Pharmacognostic standardization and evaluation of the vasodilatory potential of Capsicum annuum L. var. annuum fruit

Abstract

Capsicum annuum L. var. annuum, commonly known as Cayenne pepper, is widely cultivated across tropical regions for its medicinal and nutritional values. Traditionally, its fruits are used to treat conditions like hypertension, cardiovascular shock, fever, and pain. This study seeks to establish the pharmacognostic profile of C. annuum var. annuum fruit and evaluate its vasodilatory effects using a toad heart model. Standard methods were employed for microscopical, physicochemical, and phytochemical analyses. Acute toxicity (LD₅₀) was evaluated in mice, while the vasodilatory activity of the fruit extract was tested on isolated toad heart at concentrations ranging from 6.25 to 100 mg/mL against standard adrenaline and acetylcholine controls. Microscopic evaluation revealed distinct parenchymatous cells, fibers, glandular trichomes, calcium oxalate crystals, oil globules, starch grains, testa of epidermis, and bordered pitted vessels. Chemomicroscopy confirmed the presence of tannins, lignin, carbohydrates, oils, and proteins. Physicochemical analysis yielded a total ash value of 3.85% w/w, water-soluble ash of 1.26%, acid-insoluble ash of 2.56%, moisture content of 3.78%, water-extractive value of 5.77% w/w, and ethanol-extractive value of 4.07% w/w. The toxicological study demonstrated that the LD₅₀ in mice is greater than 5000 mg/kg, indicating a high safety profile. The pharmacological assay demonstrated a dose-dependent decrease in heart rate across all extract concentrations. The established organoleptic, microscopic, and physicochemical parameters provide essential diagnostic criteria for the authentication, quality control, and identification of C. annuum var. annuum to prevent adulteration and/or substitution. Furthermore, the dose-dependent cardiac effects could validate the traditional ethnomedicinal use of the plant as a vasodilatory and antihypertensive agent.