Microwave and ultrasound extraction of antioxidant phenolic compounds from Lantana camara Linn. leaves: Optimization, comparative study, and FT-Orbitrap MS analysis.

INTRODUCTION: The species Lantana camara is used in folk medicine. The biological activities of this medicinal plant are attributable to the presence of various derivatives of triterpenoids and phenolic compounds present in its preparations, indicating excellent economic potential. OBJECTIVE: In this study, the operational conditions of ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) were optimized using Box-Behnken design to improve the total phenolic content (TPC) recovered in hydroethanolic extracts of L. camara leaves. MATERIAL AND METHODS: The TPC, total flavonoid content (TFC), and antioxidant activities of the hydroalcoholic extracts of L. camara, prepared by UAE and MAE under the optimized extraction conditions, were compared with those of the extracts obtained by conventional extraction methods. RESULTS: Under the optimal conditions, the extracts obtained by UAE (35% ethanol, 25 min, and a solvent-to-solid ratio of 60:1 mL/g) and by MAE (53% ethanol, 15 min, and 300 W) provided high yields of 32.50% and 38.61% and TPC values of 102.89 and 109.83 mg GAE/g DW, respectively. The MAE extract showed the best results with respect to TPC, TFC, and antioxidant activities, followed by extracts obtained by UAE, Soxhlet extraction, decoction, maceration, and infusion, in that order. CONCLUSION: The results obtained indicate that L. camara may be used as an important source of antioxidant phenolic compounds to obtain products with high biological and economic potential, especially when the extraction process is performed under appropriate conditions using MAE and/or UAE, employing environmentally friendly solvents such as water and ethanol.

Chemical composition, minerals concentration, total phenolic compounds, flavonoids content and antioxidant capacity in organic and conventional vegetables.

The demand for organic vegetables is increasing worldwide, which has led to the growth of organic agriculture. However, information on chemical composition and antioxidant activity in vegetables grown organically under controlled conditions remains uncertain. For this study, 3 vegetables widely consumed in Brazil were cultivated in controlled organic and conventional cultivation systems: lettuce, coriander and tomato. Their chemical composition, mineral concentration, phenolic compound content, flavonoids and antioxidant activity (AA) were evaluated. The analyses of chemical and mineral composition revealed differences between the cultivation systems. Organic lettuce presented higher content of ashes, calcium and potassium. A higher content of phenolic compounds and flavonoids was observed in most organic vegetables. Using the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) assay, the organic tomato exhibited higher AA compared to conventional, while the ferric-reducing antioxidant power (FRAP) method showed higher AA for organic coriander and tomato than theirs conventional version. The correlation between bioactive compounds and AA was positive, higher and stronger for organic vegetables, considering phenolic compounds (including flavonoids) and DPPH or FRAP antioxidant activity. Principal Component Analysis (PCA) disclosed that organic lettuce and coriander were grouped according bioactive components. In general, organic vegetables showed better results for bioactive compounds and antioxidant activity.