Proanthocyanidins - Science topic

Greetings, good people,

I kindly request assistance in converting concentrations from µg/ml to µM.

While calculating the concentrations to evaluate compounds that may inhibit cathepsin S (the enzyme of interest) and assess their cytotoxicity using the MTT assay, I used units in "µg/ml." Now, I intend to convert them to µM, as most previous studies have utilized this unit.

The compounds in question are chlorogenic acid, quercetin, and procyanidin. According to the literature, the conversion is given by the formula: µM = µg/ml ÷ molecular weight (kD).

Regarding the conversion of g/mol to kD, we said 1 kD (kiloDalton) is equivalent to 1,000 g/mol.

For chlorogenic acid, with a molecular weight of 354.31 g/mol. Is it correct to say 10 µg/ml is equivalent to 28.22 µM?

This comes from this calculation.

µM = µg/ml ÷ (molecular weight in g/mol ÷ 1,000)

= 10 µg/ml ÷ (354.31 g/mol ÷ 1,000)

= 28.22 µM

Hello, I'd like to know if proanthocyanidins present fluorescence by their own. If not, which dye could I use to see them by fluorescence microscopy? I use them in the formulation of food emulsions and I want to determine their presence at the oil-water interface. Thank you.

I carried out an assay of condensed tannins from extracts of leaves and stems of my plant I found for extracts from ultrasound-assisted extraction that the content of condensed tannins of the leaves is higher than that of the stems . and for the maceration extracts I found the opposite. The content of condensed tannins at the stems was higher than that of the leaves. how can we interpret these results please ??

* All my samples are methanolic extract

Regarding the highlighted part of the photo below, is the blank really the one with no catechin? How can it be so since catechin standard is added to all the test tubes (except for the 0mL aliquots)?

I thought maybe that the blank should be the one with no vanillin (this is for the construction of calibration curve not the analysis of the sample extracts themselves).

Can someone please clear this up? Thanks a lot.

Complete procedure is found here:

I am just an undergraduate student and the reagents we need are really expensive in sigma-aldrich.

I had found a company that offers them in a more affordable price and lower MOQ (name is Nanjing Pars Biochem CO.,Ltd www.pariselements.com).

Will these chemicals be okay? Are they, at least, of the same quality?

Our research is about anthelmintic activities of condensed tannin extracts.

I will be analyzing condensed tannin extracts for their mDP, PD/PC ratio, and cis/trans ratio using the method of Gea et al. (2011).

For the calculation of mDP, the extension units will be identified as BM adducts (see photo).

Do I need to synthesize standards of these BM adducts? They used NaBH4 in doing so and our lab doesn't have that chemical.

Is there any alternative for NaBH4 or is there another way rather than to synthesize them?

Sephadex LH-20 is too expensive. We have silica gel, but I can't find methods on how to fractionate the tannin extract. We are specifically interested in the condensed tannins.

Can someone please provide the method for using silica gel?

How can polymer proanthocyanidins be standardized?

From my experience, FLD (Ex=230 nm, Em=320 nm) is selective for non-galloylated procyanidins. Moreover, galloylated procyanidins, prodelphinidins (and hydrolyzable tannins) are effectively not observed with FLD. What other proanthocyanidin types if any, are non-detectable by FLD?

Of course, DAD (280 nm) is non-discriminate and sees all proanthocyanidins as well as hydrolyzable tannins.

Hello. Anyone knows how can I dilute proanthocyanidin extract? I'm trying to dilute in warm saline solution, but it's not working...

As known, proanthocyanidins can be composed of catechins and epicatechins. So if I want to know which kind of monomers are the main components that comprising proanthocyanin in a particular plant, what regents or protocal should I use? We ever used acid to hydrolyze the proanthocyanidins, but have not get the perfect result. So we will be thankful for anyone's help. Thank you.

The signals shown in the attached file, lower panel, appeared as more or less constant background signals in LCMS analyses (ESI, negative mode, qTOF). Conditions and materials have been routinely used with that instrument without problems: binary gradient of water and acetonitrile, each with 0.1% formic acid, at 0.4 mL/min over a Dionex Acclaim Polar Advantage II 2.1x 100 mm column. Steel tubing in front of and PEEK tubing behind the column. The contaminant does not appear in positive mode. As we measure in positive mode most of the time it is not possible to precisely find out when the contamination took place. The first analyses that have shown the signals were acid hydrolysates of plant polyphenols (proanthocyanidins) which contained 4 M HCl. 5 µL were injected of six samples (first in positive, then in negative mode).

I have tried to learn more about that contaminant by trying some simulations of the isotope pattern (upper panel). The pattern at lower m/z values (m/z 160.8) matches 3 chlorine atoms, the other one 4 chlorine atoms, and the difference between their supposed monoisotopic signals at m/z 160.8 and 195.8 is 35.9698 u (HCl). The simulations are for Si2Cl3 (m/z 160.8) and Si2Cl4 (m/z 195.8), which was the best match so far but the m/z deviation of about 0.03 is far to big and the isotope pattern does neither fit well.

Maybe someone is familiar with this contamination or has some idea about it.

Greetings and sincere thanks in advance,

Jandirk Sendker

Professor.R.A Dixon

separate proanthocyanins from anthocyanin powder

I have two types of rice (black and red rice) and use vanillin assay to determine proanthocyanidin content. Briefly, 2.5mL vanillin assay (1% in methanol) and 2.5mL 9N H2SO4 (in methanol) mix with 1mL extract of rice sample. Catechin is developed for standard. The bank includes the reaction medium mixed with 1mL methanol (substitute for sample).

It seems I dont have problem with red rice. but black rice is high of anthocyanin and it interfered my results because the absorbance of anthocyanin is around 450 - 550 nm while the abs of vanilline reaction i set at 500nm. 

Please help me to figure out this problem. Thanks

According to the papers, acid hydrolysis should yield products like the monomers. I assume the mechanism is the same either in i-propanol/acid or butanol/acid. Is it an oxidative reaction? I can't quite draw the curved arrows correctly nor find the correct one by google. I need to know the exact structures of the hydrolysed products.

What is the role of FeNH4(SO4) and temperature in the reaction? Is there any breakdown of proanthocyanidin at room temperature, if the reaction mixture is not immediately incubated at 95 degree celcius? Also is the chromogen formed, stable over long hours?

Thanks

I want to quantify the proanthocyanidin content in my plant extracts using colorimetric method or spectrophotometry. Can anyone suggest me a suitable protocol for the same?

Thanking you in anticipation.

My ESI- shows: 1151.5 (minor peak) / 864.8 (major peak) / 576.8 (medium peak).

I was wondering if urea (1M - 10M) in samples can interfere or give false results when procyanidins are evaluated and quantified via HPLC?

Proanthocyanidins in peanuts were reported to be similar with those found in cranberries. In some references, ethyl acetate was used. How do I remove ethyl acetate and produce a pure proanthocyanidin extract?