Human neutrophil elastase (HNE) – IC50 = 0.5 μM, KD = 1.5 μM [1]
Human neutrophil cathepsin G – IC50 approximately 2.5 μM (using Azocoll as substrate) [1]
Rat neutrophil elastase – inhibition observed (percent inhibition: 79% at 10 μM, 70% at 5 μM, 31% at 2.5 μM, 1% at 1.0 μM) [1]
Hamster neutrophil elastase – inhibition observed (82% at 10 μM, 64% at 5 μM, 18% at 1.0 μM) [1]
Rabbit neutrophil elastase – inhibition observed (85% at 10 μM using a structural analog SC-36650) [1]
Hog neutrophil elastase – inhibition observed (57% at 10 μM) [1]

Lodelaben is an inhibitor of human neutrophil elastase having IC50 and Ki values of 0.5 and 1.5 μM, correspondingly. The outcomes demonstrate the non-competitive nature of Lodelaben's inhibition of human neutrophil elastase (HNE). When combined with synthetic substrates at 10 μM or with Azocoll at 5 μM, loafelaben did not exhibit any inhibitory effects. The metalloproteinase Pseudomonas aeruginosa elastase is not inhibited by loafelaben. On the other hand, Lodelaben inhibits cathepsin G activity with an IC50 of about 2.5 μM when Azocoll is utilized as a substrate [1].

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Lodelaben inhibits human neutrophil elastase (HNE) activity measured by hydrolysis of the synthetic substrate methoxysuccinyl-ala-ala-pro-val-p-nitroanilide (MeOS-AAPV-NA), with an IC50 of approximately 0.5 μM. The inhibition is non-competitive at low concentrations (0.5-1.25 μM) and mixed at higher inhibitor concentrations. Lineweaver-Burk analysis indicates non-competitive inhibition, with a projected KI of 1.5-2.0 μM from three separate experiments. [1]
Lodelaben inhibits HNE-catalyzed degradation of the natural insoluble substrate [14C]-elastin. At 14 μM inhibitor concentration, solubilized elastin decreased from 690 DPM (control) to 304 DPM (56% inhibition); at 5 μM, 633 DPM (8% inhibition); at 10 μM, 453 DPM (34% inhibition); at 20 μM, 295 DPM (57% inhibition); at 30 μM, 267 DPM (61% inhibition); at 50 μM, 134 DPM (81% inhibition). [1]
Lodelaben shows no significant inhibition of hog pancreatic elastase (13% inhibition at 20 μM, the highest concentration tested) using t-BOC-ala-NP substrate. It does not inhibit bovine α-chymotrypsin at 10 μM with synthetic substrates (t-BOC-tyr-NP or succ-ala-ala-pro-phe-NA) or at 5 μM with Azocoll. It does not inhibit Pseudomonas aeruginosa elastase at 100 μM or 50 μM using either furyl-acryloyl-ala-phe-NH2 or Azocoll as substrates. [1]
Lodelaben inhibits human neutrophil cathepsin G using Azocoll as substrate, with an IC50 of approximately 2.5 μM (79% inhibition at 5 μM, 56% at 2.5 μM, 36% at 1.25 μM). [1]
Neutrophil elastase activity from rat, hamster, rabbit, and hog was inhibited by Lodelaben (or its structural analog SC-36650 for rabbit) as determined by hydrolysis of MeOS-AAPV-NA. For rat elastase: 79% inhibition at 10 μM, 70% at 5 μM, 31% at 2.5 μM, 1% at 1.0 μM. For hamster: 82% at 10 μM, 64% at 5 μM, 18% at 1.0 μM. For rabbit (using SC-36650): 85% at 10 μM. For hog: 57% at 10 μM. Preincubation of hog neutrophil preparation with SC-39026 prior to substrate addition increased inhibition, suggesting possible competitive binding to an inhibitor protein. [1]

The saline/car and saline/Lodelaben groups had mean pulmonary artery pressures of 16.4±1.1 and 17.4±0.9 mm Hg, respectively, that were comparable. Lodelaben administration of monocrotaline rats produced considerably lower values (21.00±1.6 mm Hg, p<0.05) than the mean pulmonary artery pressure (27.5±0.8 mm Hg) in the monocrotaline/vehicle group. The percentage of arterial muscularization at the alveolar wall in saline/vehicle and saline/Lodelaben rats was merely 1.9±1.4 and 0.4±0.4%, respectively. The percentage of alveolar wall artery muscularization in rats treated with monocrotaline-injected Lodelaben was reduced to 10.0 ± 3.6% [2].

