Antibacterial, Mutagenic Properties and Chemical Characterisation of Sugar Bush (Protea caffra Meisn.): A South African Native Shrub Species

In vitro Antibacterial Activity and Secondary Metabolite Profiling of Endolichenic Fungi Isolated from Genus Parmotrema

The endolichenic fungi are an unexplored group of organisms for the production of bioactive secondary metabolites. The aim of the present study is to determine the antibacterial potential of endolichenic fungi isolated from genus Parmotrema. The study is continuation of our previous work, wherein a total of 73 endolichenic fungi were isolated from the lichenized fungi, which resulted in 47 species under 23 genera. All the isolated endolichenic fungi were screened for preliminary antibacterial activity. Five endolichenic fungi-Daldinia eschscholtzii, Nemania diffusa, Preussia sp., Trichoderma sp. and Xylaria feejeensis, were selected for further antibacterial activity by disc diffusion method. The zone of inhibition ranged from 14.3 ± 0.1 to 23.2 ± 0.1. The chemical composition of the selected endolichenic fungi was analysed through GC-MS, which yielded a total of 108 compounds from all the selected five endolichenic fungi. Diethyl phthalate, 1-hexadecanol, dibutyl phthalate, n-tetracosanol-1, 1-nonadecene, pyrrol[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methyl) and tetratetracontane were found to be common compounds among one or the other endolichenic fungi, which possibly were responsible for antibacterial activity. GC-MS data were further analysed through Principal Component Analysis which showed D. eschscholtzii to be with unique pattern of expression of metabolites. Compound confirmation test revealed coumaric acid to be responsible for antibacterial activity in D. eschscholtzii. So, the study proves that endolichenic fungi that inhabit lichenized fungal thalli could be a source of potential antibacterial compounds.

A Review of Phytochemicals and Bioactive Properties in the Proteaceae Family: A Promising Source of Functional Food

In recent decades, natural plant-based foods have been increasingly used to improve human health due to unhealthy modern dietary patterns, such as the consumption of foods high in sugar and fat. Many indigenous species have been used by Aboriginal peoples for their food and therapeutic properties. Thus, it is important to understand the health-enhancing bioactive profile of Australian indigenous species. The Proteaceae family, such as the genera of Protea, Macadamia, and Grevillea, have been commercially used in the horticulture and food industries. Researchers have reported some findings about Persoonia species, one of the genera in the Proteaceae family. The aim of this review was to provide an overview of the family Proteaceae and the genus Persoonia, including distribution, traditional and commercial uses, phytochemicals, bioactive properties, potential opportunities, and challenges. In this review, bioactive compounds and their properties related to the health benefits of the Proteaceae family, particularly the Persoonia genus, were reviewed for potential applications in the food industry.

Unveiling the Pharmacological Significance of Marine Streptomyces violaceusniger KS20: Isolation, Characterization, and Assessment of Its Biomedical Applications

Marine actinomycetes represent a highly favorable source of bioactive compounds and have been the mainstay of much research in recent years. Recent reports have shown that marine Streptomyces sp. can produce compounds with diverse and potent biological activities. Therefore, the key objective of the study was to isolate and screen a potential actinomycete from marine ecosystems of Devbagh and Tilmati beaches, Karwar. Streptomyces sp. KS20 was characterized and the ethyl acetate extract (EtOAc-Ex) was screened for biomedical applications. Streptomyces sp. KS20 produced grayish-white aerial and pale-yellow substrate mycelia and revealed an ancestral relationship with Streptomyces violaceusniger. Optimum growth of the organism was recorded at 30 °C and pH 7.0. The metabolite profiling of EtOAc-Ex expressed the existence of several bioactive metabolites, whereas the functional groups were indicated by Fourier transform infrared (FTIR) spectroscopy. A considerable antioxidant activity was shown for EtOAc-Ex with IC50 of 92.56 μg/mL. In addition to this, Streptomyces sp. KS20 exhibited significant antimicrobial properties, particularly against Escherichia coli, where a zone of inhibition measuring 36 ± 0.83 mm and a minimum inhibitory concentration (MIC) of 3.12 µg/mL were observed. The EtOAc-Ex even revealed significant antimycobacterial potency with IC50 of 6.25 μg/mL. Finally, the antiproliferative potentiality of EtOAc-Ex against A549 and PC-3 cell lines revealed a constant decline in cell viability while raising the concentration of EtOAc-Ex from 12.5 to 200 μg/mL. The IC50 values were determined as 94.73 μg/mL and 121.12 μg/mL for A549 and PC-3 cell lines, respectively. Overall, the exploration of secondary metabolites from marine Streptomyces sp. KS20 represents an exciting area of further research with the potential to discover novel bioactive compounds that could be developed into therapeutics for various medical applications.

Physicochemical Characterization and Antimicrobial Activity against Erwinia amylovora, Erwinia vitivora, and Diplodia seriata of a Light Purple Hibiscus syriacus L. Cultivar

Phytochemicals are essential raw materials for the production of formulations that can be helpful in crop protection. In particular, Hibiscus spp., which are often used in traditional medicine, are rich in potential bioactive molecules. This study presents an analysis of the thermal, vibrational, and phytochemical characteristics of a light purple variety of Hibiscus syriacus, using thermal gravimetric and differential scanning calorimetry, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectroscopy techniques. Further, with a view to its valorization, the antimicrobial activity of its extracts has been investigated in vitro against Erwinia amylovora (the phytopathogen responsible for fire blight in apples, pears, and some other members of the family Rosaceae), Erwinia vitivora (the causal agent of the "maladie d'Oléron" in grapevines), and Diplodia seriata (responsible for "Bot canker"). Higher heating values and thermal features showed similarities with kenaf biomass. The main compounds identified in the hydro-methanolic extracts were: in flowers, 1-heptacosanol, heptacosane, 1-tetracosanol, hexadecenoic acid, 9,12,15-octadecatrienoic acid, and 9,12-octadecadienoic acid; and in leaves, the coumarin derivative 4,4,6,8-tetramethyl-2-chromanone, vitamin E, phytol, and sitosterol. MIC values of 500 and 375 μg·mL^-1 were obtained against E. amylovora for flower and leaf extracts, respectively, upon conjugation with chitosan oligomers (to improve solubility and bioavailability). In the case of E. vitivora, MIC values of 250 and 500 μg·mL^-1, respectively, were registered. Regarding the antifungal activity, EC₉₀ values of 975.8 and 603.5 μg·mL^-1, respectively, were found. These findings suggest that H. syriacus (cv. 'Mathilde') may be a promising source of antimicrobials for agriculture.