Xenohormesis suggests that consuming stressed food provides physiological adaptation to the consumer for similar stresses. To evaluate this, Daphnia magna was provided with heat-stressed Nannochloropsis limnetica grown at 25℃ whereas the control group was provided Nannochloropsis limnetica grown at 12℃. In the heat tolerance experiment, Daphnia kept at 28℃ and 20℃ while consuming 25℃ algae had significantly higher heat tolerance compared to the control. Additionally, in stressed conditions, Daphnia consuming 25℃-grown food had significantly higher lifespan compared to the control. Next, Daphnia consuming 25℃-grown algae had significantly higher levels of antioxidants which could explain the lifespan extension. Finally, in fatty acid analysis, eicosatetraenoic acid (EPA) was found lower in Daphnia consuming 25℃ cultures compared to Daphnia consuming 20℃ cultures. We speculate that this lower EPA level is increasing membrane rigidity and hence higher heat tolerance is observed. These findings indicate consumption of stressed algae might provide physiological benefits in Daphnia.

Chemotherapy, employing single-molecule or multidrug concoctions inspired by the diverse repository of plant chemicals, has been the mainstay of cancer treatment for years. However, isolating single molecules has proven to be expensive along with limited therapeutic window and toxicity. On the other hand, whole foods, while preserving the natural complex balance between their constituent phytochemicals and being non-toxic, have proven to impart better disease-fighting efficacies, thus leading to an increased focus on dietary interventions to both treat and prevent cancer. Owing to the complex interactions between their constituent phytochemicals, several dietary agents have been investigated for their therapeutic and preventive efficacies. However, due to lack of emphasis on confounding factors like bioavailability, absorption, metabolism, and excretion, essentially driven by phytocomplexity, incorporation of whole foods in therapeutic regimen has not been successful. This thesis exemplifies the need to investigate factors associated with the limitations in the current approach with respect to dietary agents. Bioactivity-guided fractionation of sweet potato greens extract (SPGE) led to the identification of ~100-fold more potent fraction in vitro. However, this efficacy could not be translated in vivo. We also studied whole ginger extract (GE) for its in vitro and in vivo prostate tumor growth-inhibitory and apoptosis-inducing effects. In addition, GE proved to be more efficacious as compared to its individual most-active constituents owing to the differences in their pharmacokinetic (PK) and bioavailability measurements. Hence, these studies emphasize the crucial role of synergistic/additive interactions among the constituents of whole foods in successful translation of their therapeutic benefits. Another factor that seeks further attention is the unique cellular mechanisms engaged by these phytochemicals to confer their remarkable effects. Phenolic compounds, the most-abundant of all phytochemicals, are well known for their antioxidant properties and act via reactive oxygen species (ROS)-mediated mechanisms. We however assert the underappreciated xenohormetic prooxidant role of phenolics, where cancer cell death is caused by induction of intolerable levels of ROS. We demonstrated that a Piper betel constituent, hydroxychavicol (HC), mediates cytotoxicity via ROS-induced DNA-damage. This thesis thus provides compelling grounds for future preclinical studies to validate their potential usefulness for cancer management.