IngredientsThe scientific name of osmanthus is Osmanthus fragrans (Thunb.) Lour., a species of the Osmanthus genus in the family Oleaceae, with a long history of cultivation in China. Variously known as sweet osmanthus, sweet olive, tea olive, and fragrant olive, it is native to Asia from the Himalayas through southern China (Guangxi, Sichuan, Fujian, Zhejiang, and Taiwan) to Korea, Japan, and Southeast Asia as far as Thailand and Cambodia. It was originally grown in China with a cultivation history of over 2,500 years and was introduced into Europe in the late eighteenth century.
Botanically, O. fragrans is an evergreen tree or shrub with a height of 3–5 m and a maximum height of 18 m; the bark is gray-brown, with yellowish-brown branchlets. The genus Osmanthus is made up of more than 30 kinds of evergreen trees and shrubs, mainly distributed in temperate, subtropical, and tropical regions of China.
Within Japan, the white- and orange-blossoming subspecies are distinguished as ginmokusei (lit. "silver osmanthus") and kinmokusei (lit. "gold osmanthus"), respectively. Cultivar groups recognized in Chinese horticulture include the orange-flowered Osmanthus fragrans var. aurantiacus (Dangui group), the silver-white Yingui group, and the yellow Jingui group, each with distinct aroma profiles.
Metabolomic studies have shown that the roots, stems, leaves, flowers, and fruits of O. fragrans all have medicinal properties. The roots, stems, leaves, flowers, and fruits all have documented medicinal value. It is, however, the flowers that are most frequently used medicinally.
Flowers are widely utilized in Chinese cuisine as food ingredients, in medicinal herbal teas, and for extracting aromatic essential oils. They are used to produce osmanthus tea, osmanthus-scented jam, osmanthus cakes, dumplings, soups, and wines. In Chinese cuisine, the flowers may be infused with green or black tea leaves to create osmanthus tea (桂花茶; guìhuāchá). Beyond culinary use, osmanthus is used in the preparation of pastries, sweets, and tea, as a fragrance substance in cosmetics, and its essential oil is widely applied as an additive in cosmetics and soap because of its fragrance and whitening properties. Standardized extracts rich in phenylethanoid glycosides are produced as functional food and dietary supplement ingredients. The flower extract is a well-characterized phenylethanoid glycoside-rich extract, which has been used as a natural antioxidant.
There were over 30 prescriptions involving osmanthus in ancient Chinese medical literature, such as Zhou Hou Fang (Handbook of Prescriptions for Emergencies, 317–420 CE) and Qian Jin Fang (Prescriptions Worth a Thousand Pieces of Gold, 652 CE). O. fragrans is widely cultivated in China and was documented in the ancient pharmacopeia. During the Ming Dynasty (AD 1368–1644), the medicinal functions of O. fragrans were documented in Li Shizhen's monumental pharmaceutical encyclopaedia.
The Ben Cao Gang Mu (Compendium of Materia Medica), the foundational text of traditional Chinese medicine, describes the usefulness of the flowers for phlegm and stasis reduction, arrest of dysentery with blood in the bowel, and treatment of stomachache and diarrhea. In classical Chinese medicine, O. fragrans is classified as a pungent, warm, and nonpoisonous herb, used to promote saliva secretion, deodorize, and clear phlegm, and believed to be effective in the treatment of toothaches.
Traditional Chinese medicine also suggested the use of O. fragrans to treat weakened vision, halitosis, panting, asthma, cough, toothache, stomachache, diarrhea, and hepatitis. The roots were used to treat rheumatic numbness and low back pain. In traditional Chinese medicine, osmanthus tea has been used as an herbal tea for the treatment of irregular menstruation.
The plant is distributed widely in some Asian countries including Japan and Korea and southwestern China, where it has been utilized medicinally. The leaves of O. heterophyllus, a closely related osmanthus species, have been used as an herbal drug for vitiligo vulgaris in Japan. The intensely fragrant blossoms of kinmokusei (the orange-flowered cultivar) are among the most recognizable seasonal aromas in Japan and have a long history of cultural use in incense and perfuming garments.
Osmanthus has been prepared historically as infused teas (fresh or dried flowers steeped in water), alcoholic preparations (osmanthus liquor or wine), and decoctions. Fresh O. fragrans is often extracted by the ethanol reflux method in modern preparation; fresh plant material is first dried, crushed, and then stored. Flowers of Osmanthus fragrans are commonly used as folk medicine and additives for teas, beverages, and foods in Taiwan.
