Chlorogenic acids (CQAs), the esters of caffeic and quinic acid, are biologically important phenolic compounds present in many plant species. Nowadays the knowledge about their pro-health properties including anti-cancer activity is great. Yet the supposition that they may be helpful in fighting obesity and modify glucose-6-phosphatase involved in glucose metabolism has led to some revival of research on CQAs properties and their natural occurrence. Considering the growing interest in natural products rich in CQAs, it is not surprising that more efficient extraction methods, leading to obtained extracts with increased CQAs content, are currently being sought. It is worth mentioning here that this task is not very easy since these compounds readily degrade/transform to others. Much attention is also paid to the proper analysis of CQAs content in plants and plant products due to the fact that the main CQAs representative in nature i.e. 5-O-caffeoylquinic acid (5-CQA) is commonly employed as a marker in the quality control of various natural products. Yet due to their structural similarity and instability, and the fact that the number of commercially available standards of CQAs is limited to just a few, the correct analysis of these compounds in plants is another challenge that should be faced. The aim of this review is to summarize the recent advances in the chemical analysis of chlorogenic acids, including their natural sources, properties, and methods that have been developed to improve CQAs extraction and analysis, with special attention paid to 5-CQA as the compound of the CQAs family with many beneficial effects on human health.

Nature is a valuable source of anti-oxidants that have a health-promoting effect by inhibiting various undesirable changes leading to cell degradation and, consequently, potential disease ailments. One of them is gallic acid which has been used as a healing agent since ancient times. Currently, due to various beneficial properties, this compound is considered to be one of the main phenolic acids of great importance in numerous industries. It is commonly used as a substance protecting against the harmful effects of UV radiation, an astringent in cosmetic preparations, and a preservative in food products. Therefore, gallic acid is now deemed essential for both human health and industry. Increasingly better methods of its isolation and analysis are being developed, and new solutions are being sought to increase its production. This review, presenting a concise characterization of gallic acid, updates the knowledge about its various biological activities and methods used for its isolation and determination, including chromatographic and non-chromatographic methods.