Comparative Phytochemical Screening and In Vitro Anthelmintic Evaluation of Ethanolic and Petroleum Ether Leaf Extracts of Bougainvillea spectabilis Willd. Against Pheretima posthuma

Abstract

Background: Soil-transmitted helminth infections remain a major public health burden in resource-limited settings, and the effectiveness of benzimidazole anthelmintics is increasingly constrained by emerging drug resistance, adverse effects, and inconsistent rural access. Medicinal plants rich in tannins, flavonoids, alkaloids, and terpenoids represent a promising, comparatively underexplored reservoir of alternative anthelmintic leads. Bougainvillea spectabilis Willd. (Nyctaginaceae), a widely cultivated ornamental shrub with an established history of ethnomedicinal use, has not previously been evaluated for anthelmintic activity using a solvent-comparative approach. Objective: To evaluate and compare the phytochemical composition and in vitro anthelmintic activity of polar (ethanolic) and non-polar (petroleum ether) leaf extracts of B. spectabilis. Methods: Shade-dried, herbarium-authenticated leaves were macerated separately in ethanol and petroleum ether. Both extracts underwent physicochemical evaluation (loss on drying, ash value), extractive-yield determination, and standard qualitative phytochemical screening. Anthelmintic activity was assessed in vitro against the Indian earthworm Pheretima posthuma at 25, 50, and 100 mg/mL, using albendazole (20 mg/mL) as the reference standard and normal saline as the negative control; paralysis time (PT) and death time (DT) were recorded (mean ± SD, n = 2 worms per group). Results: Loss on drying and total ash value were 6.5% and 4% w/w, respectively. Extractive yield was higher for the ethanolic extract (15.14% w/w) than for the petroleum ether extract (10.14% w/w). The ethanolic extract contained alkaloids, glycosides, flavonoids, tannins, phenols, and saponins, whereas the petroleum ether extract contained steroids, terpenoids, and fixed oils/fats. Both extracts produced a concentrationdependent reduction in PT and DT. At 100 mg/mL, the ethanolic extract produced PT of 19.46 ± 0.29 min and DT of 30.17 ± 0.38 min — marginally shorter than albendazole at 20 mg/mL (PT 28.42 ± 0.35 min; DT 39.18 ± 0.42 min) — and consistently outperformed the petroleum ether extract at matched concentrations (100 mg/mL: PT 39.52 ± 0.37 min; DT 60.43 ± 0.46 min). Conclusion: Both extracts of B. spectabilis leaves possess concentration-dependent anthelmintic activity in this preliminary screen, with the polar (ethanolic) extract more active than the non-polar (petroleum ether) extract, plausibly reflecting its higher content of tannins, flavonoids, and phenolics. These findings provide hypothesis-generating pharmacognostic justification for bioassay-guided fractionation, compound isolation, and in vivo validation of B. spectabilis as a candidate source of plant-derived anthelmintic agents.