Flavonoids of Tripodanthus acutifolius inhibit TNF-α production in LPS-activated THP-1 and B16-F10 cells

Polymethoxylated flavonoids in citrus fruits: absorption, metabolism, and anticancer mechanisms against breast cancer

Polymethoxylated flavonoids (PMFs) are a subclass of flavonoids found in citrus fruits that have shown multifunctional biological activities and potential anticancer effects against breast cancer. We studied the absorption, metabolism, species source, toxicity, anti-cancer mechanisms, and molecular targets of PMFs to better utilize their anticancer activity against breast cancer. We discuss the absorption and metabolism of PMFs in the body, including the methylation, demethylation, and hydroxylation processes. The anticancer mechanisms of PMFs against breast cancer were also reviewed, including the estrogen activity, cytochrome P-450 enzyme system, and arylhydrocarbon receptor (AhR) inhibition, along with various molecular targets and potential anticancer effects. Although PMFs may be advantageous in the prevention and treatment for breast cancer, there is a lack of clinical evidence and data to support their efficacy. Despite their promise, there is still a long way to go before PMFs can be applied clinically.

Discovery of anti-inflammatory natural flavonoids: Diverse scaffolds and promising leads for drug discovery

Natural products have been utilized for medicinal purposes for millennia, endowing them with a rich source of chemical scaffolds and pharmacological leads for drug discovery. Among the vast array of natural products, flavonoids represent a prominent class, renowned for their diverse biological activities and promising therapeutic advantages. Notably, their anti-inflammatory properties have positioned them as promising lead compounds for developing novel drugs combating various inflammatory diseases. This review presents a comprehensive overview of flavonoids, highlighting their manifold anti-inflammatory activities and elucidating the underlying pathways in mediating inflammation. Furthermore, this review encompasses systematical classification of flavonoids, related anti-inflammatory targets, involved in vitro and in vivo test models, and detailed statistical analysis. We hope this review will provide researchers engaged in active natural products and anti-inflammatory drug discovery with practical information and potential leads.

The Chemistry and the Anti-Inflammatory Activity of Polymethoxyflavonoids from Citrus Genus

Polymethoxyflavonoids (PMFs) are a large group of compounds belonging to the more general class of flavonoids that possess a flavan carbon framework decorated with a variable number of methoxy groups. Hydroxylated polymethoxyflavonoids (HPMFs), instead, are characterized by the presence of both hydroxyl and methoxy groups in their structural unities. Some of these compounds are the aglycone part in a glycoside structure in which the glycosidic linkage can involve the -OH at various positions. These compounds are particular to Citrus genus plants, especially in fruits, and they are present mainly in the peel. A considerable number of PMFs and HPMFs have shown promising biological activities and they are considered to be important nutraceuticals, responsible for some of the known beneficial effects on health associated with a regular consumption of Citrus fruits. Among their several actions on human health, it is notable that the relevant contribution in controlling the intracellular redox imbalance is associated with the inflammation processes. In this work, we aim to describe the status concerning the chemical identification and the anti-inflammatory activity of both PMFs and HPMFs. In particular, all of the chemical entities unambiguously identified by isolation and complete NMR analysis, and for which a biochemical evaluation on the pure compound was performed, are included in this paper.

Inhibition of melanin production and tyrosinase activity by flavonoids isolated from Loranthus acutifolius

Activity-guided fractionations of leaves and stems from Loranthus acutifolius led to the isolation of 2',4',6-trimethoxyflavone (1), 3',4',5-trihydroxy-6,7,8-trimethoxyflavone (2), 2'4'-dihydroxy-6'-methoxy-chalcone (3) and 4',5-dihydroxy-6,7,8-trimethoxyflavone (4). The potential for inhibition against melanin production and tyrosinase activity of these 4 compounds was tested in B16-F10 cells. 2',4',6-trimethoxyflavone, 3',4',5-trihydroxy-6,7,8-trimethoxyflavone, 2'4'-dihydroxy-6'-methoxy-chalcone and 4',5-dihydroxy-6,7,8-trimethoxyflavone showed an inhibitory activity of melanin production with IC₅₀ of 3.6 ± 0.05 μM, 8.1 ± 0.05 μM, 1.6 ± 0.03 μM and 6.5 ± 0.05 μM, respectively. In addition, 2',4',6-trimethoxyflavone, 3',4',5-trihydroxy-6,7,8-trimethoxyflavone, 2'4'-dihydroxy-6'-methoxy-chalcone and 4',5-dihydroxy-6,7,8-trimethoxyflavone were able to inhibit tyrosinase activity with IC₅₀ of 4.0 ± 0.03 μM, 11.3 ± 0.05 μM, 5.7 ± 0.02 μM and 8.6 ± 0.04 μM, respectively. This is the first time that these compounds are reported in the L. acutifolius species showing anti-melanogenic activities.