Sumaq (Rhus Coriaria): A Comprehensive Review of the Culinary Delight and Medicinal Marvel in the Unani System of Medicine

Sumaq is a well-known spice from the Middle East, historically utilized as a condiment and flavor enhancer. ^[1][2] Its name derives from the striking red hue of the spice produced from the plant. The term "sumac" is thought to originate from the Arabic word "summaq," meaning "dark red," while some attribute it to the Syriac word "Sumaga," which also signifies "red," reflecting the color of its ripe fruits. ^[3][4][5] In fact, the word “Sum?q” is used to refer to the fruits and the rind. ^[6][7]

Traditionally, Sumaq was employed as a tanning agent for high-quality leather, earning it the title Sumaq-al-Dab?ghay’n, or tanner's sumac. ^[6][7] Its usage and trade date back to ancient times. In Middle Eastern regions, Sumaq is harvested to create powder from different parts of the plant for use in the food and cosmetics industries, often as a dressing for seasonal dishes. In the Mediterranean, it flavors meats, fish, and salads. ^[8]

The plant thrives in tough soils, preferring colder climates, and can grow up to approximately 6 feet tall. Its leaves are elongated, reddish, and velvety with serrated edges, while its flowers are small, and its fruits are in drupes and resemble flat, small Mas?r (Lens culinaris). There are wild and cultivated varieties of Sumaq, with two main types: Sh?mi (Syrian) Sumaq, which is smaller and more red, and Khoras?ni Sumaq. Younger Sum?q with brilliant red drupes that are flavourful, acidic, and have smaller seeds are regarded as superior. In terms of shelf life, it can remain viable for up to three years. ^[6][7]

Sumaq is valued in Unani medicine for its astringent, tonic, stomachic, antidiarrheal, antiemetic, wound-healing, and appetizing properties. It was once believed that hanging Sum?q inside red cotton as an amulet could effectively stop bleeding due to its hemostyptic capabilities. Sum?q is considered to have established nutraceutical benefits. ^[8] The medicinal benefits of the plant can be attributed to a wide range of active compounds such as organic acids, hydrolysable tannins, flavonoids, phenolic acids, terpenoids, and anthocyanins. ^[2] The focus of this article is to explore the medicinal uses of Sum?q, drawing from classical Unani literature and contemporary scientific research to clarify its therapeutic potential. The discussion will cover its bioactive compounds, pharmacological activities, and diverse health benefits, providing a comprehensive understanding of this remarkable plant in both traditional and modern medicine.

1. MATERIAL AND METHODS:

The research on Rhus coriaria L. involved gathering information from both traditional Unani Medicine texts and contemporary sources. A total of 17 books were referenced, including 11 Unani texts and 6 modern publications. From these, 2 Unani texts and 3 modern references were excluded due to repetition. Furthermore, data was obtained from 42 research and review papers accessible on platforms such as Pub Med, Google Scholar, Semantic Scholar, ResearchGate, Scopus, and Springer. These papers were meticulously chosen from a pool of around 61 sources. Information about the plant was searched using keywords such as Sumac, Rhus coriaria, and tanner’s sumac. Relevant Unani terms were sourced from the Standard Unani Medical Terminology published by CCRUM in collaboration with the World Health Organisation.

2. Observations:

3.1 Vernacular names

Arabic: Sum?q, Sum?q?l, Sum?q-al-Dab?ghain, Karafs-ul-M?’^[6] Garda-i-sumaq, Timtima, Tamtam ^[9]

Bengali:       Sumok ^[9]

English:       Sumac, Sumach, Sumak ^[9] European sicilian sumach ^[10]

Greek:         Rous Aqt?r, Albar?n, Atasr?n, ?sar?n ^[6]

Hindi:          Tatrak, ^[10] Tantar?k, Tam?t?r ^[6] Raitung ^[9]

Kashmiri:     Samak, Chokmusur ^[9]

Persian:        Tamtam, Tatr?, ^[6] Samaka, Samak, Sumaq ^[9]

Punjabi:        Minas, Ninawa, Samakdana, Tungla ^[9]

Sanskrit:       Tandidik ^[9]

Urdu:             Sum?q ^[9]