More than 183 compounds have been isolated and structurally identified from different plant parts of O. fragrans. A 2022 review in Food Chemistry reported a larger tally: about 300 chemical compounds including salidroside, acteoside, phillygenin, oleanolic acid, ursolic acid, and rutin have been isolated from the flowers, leaves, roots, and fruits. These compounds can be classified into lignans, terpenes, flavonoids, phenolic acids, phenolic glycosides, phenylethanoid glycosides, phenylpropanoids, and other compounds.
Among these, ionones, ionols, flavonoids, polyphenols, and iridoids, as the major bioactive substance classes, have been extensively studied and display the best bioactivity.
The primary chemical components of the essential oil extracted from O. fragrans are linalool and its oxide, α-ionone, β-ionone, nerol, γ-decalactone, 9,12,15-octadecatrienoic acid, and hexadecanoic acid; most of these are at their highest concentrations in extracts obtained from flowers at the initial flowering stage.
The main volatile components of osmanthus essential oil are 1,2-epoxylinalool, β-linalool, 5-ethenyltetrahydro-α,α,5-trimethyl-2-furanmethanol, and β-ionol. The main aroma compounds identified in O. fragrans include dihydro-β-ionone, nonanal, β-cyclocitral, β-ionone, benzaldehyde, α-ionone, and 6-methyl-5-hepten-2-one.
Terpenoids are the most abundant aroma compounds across cultivars; linalool and its oxides are the dominant aroma-active compounds due to their high contents and high odor activity values, and they impart a noticeable floral fragrance to O. fragrans flowers.
trans-β-Ocimene, trans-β-ionone, and linalool, which are major volatiles, are identified as aroma-active, while cis-3-hexenyl butanoate, γ-terpinene, and hexyl butanoate are also aroma-active compounds at lower concentrations. Aroma composition varies by cultivar: creamy-white cultivars contain more herb odors contributed by cis- and trans-β-ocimene, yellow cultivars have more woody/violet/fruity odors from trans-β-ionone, α-ionone, and hexyl butanoate, while orange cultivars feature more floral odors from cis- and trans-linalool oxide and linalool.
Phenylethanoid Glycosides: This group includes acteoside (verbascoside), salidroside, and isoacteoside. The phenylethanoid glycosides of the flower extract include acteoside, salidroside, and isoacteoside as principal components. Acteoside is the most pharmacologically studied component of the flower extract and is considered a major bioactive marker compound.
Flavonoids: Flavonoids are an important type of secondary metabolite in O. fragrans; assessment of the iron ion reduction ability and DPPH and ABTS antioxidant assays showed that these flavonoids exhibit good antioxidant activity. Identified flavonoids include naringenin, quercetin-3-O-β-D-glucopyranoside, kaempferol-3-O-β-D-glucopyranoside, kaempferol-3-O-β-D-galactopyranoside, isoscutellarein, and several methoxyflavone glycosides.
Phenolic Acids: Identified phenolic acids include chlorogenic acid, caffeic acid, p-hydroxycinnamic acid, benzoic acid, p-hydroxy-phenylacetic acid, and p-hydroxyacetophenone.
Triterpenoids: Compounds isolated from the fruits include oleanolic acid, acetyloleanolic acid, 2α-hydroxy-oleanolic acid, betulinic acid, betulin, and lupeol. From the leaves of the aurantiacus variety, bioactivity-guided isolation yielded four triterpenoids: 3α,24-dihydroxyurs-12-en-28-oic acid, pomolic acid, maslinic acid, and corosolic acid.
Iridoids: Specnuezhenide and nuezhenoside G13 are identified as major iridoid glycosides from O. fragrans seeds.
Lignans: Three new megastigmane glycosides named floraosmanosides I–III and a new γ-decalactone named floraosmanolactone I, together with 16 known constituents, were isolated from the flowers of Osmanthus fragrans var. aurantiacus cultivated in Guangxi, China. Among these, ligustroside and (+)-pinoresinol significantly inhibited nitric oxide production in lipopolysaccharide-activated RAW264.7 macrophages.
