Evaluation of extraction protocols for anti-diabetic phytochemical substances from medicinal plants

Abstract

Author contributions: Okoduwa SIR and Umar IA got the concept and design of the study; Okoduwa SIR and Habila JD perform the study and data analysis; James DB, Inuwa HM and Habila JD participated in the interpretation of data; Okoduwa SIR wrote the first version of the manuscript; Umar IA, James DB, Inuwa HM and Habila JD critically revised the manuscript for important intellectual content; all the authors read and gave a final approval of the revised version of the manuscript to be published. Abstract AIM To examine the efficacy of three extraction techniques: Soxhlet-extraction (SE), cold-maceration (CM) and micro-wave-assisted-extraction (MAE) using 80% methanol as solvent. METHODS The study was performed on each of 50 g of Vernonia amygdalina (VA) and Occimum gratissimum (OG) leaves respectively. The percentage yield, duration of extraction, volume of solvent used, qualitative and quantitative phytoconstituents present was compared. The biological activities (hypoglycemic effect) were investigated using albino wistar rat model of diabetes mellitus (n = 36) with a combined dose (1:1) of the two plants leaf ex-tracts (250 mg/kg b.w.) from the three methods. The December 15, 2016|Volume 7|Issue 20| WJD|www.wjgnet.com Okoduwa SIR et al . Effect of extraction methods on phytoconstituents extracts were administered orally, once daily for 21 d. RESULTS In this report, the percentage VA extract yield from MAE was highest (20.9% ± 1.05%) within 39 min using 250 mL of solvent, when compared to the CM (14.35% ± 0.28%) within 4320 min using 900 mL of solvent and SE (15.75% ± 0.71%) within 265 min using 500 mL of solvent. The percentage differences in OG extract yield between: MAE vs SE was 41.05%; MAE vs CM was 46.81% and SE vs CM was 9.77%. The qualitative chemical analysis of the two plants showed no difference in the various phytoconstituents tested, but differs quantitatively in the amount of the individual phytoconstituents, as MAE had significantly high yield (P > 0.05) on phenolics, saponins and tannins. SE technique gave significantly high yield (P > 0.05) on alkaloid, while CM gave significant high yield on flavonoids. The extracts from CM exhibited a significantly (P > 0.05) better hypoglycemic activity within the first 14-d of treatment (43.3% ± 3.62%) when compared to MAE (36.5% ± 0.08%) and SE methods (33.3% ± 1.60%). However, the percentage hypoglycemic activity, 21 d post-treatment with 250 mg/kg b.w. extract from MAE was 72.6% ± 1.03% and it was more comparable to 10 mg/kg b.w. glibenclamide treated group (75.0% ± 0.73%), unlike the SE (69.5% ± 0.71%) and CM (69.1% ± 1.03%). CONCLUSION CM technique produces extract with better hypo-glycemic activity, whereas; MAE is a better option for high yield of phytoconstituents using less solvent within a short time. Core tip: Extraction of active phytoconstituents from medicinal plants rely mostly on the use of appropriate extraction method. Different extraction techniques affect the yield and biological activity of phytocomponents. In this study, we observed that microwave assisted extraction produces significantly higher overall extract yield as well as in phenolic, saponin and tannin content. Cold maceration and soxhlet extraction produced higher flavonoid and alkaloid yield respectively. Maceration extracts exhibited significantly better hypoglycemic activities in diabetic rats compared to extracts from soxhlet and microwave assisted extraction. This study reveals that the choice of extraction protocol should depend primarily on the purpose of interest. Okoduwa SIR, Umar IA, James DB, Inuwa HM, Habila JD. Evaluation of extraction protocols for anti-diabetic phytochemical substances from medicinal plants. World J Diabetes 2016; 7(20): 605-614 Available from: