Manassantin B

The mTOR inhibitor manassantin B reveals a crucial role of mTORC2 signaling in Epstein-Barr virus reactivation.[Pubmed:32312752]

J Biol Chem. 2020 May 22;295(21):7431-7441.

Lytic replication of Epstein-Barr virus (EBV) is not only essential for its cell-to-cell spread and host-to-host transmission, but it also contributes to EBV-induced oncogenesis. Thus, blocking EBV lytic replication could be a strategy for managing EBV-associated diseases. Previously, we identified a series of natural lignans isolated from the roots of Saururus chinensis (Asian lizard's tail) that efficiently block EBV lytic replication and virion production with low cytotoxicity. In this study, we attempted to elucidate the molecular mechanism by which these lignans inhibit EBV lytic replication. We found that a representative compound, CSC27 (Manassantin B), inhibits EBV lytic replication by suppressing the expression of EBV immediate-early gene BZLF1 via disruption of AP-1 signal transduction. Further analysis revealed that Manassantin B specifically blocks the mammalian target of rapamycin complex 2 (mTORC2)-mediated phosphorylation of AKT Ser/Thr protein kinase at Ser-473 and protein kinase Calpha (PKCalpha) at Ser-657. Using phosphoinositide 3-kinase-AKT-specific inhibitors for kinase mapping and shRNA-mediated gene silencing, we validated that Manassantin B abrogates EBV lytic replication by inhibiting mTORC2 activity and thereby blocking the mTORC2-PKC/AKT-signaling pathway. These results suggest that mTORC2 may have utility as an antiviral drug target against EBV infections and also reveal that Manassantin B has potential therapeutic value for managing cancers that depend on mTORC2 signaling for survival.

Matrix Solid-Phase Dispersion Combined with HPLC-DAD for Simultaneous Determination of Nine Lignans in Saururus chinensis.[Pubmed:30272133]

J Chromatogr Sci. 2019 Feb 1;57(2):186-193.

A simple and rapid method, based on matrix solid-phase dispersion (MSPD) and high-performance liquid chromatography (HPLC) was developed for simultaneous determination of nine lignans, including (-)-(7R,8R)-machilin D (Wang, C., Wang, P., Chen, X., Wang, W., Jin, Y.; Saururus chinensis (Lour.) Baill blocks enterovirus 71 infection by hijacking MEK1-ERK signaling pathway; Antiviral Research, (2015); 119:47-56), dihydroguaiaretic acid (Quan, Z., Lee, Y.J., Yang, J.H., Lu,Y., Li,Y., Lee,Y.K., et al.; Ethanol extracts of Saururus chinensis suppress ovalbumin-sensitization airway inflammation; Journal of Ethnopharmacology, (2010); 132:143-149.), sauchinone (Zhuang, T., Liang, J.Y., Sun, J.B., Wu, Y., Huang, L.R., Qu, W.; Secondary metabolites from Saururus chinensis and their chemotaxonomic significance; Biochemical Systematics and Ecology, (2014); 56:95-98.), rel-(7S,8S,7'R,8'R)-3,3',4,4',5,5'-hexamethoxy-7.O.7',8.8'-lignan (Tsai, W.J., Shen, C.C., Tsai, T.H., Lin, L.C.; Lignans from the aerial parts of Saururus chinensis: isolation, structural characterization, and their effects on platelet aggregation; Journal of Natural Products, (2014); 77:125-131), licarin A (Cui, H., Xu, B., Wu, T., Xu, J., Yuan, Y., Gu, Q.; Potential antiviral lignans from the roots of Saururus chinensis with activity against Epstein-Barr virus lytic replication; Journal of Natural Products, (2014); 77:100-110.), manassantin A (Lu, Y., Piao, D., Zhang, H., Li, X., Chao, G.H., Park, S.J., et al.; Saucerneol F inhibits tumor necrosis factor-alpha and IL-6 production by suppressing Fyn-mediated pathways in FcepsilonRI-mediated mast cells; Food and Chemical Toxicology, (2013); 59:696-702.), saurucinol I (Kwon, O.E., Lee, H.S., Lee, S.W., Chung, M.Y., Bae, K.H., Rho, M.C., et al.; Manassantin A and B isolated from Saururus chinensis inhibit TNF-alpha-induced cell adhesion molecule expression of human umbilical vein endothelial cells; Archives of Pharmacal Research, (2005); 28:55-60.), Manassantin B (Hwang, B.Y., Lee, J.H., Jung, H.S., Kim, K.S., Nam, J.B., Hong, Y.S., et al.; Sauchinone, a lignan from Saururus chinensis, suppresses iNOS expression through the inhibition of transactivation activity of RelA of NF-kappaB; Planta Medica, (2003); 69:1096-01.) and licarin B (Hwang, B.Y., Lee, J.H., Nam, J.B., Hong, Y.S., Lee, J.J.; Lignans from Saururus chinensis inhibiting the transcription factor NF-kappaB; Phytochemistry, (2003); 64:765-771.) in Saururus chinensis. The parameters of MSPD were optimized to be that 0.2 g of sample, blended with 0.4 g silica gel, and eluted with 5 mL of methanol. The separation was carried out on a C18 column with acidified aqueous acetonitrile gradients. The established method was fully validated in terms of linearity (r2 >/= 0.9994), sensitivity, precision (RSD

Determination of manassantin B in rat plasma using a high performance liquid chromatography with fluorescence detection and its quantitative application to pharmacokinetic study.[Pubmed:26773890]

J Chromatogr B Analyt Technol Biomed Life Sci. 2016 Feb 1;1011:121-7.

