Quinic and caffeic acids derivatives: Affecting antioxidant capacities and phenolics contents of certain therapeutic and specialty crops employing water and ethanolic extracts

Recently, there has been a growing interest in medicinal and specialty crops due to their high content of health-promoting compounds, such as quinic acid and caffeic acid derivatives. In light of this, the objective of this study was to analyze the levels of caffeic and quinic acid, specifically caffeoylquinic acid derivatives, in water and water-ethanolic extracts obtained from medicinal plants, including chocolate mint (Mentha piperita L), lemon balm (Melissa officinalis), sweet basil (Ocimum basilicum), and sweet potato tops (Ipomoea batatas L. Lam) using high-performance liquid chromatography. The results showed that the water extracts contained significantly higher amounts of caffeoylquinic acid derivatives than the ethanolic extracts. Among the plants tested, sweetpotato leaves exhibited the highest total phenolic acids content (28.60 mg CQA·g−1), followed by lemon balm (14.71 mg CQA·g−1) and chocolate mint (5.49 mg CQA·g−1) in water-ethanolic extracts. The water-ethanolic extracts from sweet potato leaves were particularly rich in caffeoylquinic acids, especially 5-CQA (10.84±0.31 mg CQA·g−1) and 3-CQA (6.69±0.14 mg CQA·g−1), followed by lemon balm (3.81±0.14 and 1.37±0.05 mg CQA·g−1). On the other hand, sweet basil had the lowest content of all compounds (0.41 and 2.29 mg CQA·g−1). Additionally, an identifiable compound, 3, 4, 5 tri-caffeoylquinic acids (2.98±0.09 mg CQA·g−1), was detected only in sweetpotato leaves and not in the other herbs studied. The findings of this study highlight the significant phytochemical properties present in these medicinal plants, which could have potential therapeutic applications for various conditions.