11 replies to this topic

[inawe]

In the "Dropping resveratrol" thread Smith wondered weather
"Methylated RESV would not be a good idea in the long run". It
reminded me of the abstract of a paper I saw some time ago. So this
should be Smith's thread.
In that paper, genotoxicity of RSV is mentioned. Authors also state
that "methyl substitution may improve resveratrol efficacy". I
couldn't find any justification for either statement. People with more
knowledge than me might be willing to shed some light on this. Here is
the abstract:
Chem Res Toxicol. 2008 Feb 18;21(2):282-287. Epub 2008 Jan 5.
Effect of Methyl Substitution on the Antioxidative Property and Genotoxicity of Resveratrol.Fukuhara K, Nakanishi I, Matsuoka A, Matsumura T, Honda S, Hayashi M, Ozawa T, Miyata N, Saito S, Ikota N, Okuda H.
Division of Organic Chemistry, National Institute of Health Sciences, Setagaya-ku, Tokyo 158-8501, Redox Regulation Research Group, Research Center for Radiation Safety, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency, Suita, Osaka 565-0871, Division of Medical Devices, National Institute of Health Sciences, Setagaya-ku, 158-8501 Tokyo, Faculty of Science, Tokyo University of Science, Shinjuku-ku, Tokyo 162-8601, Department of Cancer Research, Toyama Institute of Health, 17-1 Nakataikouyama, Kosugi-machi, Imizu-gun, Toyama 939-0363, New Industry Creation Hatchery Center, Yokohama College of Pharmacy, Tozuka-ku, Yokohama, Kanagama 245-0066, and Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya, Aichi 467-8603, Japan fukuhara@nihs.go.jp.

Resveratrol ( trans-3,4',5-trihydroxystilbene) is a natural phytoalexin with various biological activities including inhibition of lipid peroxidation and free radical scavenging properties. In addition to its beneficial effects, resveratrol also has significant genotoxicity that leads to a high frequency of chromosome aberration together with micronucleus and sister chromatid exchanges. To enhance the radical scavenging activities and to reduce the genotoxicity of resveratrol, we designed 4'-methyl resveratrol analogues where a methyl group was introduced at the ortho position relative to the 4'-hydroxy group, which is responsible for both antioxidative activities and genotoxicity of resveratrol. These synthesized methyl analogues of resveratrol showed increased antioxidative activities against galvinoxyl radical as an oxyl radical species. Furthermore, the methyl analogues also surprisingly showed reduced in vitro genotoxicities, suggesting that methyl substitution may improve resveratrol efficacy.

PMID: 18177016 [PubMed - as supplied by publisher]

[Hedgehog]

In the "Dropping resveratrol" thread Smith wondered weather
"Methylated RESV would not be a good idea in the long run". It
reminded me of the abstract of a paper I saw some time ago. So this
should be Smith's thread.
In that paper, genotoxicity of RSV is mentioned. Authors also state
that "methyl substitution may improve resveratrol efficacy". I
couldn't find any justification for either statement. People with more
knowledge than me might be willing to shed some light on this. Here is
the abstract:
Chem Res Toxicol. 2008 Feb 18;21(2):282-287. Epub 2008 Jan 5.
Effect of Methyl Substitution on the Antioxidative Property and Genotoxicity of Resveratrol.Fukuhara K, Nakanishi I, Matsuoka A, Matsumura T, Honda S, Hayashi M, Ozawa T, Miyata N, Saito S, Ikota N, Okuda H.
Division of Organic Chemistry, National Institute of Health Sciences, Setagaya-ku, Tokyo 158-8501, Redox Regulation Research Group, Research Center for Radiation Safety, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency, Suita, Osaka 565-0871, Division of Medical Devices, National Institute of Health Sciences, Setagaya-ku, 158-8501 Tokyo, Faculty of Science, Tokyo University of Science, Shinjuku-ku, Tokyo 162-8601, Department of Cancer Research, Toyama Institute of Health, 17-1 Nakataikouyama, Kosugi-machi, Imizu-gun, Toyama 939-0363, New Industry Creation Hatchery Center, Yokohama College of Pharmacy, Tozuka-ku, Yokohama, Kanagama 245-0066, and Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya, Aichi 467-8603, Japan fukuhara@nihs.go.jp.

