The study, led by assistant professor of biology Talia Karasov, forest ecologist and professor of biology William Anderegg, and graduate student Aubrey Hawks, focused on quaking aspen, Populus tremuloides, a signature species of the mountain West and the official state tree of Utah. The researchers documented that in the growing seasons following drought exposure, aspen leaves exhibited elevated levels of salicinoid phenolic glycosides, a class of chemical compounds known to deter herbivores, the insects and animals that feed on plants. At the same time, levels of condensed tannins, another chemical defense that helps trees ward off microbes, declined in the drought-exposed trees. The team also observed that these shifts in leaf chemistry were associated with changes in the communities of fungi living on the leaves.

The finding matters because drought is rarely a clean, self-contained event for a tree. As Karasov explained, the researchers wanted to understand drought not simply as an acute stress, but as an event that may reshape how trees interact with their biotic environment long after soils have rewetted. Because drought-year conditions alone do not explain all of the delayed mortality observed in forests, the team asked whether prior water limitation leaves a persistent signature in aspen leaf chemistry and, in turn, alters interactions with herbivores and the fungal communities that inhabit leaves. The results suggest that the effects of drought can indeed persist through subsequent growing seasons, potentially influencing how aspens recover and how vulnerable they remain to pests and pathogens.

The experimental design rested on a classic tool of plant biology known as the common garden approach. Common garden experiments bring together plants from geographically divergent populations and grow them in a single location under shared conditions, allowing researchers to separate the effects of a plant’s origin from the effects of its environment. In 2021, Anderegg’s laboratory established an experimental aspen plot at the University of Utah’s Biology Research Experimental Garden, situated along the Wasatch foothills east of the Salt Lake City campus. The team planted rootstock gathered from mountain sites in five national forests in Utah and Colorado, with the original collection sites sitting at roughly 9,000 feet above sea level on south-facing aspects.

From 2021 through 2023, the researchers manipulated how much water the trees received, replicating varying levels of drought across the plot. Each year, leaves were harvested in late August and subjected to chemical analysis to determine the levels of specific compounds that concentrate in aspen leaves as defenses against plant-eating insects and wildlife, as well as against disease-causing microbes. Biology students tended the trees throughout the experiment, an effort captured in photographs of the garden showing rows of young aspens under careful cultivation. The garden has also supported two earlier studies of aspen drought response by Anderegg and his graduate students, with more work underway.

The scale of aspen’s chemical investment is striking. According to Karasov, the percentage of a dried leaf’s mass composed of these defensive compounds can reach up to 20 percent, an extraordinary allocation of resources to self-protection. Prior research has shown that even a modest increase in phenolic glycoside levels can reduce herbivory by up to 25 percent. In the new study, the elevated levels of phenolic glycosides documented in drought-exposed trees were associated with reduced canopy damage, suggesting the chemical shift had real consequences for how much leaf tissue insects consumed. Karasov noted that these compounds can essentially make the difference between a plant being totally defoliated or not, because insects do not like them.

Perhaps the most surprising result was what the researchers did not find. Despite the apparent cost of manufacturing large quantities of defensive chemistry, the team found no evidence that the trees’ increased investment in phenolic glycoside production came at the expense of growth. The researchers hypothesized that the unexpected changes in leaf chemistry observed in the year after drought exposure could reflect an adaptation to dry conditions, a possibility that raises intriguing questions about how trees balance defense, growth, and survival under a shifting climate.

The study also revealed that drought and leaf chemistry can act as filters on microbial communities, shaping which fungi inhabit aspen leaves. However, the researchers are careful to note that the work does not yet establish whether those changes ultimately help or harm aspen recovery. The direction of the effect, beneficial or detrimental, remains an open question, and one that the team considers central to understanding how Western forests will weather the increasing frequency and severity of drought expected under climate change.

The broader context gives the research urgency. Quaking aspen, the mountain West’s only dominant deciduous tree species, is in decline as a result of insects and pathogens, as well as historic fire suppression and grazing by livestock and wildlife, pressures that have enabled conifers to displace aspen across large areas. Aspens grow in clonal stands where all the individuals are genetically identical, a reproductive strategy that makes entire groves vulnerable to the same threats. The species’ range extends well beyond the Rockies, covering parts of Canada, the Upper Midwest, and New England, but its ecological heart lies in the western mountains. Reversing aspen decline is considered important to the ecological health of Western forests, yet significant gaps persist in scientists’ understanding of the causes of the decline and the solutions to it.

