D. H. S. Silva

Flavonoids from Iryanthera sagotiana

Leaves and inflorescences of Iryanthera sagotiana were found to contain three known dihydrochalcones, two flavonol rhamnosides, four flavanonol rhamnosides, one dihydrocoumaric acid, besides the new 3′,3‴-bis-2′,4′,6′-trihydroxy-4-methoxydihydrochalcone and 4′,6′-dihydroxy-4-methoxydihydrochalcone-2′-O-β-d-glucopyranoside.

Morphological and biochemical alterations activated by antitumor clerodane diterpenes

Casearia sylvestris Swartz (Salicaceae) is a plant commonly widespread in the Americas. It has oxygenated tricyclic bioactive clerodane diterpenes with antimicrobial, antiulcer, larvicidal, chemopreventive, anti-inflammatory, antioxidant and antiproliferative properties. Due to this requirement for the developing of new anticancer drugs, it was initially evaluated the cytotoxic activity of a fraction with Casearins (FC) and its clerodane diterpenes Casearin B (Cas B), D (Cas D), X (Cas X) and Caseargrewiin F (Cas F) isolated from C.sylvestris leaves against 7 tumor cell lines, Sarcoma 180 cells (S180) and on normal peripheral blood mononuclear cells (PBMC). All substances tested showed cytotoxic potential. Cas F and X were the most active compounds. Cell death analyzes with Cas F (0.5 and 1μM) and Cas X (0.7 and 1.5μM) using the HL-60 leukemia line as experimental model showed DNA synthesis and membrane integrity reduction, DNA fragmentation and mitochondrial depolarization, specially after 24h exposure, cell cycle arrest in G0/G1 phase caused by Cas X, activation of the initiator -8/-9 and effector -3/-7 caspases and phosphatidylserine externalization, all biochemical features of apoptosis corroborated by chromatinic condensation, karyorrhexis, cytoplasmic vacuolation and rarefaction and cellular shrinkage, morphological findings specially observed after 12 and 24h of incubation. Therefore, Cas X and F were the most functional molecules with more pronounced lethal and discriminating effects on tumor cells and antiproliferative action predominantly mediated by apoptosis, highlighting clerodane dipertenes as promising lead antineoplastic compounds.

Flavonolignoids from fruits of Iryanthera grandis

Abstract Fruits of Iryanthera grandis were found to contain two new pairs of diastereoisomeric flavonolignoids of the 1,4-diaryl-2,3-dimethyl-n-butyldihydrochalcone type.

Butanolides as a common feature of iryanthera lancifolia and virola surinamensis

Abstract A comparative phytochemical study between pericarps of Iryanthera lancifolia and Virola surinamensis showed that the first one contains a new pair of epimeric 2-alkenyl- γ -lactones, besides an aryltetralinic lignan and one tocotrienol, while the second species contains the lignans, galgravin and veraguensin, seven juruenolides : juruenolides C, D, F, G and epi -juruenolides D, F, G, together with three pairs of epimeric aliphatic 2-alkenyl- γ -lactones. Juruenolide F, epi -juruenolides D, F, G and the 2-alkenyl- γ -lactones are new natural compounds.