Correlation between Solid Content and Antioxidant Activities in Umbelliferae Salad Plants

Glycosylation of Quercetin by Selected Entomopathogenic Filamentous Fungi and Prediction of Its Products' Bioactivity

Quercetin is the most abundant flavonoid in food products, including berries, apples, cauliflower, tea, cabbage, nuts, onions, red wine and fruit juices. It exhibits various biological activities and is used for medical applications, such as treating allergic, inflammatory and metabolic disorders, ophthalmic and cardiovascular diseases, and arthritis. However, its low water solubility may limit quercetin's therapeutic potential. One method of increasing the solubility of active compounds is their coupling to polar molecules, such as sugars. The attachment of a glucose unit impacts the stability and solubility of flavonoids and often determines their bioavailability and bioactivity. Entomopathogenic fungi are biocatalysts well known for their ability to attach glucose and its 4-O-methyl derivative to bioactive compounds, including flavonoids. We investigated the ability of cultures of entomopathogenic fungi belonging to Beauveria, Isaria, Metapochonia, Lecanicillium and Metarhizium genera to biotransform quercetin. Three major glycosylation products were detected: (1), 7-O-β-D-(4″-O-methylglucopyranosyl)-quercetin, (2) 3-O-β-D-(4″-O-methylglucopyranosyl)-quercetin and (3) 3-O-β-D-(glucopyranosyl)-quercetin. The results show evident variability of the biotransformation process, both between strains of the tested biocatalysts from different species and between strains of the same species. Pharmacokinetic and pharmacodynamic properties of the obtained compounds were predicted with the use of cheminformatics tools. The study showed that the obtained compounds may have applications as effective modulators of intestinal flora and may be stronger hepato-, cardio- and vasoprotectants and free radical scavengers than quercetin.

Some Antioxidant Properties of Components from The Flower of Ochna integerrima and Their Beneficial Effects on HaCaT Keratinocytes and In Silico Analysis on Tyrosinase

Four compounds, luteolin ( 1 ), 6- γ , γ -Dimethylallylquercetin 7- O - β -ᴅ-glucopyranoside ( 2 ), 6- γ , γ -Dimethylallylkaempferol 7- O - β -ᴅ-gluco-pyranoside ( 3 ), and 6- γ , γ -Dimethylallyldihydrokaempferol 7- O - β -ᴅ-glucoside ( 4 ), were isolated for the first time from EtOAc extract of the O. integerrima   flower. We then evaluated the antioxidant effects of EtOAc, n -butanol, and MeOH extracts and their effects on H 2 O 2 against oxidative stress in HaCaT keratinocyte cell lines. Furthermore, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH · ) radical scavenging activities of 1 - 4 were determined and their mechanisms of action on tyrosinase were predicted by in silico studies. The results revealed that the EtOAc extract and 1 - 3 exhibited good DPPH˙radical scavenging activity. Furthermore, this extract also had a significant protective effect against H 2 O 2 -induced oxidative stress in HaCaT cells. In silico studies indicated that the activity of 1 - 3 may be due to tyrosinase inhibition with MM-GBSA free binding energies of -78.9, -70.1, -71.1 kcal mol -1 , respectively, compared to 4 with an energy -56.9 kcal mol -1 .

Intraspecific Variation of Phytochemicals, Antioxidant, and Antibacterial Activities of Different Solvent Extracts of Albizia coriaria Leaves from Some Agroecological Zones of Uganda

Albizia coriaria Welw ex. Oliver is a customary African medicinal plant, which has a long history of utilization in the management of oxidative stress-induced and bacterial diseases. However, there is no report on the phytochemicals, antioxidant, and antibacterial activities of its leaves. The aim of this study was therefore to compare the phytochemicals, antioxidant, and antibacterial potential of A. coriaria leaves from Jinja, Kole, and Mbarara districts of Uganda. Shade-dried leaf samples were ground into powder and successively extracted with ethyl acetate, ethanol, and distilled water. Phytochemical screening indicated the presence of alkaloids, phenols, saponins, flavonoids, cardiac glycosides, tannins, and terpenes as the major secondary metabolites in the extracts. Total phenolic and flavonoid contents and total in vitro antioxidant activity were found to be the highest for ethanolic extracts, with the highest contents (101.72 ± 0.22 mg GAE/g DW; 13.23 ± 0.03 mg QE/g DW) and antioxidant potential (IC₅₀ = 18.65 ± 0.06 mg/mL) being for leaves from Mbarara district. Antibacterial activity of the extracts determined by agar disc diffusion method revealed that ethanolic extracts had higher antibacterial activities with mean zones of inhibition of 6.00 ± 1.73 to 10.00 ± 1.73 mm, 5.00 ± 1.00 to 12.30 ± 1.53 mm, 17.00 ± 0.00 to 25.00 ± 2.65 mm, and 9.00 ± 1.73 to 16.00 ± 1.73 mm for Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella typhi, respectively. Ethyl acetate extracts of A. coriaria leaves from Kole and Mbarara had lower antibacterial activities, while aqueous extracts and ethyl acetate extract of leaves from Jinja showed no antibacterial activity. The current study for the first time established that A. coriaria leaves possess therapeutic phytochemicals with significant in vitro antioxidant and antibacterial activities, which lend credence to their use in traditional management of oxidative stress-induced conditions and bacterial diseases in Uganda. Structural elucidation of the responsible pure compounds for the observed bioactivities as well as toxicity studies of the extracts is recommended.