Rhizanthes is a holoparasitic plant of the Rafflesiaceae, and, just like Rafflesia, its host is Tetrastigma (Vitaceae). Unlike Rafflesia, very little research has been conducted on Rhizanthes other than a few studies focusing on its taxonomy and anatomy, and limited studies on its propagation, despite some ethnomedicinal uses in several regions of Indonesia. Wild populations of Rhizanthes are declining due to deforestation and overharvesting by locals. Artificial pollination and possible seed spread, which are similar to Rafflesia, may be useful for future propagation-based studies, which are generally very difficult and challenging for members of the Rafflesiaceae. This paper emphasizes the cultural and ethnomedicinal importance of Rhizanthes and seeks to define a conservation road-map that incorporates a scientifically-based approach to research while also seeking a four-pronged approach to the conservation of Rhizanthes: 1) conventional and biotechnology-based conservation; 2) germplasm multiplication and preservation; 3) reintroduction into the wild and conservation of wild populations; 4) policy-based protective measures.

The Rafflesiaceae family consists of three genera of parasitic plants – Rafflesia, Rhizanthes, and Sapria – with purported ethnobotanical and ethnomedicinal properties. In this study, the inhibitory properties of 21 characterized metabolites associated with Rafflesia and Sapria were tested against eight proteins linked to human diseases – including seven pathogenic-associated HMGCR, VEGFR2, acetylcholinesterase, NMT, H1N1 neuraminidase, GSK3-β, and estrogen receptor α, and one plant-pathogenic associated Colletotrichum chitin deacetylase. Each metabolite was tested using drug-likeness screening, screening metabolite activity, and molecular docking to eight diseases and microbial physiological processes. Hydrogen bonds and hydrophobic interactions between metabolite ligands and protein residues were characterized. Molecular dynamics were also assessed to analyze the stability of the protein-ligand interaction. Our results indicate that the gallotannins and flavonol phenolics from Rafflesia and Sapria display high inhibitory potential against disease proteins. All metabolite-protein pairs displayed stable fluctuations. However, some compounds disobeyed LRO5 drug-likeness and displayed moderate bioavailability and synthetic accessibility, so an improved drug delivery method is required. All 21 metabolites are available in other popular edible plants (mainly tea and certain berries) and could be used to create artificially mixed metabolite-based medicine to prevent the exploitation and endangerment of wild Rafflesia and Sapria populations. Our activity likelihood screening and molecular docking data indicate that Rafflesia and Sapria metabolites possess considerable potential as anti-cholesterol, respiratory antiviral, wound-healing, and antifungal properties. To protect Rafflesiaceae plants in the wild, metabolites can be assessed from other plant sources and combined as an artificial herbal mix.