Abstract A new lectin from marine sponge Ircinia strobilina, denominated IsL, was isolated by combination of affinity chromatography in Guar gum matrix followed by size exclusion chromatography. IsL was able to agglutinate native and enzymatically treated rabbit erythrocytes, being inhibited by galactosides, such as α-methyl-D-galactopyranoside, β-methyl-D-galactopyranoside and α-lactose. IsL hemagglutinating activity was stable at neutral to alkaline pH, however the lectin loses its activity at 40° C. The molecular mass determinated by mass spectrometry was 13.655 ± 5 Da. Approximately 40% of the primary structure of IsL was determined by mass spectrometry, but no similarity was observed with any protein. The secondary structure of IsL consists of 28% α-helix, 26% β-sheet, and 46% random region, as determined by dichroism circular. IsL was a calcium-dependent lectin, but no significant variations were observed by circular dichroism when IsL was incubated in presence of calcium and EDTA. IsL was not toxic against Artemia nauplii and did not have antimicrobial activity against bacterial cells. However, the IsL was able to significantly inhibit the biofilm formation of Staphylococcus aureus and Staphylococcus epidermidis.

Five new withanolides, designated as 15-oxo-nicaphysalin B, 6β,7α-dihydroxynicandrenone 10, 24α,25β-dihydroxy-nicandrenone-2 and a mixture of the epimers 17-(1α/1β-methylpropanone)-nicandrenone, in addition to six known others, were isolated from the leaf acetone extract from Nicandra physalodes. The complete structures of the five new withanolides, particularly their relative stereochemistries, were established by extensive spectroscopic analyses, including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HRESIMS). The main isolated withanolides were evaluated for their antibacterial, antifungal and larvicidal properties, but, except nicandrenone, which showed marginal larvicidal activity, none of them was active.

Five new diterpenes derivatives named as ornatin A, B, C, D and E, in addition to six known related diterpenes were isolated from the aerial parts of cultivated specimens of Plectranthus ornatus. The structures were elucidated using a combination of 1D/2D nuclear magnetic resonance (NMR) spectroscopy, high-resolution electrospray ionization mass spectrometry (HRESIMS) and comparison with published NMR data of analogous compounds. All isolated compounds were assayed against four human cancer cell lines, and Gram-positive and Gram-negative bacteria strains. None of them showed any cytotoxic activity, but ornatin C, D, E and three related diterpenes displayed marginal bactericidal or bacteriostatic effects against the Gram-positive strains.