Phenolic acids (PAs) are one of the utmost prevalent classes of plant-derived bioactive chemicals. They have a specific taste and odor, and are found in numerous medicinal and food plants, such as Cynomorium coccineum L., Prunus domestica (L.), and Vitis vinifera L. Their biosynthesis, physical and chemical characteristics and structure–activity relationship are well understood. These phytochemicals and their derivatives exert several bioactivities including but not limited to anticancer, cardioprotective, anti-inflammatory, immune-regulatory and anti-obesity properties. They are strong antioxidants because of hydroxyl groups which play pivotal role in their anticancer, anti-inflammatory and cardioprotective potential. They may play significant role in improving human health owing to anticarcinogenic, anti-arthritis, antihypertensive, anti-stroke, and anti-atherosclerosis activities, as several PAs have demonstrated biological activities against these disease during in vitro and in vivo studies. These PAs exhibited anticancer action by promoting apoptosis, targeting angiogenesis, and reducing abnormal cell growth, while anti-inflammatory activity was attributed to reducing proinflammatory cytokines. Pas exhibited anti-atherosclerotic activity via inhibition of platelets. Moreover, they also reduced cardiovascular complications such as myocardial infarction and stroke by activating Paraoxonase 1. The present review focuses on the plant sources, structure activity relationship, anticancer, anti-inflammatory and cardioprotective actions of PAs that is attributed to modulation of oxidative stress and signal transduction pathways, along with highlighting their mechanism of actions in disease conditions. Further, preclinical and clinical studies must be carried out to evaluate the mechanism of action and drug targets of PAs to understand their therapeutic actions and disease therapy in humans, respectively.

Background: Fruit peels are considered as waste and contribute to a major proportion of the biomass. They can be a good source of various therapeutic benefits. Peels biomass of citrus fruits is usually considered as garbage. Such peels may have many important and valuable medicinal components with pharmacological activities. Citrus reticulata, (Rutaceae family, local name tangerine) is a local seasonal fruit in Pakistan, a very good example of wastage of its peels. Objective: The study is based on the exploration of a citrus fruit peel derived essential oil, its chemical characterization, identification of various bioactive components and the exploration of pharmacological potentials (antibacterial and wound healing activity). Methods: Essential oil was recovered by hydro-distillation of freshly collected peels. Chemical constituents of oil were determined by Gas Chromatography-Mass Spectroscopy (GC-MS) analysis. Antioxidant activities were evaluated by total phenolic contents, total flavonoid content, DPPH scavenging activity and reducing power assay. Antibacterial activity was determined using disc diffusion assay. In vivo wound healing potential was determined in rabbits after topical administration of oil. Wound scoring was calculated followed by histological study. Results: GC-MS analysis showed the presence of various components with the greatest proportion of D-Limonene (89.31%). Total flavonoid and phenolic contents were found to be 14.63 ± 0.95 mg CE/g and 17.03 ± 3.24 mg GAE/g respectively, while DPPH activity was found to be 73.32%. A better antibacterial activity was shown against E. coli. In vivo studies showed significant reduction in wound diameter in essential oil treatment groups. Further, the essential oil was found non-irritant in draize scoring. Conclusion: The study concluded that essential oil of this fruit peel might be used for antibacterial and wound healing purposes.