Natural antioxidants and plant-derived compounds provide a strong defense against cellular damage caused by free-radical induced oxidative stress [16, 17]. Free-radicals and various reactive oxygen species are produced during cellular metabolism in all living systems and are responsible for oxidative cellular damage in human beings. To reduce this damage, some sort of defense mechanism is needed, and indeed, several types of natural and artificial antioxidants are used to control oxidative stress. In particular, plant-derived compounds are a potent source of novel antioxidant activity [18]. Bibenzyl derivatives isolated from D. moniliforme were examined for their antioxidant capacity using DPPH free-radical scavenging assay [11, 13, 14], a popular tool because of its simplicity and high sensitivity. This assay works on the principle that any hydrogen donor is an antioxidant. Thus, a compound’s antioxidant effect is proportional to the disappearance of DPPH radicals in test samples [19].
The natural antioxidant-rich compounds of D. moniliforme engage in many biological activities, including promoting the production of body fluids, serving neuroprotective, immunomodulatory and antioxidant functions [2, 20]. D. candidum has previously been shown to have in vitro anticancer effects on human carcinoma cells [21–27]. Indeed, it is often the case that bioactive agents of folk medicine help prevent the development of cancer by inducing apoptosis [28]. The induction of apoptosis in cancer cells is initially identified by morphological changes, including cell shrinkage, membrane blebbing, chromatin condensation, and nuclear fragmentation. The MTT assay can be used to screen the cytotoxicity of a crude extract [29]. More specifically, GC-MS can be used to detect and identify bioactive compounds in crude extracts [30, 31].
Despite the potential of D. moniliforme, little information exists on the antioxidant and cytotoxic activities of the crude extract of this orchid. To remedy that gap, the present study explored the antioxidant and cytotoxic activities of crude extracts of the plant and detected bioactive compounds present in it.
(source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913799/)