Chemical analysis and antioxidant, anti-inflammatory and toxicological evaluations of the hydromethanolic extract of Psidium guineense Swartz leaves

Abstract

Ethnopharmacological relevance: Psidium guineense, popularly known as "araçá-do-campo", is used in popular medicine for the treatment of inflammatory diseases. Our research group studied an essential oil obtained from its leaves and reported anti-inflammatory and analgesic properties. However, to date, the anti-inflammatory actions of the leaf extract have not been evaluated although the traditional folk use of this plant has these indications.

Aim of study: The current study was designed to evaluate the antioxidant and anti-inflammatory effects and toxicity of the hydromethanolic extract of the leaves from P. guineense (HME-PG), as well as to investigate the chemical composition.

Materials and methods: HME-PG was chemically investigated by Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The antioxidant activity was evaluated with 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and malondialdehyde (MDA). Swiss mice were orally (p.o.) pretreated with HME-PG (30, 100 and 300 mg/kg), and after 1 h received carrageenan via paw injection (edema, cold sensitivity and mechanical hyperalgesia were analyzed) or pleural injection (leukocyte migration was analyzed after 4 h) and for nociception using the formalin model. Acute (14 days) and subacute (28 days) toxicity was assessed with female Wistar rats orally treated with 500 and 2000 mg/kg HME-PG.

Results: HME-PG showed high levels of phenolic and flavonoid compounds. Six compounds were identified based on UHPLC-MS/MS analysis, including gallic acid, quercetin, 3'-formyl-2',4',6'-trihydroxy-5'-methyldihydrochalcone, vanillic acid, ursolic acid and corilagin. HME-PG exhibited an IC₅₀ of 48.14 μg/mL in the MDA assay and an IC₅₀ of 45.15 μg/mL in the DPPH test. The treatment with HME-PG (100 and 300 mg/kg) significantly inhibited edema at all time points evaluated, mechanical hyperalgesia after 4 h and the response to cold 3 and 4 h after carrageenan injection and anti-nociceptive effects in both phases of formalin nociception. All oral HME-PG treatments significantly inhibited leukocyte migration and plasma extravasation in the pleurisy model. Toxicity tests did not cause signs of toxicity in the treated animals.

Conclusions: The present study showed that HME-PG has antioxidant and anti-inflammatory properties, and no toxicity was detected after acute or subacute treatment with HME-PG, showing the possibility for the safe traditional use of P. guineense.

Keywords: Araçá-do-campo; Hyperalgesia; Leukocyte; Nociception; Oedema; Phytochemical analysis; Toxicity.