3.2 Taxonomical classification ^{[11] [12]}

Kingdom: Plantae

Division: Magnoliophyta

Order: Sapindales

Family: Anacardiaceae

Genus: Rhus

Species: coriaria

3.3 Morphology of the plant: Rhus coriaria is a shrub that grows to a height of 3 to 5 meters. It features long leaves with pinnate veins, consisting of 7 to 8 pairs of tiny, oval, hairy leaflets that vary in size and have a reddish brown tomentum covering their petioles and midribs. ^{[4] [13]} the spiral shape of the leaves in trifoliate or simple format distinguishes this plant from others. ^[14] The inflorescence forms a dense and upright panicle, showcasing petite, five-petaled flowers, typically found in three hues: white, green, and red, and measuring 5 to 30 cm in length. ^{[12] [14]} The plant produces sumac bobs, which are dense clusters of dark red, thin-fleshed drupes located at the tips of its branches. ^[4] The fruit is small, flattened, and measures 3.5 to 4 cm in length and 2.0 to 2.5 cm in width, with a persistent calyx (figure 1). Inside, it contains a single, polished brown seed that is hard and lenticular, measuring 0.3 to 0.5 cm in length and 0.2 to 0.3 cm in width, and has a spicy odor. ^{[9] [13]}

Figure 01. Showing the dried fruit of Sum?q

3.4 Habitat:

The plant flourishes in subtropical and temperate climates, especially in various parts of the Mediterranean, ^[10] northern Africa, and Asia ^[4] It is extensively cultivated in Italy, Spain and Sicily, around Black Sea, Persia, Afghanistan, ^[15] Turkey, Palestinian population, Syria, Israel and Jordan, ^[3] The plant was imported from Persia to India for tanning finer varieties of leather. ^{[9] [15]}

3.5 Chemical constituents:

Recognized for its functional food properties, Sumaq fruit contains a wide range of crucial nutritionally and pharmacologically significant components including proteins, essential oils, fatty acids, fibres, minerals, tannins, phenolic acids, and anthocyanins. ^[2] A study revealed the presence of 263 volatile compounds, including terpene hydrocarbons, acids, and aldehydes, as well as 83 polyphenolic compounds, with a predominant presence of Gallic acid derivatives (Table 1). ^[16]

Table 02. Shows various vitamins and minerals present in Sum?q

1. 6. Unani description:

3.6.1 Parts used:

Various parts of the Sumaq are used for their medicinal purposes. These include the fruits, rind of the fruit (epicarp), leaves, dried extract of the fruit and the plant’s gum. The fine powder obtained by crushing the fruit of the Sum?q, known as Tur?b-al-Sum?q (Sumac dust) is also used medicinally. ^{[6] [7]}

3.6.2 Temperament:

Cold² and Dry³ (B?rid² Y?bis³) ^{[6] [21]}

Cold² and Dry² (B?rid² Y?bis²) ^{[6] [9] [22]}

Cold³ and Dry² (B?rid³ Y?bis²) ^[6]

3.6.3 Taste: The outer cover of the fruit is sour in taste ^{[6] [22]}

3.6.4 Odor: The seeds of the fruit have spicy pungent odor ^[9]

3.6.5 Main function:

Stomachic (Muqawwi-i-Mi‘da), Antidiarrheal, Antiemetic and Haemostyptic (??fi’ Ish?l wa Qay’ wa S?l?n-i-Kh?n) ^[22]

3.6.6 Substitute:

As?r?n (Asarum europaeum L.), Turanj (Citrus medica L.), Kas?la T?t (Morus sp.), Sirka (vinegar), Aq?qia (Acacia arabica Lam. Willd.) ^{[6] [22]} Zirishk (Berberis vulgaris) ^[22]

3.6.7 Adverse effects:

It affects people of melancholic temperament and is considered harmful for stomach and liver of cold temperamental people. Its excessive use is harmful for the kidneys. ^{[6] [22]}

3.6.8 Corrective:

An?s?n (Pimpinella anisum L.), Mastagi (Pistacia lentiscus), ^{[6] [22]}  Luk maghs?l (Lac from Laccifera lacca) for nephroprotection. ^[6]

3.6.9 Dosage:

5.5g to 16.6g ^[7]

3 to 5 grams ^[9]

3.6.10 Actions: Table 3 lists various actions of Sum?q (figure 02)

Table 03: Actions of Sum?q according to Unani medicine

1. 7. Therapeutic uses in Unani Medicine and modern scientific studies:

3.7.1 Effects on the gastrointestinal system:

In Unani System of Medicine, Sum?q is used to strengthen the gastrointestinal organs, especially the stomach rugae, due to its astringent properties, thus improving the overall function of the gastrointestinal system. ^[7] It is a potent antidiarrheal and is used to treat acute and chronic diarrhoea ^{[7] [21] [22]} especially in children. In this case, its poultice applied over the abdomen. ^[7] It is also used in intestinal abrasion (Sahaj) and Bloody diarrhoea (Dh?sant??riy?). ^{[7] [21]} Sum?q, especially roasted, prevents excess bile flow from liver into the gastrointestinal tract. [7] It is beneficial in nausea and vomiting. ^{[7] [9] [22]} It increases the appetite and quenches excessive thirst especially in people of hot temperament. Sitz bath or enema with its decoction was used to treat intestinal ulcers (Qur?h) ^{[21] [22]} Various studies have been performed which support the use of Sum?q in various gastrointestinal conditions. A study observed the anti-secretory and antidiarrheal effects of 100 and 300 mg/kg doses of aqueous extracts from Rhus coriaria fruit against castor oil induced fluid accumulation and diarrhea in isolated rabbit jejunum. The sumac extract showed antispasmodic activity. It was found to reduce high K+-induced spastic contractions with an EC50 of 0.3 mg/ml and exhibited a Ca++ antagonist effect in rabbit jejunum. ^[23] According to another study, the administration of 2mL/kg per day, sumac aqueous extract orally, was found to prevent intestinal tissue damage in rat pups with induced necrotizing enterocolitis. This was achieved through its free radical scavenging activity and the reduction of TNF-α and IL-6 levels. ^[24]

A study conducted on breast cancer patients demonstrated that using ground Rhus coriaria fruits along with Bunium persicum B. was effective in minimizing the chemotherapy-induced nausea and vomiting experienced by the patients. ^[25] The hepatoprotective activity of Sumac aqueous fruit extract was uncovered in a study by Pourahmad et al (2010). Isolated rat hepatocytes were shielded by Sumac extract (75 and 100 µg/mL) from oxidative stress induced by cumene hydroperoxide (CHP). Sumac extract provided protection against ROS generation, lipid peroxidation, glutathione depletion, mitochondrial membrane potential, and cellular proteolysis in rat hepatocytes. Furthermore, Sumac extract exhibited potent H2O2 scavenging activity. ^[26] In a 12-week randomized placebo controlled clinical trial, it was found that providing Rhus coriaria powder to patients with nonalcoholic fatty liver disease led to a more significant reduction in liver fibrosis and liver enzymes compared to the placebo. ^[27]

3.7.2 Effect on diseases of the eyes:

In Unani Medicine, the topical application of Sumaq is used to treat conjunctivitis, epiphora, blepharitis and itching. Its prophylactic use in the eyes, during chicken pox, prevents the development of lesions in the eyes. Its gum is used as an eye tonic to strengthen the vision. ^{[7] [22]}

3.7.3 Effects on diseases of the ears:

In Unani Medicine, it is used to treat otitis. It dries up the ear canal and relieves pus discharge from the ear. If given early in the course of otitis, it can help prevent the formation of pus. ^{[21] [22]} The effects of Sum?q can be attributed to the antibacterial properties of Rhus coriaria. Sumac fruit ethanol extracts were tested for antibacterial activity and demonstrated significant concentration-dependent antimicrobial effects against a variety of bacterial strains, including both gram-positive and gram-negative bacteria. ^[28]

According to a study, comparing the antibacterial activity of water, methanolic, and ethanolic extracts of Rhus coriaria fruits, the ethanolic extract demonstrated the highest growth inhibition activity against methicillin-resistant Staphylococcus aureus (MRSA), multidrug resistant Pseudomonas aeruginosa, entrohemorrhagic Escherichia coli (EHEC), Proteus vulgaris, and Klebsiella pneumoniae with a minimum inhibitory concentration (MIC) of 1.25 mg/ml. ^[29]

3.7.4 Effects on oral cavity:

The tooth powder of Sum?q strengthens teeth and gums while gargling with its infusion relieves resistant oral ulcers and stomatitis. ^{[7] [22]} Its gum is chewed to relieve toothache ^{[6] [21]} and is useful in case of tooth decay. It alleviates dryness of tongue and mouth. ^[7]