Anderegg, whose research focuses on how trees respond to climate change, emphasized that defenses against pests and pathogens likely matter a great deal for aspen survival under both drought and normal conditions. In his view, the study fills a key gap in understanding how drought and defense production change both during and after the initial droughts themselves. That framing captures the study’s central contribution: drought is not merely a stress that trees endure and then forget, but an experience that can reorganize their chemical relationship with the living world around them.

The paper, titled Functional memory of drought affects leaf chemical defenses and microbial interactions in aspen, was published on September 13 in New Phytologist. Co-authors include Utah biology students Jaycie Fickle, Kelly Kerr, Dale Forrister, Allison Perkins, Efthymia Symeonidi, Madelyn Allen, and Cannon Fehrenbach, along with Hsiao-Nung Chen of the Department of Chemistry. Funding came from the National Institutes of Health, the National Science Foundation, and the U.S. Department of Agriculture’s National Institute of Food and Agriculture, with additional support from the Wilkes Center for Climate Science and Policy, a Phyllis Coley and Thomas A. Kursar Field Research Award, the David and Lucille Packard Foundation, and an Alan T. Waterman Award. As droughts intensify across the American West, the idea that a tree’s leaves can carry forward the chemical echo of a dry year offers both a warning and a tool: a warning that the damage of drought may linger in ways ecologists are only beginning to measure, and a tool for predicting which forests will be most resilient when the rains return.

Subject of Research: Drought-induced functional memory in aspen leaf chemical defenses and microbial interactions

Article Title: Aspens 'remember' past drought in their leaves

Article References: Aspens 'remember' past drought in their leaves. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: aspen, drought, leaf chemistry, phenolic glycosides, condensed tannins, plant defenses, herbivory, leaf fungi, common garden experiment, forest ecology, climate change, New Phytologist

The experiment took place at the Lafareg research farm in Beja, a sub-humid zone receiving around 558 millimeters of rain annually. Twenty-eight five-month-old fat-tailed Barbarine ram lambs, weighing on average 22.5 kilograms, were divided into four groups of seven, balanced by body weight. Two groups were housed in stalls and fed 400 grams of concentrate per day with oat hay available freely. The other two groups rotationally grazed a cultivated vetch pasture, receiving the same daily concentrate allowance. Within each system, one group received an extra 100 grams of acacia foliage per head per day, offered an hour before the main feed, while the other received none. The acacia is a tannin-rich legume widespread in Tunisia, containing roughly 60 grams of condensed tannins per kilogram of dry matter, and it was chosen as a natural alternative to the antibiotic growth promoters that have been banned in many regions over concerns about toxic residues in meat.

The chemical analysis of the feeds explains much of what followed. The fresh vetch grass contained 21.9 percent crude protein, more than three times the 6.7 percent found in the hay offered indoors. The concentrate supplied 16.2 percent protein, and the acacia itself 12.6 percent. Because grazing lambs could harvest this protein-dense forage directly, their total dry matter intake reached 1,342 to 1,442 grams per day, compared with only 839 to 960 grams for the stall-fed animals. Grazing lambs derived about 70 percent of their intake from forage, eating nearly a kilogram of vetch daily, while stall-fed lambs drew 47 percent of their ration from concentrate and consumed less than half as much forage as their pastured counterparts.

Growth told the same story in striking numbers. Lambs on pasture gained an average of 180 grams per day, while stall-fed lambs gained 141 grams. The extremes were even more revealing: the fastest-growing group was pasture-fed lambs without acacia, at 192 grams per day, and the slowest was stall-fed lambs without acacia, at 110 grams. The statistical interaction between feeding system and tannin supply was significant, meaning the effect of the supplement could not be judged in isolation from the basal diet. Indoors, where nitrogen arrived as true protein in hay and concentrate, the tannins appeared to offer a slight benefit, consistent with the well-documented ability of condensed tannins at low doses to bind dietary protein in the rumen and protect it from degradation, thereby increasing the flow of amino acids to the small intestine.

On pasture, however, the chemistry worked differently. The nitrogen in fresh vetch is largely in soluble form, which tannins cannot bind in the same protective way, and the vetch biomass itself already carries measurable tannins, averaging around 360 milligrams of catechin equivalents per kilogram of dry matter. Adding acacia on top of this tannin-bearing forage apparently pushed total tannin intake toward a range where the compounds begin to work against the animal, suppressing feed intake, rumen microbial activity, and digestive enzyme function. The authors note that previous work has shown low to moderate tannin inclusion can be neutral or beneficial, while larger amounts reduce nutrient digestibility and growth. The lesson is that tannins are not a simple additive but a dietary variable whose consequences hinge on context.