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In a monocrotaline-induced pulmonary hypertension rat model, oral administration of Lodelaben (40 mg/kg/dose in carboxymethylcellulose vehicle, twice daily starting 12 hours before and continuing for 8 days after monocrotaline injection) significantly reduced mean pulmonary artery pressure at 15 days after monocrotaline injection compared to vehicle-treated controls (21.0 ± 1.6 mm Hg vs. 27.5 ± 0.8 mm Hg, p < 0.05). This correlated with a significant reduction in the number of abnormally muscularized arteries at the alveolar wall level (10.0 ± 3.6% vs. 24.1 ± 2.6%, p < 0.05). The reduction in pulmonary artery pressure was significantly correlated with the percent of alveolar wall arteries muscularized (r² = 0.89, p < 0.001). Right ventricular hypertrophy (RV/FBW ratio) was also significantly lower in SC-39026-treated rats compared to vehicle-treated rats (0.54 ± 0.03 vs. 0.61 ± 0.03, p < 0.05). However, SC-39026 did not significantly reduce monocrotaline-induced medial hypertrophy of muscular arteries, endothelial injury, subendothelial edema, or increase the proportion of medial elastin (though a trend was apparent). At 3 weeks after monocrotaline injection, no significant differences were observed between SC-39026-treated and vehicle-treated rats in pulmonary artery pressure, right ventricular hypertrophy, muscularization of peripheral arteries, or medial wall thickness. [2]

Human neutrophil elastase (HNE) activity was quantified by two methods. First, the rate of hydrolysis of the synthetic substrate methoxysuccinyl-ala-ala-pro-val-p-nitroanilide (MeOS-AAPV-NA) was monitored spectrophotometrically at 410 nm in the presence or absence of inhibitor. Elastase concentration was titrated to yield an absorbance change of 0.12-0.14 optical density units per minute at 30°C in 0.2 M Tris buffer, pH 8.0. Inhibitor and substrate were prepared in dimethylsulfoxide (DMSO), with a final DMSO concentration of 10% in a 1 mL final volume. [1]
Second, hydrolysis of [14C]-elastin by HNE was quantified in the presence and absence of inhibitor. [14C]-Elastin (0.25 mg per assay, 287 dpm/μg) was incubated with HNE in a final volume of 0.2 mL. The rate of 14C solubilization was linear for 4 hours, and background (13 dpm from samples without HNE) was subtracted from all experimental values. [1]
Hog pancreatic elastase activity was quantified by measuring hydrolysis of t-BOC-ala-NP. [1]
Bovine α-chymotrypsin activity was assayed using either t-BOC-tyr-NP or succ-ala-ala-pro-phe-NA as substrates, with the PIPES buffer (pH 6.5) concentration raised from 0.05 to 0.20 M. Alternatively, Azocoll (an insoluble powdered cowhide macromolecular product) was used as substrate, with dye release quantitated spectrophotometrically. [1]
Cathepsin G activity was measured using Azocoll as substrate. [1]
Pseudomonas aeruginosa elastase activity was assayed using furyl-acryloyl-ala-phe-NH2 or Azocoll as substrates. [1]