Dihydroquercetin (DHQ) and Astilbin: DHQ is found in the petals of O. fragrans, and researchers have found that DHQ has antioxidant, antiviral, anti-inflammatory, anti-allergic, anti-apoptotic, and antitumour properties, and protects the liver. Astilbin is primarily found in the petals of O. fragrans; its molecular formula is C₂₁H₂₂O₁₁, and recent studies have found that astilbin may have antidepressant, antioxidant, antidiabetic, analgesic, and antibacterial properties, inhibit oedema, protect the liver and kidney, and promote chondrocyte proliferation.
Phillyrin: Phillyrin was identified from this plant and has multiple bioactivities including antioxidant, anti-tumor, anti-inflammatory, antiviral, antibacterial, and weight loss effects. This compound also engages a variety of signaling pathways, including nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor kappa B (NF-κB), toll-like receptor, and PI3K/AKT pathways.
Trace Elements and Amino Acids: It has been reported that O. fragrans contains a high content of total amino acids and trace elements such as potassium, iron, and zinc.
Overproduction of free radicals can cause oxidative damage and lead to chronic disease; many plants contain free radical-scavenging molecules such as phenolic acids and flavonoids, which show strong antioxidant activity. After oral administration of osmanthus flower ethanol extract (OFE) in mice, values obtained in the oxygen radical absorbance capacity assay as well as glutathione concentrations in the lungs and spleens increased, while thiobarbituric acid reactive substances decreased significantly, indicating significant in vivo antioxidant activity. In cell-free and cell-based models, the ethanol extract demonstrated higher total polyphenols (233.360 ± 3.613 g/kg) and tannin (93.350 ± 1.003 g/kg) contents, with effective DPPH scavenging activity (IC₅₀ = 0.173 ± 0.004 kg/L) and a high FRAP value (830.620 ± 6.843 g Trolox/kg).
Triterpenoids and phenolics extracted from the leaves have shown substantial anti-inflammatory activities, suppressing pro-inflammatory cytokines and pathways such as cyclooxygenase-2 (COX-2) and nuclear factor kappa B (NF-κB). At the ERK signaling level, active compounds inhibit inflammation through COX-2 and iNOS enzymes and block the ERK 1/2 MAPK signaling pathway.
Osmanthus flower methanol extract significantly suppressed fatty acid-induced intracellular triacylglycerol accumulation by partially inhibiting the gene expression of SREBP-1c and GPAT in HepG2 cells, inhibited reactive oxygen species generation, and suppressed the mRNA expression of interleukin-1β, IL-6, IL-8, TNF-α, and TGF-β. In mouse models, iridoid glycosides from O. fragrans seeds significantly reduced the liver and spleen index, reduced ALT and AST contents in plasma and MDA content in liver tissue, and increased SOD content, while also reducing plasma IFN-γ and TNF-α levels and alleviating pathological liver changes, with the mechanism related to inhibiting the phosphorylation of p38MAPK.
OFE with IC₅₀ values between 46 and 97 μg/ml inhibited lipid peroxidation in rat brain, liver, heart, and kidney mitochondria; the neuroprotective activity of OFE was investigated under different insults (glutamate, arachidonic acid, and 6-hydroxydopamine) in Wistar rat primary cortical neurons, where OFE with EC₅₀ values between 66 and 165 μg/ml attenuated neurotoxicity on MTT and LDH assays. The AKT protein expression under excitotoxicity and oxidative stress conditions was studied by western blotting; OFE was found to up-regulate the glutamate- and 6-OHDA-decreased AKT expression.
Osmanthus flower aqueous extract (OFFE) and acteoside inhibit melanogenesis induced by α-MSH in B16 melanoma cells via the MITF-tyrosinase signaling pathway. Treatment with α-MSH enhanced melanin levels and tyrosinase activity and up-regulated MITF and tyrosinase mRNA levels; these effects were counteracted by OFFE and acteoside. The acetonic extract of O. fragrans demonstrates significant inhibitory effects on melanin biosynthesis and on tyrosinase activity in an uncompetitive mode; findings from the B16F10 mouse melanoma cell model confirmed that the extract inhibits melanogenesis and tyrosinase activity in vitro.
Treatment with O. fragrans extract (500 mg/kg) significantly decreased serum malondialdehyde and increased superoxide dismutase levels in diabetic rats; oral administration of 160 mg/kg of the extract significantly decreased serum triglyceride and serum cholesterol in diabetic rats and significantly increased liver glycogen content. The chloroform fraction derived from O. fragrans flowers could efficiently inhibit α-amylase and α-glucosidase, potentially playing a role in the treatment of hyperglycemia through oxidative mechanisms.
