Kesum Leaves and Twigs
Persicaria minor (Huds.) Opiz
Polygonaceae
Figure 1 : P. minor. (a) Field planting; (b) apical shoot; (c) plant bearing inflorescence; (d) flowers with petal pink to white; (e) stalks of leaves normally used in culinary; (f) dried leaves c. 200 mesh. (Photos courtesy of Thiyagu, MARDI, 2012)
DEFINITION
Kesum herb consists of dried leaves of P. minor (Huds.) Opiz (Polygonaceae), and occasionally combined with dried twigs.
SYNONYM
Polygonum minus Huds
VERNACULAR NAMES
Knotweed (English), kesum (Malay).
CHARACTER
The dried leaves and twigs powder have a characteristic odour and slight taste.
IDENTIFICATION
Plant Morphology
An annual to perennial, small, elegant, decumbent or ascending herb, 30-75 cm tall. Stems branched, especially below, spreading, slender and glabrous. Leaves simple, lobed or unlobed, ovate-lanceolate to linear-lanceolate, linear-oblong, 2-7 cm x 0.3-2 cm, usually less than 8 mm wide, apex acute to subobtuse, appressed hairy on midrib beneath, subsessile; ocrea tubular, truncate, 0.5-1.2 cm long, short ciliate; leaf arrangement alternate, one leaf per node along the stem; leaf blade entire. Inflorescence consisting of 1-3 terminal or axillary spikes or pseudospikes, slender, erect, 1.5-5 cm x 0.5 cm, dense or interrupted; flower spikes dense, erect, stout, the flowers crowded and overlapping; petal pink to white, fused into a corolla tube and radially symmetrical; perianth approximately 2.5 mm long, usually reddish, perianth minute, pink, rarely white; bracts 2-2.5 mm long, obtuse, ciliate; stamens 5-6; pollen grains pantoporate, with spheroidal form and circular shape in polar and equatorial view, respectively. Nutlet ovoid or ellipsoid, 1.0 mm wide, 2.5 mm long, biconvex or trigonous, shiny black or brown; nut surface sculpture varies between species [ 1 , 2 , 3 ].
Microscopy
Figure 2 : Microscopic images of P. minor leaf powder. (a) Epidermis cells (magnification 10x); (b) parenchyma cells (magnification 20x); (c) druse crystal (magnification 40x); (d) stomata (magnification 20x); (e) starch granules (magnification 20x); (f) fragments of spiral vessel (magnification 20x); (g) conical brush-like trichome (magnification 20x); (h) oil glands (magnification 20x). [Scale bars: a= 50µm; b, d, e, g, h= 20 µm; c, f= 20 µm]
Colour Tests
Observed colour of solution after treatment with various reagents:
| H2SO4 (conc.) | Brown |
| 25% NH3 (l) | Yellow |
Thin Layer Chromatography (TLC)
Figure 3 : TLC profiles of quercitrin (S) and methanol extracts of P. minor dried leaves powder (L1) and dried twigs powder (L2) observed under (a) UV at 254 nm; (b) UV at 366 nm; (c) visible light after spray.
| Test Solutions | Weigh about 1.0 g of P. minor dried leaves and twigs powder separately in a 50 mL screw-capped conical flask and add 10 mL of methanol to each of the conical flask. Sonicate the mixture for 30 min and filter. Use the filtrate as test solution. |
| Standard solution | Dissolve 2.0 mg quercitrin standard [CAS no.: 522-12-3] in 10 mL methanol to produce 200 µg/mL solution. |
| Stationary Phase | HPTLC silica gel 60 F254, 10 x 10 cm |
| Mobile phase | Ethyl acetate : formic acid : glacial acetic acid : toluene; (25:3:3:5) (v/v) |
| Application |
|
| Development distance | 8 cm |
| Drying | Air drying |
| Detection |
|
High Performance Liquid Chromatography (HPLC)
| Test solution | Extract about 1.0 g of P. minor dried leaves and twigs powder separately in a 50 mL screw-capped conical flask with 10 mL of methanol. Sonicate the mixture for 30 min. Filter the solution through a 0.45 µm syringe filter and inject the filtrate into the HPLC column. |
| Standard solution | Dissolve 5.0 mg of quercitrin standard [CAS no.: 522-12-3] in 10 mL of methanol to produce 500 µg/mL solution. |
| Chromatographic system |
Detector: UV 254 nm |
| Mobile Phase (Isocratic mode) | 0.3% formic acid in water : acetonitrile, 80:20 (v/v). Run time (min) : 25 |
| System suitability requirement |
Perform at least five replicate injections of the standard solutions (0.5 mg/mL). The requirements of the system suitability parameters are as follow:
|
| Acceptance criteria |
|
Figure 4 : HPLC chromatogram of quercitrin standard solution (500 µg/mL) at tr = 12.594 min.
