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Chemical investigation of the tubers of Sinningia reitzii led to the isolation of five new naphthoquinones, 8-hydroxydehydrodunnione (1), 7-hydroxydehydrodunnione (2), 5-hydroxy-6,7-dimethoxy-α-dunnione (3), 5-hydroxy-6,7-dimethoxydunniol (4), and 8-hydroxy-7-methoxy-2-O-methylstreptocarpone (5). Three known naphthoquinones, 7-hydroxy-α-dunnione, 8-hydroxydunnione, and 6,8-dihydroxy-7-methoxy-2-O-methyldunniol, were also identified. When tested for anti-inflammatory activity in a mouse model, compound 1 (50-500 pg/paw) reduced the edema induced by carrageenan in a dose-dependent fashion. The highest dose showed a similar inhibition to that observed for the positive control dexamethasone. At lower doses (5-10 pg/paw), 1 also dose dependently reduced the mechanical hyperalgesia induced by carrageenan. Compound 1 (15 pg/paw) abolished the mechanical hyperalgesia induced by prostaglandin E and dopamine, but not that induced by dibutyryl cyclic AMP. Dipyrone (320 μg/paw) completely abolished the hyperalgesia induced by these algogens. Additionally, compound 1 did not alter heat-induced nociception. These results suggest that this new naphthoquinone exhibits important anti-inflammatory and antinociceptive activities, which is dissimilar to that of most known analgesics.

This study investigated the antinociceptive and anti-inflammatory activities of the ethanolic extract (EESAl), fractions and the compound 8-methoxylapachenol (8ML) obtained from the tubers of Sinningia allagophylla. Male Swiss mice were treated with EESAl (3-300 mg/kg) or vehicle by oral route (p.o.) 1 hr before the injection of formalin 2.5% or carrageenan (Cg) into the hind paw. EESAl (3-30 mg/kg) reduced the inflammatory phase of the nociceptive behaviour induced by formalin (around 65% for all doses). EESAl (3-300 mg/kg, p.o.) also reduced Cg-induced mechanical hyperalgesia and oedema in a dose-dependent fashion but did not change the hot-plate latency or the motor performance of the animals. Oral administration of petroleum ether fraction (PE, 3 mg/kg), but not in the methanolic fraction (30 mg/kg), reduced both Cg-induced oedema and hyperalgesia. Compound 8ML isolated from PE (1.8 mg/kg, p.o.) abolished Cg-induced hyperalgesia but also did not change hotplate latency or motor performance of the animals. 8ML administration into the paw (0.75-750 pg) dose-dependently reduced Cg-induced hyperalgesia. 8ML (750 pg) also blocked the hyperalgesia induced by tumour necrosis factor (TNF-a), interleukin1b (IL-1b) and prostaglandin E 2 (PGE 2 ) but failed to change the hyperalgesia induced by cytokine-induced neutrophil chemoattractant-1 (CINC-1) and dopamine (Dopa). These results suggest that EESAl has an important antinociceptive and anti-inflammatory activity, the former one related, at least in part, to the reduction in the hyperalgesia. Similarly, 8ML reduced Cg-induced oedema and mechanical hyperalgesia and seems to act in peripheral sites and on the prostaglandin rather than on the sympathetic component of the Cg-inflammatory hyperalgesia.Gesneriaceae is a pantropical family of ornamental plants, with 135 genera, among these Sinningia. Sinningia genus comprises 68 species, distributed in South America, mainly in Brazil [1]. Sinningia allagophylla (Martius) Wiehler is a shrub species with the popular names of clove field, field-potato or potato-of-Partridge and is considered medicinal in Brazil. The tubers are used as an emollient and tonic, while the flowers and leaves are used as febrifuge, diuretic and cleanser [2].Studies on chemical composition of Sinningia species showed the presence of flavonoids on Sinningia cardinalis [3], ethylcyclohexane derivatives and anthraquinones in Sinningia speciosa [4] and anthraquinones and aromatic compounds with a new skeleton named aggregatins A-D in Sinningia aggregata [5]. In Sinningia allagophylla, lapachenol, 8ML, anthraquinones and naphthoquinones were found [6]. Naphthoquinones and anthraquinones are classes of natural compounds commonly associated with anti-inflammatory and antinociceptive properties. For example, vitamin K3 derivatives, plumbagin and emodin among others, are known naphthoquinones and anthraquinones, which share these properties [7][8][9].Traditionally, non-steroidal anti-inflammatory drugs are the class of compounds most widely used to t...

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