A single administration of OFE significantly reduced immobility duration in forced swimming and tail suspension tests in mice without affecting locomotor activity; OFE exhibited selective enhancing effects on serotonergic (5-HTergic) function in vivo, as demonstrated by its potentiating effects on 5-hydroxytryptophan (5-HTP)-induced head-twitch behavior.
The extracts of Osmanthus fragrans flowers have been reported to have various bioactivities including free radical scavenging, anti-inflammation, neuroprotection, and antitumor effects. A large amount of antioxidant compounds, including flavonoids and phenolics, have been detected in the flowers; the extract has been found to possess free radical scavenging activity, antioxidative activity, neuroprotective properties, inhibitory effects on melanogenesis, and nitric oxide production inhibition.
Evidence strength: The antioxidant evidence for O. fragrans is robust at the in vitro and in vivo (animal) level but currently lacks controlled human clinical trials. Modern evidence regarding the therapeutic efficacy of these flowers in humans remains limited.
O. fragrans var. aurantiacus is a traditional medicine for treating various diseases, including inflammation; studies have assessed antioxidative and anti-inflammatory activities of this plant. In cell-based models, multiple molecular pathways have been identified. The ethyl acetate fraction of O. fragrans effectively suppresses cell proliferation and survival in colorectal cancer cells, attributing these effects to the inhibition of COX-2 and NF-κB pathways.
Evidence strength: Currently limited to cell-based and animal models. Many studies on biological activities were mainly based on extracts and bioactive ingredients of this plant, and the mechanisms responsible for these activities have not been well identified, with a gap in research regarding clinical effect and safety.
Osmanthus fragrans flower extract (OFE) exhibits neuroprotective, free radical scavenging, and antioxidant effects; in an aging ICR mouse model established by chronically administering d-galactose (250 mg/kg) for 8 weeks, d-galactose-induced spatial learning and memory impairments were successfully inhibited by OFE and acteoside, which could shorten escape latency, improve platform crossing times, and increase zone time.
Research on the neuroprotective effect of acteoside, a major bioactive compound of Osmanthus fragrans, showed it was capable of suppressing production of advanced glycation end products (AGEs) and neurotrophin-3 (NT-3). Additional active ingredients in O. fragrans have shown encouraging suppression of BACE1 (β-site amyloid precursor protein cleaving enzyme 1) activity, suggesting that they may have potential application to the treatment of Alzheimer's disease.
Evidence strength: Preclinical only (animal models, cell culture, and in silico). No controlled clinical studies in humans have been published.
The aim of a published study was to investigate the protective effects of methanolic flower extracts of Osmanthus fragrans and Chrysanthemum morifolium against FFA-induced lipotoxicity in hepatocytes (human HepG2 cells) and renal glomerular mesangial cells. Flower extract and its bioactive components showed anti-inflammatory, antioxidant, and neuroprotection activity, and attenuated acetaminophen-induced hepatotoxicity. Osmanthus fragrans seeds are rich in iridoid glycosides, which have demonstrated a protective effect on immune liver injury in mice caused by concanavalin A; the mechanism may be related to inhibiting the phosphorylation of p38MAPK. Osmanthus fragrans extract is effective in inhibiting the development of non-alcoholic steatohepatitis (NASH) primarily through anti-inflammatory and anti-oxidative stress mechanisms, and may also improve NASH by modulating gut flora species and restoring gut microbial homeostasis.
Evidence strength: Cell culture (HepG2) and animal models only. No human clinical data are available for hepatoprotective outcomes.
DHQ (dihydroquercetin) from O. fragrans petals can affect oxidation and hyperglycemia, and also lowers blood pressure and alleviates cardiovascular disease. DHQ may reduce the symptoms of diabetic nephropathy in rats by affecting the mTORC2/Akt signalling pathway. Alpha-glucosidase and alpha-amylase inhibition, key mechanisms in blood glucose management, have been documented in in vitro enzyme inhibition studies. Treatment with O. fragrans extract at 500 mg/kg significantly decreased serum malondialdehyde and increased superoxide dismutase in diabetic rats; oral administration of 160 mg/kg significantly decreased serum triglyceride and cholesterol in diabetic rats and significantly increased liver glycogen content.
Evidence strength: Animal and cell-based studies; one review notes these dose-specific effects in rats. No human clinical trials have been conducted.
