Antihepatotoxic and Antioxidant Activities of the Rwandan Botanicals, Ocimum lamiifolium and Crassocephalum vitellinum. Composition of their Essential Oils

The treatment of liver diseases with Rwandan botanicals occupies an important place in Rwandese traditional medicine and several plants or combinations of plants, among which Crassocephalum vitellinum and Ocimum lamiifolium leaves, are used by the traditional healers. The present work investigates the claimed antihepatotoxic and antioxidant activities of leave polar extracts, comparing to N-acetylcysteine (reference antihepatotoxicant) and both quercetin and Trolox (reference antioxidants). In order to evaluate the direct and protective effects of C. vitellinum and O. lamiifolium methanolic extracts on liver, rats precision cut liver slices (PCLS) were prepared and incubated in a Williams medium E with 1, 2, 5, 10 mg/ml of the extract either alone or in the presence of acetaminophen (hepatotoxicant, 10 mM). The measurement of ATP level and CYP2E1 activity were used as endpoints to assess liver toxicity and metabolic activity. Chlorzoxazone was used as a probe to assess CYP2E1 enzymatic activity and the metabolite 6-OH-chlorzoxazone formation was quantified by HPLC [1]. In addition to a significant hepatoprotective activity (1 mg/ml), the methanolic extracts of C. vitellinum and Ocimum lamiifolium leaves strongly scavenged the stable radical 1, 1-diphenyl-2-picryhydrazyl (DPPH) and reduced the peroxidation of linoleic acid. The essential oil was isolated by hydrodistillation (0.046% w/w yield for C. vitellinum and 0.077% w/w yied for O. lamiifolium) and analyzed with GC and GC/MS [2,3,4,5]. Identified predominating constituents of C. vitellinum oil are respectively limonene (34.8%), (E)-β-ocimene (21.8%), β-pinene (8.5%), α-pinene (6.6%),myrcene (6.3%) and β-phellandrene (5.5%) and the identified predominating constituents of O. lamiifolium oil are represented by sabinène (12.24%) and alpha phellandrène (11.62%). References: [1] Evdokinova E, et al. (2001) Toxicology in vitro 15: 683–690. [2] Dool HVD, Krats PD (1963) J. Chromatogr. 11: 463–471. [3] McLafferty FW, Stauffer DB (1989) The Wiley NBS registry of Mass Spectral Data. 2nd Edition. J.’Wiley and Son. NY [4] Adams RP (2001) Identification of Essential Oil Components by Gas chromatrography/Quadrupole Mass Spectroscopy. Allured Publishing corp., Carol Stream, IL. [5] Joulain D, König WA (1998) The Atlas of Spectral Data of Sesquiterpene Hydrocarbons. E.B. Verlag, Hamburg.