At slaughter, the pasture advantage carried through to the carcass. Grazing lambs were heavier at slaughter, had higher empty body weights, and produced both heavier hot and cold carcasses. Their commercial dressing percentage averaged 45.8 percent against 40.5 percent for stall-fed lambs. The non-carcass components also reflected the different lives the animals had led: grazing lambs developed larger red organs, including heart, liver, and lungs, and heavier kidneys, a pattern the authors attribute to the greater physical activity of animals ranging over pasture. Testis weight was higher in both pasture groups and in the tannin-supplemented stall group compared with unsupplemented stall-fed lambs, while gut weights were similar across all treatments.

Within the carcass itself, the feeding system shaped the proportions of most commercial joints, including the leg, shoulder, loin, breast, and, notably, the signature fat tail of the Barbarine breed. Pastured lambs carried tails averaging 950 grams, about 6.05 percent of carcass weight, compared with 615 grams and 4.7 percent in stalled lambs. Muscle proportions were highest in unsupplemented stall-fed lambs, while fat deposition was greater in both pasture groups and in tannin-supplemented stall lambs, an outcome that runs counter to earlier studies in which grazing animals, burning more energy on movement, laid down less fat. Across all groups, the leg and shoulder together accounted for roughly 34 percent and 20 percent of the tailed carcass, supporting the principle of anatomic harmony, the idea that joint proportions remain consistent within a breed regardless of rearing conditions.

Perhaps the most commercially reassuring finding concerned the meat itself. Neither the feeding system nor the acacia supplement produced meaningful differences in pH measured one hour and 24 hours after slaughter, in water loss during cooking, in color coordinates of lightness, redness, and yellowness, or in the chemical composition of the longissimus dorsi muscle, including dry matter, ash, protein, and intramuscular fat. Lightness values averaged 43.5 across all groups, comfortably above the threshold of 34 at or above which meat is deemed acceptable by 95 percent of consumers. Trained panelists who roasted samples from each group and scored tenderness, juiciness, flavor, and overall acceptability on nine-point scales found the meat moderately tender, between 5.7 and 6, and moderately juicy, between 5.1 and 5.8, with no distinctive off-flavors and no differences among treatments. Every sample was judged acceptable.

The broader significance of the study lies in its demonstration that natural feed additives cannot be evaluated in a vacuum. Condensed tannins have attracted intense interest as antioxidants, antimicrobials, and rumen-protective compounds that could replace banned growth promoters, but their biological activity is a double-edged sword, beneficial at low doses and detrimental at high ones. This trial shows that the dose that matters is the total dose delivered by the whole diet, not just the supplement spooned out on top. A hundred grams of acacia that gently shields protein in a hay-based ration becomes an excess burden when the lambs are already browsing tannin-bearing vetch. For producers of fat-tailed breeds like the Barbarine, the practical takeaways are twofold: well-managed grazing on protein-rich cultivated pasture remains the most effective route to faster growth and heavier carcasses, and tannin supplementation should be matched carefully to the basal forage. The authors call for further research to define optimal inclusion levels and dose-response relationships under different feeding conditions, work that will help determine whether tannin-rich foliage can take its place as a reliable tool in sustainable, antibiotic-free lamb production.

Subject of Research: Effects of Acacia cyanophylla condensed tannin supplementation and grazing versus feedlot feeding on growth, carcass traits, and meat quality of Barbarine lambs

Article Title: Effects of Acacia cyanophylla-condensed tannin supply on growth performance, carcass characteristics and meat quality of fat-tailed Barbarine lambs studied under grazing conditions or in a feedlot

Article References: Yagoubi, Y., Atti, N., Smeti, S., Abidi, J., & Mahouachi, M. (2026). Effects of Acacia cyanophylla -condensed tannin supply on growth performance, carcass characteristics and meat quality of fat-tailed Barbarine lambs studied under grazing conditions or in a feedlot. Archives Animal Breeding, 69(3), 495-505. https://doi.org/10.5194/aab-69-495-2026

Image Credits: AI Generated

DOI: 10.5194/aab-69-495-2026

Keywords: Barbarine lambs, Acacia cyanophylla, condensed tannins, grazing, feedlot, carcass quality, meat quality, sheep nutrition, sustainable livestock, vetch pasture, animal growth, Tunisia

