Anti-Inflammatory Constituents Of Randia Hispida K. Schum (Rubiaceae)

Randia hispida K. Schum (Rubiaceae) is a medicinal plant used by the Ijaws of the Niger Delta area in the southern part of Nigeria for the treatment of inflammation and pyrexia. The plant was extracted sequentially using n-hexane, dichloromethane and 70% methanol. Acute toxicity tests of the extracts were carried out using Lorkes method [1] and LD50 of the extracts were determined for n-hexane (866.02 mg/Kg), dichloromethane (1620.19 mg/kg) and methanolic extracts (2371.7 mg/kg). The anti-inflammatory studies were carried out using xylene-induced ear oedema in mice [2, 3] and egg albumin-induced paw oedema in rats [4]. The extracts were screened at various doses; n-hexane (86.60, 173.21, and 259.81 mg/kg), dichloromethane (162.02, 324.04 and 486.06 mg/kg), and methanolic extracts (237.17, 474.34 and 711.51 mg/kg). The dichloromethane and methanolic extracts displayed equal potency at all the doses used, inhibiting induced edema at 33%, 50% and 67%, the maximum dose showed equal potency with the standard drug dexamethasone (4 mg/kg) which inhibited 67% of xylene -induced inflammation, n-hexane extract gave the least inhibition. On egg albumin induced inflammation in rats, dichloromethane extract showed maximum inhibition of 80.3%, followed by n-hexane 44.9% and methanol extract 35.4%, while the standard drug acetylsalicylic acid 100 mg/kg gave 55.6% inhibition of inflammation.

Fractionation of the dichloromethane extract over silica gel column chromatography and purification using sephadex LH-20 led to the isolation of two triterpenoids: lupenol and an a triterpene acid [5], the structures of the isolated compounds were elucidated using spectroscopic techniques.

References: 1. Lorke, D (1993). A new approach to Practical acute toxicity testing. Arch. of Toxicol 54,275 – 287; 2. Abimboal, S; Femi Samuel et al (2013). Journ of Ethnopharmacol 149,191 – 194; 3 Henriques; MG et al, (1997). Mouse paw edema, a new model for inflammation. Braz Journ of Med, boil. Res. 20,243 – 249; 4. Nunez Guillen et al (1997) Journ of Pharmacog 35,99 – 101; 5. Shashi Mahato and Sucharita Sen (1997) Advances in Triterpenoid Research 1990 – 1994. Phytochem 44(5), 1185 – 1236