Ocimum Species: A Review on Chemical Constituents and Antibacterial Activity

Infection by bacteria is one of the main problems in health. The use of commercial antibiotics is still one of the treatments to overcome these problems. However, high levels of consumption lead to antibiotic resistance. Several types of antibiotics have been reported to experience resistance. One solution that can be given is the use of natural antibacterial products. There have been many studies reporting the potential antibacterial activity of the Ocimum plant. Ocimum is known to be one of the medicinal plants that have been used traditionally by local people. This plant contains components of secondary metabolites such as phenolics, flavonoids, steroids, terpenoids, and alkaloids. Therefore, in this paper, we will discuss five types of Ocimum species, namely O. americanum, O. basilicum, O. gratissimum, O. campechianum, and O. sanctum. The five species are known to contain many chemical constituents and have good antibacterial activity against several pathogenic bacteria.     

Design of Oligourea-Based Foldamers with Antibacterial and Antifungal Activities

There is an urgent need to develop new therapeutic strategies to fight the emergence of multidrug resistant bacteria. Many antimicrobial peptides (AMPs) have been identified and characterized, but clinical translation has been limited partly due to their structural instability and degradability in physiological environments. The use of unnatural backbones leading to foldamers can generate peptidomimetics with improved properties and conformational stability. We recently reported the successful design of urea-based eukaryotic cell-penetrating foldamers (CPFs). Since cell-penetrating peptides and AMPs generally share many common features, we prepared new sequences derived from CPFs by varying the distribution of histidine- and arginine-type residues at the surface of the oligourea helix, and evaluated their activity on both Gram-positive and Gram-negative bacteria as well as on fungi. In addition, we prepared and tested new amphiphilic block cofoldamers consisting of an oligourea and a peptide segment whereby polar and charged residues are located in the peptide segment and more hydrophobic residues in the oligourea segment. Several foldamer sequences were found to display potent antibacterial activities even in the presence of 50% serum. Importantly, we show that these urea-based foldamers also possess promising antifungal properties.     

Chemical Constituents from Notoseris Species

The genus Notoseris (Asteraceae) comprising of 14 species is endemic in China^[1]. Two new sesquiterpene lactones,notoserolides A and B,along with 12 known compounds were isolated from the aerial parts of N. Porphyrolepis^[2], but nothing is known about secondary metabolites of other N species.     

Bioactive Chemical Constituents of Cladiella Species

From the methanolic extract of Cladiella sp., collected from the Andaman Island, India, a new sesquiterpene, cladidiol ( 2 ), and three known diterpenes, cladiellaperoxide ( 3 ), (6E)‐2α,9α‐epoxyeunicella‐6,11(12)‐dien‐3β‐ol ( 4 ), and polyanthellin A ( 5 ) were isolated. The structures of these compounds were established by extensive spectroscopic studies. Compound 2 exhibited modest acetylcholinesterase‐inhibition activity, and compounds 3 – 5 showed antibacterial activities against Streptococcus pyogenes, Escherichia coli, and Pseudomonas aeruginosa.     

Reusable Nano-Zirconia-Catalyzed Synthesis of Benzimidazoles and Their Antibacterial and Antifungal Activities

In this article, a zirconia-based nano-catalyst (Nano-ZrO₂), with intermolecular C-N bond formation for the synthesis of various benzimidazole-fused heterocycles in a concise method is reported. The robustness of this reaction is demonstrated by the synthesis of a series of benzimidazole drugs in a one-pot method. All synthesized materials were characterized using ¹HNMR, ¹³CNMR, and LC-MS spectroscopy as well as microanalysis data. Furthermore, the synthesis of nano-ZrO₂ was processed using a standard hydrothermal technique in pure form. The crystal structure of nano-ZrO₂ and phase purity were studied, and the crystallite size was calculated from XRD analysis using the Debye–Scherrer equation. Furthermore, the antimicrobial activity of the synthesized benzimidazole drugs was evaluated in terms of Gram-positive, Gram-negative, and antifungal activity, and the results were satisfactory.     