Researchers from Iğdır University in Türkiye set out to answer a deceptively simple question: when salinity or drought intensifies, how does the phytochemistry of bermudagrass change, and does a locally adapted wild ecotype respond differently from a commercial cultivar? To find out, they grew the commercial cultivar ‘Gobi’ alongside an ecotype collected from the harsh, semi-arid landscapes of Iğdır province in eastern Türkiye. The plants were subjected to a carefully graded stress regime: six levels of sodium chloride ranging from zero to a punishing 500 millimolar, and five levels of soil water deficit in which between 25 and 95 percent of plant-available water was depleted. This dose–response design, rather than the single-stress snapshots common in the literature, allowed the team to trace how each biochemical trait shifts as stress ramps up incrementally.

The analytical scope was equally ambitious. Seven traits were quantified for every genotype–stress combination: condensed tannins, saponins, total phenolic content, total flavonoid content, total soluble sugars, and antiradical capacity measured through the DPPH radical-scavenging assay and its half-maximal inhibitory concentration, IC₅₀. Two-way factorial analysis of variance tested the genotype-by-stress interaction for each trait, and the outcome was unambiguous. Every one of the seven traits showed a statistically significant interaction at the p < 0.01 level, meaning that the way each genotype responded chemically depended on both the type and the intensity of the stress it faced. There was no single, universal stress chemistry; instead, each genotype deployed its own tailored arsenal.

Perhaps the most dramatic single finding concerned saponins, the soap-like glycosides that plants use in defence and that can affect rumen metabolism in grazing animals. Water deficit proved to be the dominant driver of saponin dynamics. In the ‘Gobi’ cultivar, saponin concentrations collapsed from 356.9 to 203.2 micrograms of diosgenin equivalents per gram of dry weight as drought intensified, an effect so strong that the corresponding F-value reached 704.82, an extraordinarily large test statistic for a plant chemistry experiment. The steepness of this decline suggests that saponin biosynthesis is either an energetically expensive luxury the cultivar abandons under water stress or a trait tightly regulated by drought-responsive signalling pathways. Either way, the drop represents one of the clearest dose-dependent secondary metabolite responses documented in this species.

Salinity told a different story. While drought reshaped saponins, salt stress most strongly modulated antiradical capacity, the plant’s ability to neutralise the reactive oxygen species that accumulate when sodium and chloride ions disrupt photosynthesis and cellular metabolism. This distinction matters because it implies that the two stresses are not interchangeable in their biochemical consequences. A breeder selecting for salt tolerance would therefore be screening a different suite of traits than one selecting for drought tolerance, even within the same species. The finding echoes a broader principle in plant stress physiology: salinity imposes both osmotic and ionic burdens, and the antioxidant arm of the response, heavily dependent on phenolic and flavonoid compounds, appears to be the most sensitive barometer of that ionic pressure.

Under the most severe drought treatment, when 95 percent of plant-available water had been depleted, the Iğdır ecotype revealed its signature strategy. It accumulated markedly more total soluble sugars than ‘Gobi’, reaching 15.7 percent of dry weight compared with the cultivar’s 10.9 percent. Soluble sugars are classic compatible solutes: small, non-toxic molecules that accumulate in cells to maintain osmotic pressure and protect proteins and membranes when water becomes scarce. The ecotype’s sugar-heavy profile points to a robust osmotic adjustment strategy, an adaptation plausibly forged by generations of natural selection in the water-limited landscapes around Iğdır. The commercial cultivar, by contrast, leaned on a phenolic- and flavonoid-based antioxidant strategy, investing in radical-scavenging chemistry rather than osmotic buffering.

Principal component analysis made this divergence visually striking. When the researchers projected all samples onto the plane defined by the first two principal components, low-stress and high-stress samples separated cleanly along an axis loaded with saponins, phenolics and IC₅₀, while the Iğdır ecotype occupied a distinct region dominated by soluble sugars. In effect, the ordination plot drew a biochemical map of two survival philosophies: one genotype fights oxidative damage with defensive phenolics, the other rides out water scarcity with osmotic sugars. That such clear separation emerged from a single species underscores how much hidden adaptive variation can reside within the gene pool of even a familiar forage grass.

Crucially for livestock producers, none of this stress chemistry compromised feed safety. Condensed tannins, compounds that bind proteins and can depress digestibility at high concentrations while offering bloat reduction and even methane mitigation at moderate levels, remained within the safe forage range across every treatment, fluctuating between 6.1 and 10.2 grams per kilogram of dry weight. This narrow, nutritionally benign window held under both salinity and drought, in both genotypes. For a grass destined to feed ruminants on marginal land, the stability of tannin levels is arguably as important as any stress-tolerance trait, because it means the forage quality of bermudagrass pastures is unlikely to deteriorate into anti-nutritional territory even as climate stress intensifies.

