Biological Activity of 6,7-Dehydroxyroyleanone and Derivatives Obtained from Plectranthus aliciae (Codd) A.J.Paton.

The Plectranthus genus (Lamiaceae) is known to be rich in abietane diterpenes. The bioactive 6,7-dehydroxyroyleanone (DHR, 1 ) was previously isolated from Plectranthus madagascariensis var. madagascariensis and var. aliciae . This study aimed to explore the occurrence of DHR, 1 , in P. aliciae and the potential bioactivities of new semisynthetic derivatives from DHR, 1 . Several extraction methods were evaluated, and the hydrodistillation, using a Clevenger apparatus, afforded the highest yield (77.8 mg/g of 1 in the essential oil). Three new acyl derivatives ( 2 - 4 ) were successfully prepared from 1 (yields of 86-95%). Compounds 1 - 4 showed antioxidant activity, antibacterial effects, potent cytotoxic activity against several cell lines, and enhanced anti-inflammatory activity that surpassed dexamethasone (positive control). These findings encourage further exploration of derivatives 2 - 4 for potential mechanisms of antitumoral, antioxidant, and anti-inflammatory capabilities, studying both safety and efficacy.