Research progress of diosgenin extraction from Dioscorea zingiberensis C. H. Wright: Inspiration of novel method with environmental protection and efficient characteristics

The Isolation, Identification and Immobilization Method of Three Novel Enzymes with Diosgenin-Producing Activity Derived from an Aspergillus flavus

Diosgenin is an important raw material used in the synthesis of steroid drugs, and it is widely used in the pharmaceutical industry. The traditional method of producing diosgenin is through using raw materials provided via the plant Dioscorea zingiberensis C. H. Wright (DZW), which is subsequently industrially hydrolyzed using a high quantity of hydrochloric and sulfuric acids at temperatures ranging from 70 °C to 175 °C. This process results in a significant amount of unmanageable wastewater, creates issues of severe environmental pollution and consumes high quantities of energy. As an alternative, the enzymolysis of DZW to produce diosgenin is an environmentally and friendly method with wide-ranging prospects for its application. However, there are still only a few enzymes that are suitable for production on an industrial scale. In this study, three new key enzymes, E1, E2, and E3, with a high conversion stability of diosgenin, were isolated and identified using an enzyme-linked-substrate autography strategy. HPLC-MS/MS identification showed that E1, a 134.45 kDa protein with 1019 amino acids (AAs), is a zinc-dependent protein similar to the M16 family. E2, a 97.89 kDa protein with 910 AAs, is a type of endo-β-1,3-glucanase. E3, a 51.6 kDa protein with 476 AAs, is a type of Xaa-Pro aminopeptidase. In addition, the method to immobilize these proteins was optimized, and stability was achieved. The results show that the optimal immobilization parameters are 3.5% sodium alginate, 3.45% calcium chloride concentration, 1.4 h fixed time, and pH 8.8; and the recovery rate of enzyme activity can reach 43.98%. A level of 70.3% relative enzyme activity can be obtained after employing six cycles of the optimized technology. Compared with free enzymes, immobilized enzymes have improved stability, acid and alkaline resistance and reusability, which are conducive to large-scale industrial production.

A pH-sensitive intelligent packaging film harnessing Dioscorea zingiberensis starch and anthocyanin for meat freshness monitoring

Abundant starch was isolated from Dioscorea zingiberensis C.H. Wright, a novel and underutilized industrial crop resource. In this study, an intelligent packaging film able to indicate food freshness was developed and characterized. D. zingiberensis starch (DZS) was bleached first, and its particle size, total starch content, amylose content, and gelatinization temperature were then measured. Butterfly pea (Clitoria ternatea Linn.) flowers were selected as the source of polyphenols, which rendered the prepared film intelligent and progressively blue-violet. SEM and FT-IR analyses showed the homogeneous dispersion of butterfly pea flower extract (BPE) in the film. The BPE-loaded film showed improved flexibility and resistance to UV and oxidation while maintaining sufficient mechanical strength and physical properties. Moreover, the film underwent a distinguishable color change from red to blue-violet and finally to green-yellow with increasing pH from 2 to 13. Similar color alteration also occurred when the film was exposed to ammonia. When the film was used to monitor the freshness of chicken stored at room temperature, it exhibited an obvious color change, implying its deterioration. Therefore, the newly developed BPE-DZS film, which was produced from readily accessible natural substances, can serve as an intelligent packaging material, indicating food freshness and prolonging shelf life.

The Functional Characterization of DzCYP72A12-4 Related to Diosgenin Biosynthesis and Drought Adaptability in Dioscorea zingiberensis

Dioscorea zingiberensis is a perennial herb famous for the production of diosgenin, which is a valuable initial material for the industrial synthesis of steroid drugs. Sterol C26-hydroxylases, such as TfCYP72A616 and PpCYP72A613, play an important role in the diosgenin biosynthesis pathway. In the present study, a novel gene, DzCYP72A12-4, was identified as C26-hydroxylase and was found to be involved in diosgenin biosynthesis, for the first time in D. zingiberensis, using comprehensive methods. Then, the diosgenin heterogenous biosynthesis pathway starting from cholesterol was created in stable transgenic tobacco (Nicotiana tabacum L.) harboring DzCYP90B71(QPZ88854), DzCYP90G6(QPZ88855) and DzCYP72A12-4. Meanwhile, diosgenin was detected in the transgenic tobacco using an ultra-performance liquid chromatography system (Vanquish UPLC 689, Thermo Fisher Scientific, Bremen, Germany) tandem MS (Q Exactive Hybrid Quadrupole-Orbitrap Mass Spectrometer, Thermo Fisher Scientific, Bremen, Germany). Further RT-qPCR analysis showed that DzCYP72A12-4 was highly expressed in both rhizomes and leaves and was upregulated under 15% polyethylene glycol (PEG) treatment, indicating that DzCYP72A12-4 may be related to drought resistance. In addition, the germination rate of the diosgenin-producing tobacco seeds was higher than that of the negative controls under 15% PEG pressure. In addition, the concentration of malonaldehyde (MDA) was lower in the diosgenin-producing tobacco seedlings than those of the control, indicating higher drought adaptability. The results of this study provide valuable information for further research on diosgenin biosynthesis in D. zingiberensis and its functions related to drought adaptability.

Dietary phytoestrogen diosgenin interrupts metabolism, physiology, and reproduction of Swiss albino mice: Possible mode of action as an emerging environmental contaminant, endocrine disruptor and reproductive toxicant

Dietary phytoestrogens are the main source of environmental contamination due to their estrogen-mimicking and endocrine-disrupting effects, posing a threat to microbial, soil, plant, and animal health. Diosgenin, a phytosteroid saponin, is used in many traditional medicines, nutraceuticals, dietary supplements, contraceptives, and hormone replacement therapies against numerous diseases and disorders. It is important to be aware of the potential risks associated with diosgenin, as well as its potential to cause reproductive and endocrine toxicity. Due to the lack of research on the safety and probable adverse side effects of diosgenin, this work evaluated the endocrine-disrupting and reproductive toxicity of diosgenin in albino mice by following acute toxicity (OECD-423), repeated dose 90-day oral toxicity (OECD-468), and F₁ extended one-generation reproductive toxicity (OECD-443) studies. Diosgenin was found to be slightly toxic, with LD₅₀ for male and female mice being 546.26 and 538.72 mg/kg, respectively. Chronic exposure of diosgenin (10, 50, 100, and 200 mg/kg) generated oxidative stress, depleted antioxidant enzymes, disturbed homeostasis of the reproductive hormones, and interrupted steroidogenesis, germ cell apoptosis, gametogenesis, sperm quality, estrous cycle, and reproductive performance in the F₀ and F₁ offspring. Long-term oral exposure of diosgenin to the mice disturbed the endocrine and reproductive functions and generated transgenerational reproductive toxic effects in F₀ and F₁ offspring. These results suggest that diosgenin should be used carefully in food products and medical applications due to its potential endocrine-disrupting and reproductive toxic effects. The findings of this study provide a better understanding of the potential adverse effects of diosgenin and the need for appropriate risk assessment and management of its use.