Figure 5 : HPLC full chromatogram of methanol extract of P. minor leaves showing peak corresponding to quercitrin (tr = 12.491min).
Figure 6 : HPLC zoom chromatogram of methanol extract of P. minor leaves showing peak corresponding to quercitrin (tr = 12.491min).
Figure 7 : HPLC full chromatogram of methanol extract of P. minor twig showing peak corresponding to quercitrin (tr = 12.212 min).
Figure 9 : UV spectrum of quercitrin standard solution (500 µg/mL) and methanol extracts of P. minor leaves and twigs.
PURITY TESTS
| Foreign Matter |
| Not more than 2% |
| Ash Contents | |
| Total ash | Not more than 9% |
| Acid-insoluble ash | Not more than 1% |
| Loss on Drying |
| Not more than 10% |
| Extractive Values | |
| Water-soluble extracts | |
| Hot method | Not less than 18% |
| Cold method | Not less than 11% |
| Ethanol-soluble extracts | |
| Hot method | Not less than 8% |
| Cold method | Not less than 5% |
SAFETY TESTS
| Heavy Metals | |
| Arsenic | Not more than 5.0 mg/kg |
| Mercury | Not more than 0.5 mg/kg |
| Lead | Not more than 10.0 mg/kg |
| Cadmium | Not more than 0.3 mg/kg |
| Microbial Limits | |
| Total bacterial count | Not more than 105 cfu/g |
| Total yeast and mould count | Not more than 104 cfu/g |
| Bile-tolerant gram negative | Not more than 104 cfu/g |
| Specific Pathogens | |
| Salmonella spp. | Absent in 25 g |
| Escherichia coli | Absent in 1 g |
| Staphylococcus aureus | Absent in 1 g |
| Pseudomonas aeruginosa | Absent in 1 g |
CHEMICAL CONSTITUENTS
Essential oil of leaves contain aldehydes (e.g. decanal, dodecanal, undecanal, tetradecanal, nonanal and hexanal), alcohols (e.g. 1-decanol, 1-dodecanol, 1-undecanol, 1-hexanol, 1-nonanol, 1-decanol and 1-dodecanol), sesquiterpenes (e.g. xanthorrhizol, α-bisabolol, β-caryophyllene, α-cubebene, (E)-caryophyllene, trans-α-bergamotene, farnesene, α-caryophyllene, β-himachalene, α-selinene, valencene, δ –cadinine, alloaromadendrene, α-curcumene, (-)-α-panasinsene, humulene, iso-caryophyllene, drimenol and Drimenin), oxygenated sesquiterpenes (e.g. cis–lanceol, farnesol, β-caryophyllene oxide, nerolidol, trans-α- (Z)-bergamotol, alloaromadendrene oxide-(1), trans-longipinocarveol and 8-bromoneoisolongifolene), monoterpenes (e.g. α-pinene) and others (e.g. undecane, n-decanoic acid, isobornyl acetate, dodecanoic acid and phytol) [ 4 , 5 ].
MEDICINAL USES
Uses described in folk medicine, not supported by experimental or clinical data
Traditionally, a decoction of the leaves is taken for indigestion and after childbirth [ 6 ].
Biological and pharmacological activities supported by experimental data
Anti-oxidant activity
The ethanol extract of P. minor leaves (1 mg/mL) had total phenolic content of 207 ± 0.011 mg/g compared to quercetin (63 ± 0.002 mg/g). The extract also showed anti-oxidant activity with ferric reduction antioxidant power (FRAP) value of 11220 ± 0.1 mmol/g compared to gallic acid (1216.67 ± 0.03 mmol/g) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibition of 89.5 ± 1.07% compared to gallic acid (88.8 ± 0.85%) [ 7 ].
