The palmarumycins are fungal metabolites isolated from Coniothyrium and Sphaeropsidales sp. with antifungal, antibacterial, antitumor and herbicidal properties. Palmarumycin C3 is a yellow-green pigment which inhibits Ras farnesyl-protein transferase. Palmarumycin C3 is a more potent antimicrobial agent against A. tumefaciens, B. subtilis, P. lachrymans, R. solanacearum, S. haemolyticus, X. vesicatoria and M. oryzae than its dehydroxy analog palmarumycin C2, with MICs in the range of 6 – 13 µg/mL. Palmarumycin C3 is a weak inhibitor of spore germination of M. oryzae and a modest antioxidant in DPPH radical scavenging and β-carotene/linoleic acid bleaching capacity assays.