We determined vitamin B12 content of Chinese black tea leaves using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Trace levels (0.25 - 0.69 μg/100g dry weight) of vitamin B12 were detected in...We determined vitamin B12 content of Chinese black tea leaves using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Trace levels (0.25 - 0.69 μg/100g dry weight) of vitamin B12 were detected in Pu’er, Fu, and Brick tea leaves. However, vitamin B12 content (0.06 - 1.37 μg/100g dry weight) of Ryubao tea leaves significantly varied. To determine whether Chinese black tea leaves contain vitamin B12 or other corrinoid compounds that are inactive in humans, corrinoid compounds were purified from Ryubao tea by an immunoaffinity column chromatography and vitamin B12 was identified by liquid chromatography-electrospray ionization/tandem mass spectrometry. Vitamin B12 content in the tea drink prepared from Ryubao tea leaves was very low (0.8 ng/100mL). Our results indicate that Chinese black tea is usually not a good source of B12, although Ryubao tea leaves with the highest B12 content may be utilized as a source of this vitamin for vegerarians.展开更多
In this study, we characterized and quantified vitamin B12 in canned apple snails, escargots, (boiled plain) using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Vitamin B12 contents of canned e...In this study, we characterized and quantified vitamin B12 in canned apple snails, escargots, (boiled plain) using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Vitamin B12 contents of canned escargots (boiled plain) were varied from approximately 0.8 μg/100g weight to approximately 5.5 μg/100g weight (mean values, 2.2 μg/100g weight). We identified vitamin B12 compounds from escargots using liquid chromatography-electrospray ionization/tandem mass spectrometry. We found that escargots contained true vitamin B12 and two inactive corrinoids, which were identified as factor IIIm (or methoxymensimidazolyl cyanocobamide), and factor S (or 2-methylmercaptoadenyl cyanocobamide). These results indicate that canned escargots (boiled plain) are not good sources of vitamin B12 for humans.展开更多
Vitamin B12 contents in the edible cyanobacterium Nostoc flagelliforme, also known as hair vegetable, were assayed using a microbiological method. We detected high vitamin B12 contents in samples of naturally grown ce...Vitamin B12 contents in the edible cyanobacterium Nostoc flagelliforme, also known as hair vegetable, were assayed using a microbiological method. We detected high vitamin B12 contents in samples of naturally grown cells (109.2 ± 18.5 μg/100g dry weight) and cultured cells (120.2 ± 53.6 μg/100g dry weight). However, commercially available hair vegetable samples, which comprised fake substitutes and Nostoc, had variable contents (4.8 - 101.6 μg/100g dry weight) because concomitant fake items contain very low vitamin B12 contents. To evaluate whether natural and cultured N. flagelliforme samples contained vitamin B12 or pseudovitamin B12, corrinoid compounds were purified and identified as pseudovitamin B12 (approximately 72%) and vitamin B12 (approximately 28%) using silica gel 60 TLC bioautography and LC/MS. The results suggested that N. flagelliforme contains substantial amounts of pseudovitamin B12, which is inactive in humans.展开更多
文摘We determined vitamin B12 content of Chinese black tea leaves using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Trace levels (0.25 - 0.69 μg/100g dry weight) of vitamin B12 were detected in Pu’er, Fu, and Brick tea leaves. However, vitamin B12 content (0.06 - 1.37 μg/100g dry weight) of Ryubao tea leaves significantly varied. To determine whether Chinese black tea leaves contain vitamin B12 or other corrinoid compounds that are inactive in humans, corrinoid compounds were purified from Ryubao tea by an immunoaffinity column chromatography and vitamin B12 was identified by liquid chromatography-electrospray ionization/tandem mass spectrometry. Vitamin B12 content in the tea drink prepared from Ryubao tea leaves was very low (0.8 ng/100mL). Our results indicate that Chinese black tea is usually not a good source of B12, although Ryubao tea leaves with the highest B12 content may be utilized as a source of this vitamin for vegerarians.
文摘In this study, we characterized and quantified vitamin B12 in canned apple snails, escargots, (boiled plain) using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Vitamin B12 contents of canned escargots (boiled plain) were varied from approximately 0.8 μg/100g weight to approximately 5.5 μg/100g weight (mean values, 2.2 μg/100g weight). We identified vitamin B12 compounds from escargots using liquid chromatography-electrospray ionization/tandem mass spectrometry. We found that escargots contained true vitamin B12 and two inactive corrinoids, which were identified as factor IIIm (or methoxymensimidazolyl cyanocobamide), and factor S (or 2-methylmercaptoadenyl cyanocobamide). These results indicate that canned escargots (boiled plain) are not good sources of vitamin B12 for humans.
文摘Vitamin B12 contents in the edible cyanobacterium Nostoc flagelliforme, also known as hair vegetable, were assayed using a microbiological method. We detected high vitamin B12 contents in samples of naturally grown cells (109.2 ± 18.5 μg/100g dry weight) and cultured cells (120.2 ± 53.6 μg/100g dry weight). However, commercially available hair vegetable samples, which comprised fake substitutes and Nostoc, had variable contents (4.8 - 101.6 μg/100g dry weight) because concomitant fake items contain very low vitamin B12 contents. To evaluate whether natural and cultured N. flagelliforme samples contained vitamin B12 or pseudovitamin B12, corrinoid compounds were purified and identified as pseudovitamin B12 (approximately 72%) and vitamin B12 (approximately 28%) using silica gel 60 TLC bioautography and LC/MS. The results suggested that N. flagelliforme contains substantial amounts of pseudovitamin B12, which is inactive in humans.