The aqueous extract of P. minor leaves (1 mg/mL) had total phenolic content of 55.5 ± 0.0021 mg/g compared to quercetin (63 ± 0.002 mg/g). This extract also showed potent anti-oxidant activity with FRAP value of 849.33 ± 0.32 mmol/g compared to gallic acid (1216.67 ± 0.03 mmol/g) and DPPH inhibition percentage of 81.88 ± 0.98% compared to gallic acid (88.8 ± 0.85%). Quercetin and gallic acid act as positive controls [ 7 ].
Juice extract of P. minor leaves and stem had total phenolic content of 165.3 ± 1.0 mg GAE/100 g extract. The extract also showed anti-oxidant activity DPPH inhibition percentage of 82.6 ± 0.7% and FRAP value of 46.3 ± 1.2 µmol Fe (II)/g [ 8 ].
The aqueous extract of P. minor leaves (200 µg/mL) had total phenolic content of 2800.6 ± 2.6 mg/100g GAE. The extract also showed potent anti-oxidant activity with lipid peroxidation inhibitory of 98.3 ± 0.4% compared to butylated hydroxytoluene (BHT) (200 μg), superoxide scavenging of 77.9 ± 1.0% compared to superoxide dismutase (SOD; 6×10-3 U/mL) and DPPH radical scavenging of 98.8 ± 0.5%. Butylated hydroxytoluene and superoxide dismutase act as positive controls [ 9 ].
Antiviral activity
The ethanol extract of P. minor leaves showed antiviral activity on Herpes simplextype 1 (HSV-1) (MIC = 0.01 mg/mL) and Vesicular stomatitis viruses (VSV) (MIC = 0.02 mg/ml) using simplified plaque reduction assay [ 10 ].
Antitumor activity
Methanol extract of P. minor leaves (200 µg/mL) had cancer chemopreventive activity with cell viability rate of > 90% and inhibitory rate of 100% on tumor-promoter-induced Epstein-Barr Virus (EBV) activation in Raji cells [ 11 ].
Cytotoxicity activity
The aqueous extract of P. minor leaves was not cytotoxic on WRL-68 human liver cell line (IC50 = 322.95 ug/mL) and Vero monkey kidney cell line (IC50 = 334.70 ug/mL) using sulforhodamine B (SRB) assay [ 9 ].
The ethanol extract of P. minor leaves showed cytotoxicity effect on human cervical carcinoma cells (HeLa) with cytotoxic dose at 50% (CD50) value of 0.1 mg/mL using microtitration cytotoxity assay [ 10 ].
Anti-ulcer activity
Aqueous extract of P. minor leaves (250 and 500 mg/kg) administered orally as single dose to male Sprague Dawley rats (aged between 6 to 8 weeks) one hour before induction of gastric ulcer with ethanol significantly (p < 0.05) increased mucus production, increased pH of gastric content, increased inhibition percentage and decreased the ulcer area [ 12 ].
