Structural and Anticancer Studies of Methoxyflavone Derivative from Strychnos pseudoquina A.St.-Hil. (Loganiaceae) from Brazilian Cerrado

The Cerrado biome is the world's largest and most diversified tropical savanna. Despite its diversity, there remains a paucity of scientific discussion and evidence about the medicinal use of Cerrado plants. One of the greatest challenges is the complexity of secondary metabolites, such as flavonoids, present in those plants and their extraction, purification, and characterization, which involves a wide range of approaches, tools, and techniques. Notwithstanding these difficulties, the search for accurately proven medicinal plants against cancer, a leading cause of death worldwide, has contributed to this growing area of research. This study set out to extract, purify, and characterize 3-O-methylquercetin isolated from the plant Strychnos pseudoquina A.St.-Hil. (Loganiaceae) and to test it for antiproliferative activity and selectivity against different tumor and nontumor human cell lines. A combined-method approach was employed using 1H and 13C nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, Hirshfeld surface analysis, and theoretical calculations to extensively characterize this bioflavonoid. 3-O-methylquercetin melts around 275 °C and crystallizes in a nonplanar conformation with an angle of 18.02° between the pyran ring (C) and the phenyl ring (B), unlike quercetin and luteolin, which are planar. Finally, the in vitro cytotoxicity of 3-O-methylquercetin was compared with data from quercetin, luteolin, and cisplatin, showing that structural differences influenced the antiproliferative activity and the selectivity against different tumor cell lines.

Diagnostic challenges in aspiration cytology of the salivary glands

The main goal of fine-needle aspiration (FNA) of salivary gland lesions is to assist the clinician in the management of patients who present with a mass lesion. Cytologic examination aims to determine, if a process is inflammatory and/or reactive, benign or malignant neoplasm and if possible renders a specific diagnosis. It has been argued that in the area of salivary gland tumors, surgical management relies less heavily on a specific preoperative diagnosis, because almost all neoplastic salivary gland lesions will undergo surgical excision. However, knowing beforehand if a lesion is malignant or benign, will aid in planning surgery and may prompt or postpone decisions for surgical intervention. The salivary glands are unique in their histologic complexity and morphological variability of tumors, which is reflected in the cytologic material. In addition to the overlapping morphologic patterns of salivary gland tumors, they also represent relatively rare lesions, thus making it more difficult to acquire diagnostic expertise in FNA. Other than approaching salivary gland tumors by a description of single entities in their benign and malignant categories, we favor a more practical approach to diagnosis based on the key morphologic features noted in FNAs. This article addresses differential diagnoses according to the predominant cytologic presentation with attention to the cell type and size, nature of the cytoplasm, and the smear background.