Anti-inflammatory effects of compounds from Kaempferia parviflora and Boesenbergia pandurata

Kaempferia parviflora and Boesenbergia pandurata are perennial herbs in the Zingiberaceae family. The rhizomes of these two plants have been used as food ingredients and in Thai traditional medicine for treatment of several inflammatory-related diseases, such as gout, allergy, apthous ulcer and peptic ulcer. The compounds isolated from the rhizomes of K. parviflora and B. pandurata were, therefore, examined for their inhibitory activities against nitric oxide (NO) production. For K. parviflora, compound 5 (5-hydroxy-3,7,3′,4′-tetramethoxyflavone) exhibited the highest activity against the NO inhibitory effect, with an IC₅₀ value of 16.1 μM, followed by 4 (IC₅₀ = 24.5 μM) and 3 (IC₅₀ = 30.6 μM). Regarding the NO inhibitory activity of B. pandurata, compound 2 (panduratin A) displayed the most potent effect with an IC₅₀ value of 5.3 μM, followed by 3 (hydroxypanduratin A, IC₅₀ = 13.3 μM) and 7 (cardamonin, IC₅₀ = 24.7 μM), respectively. The 5-hydroxy-3,7,3′,4′-tetramethoxyflavone (5), panduratin A (2) and hydroxypanduratin A (3), were also tested on prostaglandin E₂ (PGE₂) and tumour necrosis factor-alpha (TNF-α) production. 5-Hydroxy-3,7,3′,4′-tetramethoxyflavone (5) exhibited a potent inhibitory effect on PGE₂ production (IC₅₀ = 16.3 μM), but a mild effect on TNF-α (IC₅₀ > 100 μM). Panduratin A and hydroxypanduratin A showed strong activity against PGE₂ with IC₅₀ values of 10.5 and 12.3 μM, respectively, and a moderate effect on TNF-α (IC₅₀ = 60.3 and 57.3 μM, respectively). This study indicated that compound 5 (5-hydroxy-3,7,3′,4′-tetramethoxyflavone) is responsible for anti-inflammatory activity of K. parviflora, while 2 (panduratin A) and 3 (hydroxypanduratin A), the prenylated chalcones, are responsible for that of B. pandurata.