A simple, sensitive, rapid, and reproducible analytical method of Manassantin B in rat plasma by high performance liquid chromatography with fluorescence detection (HPLC-FL) was developed for its application to pharmacokinetic study in rats. Valsartan (VST) was used as an internal standard (IS) in this quantitative analytical method. Manassantin B and VST were extracted by simple and efficient protein precipitation method. Manassantin B was detected at 282/322nm (excitation/emission) wavelengths using FL detector. The chromatographic separation was obtained with reverse phase C18 column and the mobile phase composed of potassium phosphate buffer containing 0.025% trifluoroacetic acid (pH 2.5; 5mM) and acetonitrile including 0.025% trifluoroacetic acid (20:80, v/v) at 1.0mL/min flow rate. The linearity was established at 25.0-10000ng/mL and the lower limit of detection (LLOD) was 7ng/mL. The intra- and inter-day accuracy and precision values of Manassantin B were within+/-15% of the theroretical values and <9% from the nominal concentrations, respectively. Accuracy and precision values of Manassantin B after stability tests were also within the acceptable ranges. Developed assay was also successfully applied to pharmacokinetic study after intravenous administration of Manassantin B in rats.

The dineolignan from Saururus chinensis, manassantin B, inhibits tumor-induced angiogenesis via downregulation of matrix metalloproteinases 9 in human endothelial cells.[Pubmed:24920499]

Oncol Rep. 2014 Aug;32(2):659-67.

Manassantin B (MB) is a neolignan isolated from Saururus chinensis that exhibits a range of activities, including anti-inflammatory, antiseptic and antitumor activity. MB was recently found to affect cell adhesion and expression of several adhesion molecules. Based on the important roles of these adhesion molecules in angiogenesis, we evaluated a possible role for MB in tumor-induced angiogenesis in endothelial cells (ECs). In the present study, we found that MB blocked tumor-induced tube formation of ECs and significantly inhibited the invasion of ECs through the reconstituted basement membrane. MB suppressed the activity of matrix metalloproteinases (MMPs) and downregulated the expression of matrix metalloproteinases 9. Western blotting showed reduction of RUNX2 activation by MB. RUNX2 transcription factor assay and chromatin immunoprecipitation assay showed that the interaction between RUNX2 and target sequences in the matrix metalloproteinases 9 promoters was inhibited by MB. Our findings suggested that the inhibitory effects of MB on tumor-induced angiogenesis were caused by matrix metalloproteinases 9 inhibition, which was associated with the downregulation of RUNX2 transcriptional activity.

Potential antiviral lignans from the roots of Saururus chinensis with activity against Epstein-Barr virus lytic replication.[Pubmed:24359277]

J Nat Prod. 2014 Jan 24;77(1):100-10.

Epstein-Barr virus (EBV) is a member of the gamma-herpes virus subfamily and has been implicated in the pathogenesis of several human malignancies. Bioassay-guided fractionation was conducted on an EtOAc-soluble extract of the roots of Saururus chinensis and monitored using an EBV lytic replication assay. This led to the isolation of 19 new (1-19) and nine known (20-28) lignans. The absolute configurations of the new lignans were established by Mosher's ester, ECD, and computational methods. Eight lignans, including three sesquineolignans (19, 23, and 24) and five dineolignans (3, 4, 26, 27, and 28), exhibited inhibitory effects toward EBV lytic replication with EC50 values from 1.09 to 7.55 muM and SI values from 3.3 to 116.4. In particular, Manassantin B (27) exhibited the most promising inhibition, with an EC50 of 1.72 muM, low cytotoxicity, CC50 > 200 muM, and SI > 116.4. This is the first study demonstrating that lignans possess anti-EBV lytic replication activity.

Manassantin B isolated from Saururus chinensis inhibits cyclooxygenase-2-dependent prostaglandin D2 generation by blocking Fyn-mediated nuclear factor-kappaB and mitogen activated protein kinase pathways in bone marrow derived-mast cells.[Pubmed:23719635]

Biol Pharm Bull. 2013;36(8):1370-4.

