NMR-Based Metabolomic Study on Isatis tinctoria: Comparison of Different Accessions, Harvesting Dates, and the Effect of Repeated Harvesting.

Isatis tinctoria is an ancient dye and medicinal plant with potent anti-inflammatory and antiallergic properties. Metabolic differences were investigated by NMR spectroscopy of accessions from different origins that were grown under identical conditions on experimental plots. For these accessions, metabolite profiles at different harvesting dates were analyzed, and single and repeatedly harvested plants were compared. Leaf samples were shock-frozen in liquid N2 immediately after being harvested, freeze-dried, and cryomilled prior to extraction. Extracts were prepared by pressurized liquid extraction with ethyl acetate and 70% aqueous methanol. NMR spectra were analyzed using a combination of different methods of multivariate data analysis such as principal component analysis (PCA), canonical analysis (CA), and k-nearest neighbor concept (k-NN). Accessions and harvesting dates were well separated in the PCA/CA/k-NN analysis in both extracts. Pairwise statistical total correlation spectroscopy (STOCSY) revealed unsaturated fatty acids, porphyrins, carbohydrates, indole derivatives, isoprenoids, phenylpropanoids, and minor aromatic compounds as the cause of these differences. In addition, the metabolite profile was affected by the repeated harvest regime, causing a decrease of 1,5-anhydroglucitol, sucrose, unsaturated fatty acids, porphyrins, isoprenoids, and a flavonoid.

Screening of Panamanian Plants for Cosmetic Properties, and HPLC-Based Identification of Constituents with Antioxidant and UV-B Protecting Activities.

A library of 600 taxonomically diverse Panamanian plant extracts was screened for DPPH scavenging and UV-B protective activities, and the methanolic extracts of Mosquitoxylum jamaicense, Combretum cacoucia, and Casearia commersionia were submitted to HPLC-based activity profiling. The compounds located in the active time windows were isolated and identified as gallic acid derivatives and flavonoids. Gallic acid methyl ester (3) and digallic acid derivatives (2, 6) showed the highest DPPH scavenging activity (<10 µg/mL), while protocatechuic acid (7) and isoquercitrin (10) exhibited the highest UV-B protective properties.

Screening of Panamanian Plant Extracts for Pesticidal Properties and HPLC-Based Identification of Active Compounds.

A library of 600 taxonomically diverse Panamanian plant extracts was screened for fungicidal, insecticidal, and herbicidal activities. A total of 19 active extracts were submitted to HPLC-based activity profiling, and extracts of Bocconia frutescens, Miconia affinis, Myrcia splendens, Combretum aff. laxum, and Erythroxylum macrophyllum were selected for the isolation of compounds. Chelerythrine (2), macarpine (3), dihydrosanguinarine (5), and arjunolic acid (8) showed moderate-to-good fungicidal activity. Myricetin-3-O-(6''-O-galloyl)-ß-galactopyranoside (13) showed moderate insecticidal activity, but no compound with herbicidal activity was identified.