Deriving high value products from depolymerized lignin oil, aided by (bio)catalytic funneling strategies

Lignin holds tremendous and versatile possibilities to produce value-added chemicals and high performing polymeric materials. Over the years, different cutting-edge lignin depolymerization methodologies have been developed, mainly focusing on achieving excellent yields of mono-phenolic products, some even approaching the theoretical maximum. However, due to lignin's inherent heterogeneity and recalcitrance, its depolymerization leads to relatively complex product streams, also containing dimers, and higher molecular weight fragments in substantial quantities. The subsequent chemo-catalytic valorization of these higher molecular weight streams, containing difficult-to-break, mainly C-C covalent bonds, is tremendously challenging, and has consequently received much less attention. In this minireview, we present an overview of recent advances on the development of sustainable biorefinery strategies aimed at the production of well-defined chemicals and polymeric materials, the prime focus being on depolymerized lignin oils, containing high molecular weight fractions. The key central unit operation to achieve this is (bio)catalytic funneling, which holds great potential to overcome separation and purification challenges.

New Palladium(II) Complexes Containing Methyl Gallate and Octyl Gallate: Effect against Mycobacterium tuberculosis and Campylobacter jejuni

This work describes the preparation, characterization and antimicrobial activity of four palladium(II) complexes, namely, [Pd(meg)(1,10-phen)] 1, [Pd(meg)(PPh₃)₂] 2, [Pd(og)(1,10-phen)] 3 and [Pd(og)(PPh₃)₂] 4, where meg = methyl gallate, og = octyl gallate, 1,10-phen = 1,10-phenanthroline and PPh₃ = triphenylphosphine. As to the chemical structures, spectral and physicochemical studies of 1-4 indicated that methyl or octyl gallate coordinates a palladium(II) ion through two oxygen atoms upon deprotonation. A chelating bidentate phenanthroline or two triphenylphosphine molecules complete the coordination sphere of palladium(II) ion, depending on the complex. The metal complexes were tested against the Mycobacterium tuberculosis H37Rv strain and 2 exhibited high activity (MIC = 3.28 μg/mL). As to the tests with Campylobacter jejuni, complex 1 showed a significant effect in reducing bacterial population (greater than 7 log CFU) in planktonic forms, as well as in the biomass intensity (IBF: 0.87) when compared to peracetic acid (IBF: 1.11) at a concentration of 400 μg/mL. The effect provided by these complexes has specificity according to the target microorganism and represent a promising alternative for the control of microorganisms of public health importance.

Comparative Assessment of the Antioxidant and Anticancer Activities of Plicosepalus acacia and Plicosepalus curviflorus: Metabolomic Profiling and In Silico Studies

This study presents a comparison between two mistletoe plants—P. acacia and P. curviflorus—regarding their total phenolic contents and antioxidant and anticancer activities. P. curviflorus exhibited a higher total phenolics content (340.62 ± 19.46 mg GAE/g extract), and demonstrated higher DPPH free radical scavenging activity (IC₅₀ = 48.28 ± 3.41µg/mL), stronger reducing power (1.43 ± 0.54 mMol Fe⁺²/g) for ferric ions, and a greater total antioxidant capacity (41.89 ± 3.15 mg GAE/g) compared to P. acacia. The cytotoxic effects of P. acacia and P. curviflorus methanol extracts were examined on lung (A549), prostate (PC-3), ovarian (A2780) and breast (MDA-MB-231) cancer cells. The highest anticancer potential for the two extracts was observed on PC-3 prostate cancer cells, where P. curviflorus exhibited more pronounced antiproliferative activity (IC₅₀ = 25.83 μg/mL) than P. acacia (IC₅₀ = 34.12 μg/mL). In addition, both of the tested extracts arrested the cell cycle at the Pre-G1 and G1 phases, and induced apoptosis. However, P. curviflorus extract possessed the highest apoptotic effect, mediated by the upregulation of p53, Bax, and caspase-3, 8 and 9, and the downregulation of Bcl-2 expression. In the pursuit to link the chemical diversity of P. curviflorus with the exhibited bioactivities, its metabolomic profiling was achieved by the LC-ESI-TOF-MS/MS technique. This permitted the tentative identification of several phenolics—chiefly flavonoid derivatives, beside some triterpenes and sterols—in the P. curviflorus extract. Furthermore, all of the metabolites in P. curviflorus and P. acacia were inspected for their binding modes towards both CDK-2 and EGFR proteins using molecular docking studies in an attempt to understand the superiority of P. curviflorus over P. acacia regarding their antiproliferative effect on PC-3 cancer cells. Docking studies supported our experimental results; with all of this taken together, P. curviflorus could be regarded as a potential prospect for the development of chemotherapeutics for prostate cancer.

Gallic Acid: A Potential Anti-Cancer Agent

Cancer is one of the most devastating diseases worldwide and definitive therapeutics for treating cancer are not yet available despite extensive research efforts. The key challenges include limiting factors connected with traditional chemotherapeutics, primarily drug resistance, low response rates, and adverse side-effects. Therefore, there is a high demand for novel anti-cancer drugs that are both potent and safe for cancer prevention and treatment. Gallic acid (GA), a natural botanic phenolic compound, can mediate various therapeutic properties that are involved in anti-inflammation, anti-obesity, and anti-cancer activities. More recently, GA has been shown to exert anti-cancer activities via several biological pathways that include migration, metastasis, apoptosis, cell cycle arrest, angiogenesis, and oncogene expression. This review discusses two aspects, one is the anti-cancer potential of GA against different types of cancer and the underlying molecular mechanisms, the other is the bibliometric analysis of GA in cancer and tumor research. The results indicated that lung cancer, prostate cancer, stomach cancer, and colon adenocarcinoma may become a hot topic in further research. Overall, this review provides evidence that GA represents a promising novel, potent, and safe anti-cancer drug candidate for treating cancer.

