In the search for new bioactive natural products, plant sources represent a particularly suitable starting point in drug discovery. Among natural products, phenolic derivatives have a prominent place with several compounds exhibiting remarkable activities. This paper described the phenolic composition of Moquiniastrum floribundum (Asteraceae) and evaluated the inhibitory effect of isolated compounds on HIV-1 reverse transcriptase. From M. floribundum was isolated three flavones, genkwanin (1), hispidulin (2), and cirsimaritin (3), and eight chlorogenic acid derivatives, 4,5-di-O-caffeoylquinic acid (4), 3,5-di-O-caffeoylquinic acid (5), 3,4-di-O-caffeoylquinic acid (6), 3,5-di-O-caffeoylquinic acid methyl ester (7), 3,4,5-tri-O-caffeoylquinic acid methyl ester (8), 3-O-caffeoylquinic acid (9), 4-O-caffeoylquinic acid (10) and 5-O-caffeoylquinic acid (11). The most active compound was 4,5-di-O-caffeoylquinic acid (4), with 65.0 +/- 7.9% of inhibitory activity on HIV-1 reverse transcriptase and IC50 0.240 mmol L-1. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.