Secondary Metabolites from Two Species of Tolpis and Their Biological Activities

Abstract

Phytochemical research of two Tolpis species, T. proustii and T. lagopoda, led to the isolation of three new compounds: 30-chloro-3β-acetoxy-22α-hydroxyl-20(21)-taraxastene (1), 3β,22α-diacetoxy-30-ethoxy-20(21)-taraxastene (2) and 3β,28-dihydroxy-11α-hydroperoxy-12-ursene (3). The structures of the new compounds were elucidated by means of extensive IR, NMR, and MS data and by comparison of data reported in the literature. The in vitro antioxidant activities of the extracts were assessed by the DPPH and ABTS scavenging methods. The cytotoxicity of several known compounds and its derivatives was also assessed against human myeloid leukemia K-562 and K-562/ADR cell lines.

Natural and Semisynthetic Pentacyclic Triterpenes for Chronic Myeloid Leukemia Therapy: Reality, Challenges and Perspectives

“…reported a relevant decrease of cytotoxic activity of the acetylated (72‐hour IC 50 of 99.5 μM for K562 and >100 μM for K562/ADR) or esterified (72‐hour IC 50 of 59.3 μM for K562 and 64 μM for K562/ADR) compounds when compared to parental ursolic acid (72‐hour IC 50 of 40.6 μM for K562 and 49.2 μM for K562/ADR), what indicates the importance of the free oxygenated functions in C‐3 and C‐28, which will later be discussed for lupane triterpenes as well. This evidence is even stronger when we look at the IC 50 values of the compound acetyl ursolic acid methyl ester, modified in both sites: >100 μM for both cell lines [32] …”

“…Interestingly, a different study demonstrated a 72‐hour IC 50 of 33 μM in K562 cells for treatment with both compounds, in addition to the important activity of these pentacyclic triterpenes against the multidrug resistant (MDR) K562 derivative line K562/ADR, which is doxorubicin‐resistant, that overexpresses the P‐gp efflux pump [18] . Moreover, a study has shown the cytotoxicity comparison between ursolic acid and its biosynthetic derivatives acetyl ursolic acid, ursolic acid methyl ester and acetyl ursolic acid methyl ester against K562 and K562/ADR [32] . Triana et al [32] .…”

“…Moreover, a study has shown the cytotoxicity comparison between ursolic acid and its biosynthetic derivatives acetyl ursolic acid, ursolic acid methyl ester and acetyl ursolic acid methyl ester against K562 and K562/ADR [32] . Triana et al [32] . reported a relevant decrease of cytotoxic activity of the acetylated (72‐hour IC 50 of 99.5 μM for K562 and >100 μM for K562/ADR) or esterified (72‐hour IC 50 of 59.3 μM for K562 and 64 μM for K562/ADR) compounds when compared to parental ursolic acid (72‐hour IC 50 of 40.6 μM for K562 and 49.2 μM for K562/ADR), what indicates the importance of the free oxygenated functions in C‐3 and C‐28, which will later be discussed for lupane triterpenes as well.…”

Peroxy natural products

“…273 The rhizome of Vladimiria muliensis provided one antimicrobial ursane triterpenoid 1α,5α-dioxy-11α-hydroxyurs-12-en-3-one 462. 274 Other ursene triterpenoids were including 3β,28-dihydroxy-11α-hydroperoxy-12-ursene 463 from Tolpis proustii, 275 speciosaperoxide 464 from Chaenomeles speciosa, 276 and (2β,3β)-3,25-epidioxy-2,24-dihydroxyursa-12,20(30)-dien-28-oic acid 465 and (2β,3β)-3,25-epidioxy-2,24-dihydroxyurs-12-en-28-oic acid 466 from Gentiana aristata. 277 Ginsenoside SG 2 467 has been reported from black ginseng.…”

Chlorinated Plant Steroids and their Biological Activities

“…The in vitro antioxidant activities of the extracts were assessed by the DPPH and ABTS scavenging methods. The cytotoxicity of isolated compounds showed activity against the human myeloid leukaemia K-562 and K-562/ADR cell lines (Triana et al, 2012).…”