For the monocrotaline-induced pulmonary hypertension study, male Sprague-Dawley rats (250-300 g) were given a single subcutaneous injection of monocrotaline (60 mg/kg) or saline. Lodelaben (SC-39026) was suspended in carboxymethylcellulose vehicle (1 g carboxymethylcellulose in 100 mL warmed distilled water). Rats received the inhibitor (40 mg/kg/dose) or vehicle only by gavage twice daily, starting 12 hours before the monocrotaline or saline injection and continuing for 8 days after injection. On day 13 after injection, rats were anesthetized with intraperitoneal sodium pentobarbital (33 mg/kg), and indwelling catheters were inserted into the abdominal aorta and pulmonary artery. Hemodynamic measurements (pulmonary and systemic) were recorded 48 hours later (day 15) with the animals awake. After measurements, rats were anesthetized again, ventilated via tracheostomy, and the lungs were perfused via the central pulmonary artery with preheated (37°C), heparinized phosphate-buffered saline at 20 cm water pressure for 5 minutes. The right lung was then perfused at the in vivo-measured pressure for 10 minutes with cold (4°C) 1% glutaraldehyde in 4% formaldehyde solution for electron microscopy. The left lung was injected with hot (60°C) radiopaque barium-gelatin mixture at 100 cm water pressure for 5 minutes, then distended with 10% formaldehyde at 36 cm water pressure and perfused for 3 days for light microscopy. The right ventricle (RV) was dissected from the left ventricle plus septum (LV+S) and weighed separately. [2]
For the 3-week study, additional monocrotaline-injected rats were followed for 3 weeks after injection, with the same dosing regimen of SC-39026 or vehicle. Hemodynamic and morphological assessments (excluding ultrastructural analyses) were performed similarly. [2]
For plasma level determination, six additional weight-matched male Sprague-Dawley rats were gavaged with SC-39026 for 6 days. Tail vein blood (1 mL) was obtained just before the first dose and 9 hours after the last dose. [2]

Plasma levels of Lodelaben (SC-39026) were determined in rats after 6 days of oral gavage (40 mg/kg/dose twice daily). Values before gavage ranged from 0.10 to 0.24 μg/mL (background activity). Levels 9 hours after the last dose were 0.30-0.38 μg/mL in two rats and 1.30-4.17 μg/mL in the remaining four rats. Values greater than 0.6 μg/mL are considered to represent a therapeutic level. Considerable variation in the degree of absorption after oral administration in rats was observed. [2]

[1]. SC-39026, a specific human neutrophil elastase inhibitor. Biochem Biophys Res Commun. 1987 Sep 15;147(2):666-74.

[2]. SC-39026, a serine elastase inhibitor, prevents muscularization of peripheral arteries, suggesting a mechanism of monocrotaline-induced pulmonary hypertension in rats. Circ Res. 1989 Apr;64(4):814-25.

Lodelaben (SC-39026) is a benzoic acid derivative containing a hydrophobic chain. Its inhibition of human neutrophil elastase is reversible and non-competitive at low concentrations (0.5-1.25 μM), and mixed at higher concentrations. The compound does not inhibit hog pancreatic elastase, bovine α-chymotrypsin, or Pseudomonas aeruginosa elastase, but does inhibit cathepsin G, which is considered advantageous because cathepsin G is synergistic with neutrophil elastase in hydrolyzing human lung elastin. The chemical structure suggests resistance to inactivation by activated oxygen species released from neutrophils (which can oxidize and inactivate α-1-antitrypsin). [1]
In the monocrotaline-induced pulmonary hypertension rat model, the protective effect of SC-39026 (reduction in muscularization of peripheral arteries and pulmonary hypertension) did not persist at 3 weeks, suggesting continued elastase activity or that a higher or more constant level of inhibitor may be needed for a sustained response. Failure to inhibit medial hypertrophy suggests a different mechanism or a different elastase may be involved in that structural change. [2]

C25H41CLO3

425.04424

424.274

111149-90-7

56557

White to off-white solid powder

1.76E-12mmHg at 25°C

8.333

2

3

18

29

402

0

SYCYJNHKNPPDAT-UHFFFAOYSA-N

InChI=1S/C25H41ClO3/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-24(27)21-18-19-22(25(28)29)23(26)20-21/h18-20,24,27H,2-17H2,1H3,(H,28,29)

2-chloro-4-(1-hydroxyoctadecyl)benzoic acid

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)

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

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.

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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).

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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)

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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).

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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

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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.

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