Ángeles Guinda

Biochemical Basis of the Antidiabetic Activity of Oleanolic Acid and Related Pentacyclic Triterpenes

Oleanolic acid (OA), a natural component of many plant food and medicinal herbs, is endowed with a wide range of pharmacological properties whose therapeutic potential has only partly been exploited until now. Throughout complex and multifactorial mechanisms, OA exerts beneficial effects against diabetes and metabolic syndrome. It improves insulin response, preserves functionality and survival of β-cells, and protects against diabetes complications. OA may directly modulate enzymes connected to insulin biosynthesis, secretion, and signaling. However, its major contributions appear to be derived from the interaction with important transduction pathways, and many of its effects are consistently related to activation of the transcription factor Nrf2. Doing that, OA induces the expression of antioxidant enzymes and phase II response genes, blocks NF-κB, and represses the polyol pathway, AGEs production, and hyperlipidemia. The management of type 2 diabetes requires an integrated approach, which includes the early intervention to prevent or delay the disease progression, and the use of therapies to control glycemia and lipidemia in its late stages. In this sense, the use of functional foods or drugs containing OA is, undoubtedly, an interesting path.

Determination of Triterpenic Acids in Human Serum by High-Performance Liquid Chromatography: Triterpenoid Interaction with Serum Protein

Terpenic acids are under development as therapeutic agents in numerous treatments. In support of pharmacokinetic and toxicological evaluations, a robust assay based on high-performance liquid chromatography (HPLC) was developed for the analysis of the terpenoids in human serum. For a clear understanding of the differences in biological activity of these compounds, the interactions between oleanolic or betulinic acids and human serum protein have been studied by ultraviolet-visible (UV-vis) absorption under physiological conditions. A combination of liquid/liquid extraction, centrifugation, and consecutive HPLC resulted in simultaneous separation, identification, and quantification of the oleanolic, betulinic, and ursolic acids. The validity of the developed method was established by determining linearity, recovery, precision, accuracy, limit of detection, and quantification. Detection limits were in the range of 3.3-4.3 ng/mL, and linearity values ranged up to 1 μg/mL. The repeatability of the method was good. All compounds can be well-distinguished by order of elution during liquid chromatography. The pentacyclic triterpenoids have been identified by retention time comparison to pure standards and quantified by an internal standard. The results by UV-vis absorption spectra experiments (240-340 nm) indicate that protein structures have been perturbed in the presence of oleanolic and betulinic acids.

GC-FID determination and pharmacokinetic studies of oleanolic acid in human serum.

Analytical interest of OA determination in human serum has increased owing to the increasing interest in pharmaceutical research by pharmaceutical properties. A simple, specific, precise and accurate GC method with flame ionization detector (FID) developed and validated for the determination of oleanolic acid (OA) in human serum (HS). To an aliquot of HS, internal standard was added and a combination of liquid-liquid extraction with a mixture of diethyl ether-isopropyl alcohol, filtration and consecutive GC resulted in separation and quantification of OA. The organic phase was analyzed using a GC system equipped with a 30 × 0.25 mm i.d. Rtx-65TG capillary column and FID detection. Total chromatographic time was 10 min and no interfering peaks from endogenous components in blank serum were observed. The OA/internal standard peak area ratio was linearly fitted to the OA concentration (r = 0.992) over the range 10-1500 ng/mL. The mean serum extraction recovery of OA was 96.7 ± 1.0% and the lower limit of quantification based on 5 mL of serum was 10.7 ng/mL. The intra-day coefficient of variation ranged from 1.3 to 3.6% and inter-day varied from 1.4 to 4.5%. The developed method was used to study the pharmacokinetics of OA after oral administration in humans. The assay was simple, sensitive, precise and accurate for the use in the study of the mechanisms of absorption and distribution of OA in humans.

Characterization of glyceridic and unsaponifiable compounds of Sacha inchi (Plukenetia huayllabambana L.) oils.

This work deals with the characterization of the main glyceridic and unsaponifiable components of oils obtained from Sacha inchi (Plukenetia huayllabambana L.) seed ecotypes collected during two harvests in the Department of Amazonas in Peru. The seed-oil yield was 30.3-41.2%; standing out are the high percentages of the ω3- and ω6-fatty acids series whose ranges lie within those of the present Regulation for Sacha inchi oils. Triacylglycerols with even equivalent carbon number (ECN; 36-42) were the main components. Minor glyceridic polar compounds such as oxidized triglycerides, diglycerides, monoglycerides, and free fatty acids were determined by high-performance size exclusion chromatography. The low campesterol/stigmasterol ratio (1:6), unusual in the majority of vegetable oils, stands out. Regarding aliphatic hydrocarbons, these oils showed a particular profile for the saturated series of odd and even carbon atom numbers. According to our results Sacha inchi P. huayllabambana oils can be offered as a good alternative to P. volubilis, the species mainly commercialized for this vegetable oil.