Marine bacteria have not been examined as extensively as land bacteria. We screened carotenoids from orange or red pigments-producing marine bacteria belonging to rare or novel species. The new acyclic carotenoids with a C₃₀ aglycone, diapolycopenedioc acid xylosylesters A–C and methyl 5-glucosyl-5,6-dihydro-apo-4,4′-lycopenoate, were isolated from the novel Gram-negative bacterium Rubritalea squalenifaciens, which belongs to phylum Verrucomicrobia, as well as the low-GC Gram-positive bacterium Planococcus maritimus strain iso-3 belonging to the class Bacilli, phylum Firmicutes, respectively. The rare monocyclic C₄₀ carotenoids, (3R)-saproxanthin and (3R,2′S)-myxol, were isolated from novel species of Gram-negative bacteria belonging to the family Flavobacteriaceae, phylum Bacteroidetes. In this review, we report the structures and antioxidant activities of these carotenoids, and consider relationships between bacterial phyla and carotenoid structures.

The rhizome of Boesenbergia pandurata Schult. was found to possess potent antioxidant activity in a rat brain homogenate model. Bioassay-guided isolation of the active compounds from a CH2Cl2-MeOH (1:1) extract led to the isolation of 5-hydroxy-7-methoxyflavanone, panduratin A, 5,7-dihydroxyflavanone, 2',6'-dihydroxy-4'-methoxychalcone, 2',4'-dihydroxy-6'-methoxychalcone, and 4-hydroxypanduratin A. Panduratin A, 4-hydroxypanduratin A, and 2',6'-dihydroxy-4'-methoxychalcone were also found to exert neuroprotective effects.

The potent antioxidative sesquiterpene, cacalol, was isolated from Cacalia delphiniifolia Sleb et Zucc, and identified by an analysis of the MS and NMR spectral data. Cacalol showed potent antioxidative activity in a rat brain homogenate model (IC(50) of 40 nM). Cacalol also proved to be a potent neuroprotective substance which could protect neuronal hybridoma N18-RE-105 cells from L-glutamate toxicity.