The authors investigated the effect of Manassantin B (Man B) isolated from Saururus chinensis (S. chinensis) on cyclooxygenase-2 (COX-2)-dependent prostaglandin D2 (PGD2) generation in mouse bone marrow derived-mast cells (BMMCs). Man B inhibited the generation of PGD2 dose-dependently by inhibiting COX-2 expression in immunoglobulin E (IgE)/Ag-stimulated BMMCs. To elucidate the mechanism responsible for the inhibition of COX-2 expression by Man B, the effects of Man B on the activation of nuclear factor-kappaB (NF-kappaB), a transcription factor essential and mitogen-activated protein kinases (MAPKs) for COX-2 induction, were examined. Man B attenuated the nuclear translocation of NF-kappaB p65 and its DNA-binding activity by inhibiting inhibitors of kappa Balpha (IkappaBalpha) degradation and concomitantly suppressing IkappaB kinase (IKK) phosphorylation. In addition, Man B suppressed phosphorylation of MAPKs including extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun NH2-terminal kinase (JNK) and p38. It was also found that Man B suppressed Fyn kinase activation and consequent downstream signaling processes, including those involving Syk, Gab2, and Akt. Taken together, the present results suggest that Man B suppresses COX-2 dependent PGD2 generation by primarily inhibiting Fyn kinase in FcepsilonRI-mediated mast cells.

Manassantin B inhibits melanosome transport in melanocytes by disrupting the melanophilin-myosin Va interaction.[Pubmed:22863119]

Pigment Cell Melanoma Res. 2012 Nov;25(6):765-72.

Human skin hyperpigmentation disorders occur when the synthesis and/or distribution of melanin increases. The distribution of melanin in the skin is achieved by melanosome transport and transfer. The transport of melanosomes, the organelles where melanin is made, in a melanocyte precedes the transfer of the melanosomes to a keratinocyte. Therefore, hyperpigmentation can be regulated by decreasing melanosome transport. In this study, we found that an extract of Saururus chinensis Baill (ESCB) and one of its components, Manassantin B, inhibited melanosome transport in Melan-a melanocytes and normal human melanocytes (NHMs). Manassantin B disturbed melanosome transport by disrupting the interaction between melanophilin and myosin Va. Manassantin B is neither a direct nor an indirect inhibitor of tyrosinase. The total melanin content was not reduced when melanosome transport was inhibited in a Melan-a melanocyte monoculture by Manassantin B. Manassantin B decreased melanin content only when Melan-a melanocytes were co-cultured with SP-1 keratinocytes or stimulated by alpha-MSH. Therefore, we propose that specific inhibitors of melanosome transport, such as Manassantin B, are potential candidate or lead compounds for the development of agents to treat undesirable hyperpigmentation of the skin.

Effect of manassantin B, a lignan isolated from Saururus chinensis, on lipopolysaccharide-induced interleukin-1beta in RAW 264.7 cells.[Pubmed:22379572]

Korean J Anesthesiol. 2012 Feb;62(2):161-5.

BACKGROUND: Elevated systemic levels of pro-inflammatory cytokines cause hypotension during septic shock and induce capillary leakage in acute lung injury. Manassantin B has anti-inflammatory and anti-plasmoidal properties. This study examined the effects of Manassantin B on lipopolysaccharide (LPS)-induced inflammatory response in murine macrophages. METHODS: RAW 264.7 macrophage cells were incubated without or with (1, 3 and 10 microM) Manassantin B and without or with (100 ng/ml) LPS. Manassantin B dissolved in phosphate buffered saline was added to the medium 1 h prior to the addition of LPS. The degree of activation of mitogen-activated protein kinase (MAPK) including extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun amino terminal kinases (JNK) and p38 MAPK, and the level of interleukin (IL)-1beta were determined 30 min and 24 h after the addition of LPS respectively. RESULTS: Manassantin B inhibited the production of IL-1beta and attenuated the phosphorylations of ERK1/2 and p38 MAPK, but not that of JNK, in RAW 264.7 cells treated with LPS. CONCLUSIONS: Manassantin B reduces LPS-induced IL-1beta expression through effects on ERK1/2- and p38 MAPK-mediated pathways. Manassantin B has potential as a potent anti-inflammatory drug for use in pathological processes such as sepsis or acute lung injury.

Lignan, sesquilignans and dilignans, novel HIV-1 protease and cytopathic effect inhibitors purified from the rhizomes of Saururus chinensis.[Pubmed:19900481]

Antiviral Res. 2010 Feb;85(2):425-8.

Five lignans were isolated from the ethyl acetate extracts of Saururus chinensis rhizomes and evaluated for anti-HIV-1 activity. Their structures were elucidated as two dilignans, manassantin A (1), Manassantin B (2), two sesquilignans, saucerneol B (3) and saucerneol C (4), and a new lignan, saururin B (5) by spectroscopic analysis. Of these components, manassantin A (1) and saururin B (5) showed dose-dependent inhibitory activities on HIV-1 protease with IC(50) values of 38.9 and 5.6 microM. In addition, manassantins A (1), B (2) and saucerneol B (3) inhibited HIV-1-induced cytopathic effects in a human T lymphoblastoid cell line with IC(100) values of 1.0, 1.0 and 0.2 microM, respectively. Of these active constituents, saucerneol B (3) showed the most potent and selective anti-HIV-1 activity (IC(100) of 0.2 microM, CC(0) of >125.0 microM, and SI of >520.8).