Effect of Shiitake mushroom dose on colon tumorigenesis in azoxymethane-treated male Sprague-Dawley rats

Diets Containing Shiitake Mushroom Reduce Serum Lipids and Serum Lipophilic Antioxidant Capacity in Rats

BACKGROUND

We previously reported that dietary intake of shiitake mushroom (SM; Lentinus edodes) decreased serum concentrations of polar lipids in male rats.

OBJECTIVE

This study evaluated the dietary effects of SM on serum cholesterol-related and serum antioxidant indexes in rats of both sexes.

METHODS

Sprague-Dawley rats [38 dams and their offspring (20 males and 20 females/diet)] were fed diets containing 0 (control), 1%, 4%, or 10% (wt:wt) SM powder from gestation day 4 through to postnatal day (PND) 126. Biochemical indexes were monitored during the midgrowth phase (PNDs 50-66).

RESULTS

The food consumption by offspring fed the control diet and diets supplemented with SM was not different when measured on PND 65. However, the 4% and 10% SM diets resulted in male rats with 7% lower body weights than those of the other 2 groups on PND 66. SM consumption dose-dependently decreased the concentrations of lipidemia-related factors in sera, irrespective of sex. At PND 50, serum concentrations of total cholesterol, HDL cholesterol, and non-HDL cholesterol in SM-fed male and female rats were generally lower (3-27%) than those in the corresponding control groups. Consumption of the 10% SM diet resulted in significantly decreased (55%) serum triglyceride concentrations relative to the control groups for both sexes. The 10% SM diet elicited a 62% reduction of serum leptin concentrations in females but not in males, and this same diet increased serum insulin (137%) and decreased serum glucose (15%) in males compared with controls. Serum lipophilic antioxidant capacity in males and females fed SM diets was generally lower (31-86%) than that in the control groups.

CONCLUSION

SM decreased the concentrations of lipidemia-related factors in rat sera irrespective of sex. The SM-elicited reduction of lipophilic antioxidant capacity irrespective of sex may reflect a lower pro-oxidative state and, hence, improved metabolic profile.

Immunomodulatory activities of medicinal mushroom Grifola frondosa extract and its bioactive constituent

Grifola frondosa (GF), a high value medicinal mushroom in China and Japan, is popularly consumed as traditional medicines and health foods, especially for enhancing immune functions. In this study, our aim was to examine the immunomodulatory activities of GF and its bioactive compound ergosterol peroxide (EPO) in lipopolysaccharide (LPS)-induced human monocytic (THP-1) cells. At low concentrations, EPO but not other extracts showed a full protection against LPS-induced cell toxicity. EPO significantly blocked MyD88 and VCAM-1 expression, and cytokine (IL-1β, IL-6 and TNF-α) production in LPS-stimulated cells. It also effectively inhibited NF-κB activation, which was further confirmed with siRNA treatment. These results conclude that EPO may play an important role in the immunomodulatory activity of GF through inhibiting the production of pro-inflammatory mediators and activation of NF-κB signaling pathway.

Analysis of polar lipids in the serum from rats fed shiitake by liquid chromatography-mass spectrometry/mass spectrometry

Consumption of a shiitake mushroom diet has been reported to have effects on serum phospholipids. However, much less is known about the effect on serum polar lipids including lysophospholipids and free fatty acids. In the present study, the effects of a shiitake diet were evaluated on the basis of identification and quantification of individual polar lipid components in rat serum using liquid chromatography-mass spectrometry/mass spectrometry. By comparison with standards and published data, 50 lysophospholipids and 32 free fatty acids were identified, and the concentrations of 27 polar lipids in rat serum were determined. Shiitake diets decreased the levels of all individual polar lipid components in the serum of male rat. The total level of serum polar lipids in males fed 4% shiitake diets (1365.71 mol/L) was significantly lower than that of the control (2270.26 mol/L). However, shiitake diets did not significantly affect the levels of serum polar lipids in female rats.

Lack of efficacy of blueberry in nutritional prevention of azoxymethane-initiated cancers of rat small intestine and colon

Background

Blueberries may lower relative risk for cancers of the gastrointestinal tract. Previous work indicated an inhibitory effect of consumed blueberry (BB) on formation of aberrant crypt foci (ACF) in colons of male Fisher F344 rats (inbred strain). However, effects of BB on colon tumors and in both genders are unknown.

Methods

We examined efficacy of BB in inhibition of azoxymethane (AOM)-induced colon ACF and intestine tumors in male and female Sprague-Dawley rats (outbred strain). Pregnant rats were fed a diet with or without 10% BB powder; progeny were weaned to the same diet as their dam and received AOM as young adults.

Results

Male and female rats on control diet had similar numbers of ACF at 6 weeks after AOM administration. BB increased (P < 0.05) ACF numbers within the distal colon of female but not male rats. There was a significant (P < 0.05) diet by gender interaction with respect to total colon ACF number. Colon and duodenum tumor incidences were less in females than males at 17 weeks after AOM. BB tended (0.1 > P > 0.05) to reduce overall gastrointestinal tract tumor incidence in males, however, tumor incidence in females was unaffected (P > 0.1) by BB. There was a tendency (0.1 > P > 0.05) for fewer adenocarcinomas (relative to total of adenomatous polyps plus adenocarcinomas) in colons of female than male tumor-bearing rats; in small intestine, this gender difference was significant (P < 0.05). BB favored (P < 0.05) fewer adenocarcinomas and more adenomatous polyps (as a proportion of total tumor number) in female rat small intestine.

Conclusion

Results did not indicate robust cancer-preventive effects of BB. Blueberry influenced ACF occurrence in distal colon and tumor progression in duodenum, in gender-specific fashion. Data indicate the potential for slowing tumor progression (adenomatous polyp to adenocarcinoma) by BB.

Cultivation and bioactivity assessment of Grifola frondosa fruiting bodies on olive oil press cakes substrates

Grifola frondosa, a medicinal and edible mushroom, was cultivated on substrates composed of olive oil press cakes with different supplements. Crude extracts were prepared from mature fruiting bodies and tested for their capacity to stimulate splenocyte proliferation. Two wild-growing fruiting bodies were extracted for comparison. Olive oil press cakes reduced the mushroom yield, and the best biological efficiency was obtained on substrates supplemented with wheat bran and without olive oil press cakes. All extracts were capable of inducing splenocyte proliferation and were half as effective as the positive control (6.0 microg/mL phytohaemagglutinin). No correlation between substrate composition and bioactivity could be established. Extracts from wild-growing G. frondosa were superior to cultivated ones in respect to biological activity.