Biotransformation of ent-pimara-8(14),15-dien-19-oic acid and anticariogenic evaluation of the obtained derivatives
In the present work, the microbial transformation of the diterpene ent-pimara-8(14),15-dien-19 oic (PA, 1) (Figure 1) was performed using submerged shaken liquid culture of two filamentous fungi: Glomerella cingulata and Mucor rouxii (1.5×107 spores/mL). The microorganisms were grown by a two-stage fermentation procedure . PA was added as a dimethylsulfoxide solution (0.1g/L) and incubated for 10 days. The cultures were filtered and their aqueous layer were extracted with ethyl acetate to furnish the fractions codified as GcE (G. cingulata extract) and MrE (M. rouxii extract). Chemical and NMR studies of these extracts allowed us to isolate and to identify four PA derivatives (Figure 1: Compounds 2 and 3 from EGc; 4 and 5 from EMr). The antimicrobial activity of these metabolites was evaluated against the main microorganisms responsible for dental caries : Streptococcus sanguinis, S. mutans, S. salivarius, S. sobrinus, S. mitis and Lactobacillus casei. For this purpose, the broth microdilution method was applied and the minimal inhibitory concentration (MIC) values were determined . Diterpenes 1, 2 and 4 displayed significant inhibitory effect on the growth of these pathogens, showing MIC values very promising .
Acknowledgements: FAPESP (Proc. 2007/54762–8)
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