The high mortality rate of immunocompromised patients with fungal infections and the limited availability of highly efficacious and safe agents demand the development of new antifungal therapeutics. To rapidly discover such agents, we developed a high-throughput synergy screening (HTSS) strategy for novel microbial natural products. Specifically, a microbial natural product library was screened for hits that synergize the effect of a low dosage of ketoconazole (KTC) that alone shows little detectable fungicidal activity. Through screening of Ϸ20,000 microbial extracts, 12 hits were identified with broadspectrum antifungal activity. Seven of them showed little cytotoxicity against human hepatoma cells. Fractionation of the active extracts revealed beauvericin (BEA) as the most potent component, because it dramatically synergized KTC activity against diverse fungal pathogens by a checkerboard assay. Significantly, in our immunocompromised mouse model, combinations of BEA (0.5 mg/kg) and KTC (0.5 mg/kg) prolonged survival of the host infected with Candida parapsilosis and reduced fungal colony counts in animal organs including kidneys, lungs, and brains. Such an effect was not achieved even with the high dose of 50 mg/kg KTC. These data support synergism between BEA and KTC and thereby a prospective strategy for antifungal therapy.antifungal ͉ beauvericin ͉ ketoconazole

Andrographolide derivatives or analogs exhibit potent anti-inflammatory effects in several disease models through NF-κB activity. In this study, we synthesized different andrographolide derivatives and investigated their effects on the toll-like receptor (TLR)-induced production of pro-inflammatory cytokines. Among these compounds, 3b, 5a, and 5b inhibited both TNF-α/NF-κB and TLR4/NF-κB signaling pathways. Treatment with compounds 3b, 5a, and 5b and their structural analogs, 3a and 6b, suppressed the expression of pro-inflammatory cytokines upon the activation of TLR3 and TLR4 ligands. Compounds 3b and 5a, but not 3a, 5b, or 6b, inhibited the nuclear translocation of the NF-κB p65 subunit. Treatment with compounds 3b, 5a, 3a, 5b, and 6b attenuated the phosphorylation of p65 and IκBα. Compounds 6b suppressed the expression of the NF-κB p65 subunit. However, these compounds, except for 5b, did not affect the TLR9-induced NF-κB-independent production of the pro-inflammatory cytokines, TNF-α, and IFN-β. Compound 3b potentially protected mice from LPS-induced acute pulmonary inflammation through the inhibition of p65 phosphorylation and the decrease of serum pro-inflammatory cytokines and chemokine. Our study revealed a functional structure–activity relationship between andrographolide derivatives and innate immunity. We identified compound 3b as a potent immune suppressive agent with the potential to protect acute pulmonary infection.

Some 14β-phenoxy substituted derivatives of andrographolide were designed, synthesized and investigated as FXR novel antagonists.

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