Total Genistein Contents Research Articles

Consumption of Decorticated Pulses Ensures the Optimum Intake of Isoflavones by the Urban Indian Population

Sample urban population was assessed for consumption of legumes. Genistein and daidzein content of commonly consumed legumes was evaluated to estimate the isoflavone intake through the consumption of these legumes by selected population. Total genistein content of all legumes considered for analysis was found to be in the range of 0.60 to 8.65 mg per 100 g whereas total daidzein content was found to be in the range of 1.10 to 30.37 mg per 100 g in selected legumes. Chickpea, kabuli, whole (Cicer arietinum), pigeon pea, split, decorticated (Cajanus cajan), chickpea, split, decorticated (Cicer arietinum) showed a high amount of genistein and daidzein among selected legumes. Average isoflavone consumption by selected population was found to be 18.22 mg/d through the consumption of legumes. Consumption of pigeon pea (split, decorticated) and chickpea (split, decorticated) was found to be highest at 371.6 g/month and 329.7 g/month, and hence were found to contribute 18% and 14% to total isoflavone intake, respectively. The comparatively high content of isoflavones and inclusion as a staple in the diet have resulted in making the split, decorticated pulses (chickpea, pigeon pea, lentil, green gram, black gram) a chief isoflavone source for selected population irrespective of their demographic differences.

Genistein production in rice seed via transformation with soybean IFS genes

To produce genistein in rice, the isoflavone synthase (IFS) genes, SpdIFS1 and SpdIFS2 were cloned from the Korean soybean cultivar, Sinpaldalkong II as it has a higher genistein content than other soybean varieties. SpdIFS1 and SpdIFS2 show a 99.6% and 98.2% identity at the nucleotide level and 99.4% and 97.9% identity at the amino acid level, respectively, with IFS1 and IFS2 from soybean (GenBank accession Nos. AF195798 and AF195819). Plant expression vectors were constructed harboring SpdIFS1 or SpdIFS2 under the control of a rice globulin promoter that directs seed specific expression, and used to transform two rice varieties, Heugnam, a black rice, and Nakdong, a normal rice cultivar without anthocyanin pigment. Because naringenin, the substrate of SpdIFS1 and SpdIFS2, is on the anthocyanin biosynthesis pathway, the relative production rate of genistein was compared between SpdIFS-expressing transgenic Heugnam and Nakdong. Southern blot analysis of eight of the resulting transgenic rice plants revealed that the T0 plants had one to three copies of the SpdIFS1 or SpdIFS2 gene. The highest level of genistein content found in rice seeds was 103μg/g. These levels were about 30-fold higher in our transgenic rice lines than the genistein aglycon content of a non-leguminous IFS-expressing transgenic tobacco petal, equaling about 12% of total genistein content of Sinpaldalkong II. There were no significant differences found between the genistein content in Heugnam and Nakdong transgenic rice plants.

Effect of Extraction and Precipitation Conditions During Soybean Protein Isolate Production on the Genistein Series Content

AbstractThe influence of the conditions for isolation of soy protein on the content of genistein and its conjugated forms was studied. The major components of the genistein series isolated from soybean flour were malonyl genistin (54.3%), genistin (36.9%), and equal amounts (4.4%) of genistein and acetyl genistin. A modification in the conjugation profile of genistein between pH 4.5 and 8.0 and above pH 10 was attributed to the action of β‐glucosidase and the saponification reaction, respectively. A decrease in the content of total genistein in the insoluble flour residue and in the soy protein isolate (SPI) with increasing extraction pH was detected, while in the whey, the total genistein content was not affected by pH. The effect of pH variation during acid precipitation on the content of genistein and its conjugated forms, at a constant extraction pH (8.0), was also studied. Under these conditions, the highest absolute content of total genistein in the SPI was obtained at pH 3.5 and the lowest was obtained at pH 5.6. The total genistein content in the whey followed an inverse trend compared with that of the protein yield. A temperature increase did not substantially affect the distribution of the different genistein forms or their total contents. The content of total genistein was higher in the glycinin than in the β‐conglycinin protein fraction. The effect of the pH during the alcohol/water extraction of the isoflavones was also analyzed. The efficiency of the extraction was lower at pH values between 3.25 and 3.5 than at other pH values.

Nutritional Quality of Fermented Soy Foods in Thailand

Soybean has been favored by many Thai people and it has been prepared by numerous different methods. Collected samples are as follows: Thua-nao paste from Chiangrai province, dried Thua-nao for Jatujak Market, Bangkok, 3 types of commercial soybean paste, soybean sauce and 2 types of fermented soybean curd cakes with other ingredients. Moisture contents of fresh and dried Thua-nao were 68.5 and 7.6%, respectively; therefore the shelf-life of dried Thua-nao can be extended to 1 year with proper packaging. The remainder of the soy foods had moisture contents of 55.4 to 64.4%. Fat contents of fresh and dried Thua-nao were 7.4 and 19.7%, respectively, whereas other samples contained less than 3%. Dried Thua-nao had the highest CHO (carbohydrates) content (37.4%); in contrast, soybean sauce contained only 4.5%. Calcium content was highest in dried Thua-nao followed by fresh Thua-nao; the other fermented soy foods had less than 44.7 mg/100 g. Salt was added to samples other than Thua-nao resulting in high Na contents. Free and total daidzein contents of dried Thua-nao were 355 and 676 ug/g; similarly free and total genistein contents were 293 and 616.5 ㎍/g, respectively.

Dietary Genistein Inactivates Rat Thyroid Peroxidase in Vivo without an Apparent Hypothyroid Effect

Biological effects of genistein are currently under investigation by the National Toxicology Program because of widespread and increasing soy consumption by humans and evidence for modulation of endocrine function. Rats were exposed to genistein aglycone in soy-free feed fortified at 0, 5, 100, and 500 ppm starting in utero through 20 weeks. Thyroid glands and serum were analyzed for total genistein (aglycone + conjugates) using HPLC with electrospray mass spectrometric detection. Microsomal thyroid peroxidase (TPO) activity was measured spectrophotometrically. The total genistein content in rat serum was as high as 8 μM, and significant dose-dependent increases of genistein in thyroid tissue up to 1 pmol/mg were found in male and female rats. The activity of TPO in male and female rats was found to be reduced by up to 80% in a dose-dependent manner. Male and female rats consuming a standard soy-based rodent diet (NIH 31) had TPO activity approximately 50% lower than rats consuming a soy-free diet and this loss was commensurate with measured serum levels of isoflavones. Suicide inactivation of rat, porcine, and human TPO was observed in vitro at concentrations of genistein aglycone comparable to those measured in rat thyroids. Thyroid hormone levels (T3, T4, TSH) in serum, thyroid weights, and histopathology showed no differences between treated and untreated groups. These findings suggest that, even though substantial amounts of TPO activity are lost concomitant to soy isoflavone consumption by normal rats, the remaining enzymatic activity is sufficient to maintain thyroid homeostasis in the absence of additional perturbations.