Anti-inflammatory and analgesic activities of Feijoa sellowiana Berg. leaves and investigation of their phenolic constituents

Pineapple guava (Acca or Feijoa sellowiana) is a bushy shrub relative of the tropical guava [1,2]. There are many Feijoa industrialized products on the market in the form of jam, syrup, or crystallized fruits [2]. Previous few studies on the leaf, fruit and stem extracts of F. sellowiana showed antimicrobial, antitumoral, immunomodulatory and antioxidant effects [3–6]. However few phytochemical studies were reported on different parts of this plant [7,8], e.g. flavonoids [9], volatile components [10, 11], lipids [2] and tannins [12]. We report herein an extensive phytochemical study on the 70% methanol extract of the leaves of F. sellowiana cultivated in Egypt, in which twelve phenolic metabolites were isolated. The structures were elucidated as nilocitin (1), 4,6-hexahydroxydiphenoyl-β-D-⁴C₁-glucopyranose (2), castalagin (3), ellagic acid (4), ellagic acid pentoside (5), ellagic acid β-D-⁴C₁-glucopyranose (6), 3-methoxyellagic acid 3'-sulphate (7), trimethoxyellagic acid sulphate (8), methylflavogallonyl sulphate (9), avicularin (10), quercitrin (11) and hyperin (12), on the basis of chromatographic, chemical and spectroscopic evidences (UV, HRESI-MS and NMR). The investigated extract was orally non-toxic to mice up to 5g/kg body weight (max. soluble dose). In a dose dependant manner (250, 500 and 1000mg/kg b. wt.), it exhibited significant analgesic effect using both chemical and thermal stimulus. The extract showed significant anti-inflammatory effect by measuring the decrease in paw volume as compared to control. No pharmacological studies were performed on the isolated compounds.

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