A new prenylated xanthone, 1,3,5,8-tetrahydroxy-2-(3-methybut-2-enyl)-4-(3,7-dimethylocta-2,6-dienyl) xanthone (1), and a new benzophenone (2), together with four known xanthone derivatives, cheffouxanthone (3), smeathxanthone A (4), smeathxanthone B (5), ananixanthone (6), and two pentacyclic triterpenes, epi-friedelinol (7) and friedelin (8), were isolated from the stem bark of Garcinia smeathmannii. The structures of the compounds were elucidated on the basis of 1D and 2D NMR experiments, and compound 2 was further characterized and confirmed by single X-ray analysis. Compounds 1, 2, and 3 exhibited the most prominent antibacterial activity against gram-positive Enterococcus faecalis with minimal inhibitory concentration values of 8, 8, and 2 µg/mL, respectively, while compounds 1, 3, 4, and 6 showed the capacity to scavenge free radicals.

The search for bioactive natural products from the rhizomes of Paris polyphylla (Trilliaceae) has resulted in the isolation of four known constituents, 1,5-dihydroxy-7-methoxy-3-methylanthraquinone (1), diosgenin-3-O-[α-L-rhamnopyranosyl-(1 → 3)-β-D-glucopyranoside] (2), diosgenin-3-O-[α-L-rhamnopyranosyl-(1_Rha → 2_Glu)-α-L-arabinofuranosyl-(1_Ara → 4_Glu)]-β-D-glucopyranoside (3), and diosgenin-3-O-[α-L-rhamnopyranosyl-(1_Rha → 2_Glu)-α-L-rhamnopyranosyl-(1_Ara → 4_Glu)]-β-D-glucopyranoside (4). Their structures were identified by spectral comparison with the reported data. Compound 1 was isolated for the first time from this genus. The chloroform, ethyl acetate, and butanol extracts of the plant were found to have mild to moderate inhibitory potentials against the enzyme tyrosinase. Compound 1 showed strong (IC₅₀ = 0.23 µM), while compounds 2–4 and hydrolyzed product 4a showed mild to moderate (IC₅₀ = 0.93–36.87 µM) activities against the tyrosinase. Similarly, compounds 2–4 and 4a showed mild to moderate (IC₅₀ = 1.59–83.72 µg mL⁻¹) antileishmanial activities.