Production of anti-inflammatory compounds in Sphaeralcea angustifolia cell suspension cultivated in stirred tank bioreactor.

Sphaeralcea angustifolia is a plant used for the treatment of inflammatory processes. Scopoletin, tomentin, and sphaeralcic acid were identified as the compounds with anti-inflammatory and immunomodulatory effects. Successful establishment of the cell culture in Erlenmeyer flasks has been reported previously. The aim of this study was to evaluate the ability of cells in suspension from S. angustifolia grown in a stirred tank bioreactor and demonstrate their capacity to produce bioactive compounds. Cells in suspension grown at 200 rpm reached a maximal cell biomass in dry weight at 19.11 g/L and produced 3.47 mg/g of sphaeralcic acid. The mixture of scopoletin and tomentin was only detected at the beginning of the culture (12.13 µg/g). Considering that the profile of dissolved oxygen during the cultures was lesser than 15%, it is possible that the low growth at 100 rpm could be due to oxygen limitations or to cell sedimentation. At 400 rpm, a negative effect on cell viability could be caused by the increase in the hydrodynamic stress, including the impeller tip, average shear rate, and Reynolds number. The sphaeralcic acid content in the cell suspension of S. angustifolia obtained in the bioreactor was two orders of magnitude greater than that reported for the culture grown in Erlenmeyer flasks.

Sphaeralcic acid and tomentin, anti-inflammatory compounds produced in cell suspension cultures of Sphaeralcea angustifolia.

Sphaeralcea angustifolia, an endangered plant species in Mexico, is employed to treat inflammatory processes and as a wound healing remedy. Scopoletin (1) was reported as one of the main bioactive compounds in this plant. Here, we isolated and identified compounds with anti-inflammatory properties from the suspension-cultured cells of S. angustifolia. The CH2Cl2 : CH3OH extract of the cells exhibited anti-inflammatory properties in acute inflammation models. Two compounds were isolated, 5-hydroxy-6,7-dimethoxycoumarin, named tomentin (2), and 2-(1,8-dihydroxy-4-isopropyl-6-methyl-7-methoxy)-naphthoic acid, denominated as sphaeralcic acid (3). Their structures were determined by spectroscopic and spectrometric analyses. The anti-inflammatory effects of both compounds were also evaluated. At a dose of 45 mg/kg, compound 2 inhibited the formation of λ-carrageenan footpad edema at 58 %, and compound 3 at 66 %. Local application of compound 2 (225 mM per ear) or 3 (174 mM per ear) inhibited the phorbol ester-induced auricular edema formation by 57 % or 86 %, respectively. The effect of compound 3 was dose-dependent and the ED50 was 93 mM.