Records of Natural Products

A new germacrane-type sesquiterpenoid compound (1) and four known compounds (2-5) were isolated from Siegesbeckia orientalis. Chemical structures of these compounds were elucidated using 1D and 2D NMR spectroscopic data, HR-ESIMS, electronic circular dichroism (ECD) and compared with the literature. Their anti-proliferative effects were evaluated on human triple-negative breast cancer (TNBC) cell line MDA-MB-231. The results demonstrated that compound 2 significantly inhibits the proliferation of MDA-MB-231 cells by inducing apoptosis.

A new dihydrophenanthrene (Spiranthol B), along with four known compounds, were isolated from Spiranthes sinensis. The new structure was determined by various spectroscopic analyses such as 1D, 2D NMR and HRMS techniques. Its stereochemistry was resolved by using the calculated electronic circular dichroism (ECD). Compounds 1-5 showed their capabilities to attenuate palmitic acid (PA)-induced reductions in MIN6 cells viability with the dosages of 3.125 and 6.25 μM.

The consumption of raspberry (Rubus idaeus L.) leaves has a long tradition, especially as a "general pregnancy tea", although the scientific data are insufficient and contradictory. Phytochemical comparation of extracts from cultivated and wild raspberry leaves, in silico prediction of their biological activities and acute toxicity followed by in vitro antiradical activity and effects on the viability/proliferation of HeLa cells and isolated rat uterus were performed. Leaves from cultured (v. Polka) and wild individuals were extracted with distilled water, 70% v/v ethanol or 70% v/v methanol. All samples exhibited high polyphenol content and antiradical activity, with the 70% v/v ethanol extract of wild R. idaeus showing the strongest free radical scavenging ability. In silico analyzes predicted that a large number of raspberry leaves possess anti-inflammatory, apoptosis-agonistic, antinociceptive and NO signaling-related activities. Potentially toxic levels of the tested compounds could not be achieved with regular tea drinking. The tested extracts have no noticeable effects on the viability/proliferation of HeLa cells. The effects on spontaneous contraction of the isolated rat uterus were modest. Although safety is not a concern, further studies are needed to justify or deny the efficacy of raspberry leaf tea in folk medicine for healthy pregnancy and easy delivery.

The dichloromethane (DCM) and ethyl acetate (EtOAc) extracts of C. caeruleus yielded nine known compounds, including an A-nor-lupane triterpenoid identified as gouanic acid B (1). Additionally, its acetyl derivative, acetylgouanic acid B (2), is reported here for the first time as a natural product. Furthermore, we tested the bioactivity of natural products 1 and 2 and their dimethyl ester derivatives 3 and 4 against cancer cell lines MCF-7, A549, HeLa, and K562. Among these, compounds 1 (IC50 = 36.4 ± 4.0 μM), 2 (IC50 = 21.6 ± 4.3 μM), and 4 (IC50 = 33.0 ± 2.0 μM) demonstrated moderate to good activity against the K562 cell line while maintaining a satisfactory survival rate in non-cancerous bMEC cells. Notably, the natural triterpenes 1 and 2 and derivative 4 showed remarkable outcomes in cytotoxicity tests due to their specificity against K562 leukemia cells.