Resveratrol ( trans-3,4',5-trihydroxystilbene) is a natural phytoalexin with various biological activities including inhibition of lipid peroxidation and free radical scavenging properties. In addition to its beneficial effects, resveratrol also has significant genotoxicity that leads to a high frequency of chromosome aberration together with micronucleus and sister chromatid exchanges. To enhance the radical scavenging activities and to reduce the genotoxicity of resveratrol, we designed 4'-methyl resveratrol analogues where a methyl group was introduced at the ortho position relative to the 4'-hydroxy group, which is responsible for both antioxidative activities and genotoxicity of resveratrol. These synthesized methyl analogues of resveratrol showed increased antioxidative activities against galvinoxyl radical as an oxyl radical species. Furthermore, the methyl analogues also surprisingly showed reduced in vitro genotoxicities, suggesting that methyl substitution may improve resveratrol efficacy.

PMID: 18177016 [PubMed - as supplied by publisher]

Ok I have an idea,

How about I move to china. I will set up my med chem lab and then you all can visit and take home some powder?

[niner]

Resveratrol is genotoxic? How come this has never come up? Is it some kind of in vitro red herring?

[inawe]

Resveratrol is genotoxic? How come this has never come up? Is it some kind of in vitro red herring?

I never saw it anywhere else besides this paper, either. That's why I
posted it to see if anybody has a clue.

[Hedgehog]

I hate to copy paste stuff from pubmed but here you go.





Plant extracts containing phytohormones are very popular as 'alternative' medicine for many kinds of diseases. They are especially favored by women who enter menopause and are concerned about the side effects of hormone replacement therapy. However, adverse health effects of phytoestrogens have often been ignored. This review examines the literature on genotoxicity and apoptotic effects of phytohormones.

Genistein, coumestrol, quercetin, zearalenone, and resveratrol exerted genotoxic effects in in vitro test systems. Other phytoestrogens such as lignans, the isoflavones daidzein and glycetein, anthocyanidins, and the flavonol fisetin exhibited only weak or no effects in vitro. However, some metabolites of daidzein showed a genotoxic activity in vitro. Practically all of the phytoestrogens exhibit pro-apoptotic effects in some cell systems.

Further investigations regarding dose-response-relationships and other aspects relevant for extrapolation to human exposure seem necessary. Until then, care may be advised in taking concentrated phytohormones. Nevertheless, the intake of substantial amounts of plant-food in a normal diet constitutes an important, individual contribution to cancer prevention.





another one

According to an estimation of daily intake and bioavailability (of resveratrol), concentrations that were found genotoxic in vitro might be reached in human exposure. On the other side, the estrogenic acitivity might be beneficial. Therefore, further investigations of mechanisms, possibly including animal models, would be desirable to clarifiy a potential risk for humans

Therefore, concentrations that were found genotoxic in vitro might be reached in human exposure. Estrogenic activity, if present in vivo, might be beneficial as has been suggested for the uptake of other phytohormones like soy isoflavones. However, a further investigation of RES-induced genotoxicity including in vivo investigations and elucidation of the mechanism of genotoxicity would be desirable to clarify a potential risk for humans.


You have to understand that SIRT would had to have conducted genotoxic studies with resveratrol before the IND w/ the FDA. If there was even a SLIGHT hint of genotoxic studies in animals then they probably wouldn't have approved it. This is why we the users can sorta assume that is safe. Also we know that SRT501 could contain 400mg resveratrol (my personal caclulation) + to 5grams. I think they also dose at typically a 10fold lower then animal tox studies in phase I, just to be on the safe side.

Edited by hedgehog_info, 22 February 2008 - 01:22 AM.

[edward]

Snip
From study:
Genistein, coumestrol, quercetin, zearalenone, and resveratrol exerted genotoxic effects in in vitro test systems.

