Spray dried Petiveria alliacea extracts: standardization and evaluation of the antimicrobial activity

Petiveria alliacea L. (Phytolaccacea) is an herbaceous plant of great importance in folk medicine. Methabolites isolated and reported for P. alliacea include flavonoids, triterpenes, steroids, coumarin, and several sulfur-containing amino acids in the roots; as well as S-benzylcysteine sulfoxides, and S-(2-hydroxyethyl) cysteine sulfoxides. This study aimed to evaluate the in vitro antifungal activity of spray dried extracts of P. alliacea (leaves). Spray dried extracts were produced from hydro-ethanolic extract 70% (v/v) obtained by dynamic maceration of leaves. Maltodextrin and colloidal silicon dioxide at proportion of 5 and 2.5% respectively were added to the concentrated extract prior to drying (spray dryer model SD-05 LabPlant), at temperatures from 87 to 154 °C and extract feed rate of 6 g/min. The dried extracts were monitored for their antifungal activity by microdilution broth (M27-A2, CLSI) using standard ATCC strains: C. parapsilosis (2209), C. albicans (90028), C. kefyr (6258) and by concentration of total polysulphides expressed as dibenzyl trisulphide (DTS) using a UV-vis method. The antifungal activity was determined by the minimum fungicidal concentration (MFC) using fluconazole (0.125 – 16 µg/ml) as reference control. The hydro-ethanolic extract presented a MFC of 246 µg/ml for C. albicans, C. parapsilosis and C. kefyr. The dried extracts obtained at temperatures of 87 and 154 °C exhibited antifungal activity at concentration of 143 µg/ml for all strains tested, while the extract obtained at 120 °C presented MFC between 142 – 427 µg/mL. The concentrated extract showed a value of 11.7% g/g DTS while the dried extracts (temperatures 87 – 154 °C) showed an average value of 11.5% g/g. The results showed that the feed composition and drying conditions did not affect the DTS content. The dried product showed antifungal activity compared with the original concentrated extract, which presented MFC ranging from 82 µg/mL to 246 µg/mL, depending on the strains tested.