Chronic administration of O. fragrans fruit extract showed significant antidepressant-like effects in forced swimming tests (FST) and tail suspension tests (TST) in mice. Chronic administration of O. fragrans flower extract improved depression-like behavior in maternally deprived rats by enhancing antioxidant capacity in the depression-related brain regions of those rats. The serotonin system appears to be a principal mechanism. Whether O. fragrans var. thunbergii flowers consumed as a dietary supplement will have therapeutic effects on depression in humans is unknown.
Evidence strength: Preclinical (rodent behavioral models) only. No human studies.
OFFE produced a depigmenting action on UVB-induced hyperpigmentation in guinea pigs, as shown by improved skin brightness and decreased melanin staining. Triterpenoids isolated from O. fragrans leaves were found to significantly inhibit melanin production and tyrosinase activity, with active compounds down-regulating TYRP-1 and TYRP-2 expression levels.
Evidence strength: Cell-based and guinea pig model data. No human clinical trials evaluating skin brightening or depigmentation in human subjects have been published.
A study assessed the antioxidative effects of the ethanol extract of O. fragrans flowers in vivo and its therapeutic effect on allergic airway inflammation in mice; after oral administration, the oxygen radical absorbance capacity and glutathione concentrations in the lungs and spleens of mice increased, while thiobarbituric acid reactive substances decreased significantly; OFE was also therapeutically efficacious in a mouse model of ovalbumin-induced allergic airway inflammation.
Evidence strength: Animal (mouse) model only. No human data.
Osmanthus fragrans flower extract has been used to treat bad breath. Ethanol extract of O. fragrans has been studied for effects on oral pathogens; one study found that the ethanol extract attenuated Porphyromonas gingivalis lipopolysaccharide-stimulated inflammatory effects through the nuclear factor erythroid 2-related factor (Nrf2)-mediated antioxidant signaling pathway (as cited in pharmacological review literature). Pharmacological studies demonstrated that O. fragrans and its active components have a wide range of biological activities, including antibacterial activity.
Evidence strength: Cell and animal studies; no human clinical trials.
No standardized dosage guidelines from regulatory bodies such as the WHO, EMA, or NIH have been established for osmanthus as a dietary supplement. The following dosages are reported only as used in published experimental studies and should not be construed as recommended doses.
According to current research, O. fragrans extracts and components have great potential to be developed into value-added functional ingredients with preventive effects on certain chronic diseases; however, it is crucial to develop efficient, large-scale, and commercially viable extraction methods to obtain the bioactive components, and more clinical studies are highly needed to explore the beneficial functions of O. fragrans and guide its development into functional food products.
No acute lethal effect at the maximal tested OFFE dose of 10 g/kg body weight in either rats or mice was observed, suggesting that OFFE can be considered nontoxic; no evidence for mutagenicity was detected in any of three mutagenic tests.
An acute oral toxicity study, reverse mutation test, bone marrow cell micronucleus test, sperm abnormality test, and a 90-day oral toxicity study were performed on experimental animals. Acute and subacute oral administration of OFFE did not induce any observed adverse effect in the acute oral toxicity study, subchronic oral toxicity study, or in the mutation test; these results may provide supportive evidence of the safety of OFFE powder that has been used in medicine as well as in functional foods and dietary supplements.
Investigating the chemical stability of phenylethanoid glycosides in Osmanthus fragrans revealed that high temperature, high pH, and light exposure cause PhGs degradation, reducing the anti-hypoxia ability of PhGs. This has practical implications for processing, storage, and formulation of osmanthus-based products.
Many studies on biological activities were mainly based on extracts and bioactive ingredients of this plant, and the mechanisms responsible for these activities have not been well identified; there is a gap in research regarding clinical effect and safety. Detailed in vitro and in vivo studies on the mechanisms of action of pure bioactive compounds and more clinical studies are encouraged to ensure safety and effectiveness for human use.
Many studies on biological activities were mainly based on extracts and the bioactive ingredients of this plant, and the mechanism responsible for these activities has not been well identified, with a gap in research regarding clinical effect and safety. Detailed in vitro and in vivo studies and more clinical studies are therefore encouraged.
The plant is classified as O. fragrans is classified as a pungent, warm, and nonpoisonous Chinese herb in traditional Chinese medicine texts, but formal pharmacopeial monographs from the European Pharmacopoeia, WHO, ESCOP, or German Commission E have not been published for this species, and no official dietary supplement dosing guidelines exist as of current literature.
Health conditions that Osmanthus may help support.
Body systems that Osmanthus may help support.
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