Study of the dermal anti-inflammatory, antioxidant, and analgesic activity of pinostrobin

Pinostrobin is a flavanone isolated from Renealmia alpinia (Rottb.) Maas, which is used to treat painful diseases and ailments; indigenous peoples use it as plasters. Different plant species have been reported as a source of this flavonoid, among which are: Boesenbergia rotunda, Cajanus cajan, Piper ecuadorense, Piper hispidum, Teloxys graveolens, Kaempferia pandurata, among others. Pinostrobin expresses potentially useful biological activities such as antioxidant, analgesic, and dermal anti-inflammatory, at low levels nonetheless due to its low solubility. The formation of inclusion complexes deems a good strategy to improve the pharmacologic effects of many substances. In the present work, we evaluated the dermal toxicity, analgesic and dermal anti-inflammatory activity of pinostrobin included in cyclodextrins, to improve those effects on experimental animals. To include pinostrobin, we used two of beta cyclodextrin (βCD) and hydroxypropil beta cyclodextrin (HPβCD) complexes using two methods developed by Benesi-Hildebrand and Higuchi-Connors. Dermal anti-inflammatory activity was evaluated in experimental mice by inhibiting the edema generated by 12-O-tetradecanoylforbol-13-acetate (TPA). Analgesic activity was evaluated by inducing chemical pain by means of a Siegmund test. Antioxidant activities were measured with two in vitro tests. Analgesic and dermal anti-inflammatory activities of pinostrobin, as included in control and experimental complexes, showed comparatively better effects than pinostrobin without inclusion complexes. Our results indicate that both beta cyclodextrin (βCD) and hydroxypropyl beta cyclodextrin (HPβCD) enhance the different effects of pinostrobin, which may indicate greater bioavailability.