Anti-inflammatory and Antimicrobial Effects of Heat-Clearing Chinese Herbs: A Current Review

Scutellaria baicalensis (黃芩 Huáng Qín)

Scutellaria baicalensis is a species of flowering plant belonging to Lamiaceae family It is a heat-clearing, phlegm-removing herb, traditionally used to cool heat, drain fire, clear damp-heat, stop bleeding, calm the fetus, and descend yang.[11,13,14] The dry root part of Sc. baicalensis has many pharmacological effects including antipyretic, hepatoprotective, antihypertensive, diuretic, and antibiotic activities. It is mildly sedating and also used to treat dysentery and chronic hepatitis.[6,7,14,15]Sc. baicalensis has distinct effects in the treatment of inflammatory diseases; it alleviates inflammation by decreasing the expression of interleukin (IL)-1b, IL-6, and IL-12, and the production of tumor necrosis factor (TNF)-α and soluble intercellular adhesion molecule-1 (ICAM-1).[5,16] In Xie xin herbal decoction, huang qin, in combination with huang lian, inhibits nitric oxide (NO) production in vitro and in vivo in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Oroxylin A, which is a flavonoid found in dried root of Sc. baicalensis, has also shown good anti-inflammatory effect.[17,18] Moreover, Sc. baicalensis has antibacterial effect against Helicobacter pylori as well as inhibits the growth of Escherichia coli B, coagulase-negative staphylococci, and Saccharomyces cerevisiae.[7,15]

Coptis chinensis (黃連 Huáng Lián)

Coptis chinensis belongs to Ranunculaceae family. Traditionally, it has been used to drain fire, detoxify and disinfect, stop bleeding, cure eczema, burns, and ulcer, and to descend yang.[7,11,13,14,19] The main pharmacodynamic properties have long been recognized in the treatment of intestinal infections including acute gastroenteritis, cholera, and bacillary dysentery. It also used for treating various diseases including skin diseases, conjunctivitis, otitis, and hypertension.[14,19,20]C. chinensis has been demonstrated to have anti-inflammatory effects through different mechanisms. It inhibits TNF-induced Nuclear factor-kappaB (NF-kB) signaling in human keratinocytes by blocking the NF-kB–dependent pathway. It also decreases Th17 cytokine secretion and differentiation by activation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and down-regulation of phosphorylated signal transducer and activator of transcription 3 (p-STAT3) and retinoic acid-related orphan receptor ϒt (RORγt) expression. It also reduces Th1 cytokine secretion and differentiation by inhibition of protein 38 (p38) mitogen activated protein kinase (MAPK) and Jun N-terminal kinase (JNK) activation along with down-regulation of STAT1 and STAT4 activities.[21,22] In combination with other herbs, C. chinensis exhibited a good anti-inflammatory effect; the ethanol extract from Zuojin Pill inhibited inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), IL-6, IL-1β, and TNF-α expression by preventing the nuclear translocation of the NF-κB p50 and p65 subunits in RAW 264.7 cells.[23] Another Chinese medicinal formula, IBS-20, containing C. chinensis decreased LPS-stimulated pro-inflammatory cytokine secretion from JAWS II dendritic cells and also blocked the interferon gamma (IFNγ)-induced drop in transepithelial electric resistance which is an index of permeability, in fully differentiated Caco-2 monolayer.[24]C. chinensis has also significant antimicrobial activity against a variety of microorganisms including bacteria, viruses, fungi, protozoans, helminths, and Chlamydia, including Staphylococcus aureus, Pseudomonas aeruginosa, E. coli, Propionibacterium acnes, Streptococcus pneumoniae, Vibrio cholerae, Bacillus anthracis, Bacillus dysenteriae, and Sa. cerevisiae.[7,21,25] Berberine, the major active component of C. chinensis, was found to be bactericidal on V. cholera and capable of inhibiting bacterial adherence to mucosal or epithelial surfaces.[26]

Flos Lonicerae (金銀花 Jīn Yín Hūa)

