Annual Research & Review in Biology

Natural Dyes: Paving the Way towards Sustainable and Eco-friendly Industries

S. Vennila — 2026-06-09

Natural dyes have re-emerged as sustainable alternatives to synthetic colorants due to increasing environmental concerns, consumer preference for eco-friendly products, and advancements in green technologies. The present article highlights the industrial applications, sustainability dimensions, emerging innovations, and future prospects of natural dyes across textile, food, cosmetic, pharmaceutical, and handicraft sectors. Natural dyes are extensively utilized in textiles because of their biodegradable nature, non-toxicity, antimicrobial properties, and compatibility with sustainable fashion initiatives. In the food industry, pigments such as curcumin, anthocyanins, carotenoids, and betalains serve as natural colorants with additional antioxidant and health-promoting benefits. Furthermore, natural dyes contribute significantly to environmental sustainability by reducing industrial pollution, promoting renewable resource utilization, and supporting circular economy approaches through waste. Socio-economic benefits including rural livelihood generation, preservation of indigenous knowledge, women empowerment, and promotion of artisanal industries further enhance their importance. Emerging technologies such as microwave-assisted extraction, biotechnology, nanotechnology, and eco-certification systems are expected to strengthen commercialization and industrial scalability of natural dyes. Thus, natural dyes represent a promising pathway toward sustainable industrial development, green manufacturing, and circular bioeconomy systems.

Recent Developments in the Synthesis of 2,3-dideoxy-hex-2-enopyranosides: A Review

Jonatas Tavares da Silva — 2026-06-20

2,3-Dideoxy-hex-2-enopyranosides, also described as 2,3-unsaturated glycosides, constitute an important class of carbohydrate derivatives because their double bond and anomeric substituent enable diverse synthetic transformations. This review summarises recent developments in the preparation and application of O-, P-, C-, N-, S- and Se-2,3-unsaturated glycosides, with emphasis on the principal synthetic routes, catalysts and reaction outcomes described in the manuscript. Particular attention is given to the Ferrier rearrangement, which remains the most widely applied strategy for converting glycals into 2,3-unsaturated glycosyl derivatives using Lewis acid or related catalytic systems. Other routes, including the Fraser-Reid and Boctor method, the Zamojski and Achmatowicz approach, Tebbe methylenation/Claisen rearrangement and Heck coupling, are also considered as complementary procedures for constructing these scaffolds. The review further discusses the reactivity of unsaturated glycosides as substrates for functionalisation reactions, including Overman rearrangement, Mitsunobu reaction, oxidation, catalytic hydrogenation, decarboxylative allylation, glycosylation of proteins and lipids, epoxidation, cycloaddition, hydrothiolation and allyl cyanate/isocyanate rearrangement. These transformations demonstrate the usefulness of the 2,3-olefinic moiety for accessing structurally varied carbohydrate derivatives and related building blocks. The manuscript also considers reported applications involving structural modification, stereochemical control and the preparation of biologically relevant carbohydrate frameworks, while avoiding extrapolation beyond the cited reactions. Recent perspectives on greener catalytic systems, metal-free methods and late-stage functionalisation are also outlined, together with limitations associated with stereochemical control, side reactions, functional group tolerance and catalyst requirements. Overall, the manuscript presents a focused account of advances in the synthesis and use of 2,3-dideoxy-hex-2-enopyranosides in carbohydrate chemistry and identifies areas where further methodological development may be beneficial.

Agro-Industrial Wastewater as a Resource for Algal Biomass Production: Nutrient Recovery, Strain Selection and Techno-economic Barriers

Chittimothu Suresh Babu — 2026-06-20

The global agro-industrial sector generates billions of cubic metres of nutrient-rich effluents annually, constituting both a significant environmental liability and an underexploited resource for biological valorisation. Microalgal cultivation in agro-industrial wastewaters offers a dual-benefit platform: simultaneous tertiary-level wastewater treatment and production of high-value biomass for biofuels, biofertilisers, and speciality biochemicals. This comprehensive review critically examines (i) the physicochemical characteristics of dominant agro-industrial effluents, including dairy wastewater, swine effluent, palm oil mill effluent (POME), sugarcane vinasse, abattoir wastewater, and aquaculture discharge as substrates for algal cultivation; (ii) the nutrient dynamics governing nitrogen and phosphorus assimilation, with removal efficiencies reaching >95% under optimised conditions; (iii) strain-specific selection criteria encompassing tolerance to ammonia toxicity, turbidity, organic loading, and pathogen presence; (iv) comparative performance of cultivation systems from open raceway ponds to closed photobioreactors (PBRs) and hybrid configurations; and (v) techno-economic analysis (TEA) and life cycle assessment (LCA) findings that expose the current cost barriers, particularly harvesting (accounting for 20–30% of total production cost) and upstream pre-treatment. Emerging strategies including bioflocculation, microalgal–bacterial consortia, genetic strain engineering, and biorefinery integration are evaluated for their potential to reduce production costs below $2.00/kg biomass. This review synthesises evidence from peer-reviewed Q1-indexed studies (2018–2025) and identifies critical knowledge gaps that must be addressed to transition algal wastewater biorefinery from laboratory proof-of-concept towards commercially viable, potentially climate-positive technology.

Contributors to the Evolution of Virulence in Xanthomonas Bacteria: Implications for Pomegranate Biology

H. S. Ravikumar Patil — 2026-06-20

Xanthomonas axonopodis pv. punicae is an important bacterial pathogen associated with bacterial blight of pomegranate and can affect leaves, stems, branches and fruits. This review summarises factors that may contribute to virulence development, pathogen adaptation and disease progression in pomegranate. Fruit development involves biochemical, cellular and molecular changes, including alterations in sugars, organic acids, phenolic compounds, antioxidant status, cell wall metabolism and ripening-associated regulation. These changes may influence pathogen colonisation, survival and symptom development. In Xanthomonas, virulence is supported by multiple mechanisms, including extracellular polysaccharide production, biofilm formation, motility, environmental sensing, secretion systems, effector proteins and stress-tolerance responses. Type III secretion systems and associated effectors play important roles in suppressing plant immune responses and supporting bacterial growth in host tissues. Genetic processes such as mutation, recombination, horizontal gene transfer and variation in virulence-associated genes may contribute to adaptability and pathogenic diversity among strains. Environmental factors, including temperature, humidity, rainfall and osmotic or oxidative stress, may further influence pathogen survival, dispersal and disease severity. Current management approaches rely on integrated disease management, sanitation, cultural practices, chemical control, biological control agents, molecular detection, resistance screening and the identification of host resistance-related genes. By bringing these areas together, the review provides a consolidated interpretation of how fruit physiology and bacterial adaptive traits may interact during disease development. The review highlights that virulence in pomegranate-associated Xanthomonas is likely shaped by combined host, pathogen, genetic and environmental factors. A clearer understanding of these mechanisms may support improved diagnosis, resistance breeding and sustainable disease management strategies for bacterial blight of pomegranate.