Total Synthesis of Suillusin

Comparative Research of Antioxidant, Antimicrobial, Antiprotozoal and Cytotoxic Activities of Edible Suillus sp. Fruiting Body Extracts

The aim of this study was to evaluate bioactive properties of Basidiomycota fungi, mainly Suillus sp. Wide spectrum of activities were revealed for S. variegatus, S. luteus, S. bovinus and S. granulatus; and obtained results were compared with other common fungi. Total Phenolic Content (TPC) varied from 245.32 ± 5.45 to 580.77 ± 13.10 (mg (GAE) per 100 g of dry weight) in methanolic extracts of S. bovinus and S. granulatus fruiting bodies, respectively. In ethyl acetate extracts, the highest TPC were obtained for S. variegatus (310 ± 9.68, mg (GAE)/100 g, dry matter), and the lowest means for S. luteus (105 ± 3.55, mg (GAE)/100 g dry weight). The ethyl acetate extracts of the tested Suillus species exhibited a stronger antioxidant activity (AA) to scavenge DPPH● and ABTS•+ than the methanolic ones, and the highest effects were determined for S. luteus (EC50, 0.15 ± 0.05 and 0.23 ± 0.05%, respectively). In the case of methanolic extracts, the highest AA were evaluated for S. granulatus. (EC50 for DPPH● and ABTS•+, 0.81 ± 0.30 and 0.95 ± 0.22%, respectively). The ABTS•+ scavenging potential varied from 0.25 ± 0.05 to 0.74 ± 0.10 (mmol/L, TROLOX equivalent, for S. granulatus and S. variegatus fruiting body extracts, respectively) in the ethyl acetate extracts. S. granulatus extracts demonstrated the widest range of antimicrobial effects against both gram-positive and gram-negative bacteria (from 11.7 ± 1.3 to 28.5 ± 3.3 mm against Pseudomonas aeruginosa and Bacillus mycoides, respectively); and against two fungal strains (up to 13.6 ± 0.4 mm on Meyerozyma guilliermondii) in agar disc diffusion tests. Our study revealed that methanolic extracts of the most tested Suillus sp. were not active enough against the tested parasites: Trypanosoma cruzi, Trypanosoma brucei, Leishmania infantum and Plasmodium falciparum. Only S. variegatus extracts showed good antiprotozoal effects against P. falciparum (12.70 µg/mL). Cytotoxic activity was observed on human diploid lung cells MRC-5 SV2 by S. granulatus extracts (64.45 µg/mL). For comparative purposes, extracts of other common Lithuanian fungi, such as Xerocomus sp. (X. badius, X. chrysenteron and X. subtomentosus), Tylopilus felleus, Phallus impudicus and Pycnoporus cinnabarinus were investigated for their activity. The P. cinnabarinus extracts demonstrated the highest and broadest overall effects: 1.32 µg/mL against T. brucei, 1.46 µg/mL against P. falciparum, 3.93 µg/mL against T. cruzi and 21.53 µg/mL against L. infantum. Additionally, this extract exhibited strong cytotoxicity on MRC-5 cells (13.05 µg/mL). The investigation of bioactive fungal metabolites is important for the development of a new generation of antioxidants, antimicrobials, antiparasitic and anticancer agents.

Unraveling Plant Natural Chemical Diversity for Drug Discovery Purposes

The screening and testing of extracts against a variety of pharmacological targets in order to benefit from the immense natural chemical diversity is a concern in many laboratories worldwide. And several successes have been recorded in finding new actives in natural products, some of which have become new drugs or new sources of inspiration for drugs. But in view of the vast amount of research on the subject, it is surprising that not more drug candidates were found. In our view, it is fundamental to reflect upon the approaches of such drug discovery programs and the technical processes that are used, along with their inherent difficulties and biases. Based on an extensive survey of recent publications, we discuss the origin and the variety of natural chemical diversity as well as the strategies to having the potential to embrace this diversity. It seemed to us that some of the difficulties of the area could be related with the technical approaches that are used, so the present review begins with synthetizing some of the more used discovery strategies, exemplifying some key points, in order to address some of their limitations. It appears that one of the challenges of natural product-based drug discovery programs should be an easier access to renewable sources of plant-derived products. Maximizing the use of the data together with the exploration of chemical diversity while working on reasonable supply of natural product-based entities could be a way to answer this challenge. We suggested alternative ways to access and explore part of this chemical diversity with in vitro cultures. We also reinforced how important it was organizing and making available this worldwide knowledge in an "inventory" of natural products and their sources. And finally, we focused on strategies based on synthetic biology and syntheses that allow reaching industrial scale supply. Approaches based on the opportunities lying in untapped natural plant chemical diversity are also considered.