title: Effect of storage time and conditions on the diene valepotriates content of the extract of Valeriana glechomifolia obtained by supercritical carbon dioxide.
abstract: BACKGROUND
  Valepotriates (epoxy iridoid esters) represent an important group of constituents that contribute to pharmacological effects for the genus Valeriana. Storage and extraction of valepotriates is a demanding task, as these compounds are thermolabile and unstable: even when decomposition products are not formed, isovaleric acid liberation from the iridoid nucleus originate compounds with less complex substituents.
  
  
  OBJECTIVE
  To study the influence of time and storage conditions on the diene valepotriates (valtrate, isovaltrate, acevaltrate, 1-β-acevaltrate, 1-β-aceacevaltrate) content of the Valeriana glechomifolia (native to southern Brazil), extract was obtained by supercritical fluid extraction using CO₂ as the fluid (SF-CO₂).
  
  
  METHODS
  Above-ground and below-ground material of V. glechomifolia was extracted by SF-CO₂ (40 °C, 90 bar). The extract was stored under nitrogen atmosphere or solubilised in methanol. Valepotriates stability was accessed during storage at -20 °C over 8 months through reverse-phase HPLC (mobile phase acetonitrile:water 50:50 (v/v); 254 nm).
  
  
  RESULTS
  A gradual increase in valtrate levels and decrease in acevaltrate, 1-β-acevaltrate and 1-β-aceacevaltrate, concentration were observed from the first month of storage for the dry extract. However, for the methanol solubilised extract these changes occurred only after the third month and were accompanied by reduction in isovaltrate levels and formation of decomposition products.
  
  
  CONCLUSIONS
  SF-CO₂ showed high selectivity for valepotriates extraction. This is the first report on valepotriates molecular conversion, which was less accelerated when the extract was stored in methanol, but under this condition degradation products are also present, probably baldrinals, that are not observed in the dry extract.
authors.affiliation: Programa de Pós Graduação em Ciências Farmacêuticas, UFRGS. Av. Ipiranga, 2752, 90610-000 Porto Alegre, RS, Brazil.
authors.forename: Liz Girardi
authors.initials: LG
authors.lastname: Müller
authors.forename: Luisa
authors.initials: L
authors.lastname: de Andrade Salles
authors.forename: Satchie
authors.initials: S
authors.lastname: Sakamoto
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Stein
authors.forename: Simone Tasca
authors.initials: ST
authors.lastname: Cargnin
authors.forename: Eduardo
authors.initials: E
authors.lastname: Cassel
authors.forename: Rubem Figueiró
authors.initials: RF
authors.lastname: Vargas
authors.forename: Stela Maris Kuze
authors.initials: SM
authors.lastname: Rates
authors.forename: Gilsane Lino
authors.initials: GL
authors.lastname: von Poser
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D004355:Drug Stability; D004356:Drug Storage; D039823:Iridoids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D000432:Methanol / Q000737:chemistry; D015394:Molecular Structure; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D013696:Temperature; D013997:Time Factors; D014632:Valerian / Q000737:chemistry*
chemical_list: D039823:Iridoids; D010936:Plant Extracts; C009643:valtrates (combination); D002245:Carbon Dioxide; C030127:valtrate; C090810:acevaltrate; D000432:Methanol