The broader context gives these findings real urgency. The FAO’s 2024 global assessment of salt-affected soils documents the relentless spread of salinisation across agricultural land, while climate projections point to more frequent and severe drought episodes in the very regions where forage grasses must carry livestock production. Bermudagrass, already renowned for its salinity tolerance among C4 grasses, is a natural candidate for breeding programmes aimed at these converging pressures. What the new study adds is a biochemical roadmap: it identifies osmotic adjustment capacity, antioxidant phenolic profiles and stable tannin concentrations as measurable targets, and it demonstrates that wild ecotypes can carry trait combinations that commercial cultivars lack.

The Iğdır ecotype emerges from the analysis as the standout genetic resource. It combines stronger osmotic adjustment, evidenced by its superior sugar accumulation under extreme drought, with tannin levels that stayed safely within forage-quality limits throughout the experiment. The authors conclude that this locally adapted genotype represents a promising donor for stress-tolerant forage breeding and a model for managing saline and water-limited pastures. In an era when agricultural margins are being pushed onto land that conventional crops increasingly cannot occupy, the lesson from this humble Turkish grass is a compelling one: sometimes the best solutions to tomorrow’s agricultural problems are already growing, quietly and unassumingly, in the world’s harshest landscapes, waiting for science to read their chemistry.

Subject of Research: Dose-dependent secondary metabolite and antioxidant responses of two Cynodon dactylon genotypes to graded salinity and drought stress

Article Title: Phytochemical plasticity of Cynodon dactylon under progressive salinity and drought stress: dose–response profiling of secondary metabolites, antioxidant capacity, and forage quality in two contrasting genotypes

Article References: Akis, R., Temel, S., Kulak, M., Keskin, B., Tohumcu, S. A., & Şeren, Z. N. (2026). Phytochemical plasticity of Cynodon dactylon under progressive salinity and drought stress: dose–response profiling of secondary metabolites, antioxidant capacity, and forage quality in two contrasting genotypes. Plant Biosystems, 160(4), Article 219. https://doi.org/10.1007/s44473-026-00233-2

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00233-2

Keywords: bermudagrass, Cynodon dactylon, salinity stress, drought stress, secondary metabolites, saponins, condensed tannins, antioxidant capacity, osmotic adjustment, forage quality, plant breeding, abiotic stress

The research team, led by Yenealem Solomon Kebede and colleagues at Charles Sturt University, analysed thirteen sorghum varieties sourced from field trials in Bellata and Croppa Creek in New South Wales, glasshouse trials in Queensland, and commercial seed suppliers. The varieties spanned the full colour spectrum of the species, from white-pericarp Liberty and experimental white lines through red commercial hybrids MR-Buster and MR-Bazley to brown B14A111 and the black-pericarp Shawaya Short Black-1. Whole grains were milled, defatted with hexane, and extracted using acidified acetone, a solvent system chosen specifically for its ability to liberate condensed tannins and anthocyanidins that more conventional methanol extractions often miss.

The results were striking. The black sorghum variety Shawaya Short Black-1 recorded a total phenolic content of 11.08 milligrams of gallic acid equivalents per gram, roughly seventy times higher than the white variety 2069A353-01, which measured just 0.16 milligrams per gram. The brown genotype B14A111 followed closely at 8.16 milligrams per gram. Red varieties occupied an intermediate range, while white genotypes clustered at the bottom. This gradient mirrors the biology of pericarp pigmentation: varieties carrying dominant B1 and B2 genes, and particularly those with the dominant spreader gene that produces brown pericarp, accumulate far higher levels of tannins and other polyphenols in their seed coats.

Antioxidant assays told the same story. Using three complementary tests, DPPH and ABTS radical scavenging, which measure hydrogen donation, and the FRAP assay, which measures electron transfer to ferric ions, the team found that black and brown sorghum consistently outperformed their paler counterparts. Shawaya Short Black-1 topped the DPPH and FRAP rankings at 18.94 and 18.96 milligrams of Trolox equivalents per gram respectively, while the brown B14A111 led the ABTS assay at 6.31 milligrams per gram. Statistical correlations between phenolic content and antioxidant activity were exceptionally strong, with Pearson coefficients approaching 0.98 for the DPPH assay, confirming that the polyphenols themselves, rather than some other grain constituent, drive the antioxidant effect.

