PKC; PKCδ(IC50 = 3-6 μM); PKCα,β,γ (IC50 = 30-42 μM); PKCε,η,ζ(IC50 = 80-100 μM)

In primary HMVECs, rottlerin (20 μM, 2/6/24 hours) significantly and time-dependently lowers the levels of cyclin D-1 mRNA [2]. In HMVEC, rottlerin (20 μM) causes cell growth [2].

---

Rottlerin, a natural product purified from Mallotus philippinensis, has a number of target molecules and biological effects. We recently found that Rottlerin caused growth arrest in MCF-7 breast cancer cells and human immortalized keratinocytes, through inhibition of NFκB and downregulation of cyclin D-1. To evaluate whether this effect could be generalized to primary cells, human microvascular endothelial cells were treated with Rottlerin. In this study, we demonstrated that Rottlerin prevents basal and TNFα-stimulated NFκB nuclear migration and DNA binding also in human microvascular endothelial cell, where NFκB inhibition was accompanied by the downregulation of NFκB target gene products, such as cyclin D-1 and endothelin-1, which are essential molecules for endothelial cell proliferation and survival. Rottlerin, indeed, inhibited human microvascular endothelial cells proliferation and tube formation on Matrigel. Rottlerin also increases cytoplasmic free calcium and nitric oxide levels and downregulates endothelin converting enzyme-1 expression, thus contributing to the drop in endothelin-1 and growth arrest. These results suggest that Rottlerin may prove useful in the development of therapeutic agents against angiogenesis[2].

In Balb C nude mice, Rottlerin (20 mg/kg, once daily, five days a week, for six weeks) inhibits the growth of AsPC-1 pancreatic tumors without causing toxicity [3]. Rottlerin activates caspase-3 and cleaves poly(ADP-ribose) polymerase (PARP) to induce apoptosis.

---

Rottlerin-treated mice showed a significant inhibition in tumor growth which was associated with suppression of cell proliferation, activation of capase-3 and cleavage of PARP. Rottlerin inhibited the expression of Bcl-2, cyclin D1, CDK2 and CDK6, and induced the expression of Bax in tumor tissues compared to untreated control. Rottlerin inhibited the markers of angiogenesis (Cox-2, VEGF, VEGFR, and IL-8), and metastasis (MMP-2 and MMP-9), thus blocking production of tumorigenic mediators in tumor microenvironment. Rottlerin also inhibited epithelial-mesenchymal transition by up-regulating E-cadherin and inhibiting the expression of Slug and Snail. Furthermore, rottlerin treatment of xenografted tumors or pancreatic cancer cells isolated from Kras(G12D) mice showed a significant inhibition in Akt, Shh and Notch pathways compared to control groups. These data suggest that rottlerin can inhibit pancreatic cancer growth by suppressing multiple signaling pathways which are constitutively active in pancreatic cancer. Taken together, our data show that the rottlerin induces apoptosis and inhibits pancreatic cancer growth by targeting Akt, Notch and Shh signaling pathways, and provide a new therapeutic approach with translational potential for humans.[3]

Rottlerin, a compound from Mallotus philippinensis, is shown to inhibit protein kinases with some specificity for PKC. To some extent, the novel inhibitor is able to differentiate between PKC isoenzymes, with IC50 values for PKC delta of 3-6 microM, PKC alpha,beta,gamma of 30-42 microM and PKC epsilon,eta,zeta of 80-100 microM. Inhibition of PKC appears, at least in part, to be due to a competition between rottlerin and ATP. Among the protein kinases tested, only CaM-kinase III is suppressed by rottlerin as effectively as PKC delta. The chemical structure of rottlerin might serve as a basis for the development of novel inhibitors with improved selectivity for a distinct PKC isoenzyme, such as PKC delta, or for CaM-kinase III [1].

Western blot analysis[2]
Cell Types: primary HMVEC (human microvascular endothelial cells).
Tested Concentrations: 20μM.
Incubation Duration: 2, 6, 24 hrs (hours).
Experimental Results: Cyclin D-1 mRNA levels were Dramatically diminished in a time-dependent manner. After 2 hrs (hours) of treatment, mRNA levels diminished to 50% of control, after 6 hrs (hours) to approximately 40%, and after 24 hrs (hours) to 20%. A similar trend was observed at the protein level, with a decrease of approximately 50% after 2 hrs (hours), an 80% decrease after 6 hrs (hours), and a decrease to almost undetectable levels after 24 hrs (hours).

