Lycium schweinfurthii: new secondary metabolites and their cytotoxic activities.

Two new compounds, 11S-methoxy-11,12-dihydro phytuberin (2) and 9S-methoxy-benzocyclononan-7-one (6), together with twenty-six known ones were isolated from Lycium schweinfurthii (Solanaceae). Their planar structure was established by extensive spectroscopic analyses. The absolute configuration of compound 6 was determined by time dependent density functional theory calculations (TDDFT). The cytotoxic potential of the isolates was assessed in cultured skin cancer (G-361) and colon cancer (HCT-116 and CaCo-2) cell lines. Certain flavonoids showed the highest cytotoxic activity, with IC50 values ranging from 7.1 to 63.3 µM; meanwhile 5-flurouracil showed IC50 values ranging from 62.4 to >100 µM. All compounds showed minimal toxicity towards normal cells from skin (NHDF-4) and colon (CCD-841), indicating their potential selectivity and safety as cytotoxic candidates.

Naturally Occurring Chromone Glycosides: Sources, Bioactivities, and Spectroscopic Features.

Chromone glycosides comprise an important group of secondary metabolites. They are widely distributed in plants and, to a lesser extent, in fungi and bacteria. Significant biological activities, including antiviral, anti-inflammatory, antitumor, antimicrobial, etc., have been discovered for chromone glycosides, suggesting their potential as drug leads. This review compiles 192 naturally occurring chromone glycosides along with their sources, classification, biological activities, and spectroscopic features. Detailed biosynthetic pathways and chemotaxonomic studies are also described. Extensive spectroscopic features for this class of compounds have been thoroughly discussed, and detailed 13C-NMR data of compounds 1-192, have been added, except for those that have no reported 13C-NMR data.

Melanogenesis Inhibitors from the Endophytic Fungus Aspergillus amstelodami.

Two new compounds, named 3,4-dimethoxyphenyl α-d-ribofuranoside (1) and 3ß-(ß-d-glucopyranosyloxy)olean-12-ene-23,28,30-trioic acid (2), together with thirteen known compounds, were isolated from the white beans culture of the marine derived endophytic fungus Aspergillus amstelodami. Structure elucidation of the new compounds was carried out by one-, two-dimensional spectroscopy, and high resolution electrospray ionization mass. The antimelanogenic and anti-allergic activity of the isolated compounds were investigated. Compounds 4, 7, 1, 3, 11, 6 and 9 selectively suppressed melanin production in B16 melanoma cells, using arbutin as a positive control. Their IC50 values were 30.8±5.57, 38.5±6.08, 52.6±6.64, 98.0±1.16, 100.4±3.05, 112.0±0.22 and 144.7±2.35 µm, respectively, while that of arbutin was 151.7±1.27 µm. The tested compounds did not show any significant anti-allergic activity in RBL-2H3 cells, as compared to quercetin.

Bio-guided fractionation and iron chelating activity of agricultural residues.

Iron overload is implicated in many disorders in the body such as heart failure, liver cirrhosis and fibrosis, gallbladder disorders, diabetes, arthritis, depression, infertility, and cancer. Even though synthetic chelating agents are available, they have several limitations such as poor oral bioavailability, short plasma half-life, high cost and numerous side effects. Therefore, the aim of this study is using agricultural residues as sources for alternative efficient, benign, and economic iron chelators of natural origin. Eighteen agricultural residues were screened for iron chelating activity using 2, 2'-bipyridyl assay. The results showed that the extract of Mangifera indica leaves had the highest iron chelation activity (69.7%), in comparison to ethylenediaminetetraacetic acid (EDTA) (70.3%) (standard iron chelator). The M. indica leaves extract was further investigated for its flavonoidcontent, phenolic content and antioxidant activity. The high concentration of phenolic (405.5µg/g expressed as gallic acid equivalent) and flavonoid (336.9 µg/g expressed as quercetin equivalent) phytochemicals in the extract, as well as its significant antioxidant capacity (96.95%) compared to ascorbic acid (91.90%) (standard antioxidant agent), suggested that the M. indica leaves could represent a good source for new iron chelating agents in iron overload disorders.

Cytotoxic constituents of Alocasia macrorrhiza.

An indole alkaloid, 2-(5-hydroxy-1H-indol-3-yl)-2-oxo-acetic acid (1) isolated for the first time from nature, in addition to the nine known compounds 5-hydroxy-1H-indole-3-carboxylic acid methyl ester (2), alocasin B (3), hyrtiosin B (4), α-monopalmitin (5), 1-O-ß-D-glucopyranosyl-(2S, 3R, 4E, 8Z)-2-[(2(R)-hydroctadecanoyl) amido]-4,8-octadecadiene-1,3-diol (6), 3-epi-betulinic acid (7), 3-epi-ursolic acid (8), ß-sitosterol (9) and ß-sitosterol 3-O-ß-D-glucoside (10) were isolated from the rhizomes of Alocasia macrorrhiza (Araceae). Their structures were elucidated by 1D and 2D NMR spectroscopic data. Of these compounds, 6 exhibited the strongest cytotoxicity against the four tested human cancer cell lines (IC50 of about 10 µM against Hep-2 larynx cancer cells).