The analytical centrepiece of the study was a high-resolution UHPLC-DAD-ESI-QTOF-MS/MS platform coupled with online ABTS detection, a setup that allowed the researchers to separate individual phenolic compounds, fragment them for structural analysis, and simultaneously detect which ones actively scavenge radicals. In total, eighty phenolic compounds were tentatively annotated across the thirteen varieties, spanning phenolic acids, phenol amides, flavanones, flavan-3-ols, flavanonols, flavones, isoflavonoids, 3-deoxyanthocyanidins, and proanthocyanidins. Identification confidence was graded according to the Schymanski guidelines, with authentic standards of ferulic acid, caffeic acid, procyanidin B3, luteolin, and apigenin anchoring the highest-confidence assignments.

Among the most significant discoveries were the high-molecular-weight condensed tannins. The team identified B-type procyanidin dimers, trimers, and tetramers, including an A-type procyanidin tetramer rarely reported in cereals, concentrated in the black and brown varieties. Previous sorghum profiling studies using aqueous methanol had failed to detect these larger polymers, and the authors attribute their success to the acidified acetone extraction, which is known to efficiently solubilise condensed tannins. These polymeric proanthocyanidins, built from flavan-3-ol units linked by C4-C6 and C4-C8 bonds, carry abundant free hydroxyl groups that make them potent electron donors, and they are increasingly linked to anti-inflammatory and antioxidant health benefits.

The study also documented an unusually rich array of phenol amides, with N,N’-dicaffeoylspermidine emerging as the most abundant compound across all thirteen extracts. These caffeic-acid-conjugated polyamines, found in multiple isomeric forms, have been associated in prior research with anti-diabetic, anti-cancer, anti-inflammatory, and neuroprotective activities. Their ubiquity across white, red, brown, and black genotypes suggests that even pale sorghum varieties contribute meaningful bioactive chemistry, even if their total antioxidant capacity is modest.

Genotype and environment both left their fingerprints on the chemistry. The same red and white varieties grown at Bellata showed slightly higher total phenolic content than those grown at Croppa Creek, while the red commercial lines A50, A88, and A90 from Queensland displayed notably lower phenolic levels than the New South Wales red varieties. The white Liberty variety, by contrast, was statistically indistinguishable across locations. This genotype-by-environment interaction underscores a persistent challenge for breeders: selecting for high polyphenol content requires either controlled growing conditions or multi-location trials to separate genetic potential from environmental noise. The authors acknowledge this limitation and plan follow-up studies using grains grown under identical conditions to isolate genetic effects.

Several compounds detected in the study had never before been reported in sorghum. Four isomers of catechin-(4alpha->8)-pelargonidin 3′-glucoside, anthocyanin dimers covalently linked to flavan-3-ol units previously known only from strawberries, were identified in the black and brown varieties. The team also tentatively annotated a procyanidin trimer triglycoside whose detailed structure remains unresolved, along with pyrano-flavonoid derivatives and the isoflavone puerarin, a compound with documented pharmacological activity against neurological, cardiovascular, and metabolic disease in preclinical models. The only 3-deoxyanthocyanidin detected, apigeninidin, was found in red varieties and adds to growing interest in these pigments, which are more stable under heat and pH stress than common anthocyanins and have shown chemopreventive properties in recent studies.

The practical implications reach from farm to pharmacy. For breeders, the study provides a chemical roadmap for selecting varieties with superior nutritional profiles, with black and brown genotypes as obvious lead candidates. For food manufacturers, the distinct phenolic profiles suggest opportunities to formulate sorghum-based functional ingredients targeting oxidative stress and inflammation. And for consumers, the message is simple: the darker the grain, the richer the antioxidant payload. As climate variability pushes agriculture toward hardier crops, sorghum’s combination of drought resilience and bioactive chemistry may finally earn it a place on plates well beyond its traditional strongholds in Africa and Asia.

