Chemical Diversity of Metabolites from Fungi, Cyanobacteria, and Plants Relative to FDA-Approved Anticancer Agents

Abstract

A collaborative project has been undertaken to explore filamentous fungi, cyanobacteria, and tropical plants for anti-cancer drug leads. Through principal component analysis, the chemical space covered by compounds isolated and characterized from these three sources over the last four years was compared to each other and to the chemical space of selected FDA-approved anticancer drugs. Using literature precedence, nine molecular descriptors were examined: molecular weight, number of chiral centers, number of rotatable bonds, number of acceptor atoms for H-bonds (N,O,F), number of donor atoms for H-bonds (N and O), topological polar surface area using N,O polar contributions, Moriguchi octanol-water partition coefficient, number of nitrogen atoms, and number of oxygen atoms. Four principal components explained 87% of the variation found among 343 bioactive natural products and 96 FDA-approved anticancer drugs. Across the four dimensions, fungal, cyanobacterial and plant isolates occupied both similar and distinct areas of chemical space that collectively aligned well with FDA-approved anticancer agents. Thus, examining three separate re-sources for anticancer drug leads yields compounds that probe chemical space in a complementary fashion.

Figure 1

Plots of the first two principal components of the isolated secondary metabolites from (A) filamentous fungi (n = 105), (B) cyanobacteria (n = 75), and (C) tropical plants (n = 163) relative to anticancer agents (n = 96). Plot D combines the data from all three natural product sources (n = 343) vs anticancer agents (n = 96).

Figure 2

Plot of the first and third principal components of the isolated secondary metabolites from filamentous fungi (n = 105), cyanobacteria (n = 75), tropical plants (n = 163), and anticancer drugs (n = 96).