Max Watt wrote:
> Acute transperitoneal toxicity for mouse, LD50 =450mg/Kg.
> (from http://www.gplantchem.com/kinetin.htm )

Thanks for the link, but it is a manufacturer's product description and
no reference is given for the toxicity statement.
In any case, since kinetin has now been shown to be naturally occurring
in plants and is found in human urine, acute toxicity of small doses is
not the major issue. Again what is needed is a mouse lifespan test.

> and:
>
> Biochem Biophys Res Commun 1994 Jun 15;201(2):665-72
> Kinetin delays the onset of ageing characteristics in human fibroblasts.
> Rattan SI, Clark BF.
> Department of Chemistry, Aarhus University, Denmark.
>
> Kinetin (Kn) is a synthetic cytokinin plant growth hormone having
> some
> senescence-retarding effects in plants. Its effects on animal cells
> have been, until now, best considered as growth inhibitory and
> anti-tumorigenic. However, we have observed that an addition of 40-200
> microM Kn in the culture medium of human diploid fibroblasts can both
> delay the onset and decrease the extent of many of the ageing
> characteristics that appear during serial passaging of normal cells in
> culture. Age-related changes that are affected by Kn include
> morphological alterations, growth rates, cell size, cytoskeletal
> organisation, macromolecular synthesis and the intensity of
> autofluorescence due to the oxidative damage product lipofuscin. These
> anti-ageing effects of Kn are achieved without any increase in the
> cell
> culture lifespan in terms of maximum proliferative capacity in vitro.
> PMID: 8003000
> ----------------
>
> Encouraging.

Yes, this was the Rattan paper that initially peaked my interest in
kinetin, but of course it is only a cellular in vitro study.

> Perhaps if we are serious about this, we should be keeping some
> pet mice. It's not too difficult to do.

Lots of things are individually not too difficult, but often several
together are incompatible. For example, keeping pets of any kind makes
travel very difficult. Keeping some lab mice would make travel virtually
impossible without specialized help. IMO, it makes much more sense for
people to specialize and each do what s/he can do best. Unfortunately,
while many, many people are effectively supporting the research that
LEF does through their purchases of LEF supplements, none of them have
any input into what actual research is done. I have suggested many
things to Bill Faloon, but these suggestions go nowhere. Recently
Steve Spindler (gets funding from LEF) asked on sci.life-extension for
suggestions about life extension therapies to test, which was certainly
a step in the right direction. I suggested a few things, but did not
think of kinetin.

> Max Watt (Richard Kaufman)

Richard also sent me by email the following abstract:

Eur J Pharmacol. 2003 Apr 4;465(3):281-7
Inhibitory activity of kinetin on free radical formation of activated
platelets in vitro and on thrombus formation in vivo.
Hsiao G, Shen MY, Lin KH, Chou CY, Tzu NH, Lin CH, Chou DS, Chen TF, Sheu JR.
Department of Pharmacology, Taipei Medical University, Taipei, Taiwan, ROC.

Kinetin has been shown to have anti-aging effects on several
different systems, including plants and human cells. Recently, we demonstrated
that kinetin markedly inhibited platelet aggregation in washed human platelets.
In the present study, an electron spin resonance (ESR) method was used to
further evaluate the scavenging activity of kinetin on the free radicals formed.
Kinetin (70 and 150 microM) concentration dependently reduced the ESR signal
intensity of hydroxyl radicals in collagen (1 microg/ml)-activated platelets.
Furthermore, kinetin was effective in reducing the mortality of ADP-induced
acute pulmonary thromboembolism in mice when administered intravenously at doses
of 4 and 6 mg/kg. In addition, intravenous injection of kinetin (4 and 6 mg/kg)
significantly prolonged the bleeding time by approximately 1.9- and 2.1-fold as
compared with normal saline in severed mesenteric arteries of rats. A continuous
infusion of kinetin (0.6 mg/kg/min) for 10 min also significantly increased the
bleeding time by about 2.3-fold, and the bleeding time returned to baseline
within 120 min after cessation of kinetin infusion. Platelet thrombi formation
was induced by irradiation of mesenteric venules with filtered light in mice
pretreated intravenously with fluorescein sodium. When kinetin was administered
at 13 and 14 mg/kg in mice pretreated with fluorescein sodium (5 mg/kg), the
occlusion time was significantly prolonged. In conclusion, these results suggest
that kinetin has effective free radical-scavenging activity in vitro and
antithrombotic activity in vivo. Treatment with kinetin may lower the risk of
thromboembolic-related disorders. Therefore, kinetin may be a potential
therapeutic agent for arterial thrombosis, but its toxicity must be further
assessed.

PMID: 12681440

I had seen it already, but somehow I missed the part where it clearly
states that they injected and infused kinetin into live mice. This study
shows that at these fairly moderate dosages, there might be too strong
an anti-coagulative effect on the blood.

--Paul