Subject of Research: Phenolic composition and antioxidant activity of Australian-grown sorghum genotypes

Article Title: Comprehensive characterisation of phenolic composition and antioxidant activity across diverse Australian-grown sorghum ( Sorghum bicolor L. Moench) genotypes

Article References: Kebede, Y. S., Marefa, J., Budiono, B. P., Blanchard, C., & Santhakumar, A. B. (2026). Comprehensive characterisation of phenolic composition and antioxidant activity across diverse Australian-grown sorghum (Sorghum bicolor L. Moench) genotypes. Journal of Agriculture and Food Research, Article 103349. https://doi.org/10.1016/j.jafr.2026.103349

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103349

Keywords: sorghum, polyphenols, antioxidants, condensed tannins, proanthocyanidins, 3-deoxyanthocyanidins, UHPLC-MS/MS, functional foods, grain colour, genotype, flavonoids, food chemistry

The grain’s biology explains much of its chemical wealth. A sorghum caryopsis consists of three layers: the pericarp or bran, the endosperm, and the germ, with the endosperm making up about 84 percent of the grain by weight. Crucially, the phenolic compounds are concentrated in the outer layers, precisely the fractions that milling often discards or diverts to animal feed. The color of the pericarp, which ranges from white and yellow to red, brown, purple, and black, offers a rough visual guide to phenolic density. Pigmented red, brown, and black varieties generally carry far richer phenolic profiles than white types, with black sorghums accumulating exceptionally high levels of 3-deoxyanthocyanidins when exposed to sunlight. But color is an imperfect predictor. The presence of condensed tannins depends on dominant B1 and B2 genes that control the development of a pigmented testa layer, meaning some red grains lack tannins entirely while genetics can outweigh appearance altogether.

Nutritionally, the review compiles striking differences among color variants. Carbohydrate content reaches up to 80 percent of the dry grain, with protein typically between 8 and 12 percent, though red and yellow types can exceed 23 percent. White sorghums tend to offer the most starch, with amylose levels reaching 40 percent, a feature that supports resistant starch formation and low glycemic responses. Pigmented types trade some starch energy for fiber, with black sorghum reaching crude fiber contents of nearly 9 percent, and they deliver substantially more iron, zinc, and magnesium than white counterparts. Potassium is the dominant mineral across all types, with black cultivars containing up to 3,566 milligrams per 100 grams, and the consistently high potassium-to-sodium ratio positions sorghum as a dietary strategy for managing hypertension. Like most cereals, sorghum is limited in lysine, but its fatty acid profile is dominated by heart-friendlier oleic and linoleic acids, which together with palmitic acid account for roughly 90 percent of the oil fraction.

The review’s most detailed analysis concerns the phenolic compounds themselves, mapping more than 110 distinct chemicals identified through advanced HPLC-DAD-ESI-QTOF-MS/MS profiling. Ferulic acid emerges as the undisputed leader, reported in every quantitative study examined and frequently accounting for more than 60 percent of total phenolic acids, mostly in bound form attached to cell wall polysaccharides. Gallic, chlorogenic, protocatechuic, caffeic, and p-coumaric acids round out the major phenolic acids. Among flavonoids, luteolin, apigenin, taxifolin, and naringenin appear most consistently, while the signature 3-deoxyanthocyanidins, luteolinidin and apigeninidin, define the pigmented cultivars. These rare pigments lack a hydroxyl group at the C-3 position of conventional anthocyanins, a small structural difference that confers remarkable stability against pH changes, heat, and bleaching agents such as ascorbic acid and sulfites. Total phenolic content varies more than tenfold between genotypes, from around 0.24 milligrams of gallic acid equivalents per gram in white grains to 11.5 in black cultivars, and antioxidant capacity measured by DPPH, ABTS, and FRAP assays tracks this variation closely.

The health implications documented across hundreds of studies are broad and mechanistically detailed. Sorghum phenolics neutralize reactive oxygen species directly while also upregulating the body’s own antioxidant defenses, increasing the activities of superoxide dismutase, catalase, and glutathione peroxidase in animal models. For metabolic disease, condensed tannins and flavonoids act as competitive inhibitors of alpha-glucosidase and alpha-amylase, in some cases exceeding the inhibitory potency of the antidiabetic drug acarbose, thereby slowing starch digestion and blunting postprandial glucose spikes. Compounds such as taxifolin activate AMPK and Akt signaling to boost glucose uptake in muscle cells, and sorghum extracts inhibit the formation of advanced glycation end products that drive diabetic complications. Anti-inflammatory effects operate largely through suppression of the NF-kappa B pathway, with molecular docking studies showing that apigeninidin and luteolinidin bind directly to critical cysteine residues in the NF-kappa B p65 subunit. Black sorghum extracts additionally protect vascular endothelium by downregulating NOX4 and upregulating nitric oxide synthase and heme oxygenase-1.

