LAUSR

Abstract Mistletoes are extremely important plants and their extracts have been widely used as a complementary medicine towards cancer therapy. In this context, we have studied the leaves of a South Indian Mistletoe, Macrosolen capitellatus (Wight & Arn.) Danser, a parasitic plant belonging to family Loranthaceae. A bioassay-guided isolation and LC-MS dereplication strategies have led to the isolation of pinocembrin-7-O-[4”, 6"-(S)-hexahydroxy diphenoyl (HHDP)]-β-D-glucose (1). This is the first report showing the presence of 1 not only in this plant but also in the genus Macrosolen. In this study, the aforementioned parasitic plant was collected from two different host plants, Mangifera indica and Phyllanthus emblica, which were extensively studied chemically by various research groups. We have observed that 1 is present in both samples of M. capitellatus, while a thorough literature search showed that this compound 1 has not been reported from either Mangifera indica or Phyllanthus emblica. These observations indicated that the producer of 1 is nothing but parasitic plant M. capitellatus. This compound has shown moderate anti-proliferative activity against MCF-7 cell line (IC50 value-15 μM). A computational protein binding study has been performed on 1 against 25 crystallographic proteins of the BRCA-1 gene of breast cancer. The results showed interactions having -9.33 and -8.99 kcal/mol binding energy with the proteins IDs 1T15 and 1T29 respectively; which suggests that this scaffold has the potential to develop further. GRAPHICAL ABSTRACT