Mono laurina na prevenção e tratamento de pacientes com COVID-19 / Mono laurine in the prevention and treatment of patients with Covid-19

OBJETIVO: Esta nota técnica tem por objetivo apresentar informações sobre o uso da monolaurina na prevenção e no tratamento de pacientes com COVID-19. DOS FATOS: Trata-se de despacho proveniente do Centro de Operações de Emergências em Saúde Pública (COE) e encaminhado ao Departamento de Gestão e Incorporação de Tecnologias e Inovação em Saúde (DGITIS/SCTIE/MS). O despacho em questão apresenta um e-mail encaminhado pelo profissional Dr. Ronaldo Amaral de Paiva (vinculado à Universidade Federal de Viçosa), intitulado "Ações técnicas efetivas para o combate à Covid-19", que traz informações acerca do uso da monolaurina no tratamento da COVID-19 para análise no âmbito de suas competências e medidas julgadas pertinentes. BUSCA NA LITERATURA E SELEÇÃO DOS ESTUDOS: Com base na pergunta PICO estruturada, foram realizadas buscas nas bases de dados Medline (via PubMed) e Embase com acesso em 05 de maio de 2020. As estratégias de busca estão descritas conforme o Quadro 2 abaixo e mostram que não foram identificados estudos científicos sobre a questão de pesquisa. As plataformas de registros de ensaios clínicos ClinicalTrial.gov e International Clinical Trials Registry Platform (ICTRP), da Organização Mundial de Saúde (OMS), também foram consultadas. Foram utilizados os termos de busca: SARS-COV-2, COVID-19, 2019 novel coronavirus, 2019-nCoV, severe acute respiratory syndrome coronavirus 2, Wuhan coronavirus, COVID, monolaurin e glycerol monolaurate. Da mesma forma, nenhum estudo foi identificado em ambas as plataformas de registro. CONCLUSÕES: Embora haja evidências substanciais de ação antiviral de monoglicerídeos em vírus de RNA envelopados, não foram identificadas evidências científicas que corroborem o uso da monolaurina na prevenção ou tratamento de pacientes da COVID-19. Portanto, não foi possível aferir informações sobre um potencial efeito da substância sobre as membranas protetoras do SARS-CoV-2. Sendo assim, conclui-se que não há eficácia comprovada do uso na prevenção e tratamento da COVID-19. É prudente alertar sobre o crescente número de informações on-line, pretensamente fundadas em evidências científicas, que disseminam suposições de que produtos naturais, como o óleo de coco (23,24), teriam um efeito "protetor" contra a infecção pelo SARS-CoV-2. Não há qualquer regulamentação por nenhuma agência de vigilância sanitária nacional ou internacional para esses produtos que inclua essa finalidade de uso. Haja vista a precariedade de evidências acerca do tema, o presente documento será atualizado à medida que elas forem identificadas.

Effects of dietary glycerol monolaurate on productive performance, egg quality, serum biochemical indices, and intestinal morphology of laying hens / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Glycerol monolaurate (GML) has been widely used as an effective antibacterial emulsifier in the food industry. A total of 360 44-week-old Hy-Line brown laying hens were randomly distributed into four groups each with six replicates of 15 birds, and fed with corn-soybean-meal-based diets supplemented with 0, 0.15, 0.30, and 0.45 g/kg GML, respectively. Our results showed that 0.15, 0.30, and 0.45 g/kg GML treatments significantly decreased feed conversion ratios (FCRs) by 2.65%, 7.08%, and 3.54%, respectively, and significantly increased the laying rates and average egg weights. For egg quality, GML drastically increased albumen height and Haugh units, and enhanced yolk color. Notably, GML increased the concentrations of polyunsaturated and monounsaturated fatty acids and reduced the concentration of total saturated fatty acids in the yolk. The albumen composition was also significantly modified, with an increase of 1.02% in total protein content, and increased contents of His (4.55%) and Glu (2.02%) under the 0.30 g/kg GML treatment. Additionally, GML treatments had positive effects on the lipid metabolism of laying hens, including lowering the serum triglyceride and total cholesterol levels and reducing fat deposition in abdominal adipose tissue. Intestinal morphology was also improved by GML treatment, with increased villus length and villus height to crypt depth ratio. Our data demonstrated that GML supplementation of laying hens could have beneficial effects on both their productivity and physiological properties, which indicates the potential application of GML as a functional feed additive and gives us a new insight into this traditional food additive.

