Acid diterpenes from Copaiba oleoresin (Copaifera langsdorffii): Chemical and plasma stability and intestinal permeability using Caco-2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Copaiba oleoresin has been used in folk medicine in the treatment of bronchitis, syphilis, skin diseases and ulcers due to its anti-inflammatory and antiseptic activities, but there is no information about major compounds oral absorption to support the traditional use.

AIM OF STUDY

Considering the potential of copalic (CA) and kaurenoic acid (KA) - major biological activity (in vitro) diterpenes found in the oleoresin, this study aimed to evaluate the intestinal permeability of CA and KA using Caco-2 cells model as predictive test for oral drug absorption.

MATERIALS AND METHODS

Chemical stability at pH 1.2 and 7.4 and plasma stability were evaluated to mimic physiological conditions of the gastrointestinal tract. The intestinal permeability of CA and KA was evaluated in Caco-2 cells in the presence and absence of the P-glycoprotein inhibitor verapamil.

RESULTS

CA and KA were rapidly degraded at pH 1.2 (0.2 M Clark-Lubs buffer). At pH 7.4 (0.1 M phosphate buffer), CA was stable for up to 24 h and KA for up to 6 h. In human plasma, CA and KA can be considered stable for 24 h and 12 h at 37 °C, respectively. Caco-2 cells were considered viable when incubated with CA or KA in the range of 3.9-250 μM for 24 h. CA and KA exhibited moderate apparent permeability (P_app) of 4.67 (±0.08) × 10^-6 cm/s and 4.66 (±0.04) × 10^-6 cm/s, respectively. Simultaneous incubation with verapamil showed that P-glycoprotein does not play a relevant role on CA and KA oral absorption, with P_app of 4.48 (±0.26) × 10^-6 cm/s and 5.37 (±0.72) × 10^-6 cm/s observed for CA and KA, respectively.

CONCLUSION

The oral absorption of both CA and KA is driven by mainly passive permeability, is not limited by p-glycoprotein, but enteric-coated dosage forms should be used to avoid chemical instability in the gastric pH.

An integrative omics perspective for the analysis of chemical signals in ecological interactions

All living organisms emit, detect, and respond to chemical stimuli, thus creating an almost limitless number of interactions by means of chemical signals.

GH11 xylanase from Aspergillus tamarii Kita: Purification by one-step chromatography and xylooligosaccharides hydrolysis monitored in real-time by mass spectrometry

The present study describes the one-step purification and biochemical characterization of an endo-1,4-β-xylanase from Aspergillus tamarii Kita. Extracellular xylanase was purified to homogeneity 7.43-fold through CM-cellulose. Enzyme molecular weight and pI were estimated to be 19.5kDa and 8.5, respectively. The highest activity of the xylanase was obtained at 60°C and it was active over a broad pH range (4.0-9.0), with maximal activity at pH 5.5. The enzyme was thermostable at 50°C, retaining more than 70% of its initial activity for 480min. The K_0.5 and V_max values on beechwood xylan were 8.13mg/mL and 1,330.20μmol/min/mg of protein, respectively. The ions Ba²⁺ and Ni²⁺, and the compounds β-mercaptoethanol and DTT enhanced xylanase activity, while the heavy metals (Co²⁺, Cu²⁺, Hg⁺, Pb²⁺ and Zn²⁺) strongly inhibited the enzyme, at 5mM. Enzymatic hydrolysis of xylooligosaccharides monitored in real-time by mass spectrometer showed that the shortest xylooligosaccharide more efficiently hydrolyzed by A. tamarii Kita xylanase corresponded to xylopentaose. In agreement, HPLC analyzes did not detect xylopentaose among the hydrolysis products of xylan. Therefore, this novel GH11 endo-xylanase displays a series of physicochemical properties favorable to its application in the food, feed, pharmaceutical and paper industries.

Distribution and some properties of bile salt-binding proteins in rainbow trout, Salmo gairdneri

Trout liver cytosol has proteins that bind bile salts and 8-anilino-1-naphthalene sulphonate and that co-elute from Sephadex G-75. The binding of 8-anilino-1-naphthalene sulphonate is decreased by 90% in the presence of 33 microM lithocholate, implying the proteins are the same. Bile salt-binding protein is present in liver, but was not detected in gills, kidney, muscle or intestine. Bile salt-binding protein, partially-purified by Sephadex G-75 chromatography, was resolved into 2 fractions by cholate-affinity chromatography. Fatty acids do not appear to be bound by bile salt-binding protein. No fatty acid-binding protein was detected in trout liver cytosol.

Distribution and some properties of the glutathione S-transferase and gamma-glutamyl transpeptidase activities of rainbow trout

1. Gills, kidney, intestinal caeca and liver of trout have glutathione S-transferase activity with 1-chloro-2,4-dinitrobenzene (200 500 nmol/min/mg protein), and reduced glutathione (0.5 2.0 mmol/kg tissue). 2. Only kidney and intestinal caeca have substantial gamma-glutamyl transpeptidase activity with gamma-glutamyl-rho-nitroanilide (2-9 nmol/min/mg protein). 3. Renal gamma-glutamyl transpeptidase is membrane-bound and has similar kinetic properties to its mammalian counterparts. 4. The data are consistent with the presence of a mercapturic acid pathway in trout.

A theoretical analysis of the use of zonal gel filtration in the detection and purification of protein-ligand complexes

A simple model of zonal gel filtration is analysed numerically to establish semiquantitatively how the capacity of a protein-ligand complex to survive gel filtration intact depends on several experimental variables and on the kinetic characteristics of the complex. The design of gel-filtration experiments aimed at detecting and partially purifying binding proteins is discussed.