EXTRACTION OF URSOLIC ACID FROM OCIMUM SANCTUM AND SYNTHESIS OF ITS DERIVATIVES: COMPARATIVE EVALUATION OF ANTI-OXIDANT ACTIVITIES

The objective of this study was to extract ursolic acid (UA) from Ocimum sanctum, to synthesize its derivatives and to examine the improvement of the antioxidative activity. Present work involved structural modification of UA at the C-3 and C-28 positions. UA derivatives, namely UA-4 and UA-7 with distinct property were synthesized. Comparative evaluation of antioxidant activity of UA, UA-4 and UA-7 using in-vitro assays and lymphocyte model system involved: (i) inhibition of liposomal lipid peroxidation by UA and its derivatives (ii) assessment of trolox equivalent antioxidative capacity (TEAC) (iii) ABTS and DPPH radicals scavenging ability and (iv) cell death (MTT assay) under hydrogen peroxide (H₂O₂) induced oxidative stress. A moderate increase in antioxidant activity of compound UA-4 compared to UA was observed. In contrast, significant improvement in the antioxidant activity of UA-7 was observed. To evaluate antioxidant effects on lymphocytes, we exposed cells with UA and its derivatives along with hydrogen peroxide. This was followed by measurement of cell viability by trypan blue exclusion assay and cell death using MTT assay. UA-7 significantly protected lymphocytes against H₂O₂ induced oxidative stress. In conclusion, we propose that UA might be chemically modified to increase its antioxidant potential. Our studies also clearly showed that UA derivatives significantly decreased hydrogen peroxide-induced cell death due to the mitigation of oxidative injury.