---

Cell proliferation assay [2]
Cell Types: primary HMVEC (human microvascular endothelial cells).
Tested Concentrations: 20μM.
Incubation Duration: 24/48 hrs (hours).
Experimental Results: demonstrated strong growth inhibition, with thymidine incorporation diminished by approximately 75% and 80%, respectively, relative to control cells (DMSO 0.1%).

Animal/Disease Models: Balb C nude mice (4-6 weeks old) were injected with AsPC-1 cells (2×106 cells mixed with Matrigel, 50:50 ratio) [3].
Doses: 0 or 20 mg/kg.
Route of Administration: Administer one time/day, 5 days a week, for 6 weeks.
Experimental Results: Inhibited the growth of AsPC-1 pancreatic tumors in Balb C nude mice and had no effect on the body weight of AsPC-1 tumor-bearing mice.

rat LDLo oral 750 mg/kg Indian Journal of Physiology and Pharmacology., 3(168), 1959 [PMID:13841348]

[1]. Rottlerin, a novel protein kinase inhibitor. Biochem Biophys Res Commun. 1994 Feb 28;199(1):93-8.

[2]. Rottlerin exhibits antiangiogenic effects in vitro. Chem Biol Drug Des. 2011 Jun;77(6):460-70.

[3]. Rottlerin suppresses growth of human pancreatic tumors in nude mice, and pancreatic cancer cells isolated from KrasG12D mice. Cancer Letters 353 (2014) 32-40.

[4]. Protein kinase Ctheta is a specific target for inhibition of the HIV type 1 replication in CD4+ T lymphocytes. J Biol Chem. 2011 Aug 5;286(31):27363-77.

[5]. Kinase inhibitors tyrphostin 9 and rottlerin block early steps of rabies virus cycle. Antiviral Res. 2019 Aug;168:51-60.

Rottlerin is a chromenol that is 2,2-dimethyl-2H-chromene substituted by hydroxy groups at positions 5 and 7, a 3-acetyl-2,4,6-trihydroxy-5-methylbenzyl group at position 6 and a (1E)-3-oxo-1-phenylprop-1-en-3-yl group at position 8. A potassium channel opener, it is isolated from Mallotus philippensis. It has a role as an antineoplastic agent, an apoptosis inducer, a metabolite, a K-ATP channel agonist, an antihypertensive agent and an anti-allergic agent. It is an enone, a chromenol, a benzenetriol, a methyl ketone and an aromatic ketone.
Rottlerin has been reported in Mallotus philippensis with data available.

---

The purpose of the study was to examine the molecular mechanisms by which rottlerin inhibited growth of human pancreatic tumors in Balb C nude mice, and pancreatic cancer cells isolated from Kras(G12D) mice. AsPC-1 cells were injected subcutaneously into Balb c nude mice, and tumor-bearing mice were treated with rottlerin. Cell proliferation and apoptosis were measured by Ki67 and TUNEL staining, respectively. The expression of components of Akt, Notch, and Sonic Hedgehog (Shh) pathways were measured by the immunohistochemistry, Western blot analysis, and/or q-RT-PCR. The effects of rottlerin on pancreatic cancer cells isolated from Kras(G12D) mice were also examined. Rottlerin-treated mice showed a significant inhibition in tumor growth which was associated with suppression of cell proliferation, activation of capase-3 and cleavage of PARP. Rottlerin inhibited the expression of Bcl-2, cyclin D1, CDK2 and CDK6, and induced the expression of Bax in tumor tissues compared to untreated control. Rottlerin inhibited the markers of angiogenesis (Cox-2, VEGF, VEGFR, and IL-8), and metastasis (MMP-2 and MMP-9), thus blocking production of tumorigenic mediators in tumor microenvironment. Rottlerin also inhibited epithelial-mesenchymal transition by up-regulating E-cadherin and inhibiting the expression of Slug and Snail. Furthermore, rottlerin treatment of xenografted tumors or pancreatic cancer cells isolated from Kras(G12D) mice showed a significant inhibition in Akt, Shh and Notch pathways compared to control groups. These data suggest that rottlerin can inhibit pancreatic cancer growth by suppressing multiple signaling pathways which are constitutively active in pancreatic cancer. Taken together, our data show that the rottlerin induces apoptosis and inhibits pancreatic cancer growth by targeting Akt, Notch and Shh signaling pathways, and provide a new therapeutic approach with translational potential for humans.[3]

