from C. parqui (40-250 μg/ml) at 37°C and 5% CO(2). The mode of spermicidal action was evaluated by sperm motility and vitality at different intervals ranging from 5 to 240 minutes. Morphological changes in human spermatozoa after exposure to the extract were evaluated under transmission electron microscope.

RESULTS

A dose- and time-dependent effect of this extract on sperm motility and viability was observed. The mean effective concentration of extracts that induced irreversible immobilization was 250 μg/ml. Transmission electron microscope revealed a significant damage to sperm membrane in head and acrosomal membranes, notable swelling and disruption.

CONCLUSION

Our study indicates that this natural extract has potential spermicidal effect in vitro. It can adequately replace nonoxynol-9 in vaginal contraceptives to make them more vaginally safe and ecofriendly.

Soy consumption and colorectal cancer risk in humans: a meta-analysis

The purpose of the present study was to determine the relationship between soy consumption and colorectal cancer risk in humans by conducting a meta-analysis of available epidemiologic studies. We systematically reviewed publications obtained through a Medline literature search and identified four cohort and seven case-control studies on soy and colorectal cancer risk that met the inclusion criteria. We extracted the risk estimate (hazard ratio, relative risk, or odds ratio) of the highest and the lowest reported categories of intake from each study and conducted this analysis using a random-effects model. Our analysis did not find that soy consumption was associated with colorectal cancer risk [combined risk estimate, 0.90; 95% confidence interval (95% CI), 0.79-1.03] nor did the separate analyses on colon cancer (combined risk estimate, 0.88; 95% CI, 0.74-1.06) and rectal cancer (combined risk estimate, 0.88; 95% CI, 0.67-1.14). However, when separately analyzed on the basis of gender, we found that soy was associated with an approximately 21% reduction in colorectal cancer risk in women (combined risk estimate, 0.79; 95% CI, 0.65-0.97; P = 0.026), but not in men (combined risk estimate, 1.10; 95% CI, 0.90-1.33). Thus, consumption of soy foods may be associated with a reduction in colorectal cancer risk in women, but not in men.

Spermicidal activity of extract from Cestrum parqui

OBJECTIVE

The leaf extract of Cestrum parqui was examined for its effects on sperm motility in vitro.

METHODS

Washed sperm were prepared by discontinuous buoyant density gradient centrifugation and incubated with varying concentrations of extract from C. parqui (40-250 microg/mL) at 37 degrees C and 5% CO(2). Sperm motility and viability were assessed at different intervals ranging from 5 to 240 min. Morphological changes in human ejaculated spermatozoa after exposure to the extract were evaluated under transmission electron microscope.

RESULTS

A dose- and time-dependent effect of this extract on sperm motility and viability was observed. The maximal spermicidal effect was observed with a 250-microg/mL dose of the extract. Transmission electron microscope revealed a significant damage to sperm membrane in both head and acrosomal membranes, notable swelling and disruption.

CONCLUSION

The present study indicates that this natural extract has potential spermicidal effect in vitro.