Preservative prospect of Ugni candollei (Barnéoud) O.Berg, an underexploited edible berry tree from Chile.

Ugni candollei (Barnéoud) O.Berg), also known as "white murta", represents one of the three species of Ugni native to Chile that are called "murta". The other two species are U. molinae (red murta) and U. selkirkii. The fruits of these species are used as an ingredient in a popular brew known as Chilean Chicha. This type of beer is based on combinations of corn and cassava tubers in which "murta" is added because it provides colour as well as acting as a preservative. To date only the antibacterial activity of "red murta" has been reported and the activity has been linked to phenolic compounds. The present investigation examined the utilization of U. candollei as a natural preservative through its ability to inhibit the growth of microbes and identify triterpenoids associated with this activity. A bio-guided fractionation approach was used to identify the active compounds. Active extracts were split into fractions, and active fractions were purified using chromatographic methods. The structures of isolated compounds were elucidated by means of spectroscopic and mass spectrometric analyses. The active extracts were found to be rich in pentacyclic triterpenoids of which taraxastanes, ursanes, oleananes and lupanes were the primary types. The major compound, a previously undescribed taraxastane-type molecule, showed notable potency against S. aureus (MIC = 3.8 μM). Four additional previously unreported minor analogues were also isolated, along with eleven known related compounds. The chemical diversity in their structures occurred on rings A, C and E of the pentacyclic skeleton. The current antibacterial findings lend support to the plant's traditional use as a preservative.