Extraction and evaluation of eugenol from Syzgium aromaticum as topical anesthetic for toothaches

Objective — this study intends to extract and identify the eugenol from Syzgium aromaticum and evaluate its analgesic effects in laboratory animals and clinically in volunteer patients suffering from toothaches. Materials and methods. Direct stem distillation was used to extract eugenol from cloves, followed by chemical extractions. The extracted products were identified by thin-layer chromatography (TLC) and 1H NMR spectroscopy, and tested clinically in 51 volunteer patients suffered from acute toothache. Those patients was divided into 3 equal groups: patients of the first (control) group (G1) was given the hydroxypropyl methylcellulose (HPMC) gel mixed with distilled water — placebo; patients of the second group (G2) received the prepared clove gel — eugenol previously extracted (2% in HPMC); patients of the third group (G3) received commercial “Orajel” containing benzocaine 10%. The patients were advised to apply a small amount of gel the size of a chickpea into the tooth cavity or the toothache area. Results. Eugenol was extracted as bright yellow oil (about 2.02 g, 5% recovery) with a solid particular clove smell from the clove. TLC revealed various Rf value spots ranging between 0.6 and 0.9. The 1H NMR spectroscopy showed various analysis data, including 3.28—3.32 (3H), 5.5 (1H, C=C—H), 5.9 (aromatic 2H), and 6.6 (aromatics). All patients in G1 exhibited continuous toothache pain. In contrast, within G2 and G3, 14 (82%) and 15 (88%) of subjects, respectively, reported a reduction in toothache intensity within a 5-minute timeframe. The majority of patients in both G2 and G3, 13 (76%) and 12 (71%) patients, respectively, experienced a duration of pain relief of 72 hours. Conclusion. Clove-extracted products are as effective as benzocaine when used as intraoral topical anesthesia. The authors recommend future studies to investigate the analgesic effects mechanism of clove extract.