Siamycin I (BMY-29304) is a 21-residue tricyclic peptide that is a secondary metabolite (SM, chemical compound) of actinomycetes. Siamycin I is an HIV fusion inhibitor (antagonist) with an ED50 of 0.05-5.7 μM for acute HIV type 1 (HIV-1) and HIV-2 infection. Siamycin I inhibits gelatinase and gelatinase biosynthesis activating pheromone (GBAP) signaling through the FsrC-FsrA two-component regulatory system in a noncompetitive manner. Siamycin I inhibits the expression of fsrBDC and gelE-sprE transcripts. Siamycin I is a lariat peptide that interacts with lipid II and inhibits cell wall biosynthesis. Siamycin I is an antibiotic with potential for use in the study of enterococcal infections.

Physicochemical Properties

Molecular Formula	C97H131N23O26S4
Molecular Weight	2163.48
Exact Mass	2161.85
CAS #	164802-68-0
PubChem CID	16130275
Appearance	Typically exists as solid at room temperature
LogP	2.169
Hydrogen Bond Donor Count	26
Hydrogen Bond Acceptor Count	30
Rotatable Bond Count	22
Heavy Atom Count	150
Complexity	4720
Defined Atom Stereocenter Count	18
SMILES	CC(C[C@H]1C(=O)NCC(=O)N[C@@H](C(C)C)C(=O)NCC(=O)N[C@@H](CO)C(=O)N[C@H]2C(N[C@H](C(N[C@@H]3C(N[C@H](C(N[C@H](C(NCC(N[C@H](C(NCC(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@H](C(N[C@@H](CC4=CNC5=CC=CC=C45)C(=O)O)=O)CC4C=CC=CC=4)=O)CSSC2)=O)C(C)C)=O)[C@H](CC)C)=O)C)=O)CC2C=CC(O)=CC=2)=O)=O)CSSC[C@H](NC(C3)=O)C(=O)N1)=O)=O)C)=O)CC1C=CC=CC=1)=O)=O)CC(=O)N)=O)C
InChi Key	TXYRKTDGDMHVHR-NEKRQKPVSA-N
InChi Code	InChI=1S/C97H131N23O26S4/c1-11-50(8)80-96(144)119-79(49(6)7)95(143)117-71(93(141)112-63(32-54-22-16-13-17-23-54)87(135)115-66(97(145)146)34-56-37-99-59-25-19-18-24-58(56)59)46-150-149-45-70-92(140)113-64(35-72(98)123)88(136)114-65-36-73(124)108-69(91(139)110-60(30-47(2)3)83(131)101-41-77(128)118-78(48(4)5)94(142)103-40-75(126)107-67(42-121)90(138)116-70)44-148-147-43-68(109-76(127)38-100-81(129)51(9)104-86(134)62(111-89(65)137)31-53-20-14-12-15-21-53)84(132)102-39-74(125)106-61(33-55-26-28-57(122)29-27-55)85(133)105-52(10)82(130)120-80/h12-29,37,47-52,60-71,78-80,99,121-122H,11,30-36,38-46H2,1-10H3,(H2,98,123)(H,100,129)(H,101,131)(H,102,132)(H,103,142)(H,104,134)(H,105,133)(H,106,125)(H,107,126)(H,108,124)(H,109,127)(H,110,139)(H,111,137)(H,112,141)(H,113,140)(H,114,136)(H,115,135)(H,116,138)(H,117,143)(H,118,128)(H,119,144)(H,120,130)(H,145,146)/t50-,51-,52-,60-,61-,62-,63-,64-,65-,66-,67-,68-,69-,70-,71-,78-,79-,80-/m0/s1
Chemical Name	(2S)-2-[[(2S)-2-[[(1S,4S,7S,13R,19S,22S,25S,28S,31R,36R,39S,45S,51S,54R,60S)-60-(2-amino-2-oxoethyl)-4-benzyl-25-[(2S)-butan-2-yl]-39-(hydroxymethyl)-19-[(4-hydroxyphenyl)methyl]-7,22-dimethyl-51-(2-methylpropyl)-2,5,8,11,14,17,20,23,26,29,38,41,44,47,50,53,56,59,62-nonadecaoxo-28,45-di(propan-2-yl)-33,34,64,65-tetrathia-3,6,9,12,15,18,21,24,27,30,37,40,43,46,49,52,55,58,61-nonadecazatricyclo[34.21.5.413,54]hexahexacontane-31-carbonyl]amino]-3-phenylpropanoyl]amino]-3-(1H-indol-3-yl)propanoic acid
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	HIV-1 HIV-2
ln Vitro	At 1 μM, Siamycin I partially inhibits E. faecalis growth (80% growth 5 hours after inoculation), while at 5 μM, it fully inhibits growth (no growth 12 hours after inoculation) [3]. At a concentration of 0.25 μM, siamycin I (0-1 μM; 24 hours) significantly suppresses the formation of biofilms; at concentrations above 0.5 μM, the inhibitory impact is significant [3]. The fusing of C8166 cells with chronic HIV-positive CEM-SS cells is inhibited by siamycin I (ED50=0.08 μM), but mouse myoblast fusion and Sendai virus-induced fusion are unaffected [4].
References	[1]. Pikyee Ma, et al. Anti-HIV siamycin I directly inhibits autophosphorylation activity of the bacterial FsrC quorum sensor and other ATP-dependent enzyme activities. FEBS Lett. 2011 Sep 2;585(17):2660-4. [2]. Stephanie Tan, et al. The Lasso Peptide Siamycin-I Targets Lipid II at the Gram-Positive Cell Surface. ACS Chem Biol. 2019 May 17;14(5):966-974. [3]. Jiro Nakayama, et al. Siamycin attenuates fsr quorum sensing mediated by a gelatinase biosynthesis-activating pheromone in Enterococcus faecalis. J Bacteriol. 2007 Feb;189(4):1358-65. [4]. M Tsunakawa, et al. Siamycins I and II, new anti-HIV peptides: I. Fermentation, isolation, biological activity and initial characterization. J Antibiot (Tokyo). 1995 May;48(5):433-4.
Additional Infomation	Siamycin I has been reported in Streptomyces with data available.

Solubility Data

Solubility (In Vitro)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Solubility (In Vivo)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples. Injection Formulations (e.g. IP/IV/IM/SC) Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] *Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline) Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline) Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline) Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil) Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Oral Formulations Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). Oral Formulation 3: Dissolved in PEG400 Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose Oral Formulation 6: Mixing with food powders Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	0.4622 mL	2.3111 mL	4.6222 mL
	5 mM	0.0924 mL	0.4622 mL	0.9244 mL
	10 mM	0.0462 mL	0.2311 mL	0.4622 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.