Flos lonicerae is a honeysuckle flower belonging to Caprifoliaceae family. It is a widely used herb in China for the treatment of infection by exopathogenic wind-heat or epidemic febrile diseases.[11,14,27,28] The dried flower and buds of Flos Lonicerae have shown various pharmacological effects including anti-nociceptive, anti-diabetic, anti-tumor, antioxidant, anti-angiogenic, antipyretic, antiviral, and hepatoprotective activities.[6,29,30,31]Flos Lonicerae demonstrated anti-inflammatory properties through suppression of mediator release from the mast cells activated by secretagogues.[32] In addition, the n-butanol fraction containing Flos Lonicerae can alleviate inflammation better than celecoxib in carrageen- and croton oil-induced paw edema and ear edema.[29]Flos Lonicerae contains various active compounds that have marked anti-inflammatory effect, including luteolin (suppresses inflammatory mediator release by blocking NF-kB and MAPKs pathway activation in HMC-11 cells), chlorogenic acid (inhibits rat reflux esophagitis induced by pylorus and forestomach ligation), and loncerin (reduces edema by suppressing T cell proliferation, NO production from the macrophages, and shifting cellular immunity from Th1- toward Th2-type responses).[33,34,35]Flos Lonicerae has significant antimicrobial activity against diverse species of bacteria and fungi. It has inhibitory effect against H. pylori and Porphyromonas gingivalis,[15] and it treats candidal septic arthritis.[35] It also has antimicrobial effect against oral pathogens including Streptococcus mutans, Actinomyces viscosus, and Bacteroides melaninogenicus.[6]

Forsythia suspensa (連翹 Lián Qiào)

Forsythia suspensa is a flowering plant belonging to the family Oleaceae. Traditionally, it used to treat carbuncle, disperse lumps, and stagnation, and to expel wind and heat.[11,13,14] The fruit of F. suspensa has potent pharmacological actions such as antiviral, choleretic, antipyretic, hepatoprotective, antiemetic, and diuretic effects.[14,27]F. suspensa alleviates inflammation by reducing the anaphylactic antibodies, mast cell degranulation, and histamine release. It also significantly suppresses β-conglycinin–induced T lymphocyte proliferation and IL-4 synthesis.[36,37]F. suspensa fruit inhibits NO production and iNOS gene expression by its active components rengyolone, dibenzylbutyrolactone lignans, as well as its butanol fraction of the aqueous extract. It also inhibits TNF-α and COX-2 production.[38,39,40] Another bioactive agent, arctigenin, inhibits increase in capillary permeability and leukocyte recruitment into inflamed tissues, by reduction of the vascular leakage and cellular events through inhibition of production of inflammatory mediators such as NO and pro-inflammatory cytokines such as IL-1b, IL-6, TNF-α, and prostaglandin E2 (PGE2).[38,39,41] Moreover, F. suspensa inhibits NF-kB nucleus translocation through reduction in I-kappa-B (IkB) phosphorylation and suppression of NF-kB–regulated proteins, and also reduces the activation of MAPKs.[39,40,41] Various studies have reported the antimicrobial effect of F. suspensa. It has potent antibacterial activity against E. coli, Sta. aureus, Bacillus subtilis, Str. mutans, and Po. gingivalis and antifungal activity against Aspergillus flavus, Rhizopus stolonifer, Penicillium citrinum, Aspergillus niger, and Saccharomyces carlsbergensis.[6,42]F. suspensa suppresses influenza A virus–induced RANTES secretion by human bronchial epithelial cells to stop accumulation of inflammatory cells in the infective sites, which has been reported to play a crucial role in the progression of chronic inflammation and multiple sclerosis after viral infection.[27]

Isatidis folium (大青葉 Dà Qīng Yè)

Isatidis folium is a flowering plant belonging to the family Brassicaceae. The leaves of Isatidis Folium are traditionally used for the treatment of sore throat, redness of skin, and as an antipyretic.[13,14,27,43,44]Isatidis Folium has also been used to treat encephalitis, acute dysentery, hepatitis, measles, pneumonia, influenza, epidemic cerebrospinal meningitis, encephalitis B, viral pneumonia, mumps, and diabetics.[27,45,46] Tryptanthrin, an alkaloid isolated from Isatidis leaves, has shown anti-inflammatory effect due to its strong inhibitory effect on the COX-2 enzyme.[47] Several derivatives of hydroxycinnamic acid, including ferulic acid and sinapic acid, are also thought to be important to inhibit inflammation.[25]Isatidis Folium possesses valuable viricidal effect in the control of pseudorabies infection in swine.[48,49]

