Toward understanding of the methoxylated flavonoid biosynthesis pathway in Dracocephalum kotschyi Boiss

Nowadays, with the development and advancement of next-generation sequencing technologies, a new path has been provided for transcriptomic studies. In this study, the transcriptome of Dracocephalum kotschyi Boiss., as an endemic and endangered plant which is contained a large amount of valuable secondary metabolites with antioxidant and anticancer properties, was sequenced. Then functional annotation and gene ontology analysis for 165,597 assembled transcripts were performed, most were associated with the metabolic pathways. This might be because there are various active biochemical pathways in this plant. Furthermore, after comprehensive transcript annotation, the putative genes involved in the main metabolic pathways of D. kotschyi were identified. Then, the biosynthetic pathway of its valuable methoxylated flavones was proposed. Finally, the accumulations of important methoxylated-flavone metabolites in three different tissues were quantified by HPLC. The relative expression of the genes involved in the proposed pathway was investigated by qRT-PCR, which indicated high expression levels in the bud tissue. The present results may lead to the design strategies to preserve the genetic diversity of endangered D. kotschyi plants and apply the new methods for engineering its valuable methoxylated-flavones pathway.

Citrus peel derived’ Poly-Methoxylated Flavones (PMF)

The prevalence of obesity has increased substantially over the last several decades and several environmental factors have accelerated this trend. Poly-methoxy flavones (PMFs) exist abundantly in the peels of citrus, and their biological activities have been broadly examined in recent years. Several studies have examined the effects of PMFs on obesity and its-related diseases. This systematic review conducted to focus on the effect of PMFs on obesity and its related conditions management. The PubMed, Google Scholar, Scopus, and Science Direct databases were searched for relevant studies published before November 2020. Out of 1,615 records screened, 16 studies met the study criteria. The range of dosage of PMFs was varied from 10 to 200 mg/kg (5–26 weeks) and 1–100 μmol (2h–8 days) across selected animal and in vitro studies, respectively. The literature reviewed shows that PMFs modulate several biological processes associated with obesity such as lipid and glucose metabolism, inflammation, energy balance, and oxidative stress by different mechanisms. All of the animal studies showed significant positive effects of PMFs on obesity by reducing body weight (e.g. reduced weight gain by 21.04%), insulin resistance, energy expenditure, inhibiting lipogenesis and reduced blood lipids (e.g. reduced total cholesterol by 23.10%, TG by 44.35% and LDL by 34.41%). The results of the reviewed in vitro studies have revealed that treatment with PMFs significantly inhibits lipid accumulation in adipocytes (e.g. reduced lipid accumulation by 55–60%) and 3T3-L1 pre-adipocyte differentiation as well by decreasing the expression of PPARγ and C/EBPα and also reduces the number and size of fat cells and reduced TG content in adipocytes by 45.67% and 23.10% and 16.08% for nobiletin, tangeretin and hesperetin, respectively. Although current evidence supports the use of PMFs as a complementary treatment in obesity, future research is needed to validate this promising treatment modality.

Microbial Biosynthesis of Antibacterial Chrysoeriol in Recombinant Escherichia coli and Bioactivity Assessment

Various flavonoid derivatives including methoxylated flavones display remarkable biological activities. Chrysoeriol is a methoxylated flavone of great scientific interest because of its promising anti-microbial activities against various Gram-negative and Gram-positive bacteria. Sustainable production of such compounds is therefore of pronounced interest to biotechnologists in the pharmaceutical and nutraceutical industries. Here, we used a sugar O-methyltransferase enzyme from a spinosyn biosynthesis gene cluster of Saccharopolyspora spinosa to regioselectively produce chrysoeriol (15% conversion of luteolin; 30 µM) in a microbial host. The biosynthesized chrysoeriol was structurally characterized using high-resolution mass spectrometry and various nuclear magnetic resonance analyses. Moreover, the molecule was investigated against 17 superbugs, including thirteen Gram-positive and four Gram-negative pathogens, for anti-microbial effects. Chrysoeriol exhibited antimicrobial activity against nine pathogens in a disc diffusion assay at the concentration of 40 µg per disc. It has minimum inhibitory concentration (MIC) values of 1.25 µg/mL against a methicillin-resistant Staphylococcus aureus 3640 (MRSA) for which the parent luteolin has an MIC value of sixteen-fold higher concentration (i.e., 20 µg/mL). Similarly, chrysoeriol showed better anti-microbial activity (~1.7-fold lower MIC value) than luteolin against Proteus hauseri, a Gram-negative pathogen. In contrast, a luteolin 4′-O-methylated derivative, diosmetin, did not exhibit any anti-microbial activities against any tested pathogen.

Bioactive Compounds from Artemisia campestris L. Subsp. Campestris

Artemisia campestris L. (field wormwood) is a known medicinal plant used mainly in Asian medicine and most often overlooked in the western world, despite its cosmopolitan distribution. The aim of this study was to investigate the phytochemical composition of A. campestris from Romanian spontaneous flora in order to determine the bioactive molecules and to assess the antioxidant effect of the plant extract. For this purpose, we applied LC-MS methods for the analysis of phytosterols and polyphenols and developed new methods for the analysis of methoxylated flavones and sesquiterpene lactones, specific compounds in Artemisia genus. The paper is the first to report the concentration of these compounds in the indigenous plant and also to identify some new compounds, previously not reported in this species, such as eupatorin, casticin, and acacetin. The plant extract showed significant antioxidant activity in both radical scavenging and reducing power assay, well correlated with the polyphenolic profile.