Multiple studies have been performed that demonstrate the effects of Rhus coriaria on oral health. According to a study, aqueous extract of Rhus coriaria inhibited the growth of five common oral bacteria, including Streptococcus mutans, Streptococcus sanguinis, Streptococcus sobrinus, Streptococcus salivarius, and Enterococcis faecalis, in a concentration-dependent manner. The aqueous extract of Rhus coriaria fruit effectively prevented the formation of Streptococcus mutans biofilm, with an MIC of 1.56 mg/ml. ^[30] In 2016, Seseogullari-Dirihan et al, conducted a study to assess the effect of different collagen cross-linkers, including Rhus coriaria fruit extract, on the matrix metalloproteinase activity of demineralized dentin matrix. The results showed that the extract led to a significant reduction in total dentin MMP activity compared to the control. ^[31] Another study found that administering an orogastric ethanolic extract of Sumac fruit (20mg/kg/day) to Wistar rats with ligature-induced periodontitis reduced alveolar bone loss. The extract achieved this by influencing the balance of RANKL/OPG, as well as total oxidant status and oxidative stress in the rats receiving the treatment. ^[32]

3.7.5 Effects on blood vascular system:

Sumaq has haemostyptic action and stops bleeding by local vasoconstriction. It is therefore used in case of haemorrhage, menorrhagia, haemoptysis, epistaxis and haemorrhoids. ^{[7] [21] [22]} A cloth drenched in its infusion and kept over the forehead can stop epistaxis. ^[21] Its liniment can stop bleeding from haemorrhoids. ^{[7] [21]}

The use of Rhus coriaria as a haemostyptic agent can be attributed to its rich contents of tannins. The bioactive components of sumac have been extensively documented in various reports, with hydrolysable tannins identified as the predominant group of compounds found in Sumac fruits. ^[4] Tannins can affect platelet functions by influencing the release of arachidonic acid and the subsequent production of eicosanoids, which are essential for haemostasis. Tannins can inhibit the metabolism of arachidonic acid, leading to an impact on the synthesis of thromboxane and other eicosanoids involved in platelet activation. Some studies also suggest that tannins may exhibit pro-coagulant effects in specific situations, such as in diabetic models. ^[33]

3.7.6 Effect on genitourinary system:

Due to its astringent properties, it is beneficial in leucorrhoea, menorrhagia, polyuria and urinary incontinence. ^{[7] [22]} These functions of Sumac can be attributed to antibacterial and immune-stimulating action of tannins and flavonoids found in sumac like quercetin, which suggests that it could also help against common bacterial infections affecting gastrointestinal, respiratory, and urinary systems. ^[34] This antibacterial activity of Rhus coriaria could be responsible for treating infections thus reducing frequency, urgency and polyuria. Symptoms in Overactive Bladder patients may be influenced by inflammation and oxidative stress. The flavonoids and tannins reduce inflammation and oxidative stress in the urinary tract thereby improving the symptoms of overactive bladder. ^[35]

3.7.7 Effects on wounds, swellings and inflammations:

As a divergent and vasoconstrictor, its local application prevents swellings, oedema and bruise formation. If applied over a swelling, it stops its progression in size. ^{[6] [7]} Applying Sum?q over a sprain can strengthen the injured organ ^[21] and its local irrigation prevents the development of oedema. Therefore, in case of head injury, its water was applied on the cranium to prevent inflammation and swelling of the brain. The local application of its leaves with crushed leaves of B?rtang (Plantago major) or along with vinegar and honey, stops the progression of necrosis in case of gangrene. ^{[6] [7]} Its gum is applied on fresh wounds to accelerate healing. ^[6]

These effects of the drug can be attributed to the anti-inflammatory, antioxidant and wound healing properties of Rhus coriaria. Extensive research has been conducted on the antioxidant characteristics of different extracts from Sumac fruits and leaves. One study demonstrated that both the aqueous extract and nanoparticles synthesized from Rhus coriaria exhibited noteworthy antioxidant properties when tested using ABTS and DPPH assays. ^[36] Another research study found that Sumac's aqueous fruit extract demonstrated potent antioxidant properties and effectively scavenged free radicals. The aqueous extract of Sumac showed efficient radical scavenging activity, with an EC50 of 36.4 µg/mL for DPPH free radical and 44.7 µg/mL for DMPD cation radical. ^[37]

Another study evaluated the biological effects of lyophilized hydrophilic extracts of Rhus coriaria on wound healing, myeloperoxidase activity, and microbial infections of skin wound tissues in animal models. The study proved the potent anti-inflammatory, anti-oxidant and antimicrobial properties of sumac play a good potential role in accelerating wound healing activity via promoting myofibroblast activity, increase of hydroxyproline and collagen deposition, and regulation of MMP-8 and MPO enzyme activities. ^[38] A similar study performed on diabetic and non-diabetic rats found that the methanolic extracts of Rhus coriaria fruit enhanced wound contraction and increased hydroxyproline and collagen content. This supports the early wound healing properties of R. coriaria, indicating that the methanolic fruit extract may be effective in topical wound therapy due to its potent wound healing capacity. ^[39]

