Prophylactic Peperomia pellucida Extract Preserves Myocardial Histomorphology in Secondhand Smoke-Exposed Wistar Rats: A Histopathological Study

Secondhand smoke (SHS) is a persistent involuntary exposure; the World Health Organization estimates that ~1.6 million non-smokers die annually from SHS, and global cardiovascular deaths attributable to SHS reached 598,500 in 2019. We evaluated whether prophylactic Peperomia pellucida extract preserves myocardial histomorphology in SHS-exposed rats. An ethanolic aerial-part extract was prepared by 72-h maceration in 96% ethanol. Thirty male Wistar rats (6-8 weeks; 220-280 g) were randomized to Vehicle (ambient air), SHS (one cigarette/rat/day for 4 weeks), or SHS + P. pellucida (200 mg/kg/day by oral gavage), initiated 7 days before SHS and continued throughout exposure (n=10/group). At study endpoint, hearts were excised under ketamine-xylazine anesthesia, fixed in 10% neutral buffered formalin for 24 h, paraffin-embedded, sectioned (4-5 μm), and stained with hematoxylin-eosin. Slides were digitized (Aperio CS2) and reviewed in ImageScope. Myocardial injury in ventricular sections was graded on a 0-4 semi-quantitative scale and compared using Kruskal-Wallis with Dunn’s post hoc testing. SHS produced prominent disruption of myofiber organization with interstitial expansion and significantly increased injury scores versus Vehicle (p < 0.0001). Prophylactic P. pellucida reduced injury severity relative to SHS alone (p = 0.0229), shifting scores toward milder grades. These findings indicate that prophylactic P. pellucida partially preserves myocardial architecture under SHS exposure, supporting follow-up studies that integrate functional endpoints and mechanistic biomarkers.