A number of stilbenoid and chalconoid derivatives were prepared by straightforward methods, and their ability to modulate tyrosinase activity and to scavenge free radicals were evaluated in vitro. The cell-free in vitro evaluation revealed two diarylpropanes, 24 and 25, as potent tyrosinase inhibitors, whereas diarylpropenoic acids seemed to enhance the enzymatic activity. An in silico evaluation of the binding affinity of the selected compounds with the crystal structure of tyrosinase was also conducted in order to obtain better insight into the mechanism. Representative synthetic compounds with inhibitory and activating properties were further evaluated in melanoma cell lines B16F1 and B16F10 for their ability to moderate tyrosinase activity and affect melanin production. Dihydrostilbene analogues I and II, exhibited a stronger anti-melanogenic effect than kojic acid through the inhibition of cellular tyrosinase activity and melanin formation, while diarylpropanoic acid 44 proved to be a potent melanogenic factor, inducing cellular tyrosinase activity and melanin formation. Moreover, the antioxidant evaluation disclosed two analogues (29 and 11) with significant free-radical-scavenging activity (12.4 and 20.3 μM), which were 10- and 6-fold more potent than ascorbic acid (122.1 μΜ), respectively.

Medicinal and Aromatic Plant (MAP) by-products constitute a vast reservoir of bioactive metabolites with antioxidant and antimicrobial properties, offering potential for the development of high added value natural products. This study focuses on the by-product (tepals) remaining during the process of receiving the stigma of Crocus sativus L. Iridaceae (saffron), which is the commercially exploitable part of the flowers. The tepals are the main part of the flowers (>95%) and are still discarded in the fields during the collection of the stigmas in Kozani, Greece. According to numerous findings, the saffron tepals are rich in flavonoids with notable biological properties, and our aim was to investigate an alternative for their management. Within this context, dry and frozen tepals were extracted at a laboratory scale through microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE), followed by adsorption resin technology (ART) for the preparation of enriched extracts. Furthermore, their HPTLC profiling, the phenolic (TPC) and flavonoid (TFC) content, and the free-radical-scavenging (DPPH) and anti-tyrosinase activity were evaluated. The frozen tepals were further extracted at a pilot scale using MAE and maceration (Mc) techniques, followed by ART treatment to remove the contained sugars. The enriched extract produced at a pilot scale using MAE and ART sequentially is characterized by a high phenolic (147.2 mg GAE/g dry extract) and flavonoid (114.8 mg QUE/g dry extract) load. These findings demonstrate that saffron tepals, traditionally considered waste, can serve as a valuable raw material for producing extracts rich in phenolic derivatives, particularly flavonoids and anthocyanins.

This study aims to evaluate the antioxidant and anti-inflammatory potential of dichloromethanic, methanolic and hydroalcoholic extracts of seventeen different selected Balkan medicinal herbs with ethnopharmacological interest, with the goal of identifying the most bioactive candidates for further investigation of their therapeutic efficacy in human diseases. A total of fifty-four extracts were initially screened; due to the high sample number, only the most active samples were advanced to subsequent assays in order to identify bioactive candidates with potential therapeutic efficacy in human diseases. The methanolic extract of Cotinus coggygria showed the highest radical scavenging activity (DPPH: 96.4% inhibition), the hydroalcoholic extract of Hypericum empetrifolium exhibited the most potent iron chelation (IC₅₀: 5.0 μg/mL) and the methanolic extract of Sedum sediforme presented the best anti-inflammatory activity in in vitro assays (LOX IC₅₀: 39.4 μg/mL, COX-1 inhibition: 93.1% and COX-2 inhibition: 94.0%). Furthermore, significant inhibition of tyrosinase and collagenase was observed for the methanolic extract of Cistus creticus (94.2% tyrosinase inhibition, 86.8% collagenase inhibition) and the methanolic extract of Cotinus coggygria (83.1% tyrosinase inhibition, 96.1% collagenase inhibition). In vivo, five promising plant extracts were selected and evaluated for their anti-inflammatory activity using a carrageenan-induced paw edema model in female C57BL/6 mice. The study aimed to assess the in vivo anti-inflammatory potential of these extracts under acute inflammatory conditions. The methanolic extract of Cotinus coggygria proved the most active, significantly reducing paw edema by 34% compared to the non-treated control, indicating a pronounced anti-inflammatory effect and supporting its potential as a source of bioactive compounds with therapeutic relevance. The results of this study indicate that several selected herbal extracts exhibit notable pharmacological activities. Given their antioxidant, anti-inflammatory, and inhibitory properties against enzymes related to skin function, these extracts warrant further in vivo and (pre)clinical investigation for potential use in cosmetic and pharmaceutical products targeting skin disorders associated with inflammation and oxidative stress.