Inter-species comparative antioxidant assay and HPTLC analysis of sakuranetin in the chloroform and ethanol extracts of aerial parts of Rhus retinorrhoea and Rhus tripartita

In vitro antibacterial activities, DPPH radical scavenging, and molecular simulation of isolated compounds from the leaves of Rhus ruspolii

Rhus ruspolii Engl. plant is traditionally used in Ethiopia to treat various diseases. However, the biological and phytochemical properties of the leaves are not well documented. Hence, this study aimed to isolate phytochemicals from R. ruspolii leaves and evaluate their antibacterial and DPPH radical scavenging activities. GC-MS analysis identified 16 compounds from combined fractions 6-10. Chromatographic separation and NMR analysis resulted in the isolation and characterization of palmitic acid (7), 3,4-dihydroxybenzoic acid (17), cupressuflavone (18), amentoflavone (19), shikimic acid (20), avicularin (21), and myricetin-3-O-5''-acetylarabinofuranoside (22). The inhibition zones of extracts (100 mg/mL) and isolated compounds (5 mg/mL) ranged from 8.33 ± 0.50 to 16.33 ± 0.47 mm against all evaluated bacteria. Of all isolated compounds, compounds 18 and 21 showed good activity against Gram-negative (supported by in silico molecular docking studies) and Gram-positive bacteria, respectively. The lowest (49.1 %) and the highest (91.3 %) DPPH radicals were inhibited by combined fractions 6-10 and compound 17, respectively, at 62.5 μg/mL. The SwissADME online analysis showed compounds 17 and 20 have good solubility and permeability. The Pro Tox 3.0 online analysis revealed none of the isolated compounds are fatal if swallowed. Therefore, the findings of this study support the traditional use of the plant for treating bacteria diseases.

Sakuranetin and its therapeutic potentials - a comprehensive review

Sakuranetin (SKN), a naturally derived 7-O-methylated flavonoid, was first identified in the bark of the cherry tree (Prunus spp.) as an aglycone of sakuranin and then purified from the bark of Prunus puddum. It was later reported in many other plants including Artemisia campestris, Boesenbergia pandurata, Baccharis spp., Betula spp., Juglans spp., and Rhus spp. In plants, it functions as a phytoalexin synthesized from its precursor naringenin and is the only known phenolic phytoalexin in rice, which is released in response to different abiotic and biotic stresses such as UV-irradiation, jasmonic acid, cupric chloride, L-methionine, and the phytotoxin coronatine. Till date, SKN has been widely reported for its diverse pharmacological benefits including antioxidant, anti-inflammatory, antimycobacterial, antiviral, antifungal, antileishmanial, antitrypanosomal, glucose uptake stimulation, neuroprotective, antimelanogenic, and antitumor properties. Its pharmacokinetics and toxicological properties have been poorly understood, thus warranting further evaluation together with exploring other pharmacological properties such as antidiabetic, neuroprotective, and antinociceptive effects. Besides, in vivo studies or clinical investigations can be done for proving its effects as antioxidant and anti-inflammatory, antimelanogenic, and antitumor agent. This review summarizes all the reported investigations with SKN for its health-beneficial roles and can be used as a guideline for future studies.

The Chemistry, Biology, and Modulation of Ammonium Nitrification in Soil

Approximately two percent of the world's energy is consumed in the production of ammonia from hydrogen and nitrogen gas. Ammonia is used as a fertilizer ingredient for agriculture and distributed in the environment on an enormous scale to promote crop growth in intensive farming. Only 30-50 % of the nitrogen applied is assimilated by crop plants; the remaining 50-70 % goes into biological processes such as nitrification by microbial metabolism in the soil. This leads to an imbalance in the global nitrogen cycle and higher nitrous oxide emissions (a potent and significant greenhouse gas) as well as contamination of ground and surface waters by nitrate from the nitrogen-fertilized farmland. This Review gives a critical overview of the current knowledge of soil microbes involved in the chemistry of ammonia nitrification, the structures and mechanisms of the enzymes involved, and phytochemicals capable of inhibiting ammonia nitrification.