Clinical studies
A randomised, double-blind, placebo-controlled trial was conducted to evaluate the benefits of standardized water extract of P. minor leaves supplementation towards mood and cognitive function among middle aged women. This trial involves women aged 35 to 55 years with body mass index (BMI) of less than 40.0 kg/m2. The patients either took two P. minus extract capsules (250mg/per capsule) or placebo whilst the controlled group received placebo capsules containing 100 mg maltodextrin daily for a duration of six weeks. Results showed significant improvement (p < 0.05) on parameters related to mood and quality of life including energy/fatigue, social functioning and general health [15]
A multicentre, double-blinded, randomised, placebo-controlled trial was conducted to evaluate the effects of 6 months standardized water extract of P. minor leaves supplement on cognitive function, mood, neurotrophin, oxidative stress, and inflammation biomarkers as well as fMRI brain activity among older adults with mild cognitive impairment (MCI). This trial involves older adults aged 60 to 75 years with MCI using a series of neuropsychological tests. The patients took either 250 mg/capsule of the standardized water extract of P. minor leaves or sensory-identical placebo composed of maltodextrin (280 mg/capsule) for a duration of 6 months. Results showed significantly improved visuospatial memory (p = 0.012; MD =+ 9.80%), tension (p = 0.042, partial η2 =0.147), anger (p = 0.010, partial η2 = 0.207), confusion (p = 0.041, partial η2 = 0.148) and total negative subscales (p = 0.043, partial η2 = 0.145), triglyceride (p = 0.029, partial η2 = 0.237) and brain-derived neurotrophic factor level (p = 0.020, partial η2 = 0.179) among older adults with MCI. [16]
SAFETY INFORMATION
Preclinical studies (Toxicology studies)
Oral single dose acute toxicity study on female Sprague Dawley rats (aged between 8 to 12 weeks old) using aqueous mixture of dried powder of P. minor leaves showed no toxic effect on the parameters observed including behavior, body weight, food and water intakes. All rats were observed for 14 days prior to necropsy. No death was found throughout the study period. Necropsy revealed no significant abnormality. Approximate lethal dose (LD50) is more than 2,000 mg/kg body weight. Study on aqueous mixture of dried powder P. minor twigs produced similar results [ 13 , 14 ].
The aqueous extract of P. minor leaves (250 and 500 mg/kg) administered orally as a single dose to male and female Sprague Dawley rats (aged between 6 to 8 weeks old) for a duration of 14 days showed no toxic effect with LD50 value of > 5 mL/kg [ 12 ].
Others (Adverse reaction, contraindication, side effect, warning, precaution)
Information and data have not been established.
DOSAGE
Information and data have not been established.
STORAGE
Store below 30°C. Protect from light and moisture.
REFERENCES
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- Maizura M, Aminah A, Aida WW. Total phenolic content and antioxidant activity of kesum (Polygonum minus), ginger (Zingiber officinale) and turmeric (Curcuma longa) extract. International Food Research Journal. 2011;18:529-534.
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- Ali AM, Mackeen MM, El-Sharkawy SH, Abdul Hamid J, Ismail NH, Ahmad F, Lajis MN. Antiviral and cytotoxic activities of some plants used in Malaysian indigenous medicine. Pertanika Journal of Tropical Agricultural Science. 1996;19(2/3):129-136.
- Akira M, Manaf AA, Kamaruddin M, Koichi K, Hajime O. Screening for the in vitro anti-tumor-promoting activities of edible plants from Malaysia. Bioscience, Biotechnology and Biochemistry. 1999;64(1):9-16.
- Wasman S, Mahmood A, Salehhuddin H, Zahra A, Salmah I. Cytoprotective activities of Polygonum minus aqueous leaf extract on ethanol-induced gastric ulcer in rats. Journal of Medicinal Plants Research. 2010;4(24):2658-2665.
- Teh BP, Hamzah NF, Rosli SNS, Yahaya MAF, Zakiah I, Murizal Z. Acute oral toxicity study of selected Malaysian medicinal herbs on Sprague Dawley rats. Institute for Medical Research Ministry of Health; 2012. Report No.: HMRC 11-045/01/PM/L/J.
- Teh BP, Hamzah NF, Rosli SNS, Yahaya MAF, Zakiah I, Murizal Z. Acute oral toxicity study of selected Malaysian medicinal herbs on Sprague Dawley rats. Institute for Medical Research Ministry of Health; 2012. Report No.: HMRC 11-045/01/PM/T/J.
- Yahya HM, Shahar S, Ismail SN, Aziz AF, Che Din N, Abdul Hakim BN. Mood, cognitive function and quality of life improvements in middle aged women following supplementation with Polygonum Minus extract. Sains Malaysiana. 2017 Feb 1;46(2):245-54.
- Lau H, Shahar S, Mohamad M, Rajab NF, Yahya HM, Din NC, Hamid HA. The effects of six months Persicaria minor extract supplement among older adults with mild cognitive impairment: A double-blinded, randomized, and placebo-controlled trial. BMC complementary medicine and therapies. 2020 Dec;20(1):1-5.