Evaluation of anti-inflammatory, antinociceptive and biological activities of Cenostigma macrophyllum standardized extracts and determination and quantification of the main metabolites

The stem barks and leaves of Cenostigma macrophyllum are used in Brazilian folk medicines in the treatment of stomach and intestinal diseases. However, there are no reports of chromatographic methods used to evaluate the bioactives of its standardized extracts and for biological evaluation. An analytical method was developed and validated for simultaneous determination and quantification of the bioactive phenolics gallic acid, methyl gallate, ellagic acid and, the biflavonoids agathisflavone and amentoflavone in the leaves and stem bark of C. macrophyllum. HPLC operating conditions were optimized and the parameters such as selectivity, linearity, precision, accuracy, LOD, LOQ and, robustness of the method were also evaluated. Robustness was evaluated using a multivariate optimization technique. Linear relationships within the range of investigated concentrations were observed with their correlation coefficients greater than 0.9991. The method was validated for repeatability (RSD ≤ 2.88%), intermediate precision (RSD ≤ 3.38%) with recovery between 84.12 and 106.64% and the RSD less than 3.40% and proved to be robust. Besides, antioxidant, acetylcholinesterase inhibition, anti-inflammatory and antinociceptive activities of the standardized hydromethanolic extracts of leaves and stem bark of this species were evaluated. The method was successfully applied in the quantification of the gallic acid, methyl gallate, ellagic acid, agathisflavone and amentoflavone of standardized extracts. The results showed the present method developed was simple, sensitive, reproducible, accurate and precise. The standardized hydromethanolic extracts of leaves and stem bark of C. macrophyllum showed antioxidant activity (EC₅₀ 69.09 and 83.06 μg mL⁻¹), acetylcholinesterase inhibition (52.23 and 83.36%) and they were able to inhibit the formalin-induced nociception and also reduced the edema formations at 100 mg kg⁻¹ doses. The anti-inflammatory potentials were evaluated by the decrease of the Cg-induced neutrophils migrations at the same doses.

The stem barks and leaves of Cenostigma macrophyllum are used in Brazilian folk medicines in the treatment of stomach and intestinal diseases.

Chemical constituents from Sanguisorba officinalis L. and their inhibitory effects on LPS-stimulated pro-inflammatory cytokine production in bone marrow-derived dendritic cells

Sanguisorba officinalis L. (Rosaceae) is a perennial herbaceous plant and its roots have been used as an important astringent medicine in Eastern Asian countries over many thousand years. In this phytochemical research, 23 compounds (1-23) were isolated from the roots of S. officinalis. Their chemical structures were identified by extensive spectroscopic methods, including 1D and 2D NMR experiments. The anti-inflammatory effects of extracts and isolated compounds were investigated by measuring the production of pro-inflammatory cytokine IL-12 p40, IL-6 and TNF-α in LPS-stimulated bone marrow-derived dendritic cell. Compounds 1, 3, 7-8, 11-14 revealed promising anti-inflammatory effects. These results suggested that some phenolic compounds and monoterpenoids from S. officinalis could be potential candidates for anti-inflammatory treatments.

Post-Stroke Depression Modulation and in Vivo Antioxidant Activity of Gallic Acid and Its Synthetic Derivatives in a Murine Model System

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a plant secondary metabolite, which shows antioxidant activity and is commonly found in many plant-based foods and beverages. Recent evidence suggests that oxidative stress contributes to the development of many human chronic diseases, including cardiovascular and neurodegenerative pathologies, metabolic syndrome, type 2 diabetes and cancer. GA and its derivative, methyl-3-O-methyl gallate (M3OMG), possess physiological and pharmacological activities closely related to their antioxidant properties. This paper describes the antidepressive-like effects of intraperitoneal administration of GA and two synthetic analogues, M3OMG and P3OMG (propyl-3-O-methylgallate), in balb/c mice with post-stroke depression, a secondary form of depression that could be due to oxidative stress occurring during cerebral ischemia and the following reperfusion. Moreover, this study determined the in vivo antioxidant activity of these compounds through the evaluation of superoxide dismutase (SOD) and catalase (Cat) activity, thiobarbituric acid-reactive substances (TBARS) and reduced glutathione (GSH) levels in mouse brain. GA and its synthetic analogues were found to be active (at doses of 25 and 50 mg/kg) in the modulation of depressive symptoms and the reduction of oxidative stress, restoring normal behavior and, at least in part, antioxidant endogenous defenses, with M3OMG being the most active of these compounds. SOD, TBARS, and GSH all showed strong correlation with behavioral parameters, suggesting that oxidative stress is tightly linked to the pathological processes involved in stroke and PSD. As a whole, the obtained results show that the administration of GA, M3OMG and P3OMG induce a reduction in depressive symptoms and oxidative stress.