Chemical composition and vasodilator activity of different Alpinia zerumbet leaf extracts, a potential source of bioactive flavonoids

A polyphenol-rich extract with an expressive vasodilator effect was obtained from fresh leaves of Alpinia zerumbet (AZ), a medicinal plant. The vasodilator effects of AZ from different extraction conditions were studied in the perfused mesenteric vascular bed, and total polyphenol content (TPC) was determined for all samples. UHPLC/ESI-QTOF-MS analysis established the chemical composition of AZ extracts, and a molecular network from GNPS (Global Natural Products Social Molecular Networking) generated a list of putative compounds. Briefly, results show a 50% hydroethanolic extract from fresh leaves (AZE4) as the best extraction condition, presenting the greatest vasodilator effect (ED50 = 7.1 +/- 1.7 mu g) and TPC (16.30 mg GAE/g +/- 0.44). Flavonoids are the main constituents and alpinetin, kaempferol-3-O-glucuronide, (-)-epicatechin, and pinocembrin were identified as major compounds. The least effective extraction condition was 50% hydroethanolic extract from dried leaves without heating. This extract showed the smallest vasodilator response (ED50 = 29.1 +/- 4.3 mu g) and TPC (6.35 mg GAE/g +/- 0.08), reinforcing the use of fresh leaves and heating step to improve extracts performance. The vasodilator effect and the main flavonoid composition of AZE4 provide experimental support, suggesting this extract as a potential source of bioactive flavonoids to treat cardiovascular diseases.