Radix Isatidis (板藍根 Bǎn Lán Gēn)

Isatidis radix belongs to the family Brassicaceae. Traditionally, it used to cool blood.[13,14,19] The dry root of Isatidis Radix has many pharmacological activities such as antibiotic, anti-diabetic, and immune-stimulating effects and is used to treat encephalitis B and viral infections.[48,50] Methanolic extracts of Isatidis Radix can significantly inhibit the release of inflammatory mediators from the macrophages, such as NO, PGE2, and pro-inflammatory cytokines.[51] Isatidis Radix has also been demonstrated to suppress the growth of E. coli and H. pylori and increases blood neutrophil phagocytosis of ³²P-labeled Sta. aureus.[15,52,53] Syringic acid isolated from Isatidis Radix inhibited LPS-induced endotoxin shock.[51] Besides, Isatidis Radix is found to be clinically effective against the infections caused by various subtypes and strains of influenza viruses including Severe Acute Respiratory Syndrome (SARS).[44,50]

Viola yedoensis (紫花地丁 Zǐ Huā Dì Dīng)

Viola yedoensis is a flowering plant belonging to the violet family of Violaceae. Traditionally, it used to cool heat, and disinfect and detoxify.[11,13,14]V. yedoensis has several pharmacological effects including antibiotic, anti-inflammatory, and antipyretic activities. It can also be used for the treatment of skin diseases, i.e. eczema, impetigo, acne, pruritus, and cradle cap, and for upper respiratory tract infections with fever.[12,14] It has been reported to have antimicrobial activity against B. subtilis, Str. mutans, and Po. gingivalis.[54] It inhibits the replication of herpes simplex virus-1 and enterovirus 71 in the human neuroblastoma SK-N-SH cell line. Cyclotides from Viola are shown to be effective in inhibiting human immunodeficiency virus (HIV) replication.[50,55]

Pulsatilla radix (白頭翁 Bái Tóu Wēng)

Pulsatilla radix is a medicinal root plant of the Ranunculaceae. It used to cool heat, disinfect and detoxify, and clear damp-heat in TCM.[13,14] The root of Pulsatilla Radix has anti-inflammatory, antiparasitic, and antimicrobial action. It can treat dyspepsia, premenstrual tension, and psychosomatic disturbances.[14] A quinine-type compound, pulsaquinone, isolated from the aqueous ethanol extract of the roots of Pulsatilla Radix exhibited antimicrobial activities against an anaerobic non–spore-forming gram-positive bacillus, Pr. acnes, which is related to the pathogenesis of the inflamed lesions in a common skin disease, acne vulgaris.[56] Moreover, 4-hydroxy-3-methoxycinnamic acid of Pulsatilla Radix is found to have a selective growth inhibitor of the human intestinal bacteria, Clostridium perfringens and E. coli.[57]

Andrographis paniculata (穿心蓮 Chuān Xīn Lián)

Andrographis paniculata is also known as nemone chinensi and belongs to Acanthaceae family.[11] The active compounds isolated from An. paniculata, including diterpene, lactone, and andrographolide, have shown anti-inflammatory, anti-allergic, immune-stimulatory, and antiviral activities.[58,59]An. paniculata alleviates inflammation by inhibiting iNOS, TNF-α, IL-1b, IL-6, and IL-12 expression and NO production by down-regulation of p38MAPKs signaling pathways.[5,60] It also suppresses influenza A virus-induced RANTES secretion by human bronchial epithelial cells.[27]

Houttuynia cordata (魚腥草 Yú Xīng Cǎo)

Houttuynia cordata is one of the two species in the genus Houttuynia and belongs to the family Saururaceae.[14] It has many pharmacological effects including immune-stimulating, anti-inflammatory, antibiotic, antiviral, diuretic, analgesic, and hemostatic effects. It also used to treat pneumonia, bronchitis, colitis, urogenital tract infections, and chronic obstructive respiratory diseases, and topically to treat herpes simplex.[61]

This study was supported by Tianjin University of Traditional Chinese Medicine (TUTCM).