Hedgehog:
You have to understand that SIRT would had to have conducted genotoxic studies with resveratrol before the IND w/ the FDA. If there was even a SLIGHT hint of genotoxic studies in animals then they probably wouldn't have approved it.

I think these two statements are key.

Especially about Quercetin being genotoxic in vitro (well if that translates in vivo then the whole human race particularly those who eat lots of fruits and vegetables are goners... this isn't so)... I would like to know how these studies are defining "genotoxic" are we talking mutagenic, carcinogenic, or simply that it alters the functioning of genes (what we want)

The FDA is so paranoid these days about genotoxic substances (defined as mutagenic or carcinogenic) that if there was even the possibility of Resveratrol being such in vivo, Sirtris, as hedgehog mentioned, wouldn't have even pursued it as there is no point in investing millions of dollars on something that works only to pull it in the end because of genotoxic actions.

Edited by edward, 22 February 2008 - 02:28 AM.

[maxwatt]

Snip
From study:
Genistein, coumestrol, quercetin, zearalenone, and resveratrol exerted genotoxic effects in in vitro test systems.

Hedgehog:
You have to understand that SIRT would had to have conducted genotoxic studies with resveratrol before the IND w/ the FDA. If there was even a SLIGHT hint of genotoxic studies in animals then they probably wouldn't have approved it.

I think these two statements are key.

Especially about Quercetin being genotoxic in vitro (well if that translates in vivo then the whole human race particularly those who eat lots of fruits and vegetables are goners... this isn't so)... I would like to know how these studies are defining "genotoxic" are we talking mutagenic, carcinogenic, or simply that it alters the functioning of genes (what we want)

The FDA is so paranoid these days about genotoxic substances (defined as mutagenic or carcinogenic) that if there was even the possibility of Resveratrol being such in vivo, Sirtris, as hedgehog mentioned, wouldn't have even pursued it as there is no point in investing millions of dollars on something that works only to pull it in the end because of genotoxic actions.

Yeah. The NIH toxicity study, all 80 pages of it, found no basis for genotoxicity. And most things are genotoxic, in vitro, if you use enough of it.. Coffee, LSD, strawberries, asbestos..... (That is not my supplement list.)

PS, one of Sinclair's papers mentions that methoxylating the 4' position eliminates resveratrol's sirtuin activating properties. Acetylating the 4' position on the other hand makes it water-soluble and gets it into the cell membrane where it turns to resveratrol and is highly active.

Edited by maxwatt, 22 February 2008 - 02:39 AM.

[inawe]

When I first saw the abstract of PMID: 18177016 I wondered what genotoxicity they were talking about. By posting the abstract I hopped somebody would take a look at the full paper and explain it. After all it's a paper published in a peer reviewed journal. And it took 11 people to come up with this thing. None of these guys is at a top university like, let's say Oral Roberts. But still, we shouldn't dismiss the Japanese National Institute of Health Sciences, where the lead author Fuckuhara is. By the way, anybody knows what uhara is? Or is it a Hara guy he's referring to?

[Hedgehog]

When I first saw the abstract of PMID: 18177016 I wondered what genotoxicity they were talking about. By posting the abstract I hopped somebody would take a look at the full paper and explain it. After all it's a paper published in a peer reviewed journal. And it took 11 people to come up with this thing. None of these guys is at a top university like, let's say Oral Roberts. But still, we shouldn't dismiss the Japanese National Institute of Health Sciences, where the lead author Fuckuhara is. By the way, anybody knows what uhara is? Or is it a Hara guy he's referring to?

As shown in Table 1, 3′-methylresveratrol (1), where one methyl group was introduced at the ortho position relative to the 4′-hydroxyl group, showed a significantly increased radical scavenging activity ascompared to resveratrol. A greater k_HT value was also obtained in compound 2, which has methyl groups at both positions ortho to the 4′-hydroxyl group. In comparison to resveratrol, a 6-fold greater k_HT value was observed with 4-methylresveratrol, indicating that the 4-methyl group also affects the radical scavenging activities of the 4′-hydroxyl group. Similar to the methyl analogues (1 and 2) of resveratrol, the k_HT value of 4-methylresveratrol was increased by the introduction of methyl ortho to the 4′-hydroxyl group. Among resveratrol and its derivatives, compound 4 had the strongest antioxidative activity with a 60-fold greater k_HT value than that of resveratrol.


