Antifungal activity of selected Malassezia indolic compounds detected in culture

Antimicrobial activity of natural and semi-synthetic carbazole alkaloids

Since the first natural carbazole alkaloid, murrayanine, was isolated from Mwraya Spreng, carbazole alkaloid derivatives have been widely concerned for their anti-tumor, anti-viral and anti-bacterial activities. In recent decades, a growing body of data suggest that carbazole alkaloids and their derivatives have different biological activities. This is the first comprehensive description of the antifungal and antibacterial activities of carbazole alkaloids in the past decade (2012-2022), including natural and partially synthesized carbazole alkaloids in the past decade. Finally, the challenges and problems faced by this kind of alkaloids are summarized. This paper will be helpful for further exploration of this kind of alkaloids.

Bioprospecting the Skin Microbiome: Advances in Therapeutics and Personal Care Products

Bioprospecting is the discovery and exploration of biological diversity found within organisms, genetic elements or produced compounds with prospective commercial or therapeutic applications. The human skin is an ecological niche which harbours a rich and compositional diversity microbiome stemming from the multifactorial interactions between the host and microbiota facilitated by exploitable effector compounds. Advances in the understanding of microbial colonisation mechanisms alongside species and strain interactions have revealed a novel chemical and biological understanding which displays applicative potential. Studies elucidating the organismal interfaces and concomitant understanding of the central processes of skin biology have begun to unravel a potential wealth of molecules which can exploited for their proposed functions. A variety of skin-microbiome-derived compounds display prospective therapeutic applications, ranging from antioncogenic agents relevant in skin cancer therapy to treatment strategies for antimicrobial-resistant bacterial and fungal infections. Considerable opportunities have emerged for the translation to personal care products, such as topical agents to mitigate various skin conditions such as acne and eczema. Adjacent compound developments have focused on cosmetic applications such as reducing skin ageing and its associated changes to skin properties and the microbiome. The skin microbiome contains a wealth of prospective compounds with therapeutic and commercial applications; however, considerable work is required for the translation of in vitro findings to relevant in vivo models to ensure translatability.

Marine Alkaloid Pityriacitrin and Its Analogues: Discovery, Structures, Synthetic Methods and Biological Properties

Pityriacitrin is a natural marine alkaloid with a typical β-carboline scaffold, and which has been demonstrated to exhibit diverse biological functions. The special structural features for pityriacitrin lead to the increasing research interest and the emergence of versatile derivatives, and many pityriacitrin analogues have been isolated or synthesized over the past decades. The structural diversity and evolved biological activity of these natural alkaloids can offer opportunities for the development of highly potential novel drugs with a new mechanism of action, and therefore, the aim of this brief review is to describe the discovery, synthesis, and biological properties of natural pityriacitrin and its derivatives, as well as the isolation source.

Expeditious Approach to Indoloquinazolinones via Double Annulations of o-Aminoacetophenones and Isocyanates

A novel procedure for a one-pot cascade reaction of o-aminoacetophenones and aryl/aliphatic isocyanates catalyzed/oxidized by the [Pd]/[Ag] system was developed. The reaction involves two C-N bond and one C-C bond formations during the double annulation process and the desired indoloquinazolinones and derivatives were afforded up to 81% yields from readily available substrates with a tolerance of a broad variety.

Natural alkaloid tryptanthrin exhibits novel anticryptococcal activity

Cryptococcal meningitis is a prevalent invasive fungal infection that causes around 180 000 deaths annually. Currently, treatment for cryptococcal meningitis is limited and new therapeutic options are needed. Historically, medicinal plants are used to treat infectious and inflammatory skin infections. Tryptanthrin is a natural product commonly found in these plants. In this study, we demonstrated that tryptanthrin had antifungal activity with minimum inhibitory concentration (MIC) of 2 μg/ml against Cryptococcus species and of 8 μg/ml against Trichophyton rubrum. Further analysis demonstrated that tryptanthrin exerted fungistatic and potent antifungal activity at elevated temperature. In addition, tryptanthrin exhibited a synergistic effect with the calcineurin inhibitors FK506 and cyclosporine A against Cryptococcus neoformans. Furthermore, our data showed that tryptanthrin induced cell cycle arrest at the G1/S phase by regulating the expression of genes encoding cyclins and the SBF/MBF complex (CLN1, MBS1, PCL1, and WHI5) in C. neoformans. Screening of a C. neoformans mutant library further revealed that tryptanthrin was associated with various transporters and signaling pathways such as the calcium transporter (Pmc1) and protein kinase A signaling pathway. In conclusion, tryptanthrin exerted novel antifungal activity against Cryptococcus species through a mechanism that interferes with the cell cycle and signaling pathways.

LAY SUMMARY

The natural product tryptanthrin had antifungal activity against Cryptococcus species by interfering cell cycle and exerted synergistic effects with immunosuppressants FK506 and cyclosporine A. Our findings suggest that tryptanthrin may be a potential drug or adjuvant for the treatment of cryptococcosis.