Chemical Constituents of Three Species of Rubus

There are about 700 species of Rubus widely spreading in the world, about 194 species in our country11. Their traditional use is for bums. There will be no scar on the skin after recovery. Our research indicated the predominant constituents were triterpenoids and tannins. The primary activity assay revealed that the EtOAc extracts had anti-bacteria and anti-fungi activity. We now report the triterpenoids from these three plants.     

Chemical Constituents from Acanthopanax senticosus and Their Cytotoxic Activities

Chemistry of Natural Compounds - A new lignan, named 1,6-bis-(3-methoxy-4-hydroxyphenyl)hexane-1,6-dione (1), together with seven known compounds (2–8) were isolated from the EtOAc-soluble...     

Constituents of the Leaves and Stem Bark of Aglaia foveolata

The previously known potent cytotoxic agent silvestrol (1) (0.002% w/w yield) and five new flavagline derivatives (2-6) were isolated from the leaves of Aglaia foveolata collected in Indonesia. The new compound 5 has an unprecedented cyclic amide moiety in its cyclopenta[b]benzopyran skeleton, while compound 6 is a novel benzo[b]oxepine derivative in which the oxepine ring is cleaved. Pyramidatine (7), a biogenetic precursor of the new flavaglines 2-6, was isolated from the leaf extract investigated. Silvestrol was also isolated from the stem bark of A. foveolata (yield of 0.02% w/w) along with a new baccharane-type triterpenoid (8). The structures of the new compounds were elucidated on the basis of their NMR and mass spectrometric data. All new compounds isolated were tested against a panel of cancer cell lines, but only compound 2 was cytotoxic (IC₅₀ range=1.4-1.8 μM), and is the first member of the cyclopenta[b]benzopyran class found to exhibit this type of activity. Compound 2 also showed significant NF-κB inhibitory activity in an Elisa assay (IC₅₀=0.37 μM).     

Deciphering the Biological Activities of Antifungal Agents with Chemical Probes

The growing number of fungal infections caused by pathogens resistant to one or more classes of antifungal drugs emphasizes the threat that these microorganisms pose to animal and human health and global food security. Open questions remain regarding the mechanisms of action of the limited repertoire of antifungal agents, making it challenging to rationally develop more efficacious therapeutics. In recent years, the use of chemical biology approaches has resolved some of these questions and has provided new promising concepts to guide the design of antifungal agents. By focusing on examples from studies carried out in recent years, this minireview describes the key roles that probes based on antifungal agents and their derivatives have played in uncovering details about their activities, in detecting resistance, and in characterizing the interactions between these agents and their targets.     

Green Synthesis,Antibacterial, and Antifungal Activities of 1,3,4‐Oxadiazines

1,3,4‐Oxadiazine derivatives were prepared via green and more sustainable procedure employing Grinding Chemistry. The green context of the procedure was evaluated by comparing its components with that of the conventional one. The antibacterial and antifungal activities of all the synthesized compounds were evaluated against some bacterial and fungal strains and showed promising results. The structures of the resulted compounds were identified and confirmed by elemental analysis and mass, ¹H‐NMR, and ¹³C‐NMR spectroscopies.     

Chemical Constituents and Biological Activities of the Leaves of Knema saxatilis

Chemistry of Natural Compounds -     

Chemical Constituents and Cytotoxic Activities of Stem Bark of Dialium cochinchinense

Chemistry of Natural Compounds -     

Chemical Constituents of Two Liverworts Metacalypogeia Alternifolia and Chandonanthus Hirtellus

A novel linear dihydrodichromene derivative, metacalypogin, was identified from the Taiwanese liverwort Metacalypogeia alternifolia. Together with data from M. cordifolia, the chemical marker of the genus Metacalypogeia is obvious chroman derivatives, which is far different from that of Calypogeia, the other genus in the same family. In addition, two isomeric diterpenoids of cembrane‐type were identified from the Chinese liverwort Chandonanthus hirtellus. The relative stereostructures of the latter two isomers were proved by X‐ray crystallography. Both compounds were unstable in chloroform solution and further oxidized to the corresponding peroxy hemiacetal derivatives.