Perhaps most striking is the evidence that sorghum phenolics reshape the gut ecosystem. Because many phenolic acids are covalently bound to fiber, they survive upper digestion and reach the colon, where gut microbes release them and ferment them into short-chain fatty acids such as acetate, propionate, and butyrate. Diets rich in sorghum polyphenols increase beneficial genera including Akkermansia, Lactobacillus, Bifidobacterium, and Roseburia, while suppressing potentially harmful taxa such as Proteobacteria. The enrichment of Akkermansia is particularly noteworthy given its association with improved insulin sensitivity and metabolic health. Sorghum phenolics also strengthen the intestinal barrier by inducing tight junction proteins, raise villus height and goblet cell numbers in experimental models, and reduce colonic inflammation in chemically induced colitis. Early research even points toward neuroprotection, with sorghum extracts showing acetylcholinesterase inhibition and interference with amyloid-beta aggregation, though the authors caution that such findings remain confined to laboratory and preclinical settings.

The same chemistry that delivers benefits can also work against nutrition. Condensed tannins bind proline-rich kafirin storage proteins into complexes resistant to digestive enzymes, reducing protein digestibility, and catechol- and galloyl-containing tannins in brown sorghum form poorly absorbable complexes with iron in a dose-dependent manner. The review emphasizes that processing is the decisive lever for tipping this balance. Germination roughly doubles total phenolic content within 72 hours while cutting tannins by up to 38 percent and phytic acid by about 20 percent. Lactic acid fermentation releases bound phenolics through microbial esterases and glucosidases, raising antioxidant activity by up to 46 percent while degrading antinutrients. Extrusion cooking reduces tannins by 44 percent in red varieties even as total phenolics decline, and nixtamalization with lime slashes tannin content by as much as 82 percent. Remarkably, dry-heat treatments such as roasting and microwave heating often increase measurable phenolics and antioxidant activity, apparently by liberating bound compounds from the cell wall matrix.

Industrial applications are already emerging. White sorghum extract eliminated Campylobacter jejuni from inoculated chicken fillets within as little as six days while improving sensory scores, and tannin-rich sorghum combined with cowpea protein produces plant-based burgers with more protein, iron, and zinc and a firmer, meat-like bite. Greek yogurt fortified with 4 percent sorghum flour doubled its antioxidant capacity, and fermented sorghum beverages showed 57 percent inhibition of ACE-I, relevant to blood pressure control. Sorghum grain waste has been upcycled into biodegradable packaging films that extend the shelf life of fresh-cut apples by preventing browning and microbial growth. Meanwhile, the 3-deoxyanthocyanidins are positioning themselves as a natural colorant of unusual industrial value: their solutions retain 80 to 90 percent of their color after two hours at 95 degrees Celsius across the pH range of most foods, and they survive sterilization conditions that destroy ordinary anthocyanins.

The review’s authors, an Indonesian team led by Miftahurrahmi and colleagues working under the RIIM LPDP grant and the National Research and Innovation Agency, close with a research agenda that calls for randomized human clinical trials to validate the largely in vitro health evidence, standardized analytical protocols to make studies comparable, breeding programs that use genomic markers to stack beneficial phenolic traits, and scalable green extraction technologies such as ultrasound, microwave, and subcritical water methods that cut solvent use and processing time dramatically. They also highlight an underexplored frontier: phenolic-rich bran fractions that are currently diverted to animal feed could be valorized as functional food ingredients, a shift with particular relevance for Indonesia’s diverse sorghum cultivars and its push toward food diversification. As climate pressures intensify and consumers seek gluten-free, nutrient-dense alternatives, the humble grain once dismissed as birdseed may prove to be one of agriculture’s most quietly powerful assets.

Subject of Research: Phenolic compounds in sorghum grains, their chemistry, health effects, processing impacts, and applications in functional foods.

Article Title: Sorghum phenolic compounds: Chemistry, health benefits, processing effects, and applications in functional foods

Article References: Miftahurrahmi, Antarlina, S. S., Ginting, E., Khamidah, A., Purwani, E. Y., Sihono, Ismail, N., Yustina, I., Ambarsari, I., & Fauziah, L. (2026). Sorghum phenolic compounds: Chemistry, health benefits, processing effects, and applications in functional foods. Journal of Agriculture and Food Research, 31, Article 103269. https://doi.org/10.1016/j.jafr.2026.103269

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103269

Keywords: sorghum, phenolic compounds, 3-deoxyanthocyanidins, condensed tannins, antioxidants, functional foods, gluten-free grains, food processing, fermentation, natural food colorants, gut microbiota, food security