Figure 2. Chromosome aberrations induced in vitro by resveratrol and its methyl analogues. CHL cells were treated with the chemicals for 48 h.

Therefore, it is possible that the lower CA frequency for 1–4 as compared to resveratrol could be explained by the steric hindrance of the o-methyl group with respect to the radical scavenging reaction between the 4′-hydroxyl group and the tyrosyl radical. On the other hand, comparison of resveratrol and its o-methyl analogue (1 and 2) to the 4-methyl analogues (4-methyresveratrol, 3 and 4), which have increased CA, shows a potential functional relationship between structure and enhanced radical scavenging activity. That is, slight increasing CA frequency in the corresponding 4-methyl analogues may be attributed to their enhanced radical scavenging activities that are responsible for theinhibition of ribonucleotide reductase. Further detailed insight and in vivo studies to fully exploit these potential benefits are currently underway.

So they did a study based on resveratrol analogs but they didn't use a control. So we don't really know how common this for the CHL cell line. It still doesn't worry me since SIRT got FDA IND approval.

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[inawe]

As Maxwatt pointed out "most things are genotoxic, in vitro, if you use enough of it". Most papers dealing with RSV don't even touch on the toxicity issue. May be from these guys we can learn what's the maximum we can safely take.
As for the FDA IND approval, ever heard of Baycol, Vioxx, Avandia ... ?

[niner]

OK, the big genotox was observed when cells were soaked for two days and nights in 88 uM resveratrol. At normal doses of the sort we would see in vivo in humans, you wouldn't see a thing. Unless there were a mechanism for concentrating resveratrol in human cells, which is not entirely farfetched. Another way you might run into this is with topical/transdermal application. There you might see pretty high concentrations in skin and subsurface tissues.

[krillin]

OK, the big genotox was observed when cells were soaked for two days and nights in 88 uM resveratrol. At normal doses of the sort we would see in vivo in humans, you wouldn't see a thing.

That's somewhat above the concentration that inhibits topoisomerase II.

J Agric Food Chem. 2006 Mar 22;54(6):2083-7.
Catalytic inhibition of human DNA topoisomerase II by interactions of grape cell culture polyphenols.
Jo JY, Gonzalez de Mejia E, Lila MA.
Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, 1201 South Dorner Drive, Urbana, Illinois 61801, USA.

Previously, we isolated mixed polyphenolic fractions on a toyopearl matrix (TP-2 to TP-6) from grape cell cultures that were highly potent catalytic inhibitors in a human DNA topoisomerase II assay for cancer chemoprevention. The objectives of this study were to evaluate the potency of, and potential interactions between, individual fractions and some of the purified bioactive polyphenols that comprise these fractions on human DNA topoisomerase II catalytic activity. Treatments that combined anthocyanin-rich fractions (TP-2; 0.5 or 2.0 microg of dried material/mL), fractions containing catechins, procyanidin dimers, and flavanones (TP-4; 0.25 microg of dried material/mL), and/or fractions enriched with procyanidin oligomers and polymers (TP-6; 0.15 or 0.5 microg of dried material/mL) showed additive effects toward catalytic inhibition of the enzyme. Epicatechin gallate (IC50 = 0.029 microM), myricetin (0.39 microM), procyanidin B2 (PB2, 4.5 microM), and resveratrol (65.7 microM), constituents of the most bioactive mixed fraction from grape cell culture (TP-4), each individually provided potent catalytic inhibition of topoisomerase II. In addition, potentiating interactions between the PB2 and the other polyphenolic constituents mentioned above and between myricetin and resveratrol were clearly demonstrated. A synergistic interaction between myricetin and resveratrol was also confirmed with isobolographic analysis at a molar ratio of 1:70.

PMID: 16536579