Screening of Lichen Extracts Using Tyrosinase Inhibition and Toxicity Against Artemia salina

Nine lichen extracts were evaluated for tyrosinase inhibition and toxicity against Artemia salina larvae. Extract compositions were investigated by TLC and NMR analysis. The activity of constituents against tyrosinase was evaluated by bioautography, and the percent of inhibition was calculated based on the dopachrome produced during a set time interval. Cladia aggregata, Cladonia dimorphoclada, Stereocaulon ramulosum and Stereocaulon microcarpum extracts were active for tyrosinase inhibition. Barbatic, usnic, anziaic acids and an unidentified compound present in the extracts, are possibly responsible for tyrosinase inhibition. Cladia aggregata, Cladonia crispatula, Cladonia furcata, Lobaria erosa, Punctelia canaliculata and S. microcarpum proved to be less toxic to A. salina (LC50 > 500 mg/mL) than Cladonia confusa and S. ramulosum (LC50 45.0 and 100.3 mg/mL, respectively), while the extract of C. dimorphoclada was highly toxic (LC50 < 10 mg/mL). DOI: http://dx.doi.org/10.17807/orbital.v8i3.842 &nbsp

Effects of Fumarprotocetraric Acid, a Depsidone from the Lichen Cladonia verticillaris, on Tyrosinase Activity

Lichens are widely distributed around the world. Their phenolic compounds, consisting mainly of depsides and depsidones, have been extensively studied for important biological activities. More recently, these compounds have been evaluated for their inhibitory activity against enzymes such as tyrosinase, a key agent in melanin biosynthesis. In the present investigation, the depsidone fumarprotocetraric acid isolated from the lichen Cladonia verticillaris (Raddi) Fr. was evaluated for its inhibitory activity against this critical enzyme. Kinetic study showed that depsidone at 0.6 mM inhibited tyrosinase activity by 39.8%. Lineweaver–Burk plots revealed that fumarprotocetraric acid can act as an uncompetitive or mixed-type inhibitor, depending on concentration. DOI: http://dx.doi.org/10.17807/orbital.v9i4.99

Screening of Lichen Extracts Using Tyrosinase Inhibition and Toxicity Against Artemia salina

Nine lichen extracts were evaluated for tyrosinase inhibition and toxicity against Artemia salina larvae. Extract compositions were investigated by TLC and NMR analysis. The activity of constituents against tyrosinase was evaluated by bioautography, and the percent of inhibition was calculated based on the dopachrome produced during a set time interval. Cladia aggregata, Cladonia dimorphoclada, Stereocaulon ramulosum and Stereocaulon microcarpum extracts were active for tyrosinase inhibition. Barbatic, usnic, anziaic acids and an unidentified compound present in the extracts, are possibly responsible for tyrosinase inhibition. Cladia aggregata, Cladonia crispatula, Cladonia furcata, Lobaria erosa, Punctelia canaliculata and S. microcarpum proved to be less toxic to A. salina (LC50 > 500 mg/mL) than Cladonia confusa and S. ramulosum (LC50 45.0 and 100.3 mg/mL, respectively), while the extract of C. dimorphoclada was highly toxic (LC50 < 10 mg/mL). DOI: http://dx.doi.org/10.17807/orbital.v8i3.842

Phenolic derivatives and other chemical compounds from Cochlospermum regium

This study describes the chemical investigation of the ethyl acetate fraction obtained from the hydroethanolic extract of the xylopodium of Cochlospermum regium (Mart. & Schr.) Pilger, which has been associated with antimicrobial activity. Phytochemical investigation produced seven phenol derivatives: ellagic acid, gallic acid, dihydrokaempferol, dihydrokaempferol-3-O-β-glucopyranoside, dihydrokaempferol-3-O-β-(6"-galloyl)-glucopyranoside, pinoresinol, and excelsin. It also contained two triacylbenzenes, known as cochlospermines A and B. The hydroethanolic extract and its fractions exhibited antimicrobial activity (0.1 mg/mL) against Staphylococcus aureus and Pseudomonas aeruginosa. Gallic acid showed activity against S. aureus. Dihydrokaempferol-3-O-β-(6"-galloyl)-glucopyranoside is reported here for the first time in the literature

Cytotoxic Activity of Compounds from Lichens of the Cerrado Biome in Brazil

Lichens are sources of numerous biologically active compounds and many of these have demonstrated antitumor potential. The purposes of this study were to evaluate the antiproliferative activity and selectivity of the following compounds isolated from lichens: atranorin and diffractaic, divaricatic, perlatolic, psoromic, norstictic, and protocetraric acids. Cytotoxicity tests based on sulforhodamine B were performed on normal cells (NIH/3T3, fibroblast) and cancer cell lines 786-0 (renal), MCF7 (breast), HT-29 (colon), PC-3 (prostate), and HEp2 (laryngeal). Diffractaic acid exhibited GI50 values in the 58.6-98.9 µM range. Divaricatic and perlatolic acids were the most active compounds, with GI50 values of 9.8 and 15.5 µM for PC-3 and MCF7 cells, respectively. Protocetraric acid proved active only against HEp2 cells (GI50 = 41.4 µM).  Atranorin, psoromic acid, and norstictic acids were inactive against all the cells tested.  Chemometrics was used to evaluate the effect of the compounds against the cell lines tested. PCA (Principal Component Analysis) based on GI50 values ​​separated compounds into two groups compared to doxorubucin, while HCA (Hierarchical Cluster Analysis) separated them into three groups based on SI values. DOI: http://dx.doi.org/10.17807/orbital.v12i1.1397 </p

Effects of Fumarprotocetraric Acid, a Depsidone from the Lichen Cladonia verticillaris, on Tyrosinase Activity

Lichens are widely distributed around the world. Their phenolic compounds, consisting mainly of depsides and depsidones, have been extensively studied for important biological activities. More recently, these compounds have been evaluated for their inhibitory activity against enzymes such as tyrosinase, a key agent in melanin biosynthesis. In the present investigation, the depsidone fumarprotocetraric acid isolated from the lichen Cladonia verticillaris (Raddi) Fr. was evaluated for its inhibitory activity against this critical enzyme. Kinetic study showed that depsidone at 0.6 mM inhibited tyrosinase activity by 39.8%. Lineweaver–Burk plots revealed that fumarprotocetraric acid can act as an uncompetitive or mixed-type inhibitor, depending on concentration. DOI: http://dx.doi.org/10.17807/orbital.v9i4.999 </p