Serine protease inhibitors and activators from Dalbergia tonkinensis species

Siamese, Indian, and Brazilian Rosewoods: A Review on Phytochemistry, Applications, and Pharmacology

For the first time, the current review fully provides information on the phytochemicals, applications, and pharmacological aspects relating to 3 Dalbergia species, Siamese Rosewood ( Dalbergia cochinchinensis Pierre ex Laness.), Indian Rosewood ( D sissoo Roxb.), and Brazilian Rosewood ( D nigra (Vell.) Benth.). Based on chromatographic separation, phytochemical studies on these plants have, to date, resulted in the isolation and structural elucidation of 136 secondary metabolites. Among them, flavonoids and simple phenols are major components, whereas terpenoids, quinones, benzofurans, benzophenols, phytosterols, stilbenes, phthalates, xanthones, and lignans have been also detected. Dalbergia rosewoods are heavy and strong, taking an outstanding polish, and are very suitable for furniture. They are also used as natural dyes, raw materials for removing contaminants from water, and might be a rich resource of essential oils, polysaccharides, and active glycosidase enzymes. Dalbergia crude extracts and their secondary metabolites have a wide range of pharmacological actions, such as anti-inflammatory, anti-oxidative, anti-aging, anti-bacterial, anti-nociceptive, anti-diarrheal, anti-pyretic, gastrointestinal, biocontrol activities, but sexual and anti-osteoporosis activities are the most valuable.

Recent Advances in Bioactive Flavonoid Hybrids Linked by 1,2,3-Triazole Ring Obtained by Click Chemistry

As a result of the biological activities of natural flavonoids, several synthetic strategies aiming to obtain analogues with improved potency and/or pharmacokinetic profile have been developed. Since the triazole ring has been associated with several biological activities and metabolic stability, hybridization with a 1,2,3-triazole ring has been increasingly reported over the last years. The feasible synthesis through copper (I) catalyzed azide-alkyne cycloaddition (CuAAC) has allowed the accomplishment of several hybrids. Since 2017, almost 700 flavonoid hybrids conjugated with 1,2,3-triazole, including chalcones, flavones, flavanones and flavonols, among others, with antitumor, antimicrobial, antidiabetic, neuroprotective, anti-inflammatory, antioxidant, and antifouling activity have been reported. This review compiles the biological activities recently described for these hybrids, highlighting the mechanism of action and structure-activity relationship (SAR) studies.

Flavonoids as inhibitors of human neutrophil elastase

Elastase is a proteolytic enzyme belonging to the family of hydrolases produced by human neutrophils, monocytes, macrophages, and endothelial cells. Human neutrophil elastase is known to play multiple roles in the human body, but an increase in its activity may cause a variety of diseases. Elastase inhibitors may prevent the development of psoriasis, chronic kidney disease, respiratory disorders (including COVID-19), immune disorders, and even cancers. Among polyphenolic compounds, some flavonoids and their derivatives, which are mostly found in herbal plants, have been revealed to influence elastase release and its action on human cells. This review focuses on elastase inhibitors that have been discovered from natural sources and are biochemically characterised as flavonoids. The inhibitory activity on elastase is a characteristic of flavonoid aglycones and their glycoside and methylated, acetylated and hydroxylated derivatives. The presented analysis of structure-activity relationship (SAR) enables the determination of the chemical groups responsible for evoking an inhibitory effect on elastase. Further study especially of the in vivo efficacy and safety of the described natural compounds is of interest in order to gain better understanding of their health-promoting potential.