Effects of artepillin C on model membranes displaying liquid immiscibility

It has been hypothesized that the therapeutic effects of artepillin C, a natural compound derived from Brazilian green propolis, are likely related to its partition in the lipid bilayer component of biological membranes. To test this hypothesis, we investigated the effects of the major compound of green propolis, artepillin C, on model membranes (small and giant unilamelar vesicles) composed of ternary lipid mixtures containing cholesterol, which display liquid-ordered (lo) and liquid-disordered (ld) phase coexistence. Specifically, we explored potential changes in relevant membrane parameters upon addition of artepillin C presenting both neutral and deprotonated states by means of small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and confocal and multiphoton excitation fluorescence microscopy. Thermotropic analysis obtained from DSC experiments indicated a loss in the lipid cooperativity of lo phase at equilibrium conditions, while at similar conditions spontaneous formation of unilamellar vesicles from SAXS experiments showed that deprotonated artepillin C preferentially located at the surface of the membrane. Time-resolved experiments using fluorescence microscopy showed that at doses above 100 µM, artepillin C in its neutral state interacted with both liquid-ordered and liquid-disordered phases, inducing curvature stress and promoting dehydration at the membrane interface.

Switch of substrate specificity of hyperthermophilic acylaminoacyl peptidase by combination of protein and solvent engineering

The inherent evolvability of promiscuous enzymes endows them with great potential to be artificially evolved for novel functions. Previously, we succeeded in transforming a promiscuous acylaminoacyl peptidase (apAAP) from the hyperthermophilic archaeon Aeropyrum pernix K1 into a specific carboxylesterase by making a single mutation. In order to fulfill the urgent requirement of thermostable lipolytic enzymes, in this paper we describe how the substrate preference of apAAP can be further changed from p-nitrophenyl caprylate (pNP-C8) to p-nitrophenyl laurate (pNP-C12) by protein and solvent engineering. After one round of directed evolution and subsequent saturation mutagenesis at selected residues in the active site, three variants with enhanced activity towards pNP-C12 were identified. Additionally, a combined mutant W474V/F488G/R526V/T560W was generated, which had the highest catalytic efficiency (k (cat)/K (m)) for pNP-C12, about 71-fold higher than the wild type. Its activity was further increased by solvent engineering, resulting in an activity enhancement of 280-fold compared with the wild type in the presence of 30% DMSO. The structural basis for the improved activity was studied by substrate docking and molecular dynamics simulation. It was revealed that W474V and F488G mutations caused a significant change in the geometry of the active center, which may facilitate binding and subsequent hydrolysis of bulky substrates. In conclusion, the combination of protein and solvent engineering may be an effective approach to improve the activities of promiscuous enzymes and could be used to create naturally rare hyperthermophilic enzymes.

Synthesis of glucose laurate monoester catalyzed by Candida antarctica lipase B-displaying Pichia pastoris whole-cells / 生物工程学报

We developed a new enzymatic-catalyzing producing process of glucose laurate monoester. In the process we used Candida antarctica lipase B-displaying Pichia pastoris whole-cells as biocatalyst, glucose as the acyl acceptor and lauric acid as the acyl donor. The product glucose laurate monoester was purified by silica gel column chromatography and preparative liquid chromatography, and identified by liquid chromatography-mass spectrometry. Then we optimized the process from various aspects, such as solvent composition, ratio of dmethyl sulfoxide to 2-Methyl-2-butanol (V/V), catalyst dosage, substrate concentration, water activity and temperature. The optimal reaction conditions were: glucose 0.5 mmol/L, lauric acid 1.0 mmol/L, ratio of 2-Methyl-2-butanol to Dmethyl sulfoxide is 7:3 in 5 mL volume, temperature 60 degrees C, the best initial water activity of whole-cells biocatalyst is 0.11. The maximum glucose conversion could be 48.7% after 72 h.