---

Integration of HIV-1 genome in CD4(+) T cells produces latent reservoirs with long half-life that impedes the eradication of the infection. Control of viral replication is essential to reduce the size of latent reservoirs, mainly during primary infection when HIV-1 infects CD4(+) T cells massively. The addition of immunosuppressive agents to highly active antiretroviral therapy during primary infection would suppress HIV-1 replication by limiting T cell activation, but these agents show potential risk for causing lymphoproliferative disorders. Selective inhibition of PKC, crucial for T cell function, would limit T cell activation and HIV-1 replication without causing general immunosuppression due to PKC being mostly expressed in T cells. Accordingly, the effect of rottlerin, a dose-dependent PKC inhibitor, on HIV-1 replication was analyzed in T cells. Rottlerin was able to reduce HIV-1 replication more than 20-fold in MT-2 (IC(50) = 5.2 μM) and Jurkat (IC(50) = 2.2 μM) cells and more than 4-fold in peripheral blood lymphocytes (IC(50) = 4.4 μM). Selective inhibition of PKC, but not PKCδ or -ζ, was observed at <6.0 μM, decreasing the phosphorylation at residue Thr(538) on the kinase catalytic domain activation loop and avoiding PKC translocation to the lipid rafts. Consequently, the main effector at the end of PKC pathway, NF-κB, was repressed. Rottlerin also caused a significant inhibition of HIV-1 integration. Recently, several specific PKC inhibitors have been designed for the treatment of autoimmune diseases. Using these inhibitors in combination with highly active antiretroviral therapy during primary infection could be helpful to avoid massive viral infection and replication from infected CD4(+) T cells, reducing the reservoir size at early stages of the infection.[4]

---

Rabies virus (RABV) is a neurotropic virus that causes fatal encephalitis in humans and animals and still kills up to 59,000 people worldwide every year. To date, only preventive or post-exposure vaccination protects against the disease but therapeutics are missing. After screening a library of 80 kinases inhibitors, we identified two compounds as potent inhibitors of RABV infection: tyrphostin 9 and rottlerin. Mechanism of action studies show that both inhibitors interfere with an early step of viral cycle and can prevent viral replication. In presence of tyrphostin 9, the viral entry through endocytosis is disturbed leading to improper delivery of viral particles in cytoplasm, whereas rottlerin is inhibiting the transcription, most likely by decreasing intracellular ATP concentration, and therefore the replication of the viral genome.[5]

C30H28O8

516.53852

516.178

C, 69.76; H, 5.46; O, 24.78

82-08-6

5281847

Brown to reddish brown solid powder

1.4±0.1 g/cm3

800.4±65.0 °C at 760 mmHg

200 °C

266.0±27.8 °C

0.0±2.9 mmHg at 25°C

1.682

8.66

5

8

6

38

921

0

CC1=C(C(=C(C(=C1O)C(=O)C)O)CC2=C(C(=C3C(=C2O)C=CC(O3)(C)C)C(=O)/C=C/C4=CC=CC=C4)O)O

DEZFNHCVIZBHBI-ZHACJKMWSA-N

InChI=1S/C30H28O8/c1-15-24(33)19(27(36)22(16(2)31)25(15)34)14-20-26(35)18-12-13-30(3,4)38-29(18)23(28(20)37)21(32)11-10-17-8-6-5-7-9-17/h5-13,33-37H,14H2,1-4H3/b11-10+

(E)-1-(6-((3-Acetyl-2,4,6-trihydroxy-5-methylphenyl)methyl)-5,7-dihydroxy-2,2-dimethyl-2H-1-benzopyran-8-yl)-3-phenyl-2-propen-1-one

Mallotoxin; NSC 56346; rottlerin; Mallotoxin; 82-08-6; Kamalin; UNII-E29LP3ZMUH; E29LP3ZMUH; EINECS 201-395-4; NSC 94525; NSC56346; NSC94525; Kamalin; NSC-56346; NSC-94525.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~12.5 mg/mL (~24.20 mM)

Solubility in Formulation 1: ≥ 1.25 mg/mL (2.42 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: ≥ 1.25 mg/mL (2.42 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

View More

Solubility in Formulation 3: 22 mg/mL (42.59 mM) in 0.5% CMC-Na/saline water (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

 (Please use freshly prepared in vivo formulations for optimal results.)