3.7.8 Effects on hair:

Its decoction is used as a dye to colour the hair black. ^{[7] [21] [22]}

1. 8. Other pharmacological actions:

3.8.1 Cardio-protective activity:

A study demonstrated that the methanolic extracts from the leaves of Rhus coriaria have a cardiovascular protective impact on isolated rabbit hearts. The extract showed a dose-dependent protection against myocardial injury caused by ischemia reperfusion, when perfused with different concentrations of Rhus coriaria leaf extract for 20 minutes prior to ischemia. [40] The ethanolic extract of Rhus coriaria fruit, in a concentration of 0.3-1.0 mg/ml, elicited a concentration dependent vasorelaxation of rat aorta. ^[41]

3.8.2 Neuroprotective activity:

The neuroprotective effects of sumac fruit extract were documented in a study using an in vitro cellular model of neuroinflammation. Inhibition of ROS nitric oxide, reduction of TNF-α, iNOS, and COX-2 mRNA expression levels, and potent anti-inflammatory potential on the cell lines were demonstrated by the extract. ^[42]

In another study, the potential neuroprotective impacts of ethanolic Rhus coriaria fruit extracts were examined on retinal degeneration in vitro using the RGC-5 rat retinal ganglion cell line. The findings indicated a notable decrease in serum deprivation-induced cell mortality in RGC-5 cells attributable to the extract. ^[43]

3.8.3 Anti-hyperlipidemic activity:

The total cholesterol and triglyceride levels in hypercholesterolemic rats were significantly reduced after 15 days of treatment with 100 and 200 mg/kg/day of the methanolic fruit extract of Sumac. ^[44]

During a triple blind, randomized, placebo-controlled crossover study involving individuals with hyperlipidemia, taking sumac fruit powder (500 mg, twice daily) for 4 weeks resulted in a marked reduction in BMI, systolic blood pressure, diastolic blood pressure, and total cholesterol levels. ^[45]

3.8.4 Anti-obesity effects:

According to a study, the extract from the leaves and fruit epicarp of Rhus coriaria showed strong inhibition of pancreatic lipase activity when tested in vitro. ^[46]

A trial conducted by Hyderi et al (2019) indicated that incorporating Sumac fruit into the diet resulted in significant weight reduction, reduced waist circumference, and lower body mass index among individuals who were obese. ^[47]

3.8.5 Antidiabetic activity:

Oral administration of lyophilized hydrophilic extract of sumac fruit to diabetic rats for 3 weeks resulted in a notable decrease in glucose, HbA1c, TG, TC, and LDL levels in the serum. Additionally, there was a decrease in alpha-glucosidase activity and a significant increase in serum insulin levels as well. ^[48]

During a trial involving type II diabetes patients, it was observed that consuming 3g of sumac powder daily for 3 months led to a notable reduction in serum glucose levels, as well as decreased levels of HbA1c and Aapo-B. Additionally, there was a significant decrease in the apoB/apoA-I ratio. ^[49]

3.8.6 Anticancer activity

3.8.6.1 Breast cancer:

In a study by El-Hasasna et al (2015), the anti-breast cancer effects of sumac extract were demonstrated across different breast cancer cell lines (MDA-MB-231, MCF-7 and T47D). The study revealed that sumac extracts induced senescence and autophagic cell death, while also inhibiting cell migration, invasion, and metastasis. ^[50]

3.8.6.2 Colon cancer:

Treatment with ethanolic sumac extract resulted in significant inhibition of the viability and colony growth of colon cancer cells in vivo using a mouse xenograft model, in both HT-29 and Caco-2 human colorectal cancer cells. ^[51]

3.8.7 Photo-protective effects:

Researchers studied the protective effects of macerated ethanol extract from Rhus coriaria L. fruit on microvascular endothelial cells (HMCE-1), which serve as a model for skin microvascular endothelium cells. The study demonstrated the protective role of Rhus coriaria L. extracts against damage caused by UV-A. These extracts not only decreased the levels of UV-A induced ROS production, but also effectively prevented the formation of DNA lesions in cells exposed to moderate UV-A doses. ^[52]

1. 9. Important Unani formulations: ^[53]