Transcriptome analysis to identify genes involved in lignan, sesquiterpenoid and triterpenoid biosynthesis in medicinal plant Kadsura heteroclita

Stems and roots of Kadsura plant species were the significant ingredients of traditional Chinese medicine. Kadsura heteroclita is one of the popular medicinal plants used in Tujia and Yao nationalities of China. Antioxidant compounds like lignan, sesquiterpenoid and triterpenoid are the major active components of K. hetroclita. Mass cultivation and bio-manufacturing strategies were being proposed to meet the increasing demand of Kadsura species plant parts. Therefore, it is important to reveal the molecular networks involved in biosynthesis of these highly efficient medicinal compounds. Here, transcriptomes of roots, stems and leaves in K. heteroclite seedling were sequenced by Hiseq2000 and unigenes involved in biosynthesis of lignan, sesquiterpenoid and triterpenoid biosynthesis were mined. As a result, 472 million clean reads were obtained which after aligning resulted in 160,248 transcripts and 98,005 genes. 191 and 279 unigenes were expected to be involved in biosynthesis of lignan, sesquiterpenoid and triterpenoid biosynthetic pathways respectively. Lignan, sesquiterpenoid and triterpenoid biosynthesis pathway genes were highly significant and differentially upregulated in roots and stems and downregulated in leaves. Also, genes encoding for MYB and bHLH transcription factors possibly involved in regulation of lignan, sesquiterpenoid and triterpenoid biosynthesis were discovered. These results provide the fundamental genomic resources for dissecting of biosynthetic pathways of the active components in K. hetroclita.

Phenolic Profiles, Antioxidant, and Inhibitory Activities of Kadsura heteroclita (Roxb.) Craib and Kadsura coccinea (Lem.) A.C. Sm.

Kadsura spp. in the Schisandraceae family are woody vine plants, which produce edible red fruits that are rich in nutrients and antioxidant activities. Despite their valuable food applications, Kadsura spp. are only able to grow naturally in the forest, and reproduction handled by botanists is still in progress with a very low growth rate. Subsequently, Kadsura spp. were listed as endangered species by the International Union for Conservation of Nature and Natural Resources (IUCN) in 2011. Two different Kadsura spp., including Kadsura coccinea (Lem.) A.C. Sm. and Kadsura heteroclita (Roxb.) Craib, are mostly found in northern Thailand. These rare, wild fruits are unrecognizable to outsiders, and there have only been limited investigations into its biological properties. This study, therefore, aimed to comparatively investigate the phenolic profiles, antioxidant activities, and inhibitory activities against the key enzymes involved in diabetes (α-glucosidase and α-amylase) and Alzheimer’s disease (acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and beta-secretase 1 (BACE-1)) in different fruit parts (exocarp, mesocarp (edible part), seed, and core) of Kadsura coccinea (Lem.) A.C. Sm. and Kadsura heteroclita (Roxb.) Craib. The results suggested that Kadsura spp. extracts were rich in flavonol (quercetin), flavanone (naringenin), anthocyanidins (cyanidin and delphinidin), and anthocyanins (cyanidin 3-O-glucoside (kuromanin), cyanidin 3-O-galactoside (ideain), cyanidin 3-O-rutinoside (keracyanin), and cyanidin 3,5-di-O-glucoside (cyanin)). These flavonoids were found to be responsible for the high antioxidant activities and key enzyme inhibitions detected in Kadsura spp. extracts. The findings of the present study can support further development of Kadsura spp. as a potential source of phenolics and anti-oxidative agents with health benefits against diabetes and Alzheimer’s disease. Besides, exocarp and the core of Kadsura spp. exhibited higher phenolic contents, antioxidant activities, and key enzyme inhibitory activities compared to the mesocarp and seeds, respectively. This information can promote the use of fruit parts other than the edible mesocarp for future food applications using Kadsura spp. rather than these being wasted.