Antimicrobial and Antioxidant Properties of Theobroma cacao, Bourreria huanita, Eriobotrya japonica, and Elettaria cardamomum - Traditional Plants Used in Central America.

The search for alternative naturally occurring antimicrobial agents will always continue, especially when emerging diseases like COVID-19 provide an urgency to identify and develop safe and effective ways to prevent or treat these infections. The purpose of this study was to evaluate the potential antimicrobial activity as well as antioxidant properties of commercial samples from four traditional medicinal plants used in Central America: Theobroma cacao, Bourreria huanita, Eriobotrya japonica, and Elettaria cardamomum. Ethanolic extracts were prepared from commercial products derived from the seeds or flowers of these plants. Total phenolics and antioxidant activity were assessed using commercial kits. The cytotoxicity and antiviral activity against severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) were evaluated using the XTT colorimetric assay and a SARS-CoV-2 delta pseudoviral model. The half-maximal cytotoxic concentration (CC50) and half-maximal effective concentration (EC50) were used to calculate the therapeutic index (TI). Additionally, the antibacterial activity against Escherichia coli and Staphylococcus epidermidis was tested using a spectrophotometric method. The extracts showed total phenolics in the range of 0.06 to 1.85 nM/µL catechin equivalents, with T. cacao bean extract showing the highest content. The antioxidant activity showed values between 0.02 and 0.44 mM Trolox equivalents. T. cacao bean extract showed the highest antioxidant activity. Most plant extracts showed zero to moderate selective antiviral activity; however, one T. cacao beans sample showed excellent antiviral activity against SARS-CoV-2 with a TI value of 30.3, and one sample of E. japonica showed selective antiviral activity with a TI value of 18.7. Significant inhibition of E. coli and S. epidermidis by an E. japonica ethanolic extract (p<0.001) was observed using a spectrophotometric method that monitors bacterial growth over time. Additionally, ethanolic extracts of E. cardamomum showed significant inhibition of S. epidermidis growth (p<0.001). The results warrant further investigation of the antimicrobial and antioxidant properties of these plant extracts.

Antiviral activity of aframomum melegueta against severe acute respiratory syndrome coronaviruses type 1 and 2.

Plant-based compounds with antiviral properties against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been identified in Aframomum melegueta through computational models. The seed extract have been traditionally used to treat different illnesses. In this study, ethanolic extracts were prepared for six commercial samples of A. melegueta seeds. Antiviral activity was tested using the XTT cytotoxicity assay and cell-based SARS-CoV-1 and 2 pseudoviral models. The presence of gingerols and other non-volatile components in the seed extracts was determined using an Agilent 1290 UPLC/DAD in tandem with an Agilent 6546 QTOF-MS. Our results showed selective antiviral activity with TI values as high as 13.1. Fifteen gingerols were identified by chromatographic analysis, with 6-gingerol being the dominant component in each seed extract. A combination of 6-gingerol with techtochrysin, previously identified in computational models as a potential active ingredient against SARS-CoV-2, demonstrated additive antiviral activity with CI values between 0.8715 and 0.9426. We confirmed the antiviral activity of A. melegueta predicted through computational models and identified a different compound, 6-gingerol, as a potential active ingredient.

Biology, chemistry, and pharmacological activity of Kigelia africana (Bignoniaceae) and Garcinia kola (Clusiaceae) - a review.

Kigelia africana and Garcinia kola are two West African medicinal plants traditionally used to treat or alleviate various medical conditions such as skin ailments, respiratory disorders, and digestive problems. Phytochemical analyses indicated the presence of bioactive constituents, including flavonoids and phenolic acids, suggesting that the extracts of these two plants can interfere with reactive oxygen species-induced oxidative stress, inflammation, and microbial growth. This paper reviews the biochemical properties and the antioxidant, anti-inflammatory, and antibacterial activities of these two relevant West African medicinal plants.

Algal and Cyanobacterial Lectins and Their Antimicrobial Properties.

Lectins are proteins with a remarkably high affinity and specificity for carbohydrates. Many organisms naturally produce them, including animals, plants, fungi, protists, bacteria, archaea, and viruses. The present report focuses on lectins produced by marine or freshwater organisms, in particular algae and cyanobacteria. We explore their structure, function, classification, and antimicrobial properties. Furthermore, we look at the expression of lectins in heterologous systems and the current research on the preclinical and clinical evaluation of these fascinating molecules. The further development of these molecules might positively impact human health, particularly the prevention or treatment of diseases caused by pathogens such as human immunodeficiency virus, influenza, and severe acute respiratory coronaviruses, among others.

In polycistronic Qbeta RNA, single-strandedness at one ribosome binding site directly affects translational initiations at a distal upstream cistron.

In Qß RNA, sequestering the coat gene ribosome binding site in a putatively strong hairpin stem structure eliminated synthesis of coat protein and activated protein synthesis from the much weaker maturation gene initiation site, located 1300 nucleotides upstream. As the stability of a hairpin stem comprising the coat gene Shine-Dalgarno site was incrementally increased, there was a corresponding increase in translation of maturation protein. The effect of the downstream coat gene ribosome binding sequence on maturation gene expression appeared to have occurred only in cis and did not require an AUG start codon or initiation of coat protein synthesis. In all cases, no structural reorganization was predicted to occur within Qß RNA. Our results suggest that protein synthesis from a relatively weak translational initiation site is greatly influenced by the presence or absence of a stronger ribosome binding site located elsewhere on the same RNA molecule. The data are consistent with a mechanism in which multiple ribosome binding sites compete in cis for translational initiations as a means of regulating protein synthesis on a polycistronic messenger RNA.