Research

Eighteen herbs used in the treatment of infectious diseases
in traditional Chinese medicine were evaluated for in vitro activity against
ten microbial pathogens. Lyophilized teas were tested by the agar dilution
technique at 100-1600 micrograms/ml. Eleven of the preparations were active
against at least one microorganism and six of these were active against at
least three of the test isolates. Scutellaria baicalensis and Coptis chinensis
were each active against five of the isolates.*

Scutellaria baicalensis inhibited Klebsiella pneumoniae and
Proteus vulgaris at 200 micrograms/ml. Scutellaria baicalensis alone showed
strong activity against Mycobacterium smegmatis (less than or equal to 100
micrograms/ml) and Candida albicans (200 micrograms/ml). The antimicrobial
activity of various teas, prepared with equal weights of herbs, could be
compared against a particular pathogen by considering both the percentage of
water-soluble material in the herbs and the minimum inhibitory concentrations
of the filtered, lyophilized decoctions.[1]*

Anemone chinensis (Synonym: Pulsatilla chinensis)

Anemone chinensis also known as Pulsatilla chinensis is rich
in triterpenoid saponins, such as anemoside B4, anemoside A3, and
23-hydroxybetulinic acid. It has been researched for its use as adjunctive
treatment for intestinal amebiasis, malaria, vaginal trichomoniasis, bacterial
infections, and malignant tumours, owing to its anti-inflammatory and
immunomodulatory activities.[2]* 

Antibacterial*

A. chinensis infusion had inhibitory effect on S.
aureus and bacteriostatic effect on S. dysenteriae and S. typhi.[3] A.
chinensis reduced cecum colonization of E. coli, L. monocytogenes, and S.
enteritidis in vitro. A. chinensis Bunge, significantly reduced S. enteritidis
by ≥ 99.99% within 6 h.[4]*

Modified Pulsatilla powder (MPP) can be effective in the
treatment of E. coli O101-induced diarrhea. MPP can improve the weight loss
caused by diarrhea, increase spleen and thymus indices, and reduce the diarrhea
index. MPP can reduce the number of WBC, regulate the level of cytokines, and
regulate the intestinal microbial flora.[5]*

Anemone chinensis has shown an inhibitory effect against
Staphylocoαus aureus, Pseudomonas aeruginosa, Bacillus dysenteriae, Salmonella
typhi, Bacillus subtilis, Corynebacterium diptheriae, Mycobacterium
tuberculosis, Candida albicans.[6]*

Pneumonia*

Anemoside B4, the major ingredient of A. chinensis has a
potential for regulating pro-inflammatory cytokines such as IL-1β, IL-6, and
TNF-α. Anemoside B4 attenuates pneumonia via the TLR4/Myd88 signalling pathway,
suggesting that anemoside B4 is a promising therapeutic candidate for
bacterial- infected or viral-infected pneumonia.[7]*

Antiprotozoal activity*

Giardia. A. chinensis plant extracts have been used to
clinically treat the anaerobic protozoal infections, amoebiasis and
trichomoniasis.*

Pulsatilla water extract was tested for its in vitro effect
on Giardia, revealing a 99 % reduction in parasite proliferation when exposed
to a concentration of 2.5 mg/ml. Previous studies have also demonstrated
anti-amoebic and anti-Trichomonas activity of Pulsatilla.[8]*

Amoebic dysentery. In China, A. chinensis was widely used as
a clinical treatment of amoebic dysentery, as early as 1959. Oral
administration of A. chinensis water extract was found to cure the amoebic
dysentery when used as two treatments. Seriously ill patients were further
given an enema with PWE at the same time as the oral treatment for three to
five times over 1 week.[9]* 

Trichomonas vaginalis. Yan et al. showed that using
increased concentrations of A. chinensis for a prolonged time was associated
with increased the mortality of Trichomonas vaginalis. The low effective
concentration of A. chinensis water extract against Trichomonas was 2.5 mg/ml.[10]*

Dictamnus desycarpus

Dictamnus desycarpus contains the potent botanical
constituents: Furoquinoline alkaloids, Limonoids and flavonoids.*

Antimicrobial activity*

Studies have shown that Limonin in Dictamnus desycarpus has
an effective bacteriostatic effect on Escherichia coli, Staphylococcus aureus,
Bacillus thuringiensis, Bacillus cereus, Salmonella, Micrococcus luteus, and
Shigella spp., and also has great bacteriostasis on fungi.[11]*

The antimicrobial activity of the essential oil from
Dictamnus desycarpus showed strong bactericidal activity against Staphylococcus
aureus ATCC 25923 and methicillin-resistant S. aureus.[12]*

Two fungicidal compounds were isolated from Dictamnus
dasycarpus Turcz were identified as fraxinellone and dictamnine by 1H NMR and
13C NMR. The results showed that the EC50 of fraxinellone were determined as
64.2μg/mL against Alternaria longipes, and 123.3μg/mL against Curvulavia
lunata. The EC50 of dictamnine were determined as 91.7μg/mL against Alternaria
longipes, and 46.6μg/mL against Curvulavia lunata.[13]*

Biofilm*

Limonin can effectively inhibit intercellular communication,
biofilm formation, and type three secretion system (TTSS) of enterohemorrhagic
Escherichia coli (EHEC) via a quorum sensing-dependent fashion.[14]*

Anti-protozoal activity*

Plasmodium falciparum. Limonin exhibited good antimalarial
activity against new ring-stage Plasmodium falciparum with IC50 values of 2.7
μM. Schistosoma mansoni. Other studies found that limonin had effective
bioactivity against Schistosoma mansoni in juvenile and adult stages, and its
anti-parasitic activity was enhanced in a dose-dependent manner.[15]*

Anti-viral*

Human immunodeficiency virus-1 (HIV-1). In-vitro studies
show that Limonin can effectively inhibit the replication of human
immunodeficiency virus-1 (HIV-1) (EC50 = 60.0 μM) in a dose-dependent manner,
and its mechanism may be related to the inhibition of HIV-1 protease activity.
The HIV-1 gag expression was completely inhibited by limonin with a
concentration of 1 μg/mL. Hence, limonin had effective antiretroviral activity
against HTLV-1 and HIV-1 infection in vitro.[16]*

Herpes simplex virus (HSV) type 1 and 2. Research has
reported that the concentration of limonin at 100 μg/mL inhibited the
infectious activity of herpes simplex virus (HSV) type 1 and 2.*

Human T-lymphotropic virus 1 (HTLV-1). Limonin can inhibit
human T-lymphotropic virus 1 (HTLV-1) tax/rex expression at the concentration
of 5 μg/mL.[17]*

Antihistamine*

Dictamnus dasycarpus was effective in antagonizing certain
pharmacological effects induced by compound 48/80 that occurred via both
histamine and serotonin released from mast cells. In conclusion, DDT may be
effective in the relief of symptoms of allergic atopic dermatitis and other
allergy-related diseases.[18]*

Coptis chinensis

Modern pharmacological research identified the major
chemical constituents of Coptis chinensis to be alkaloids including berberine,
coptisine, worenine, palmatine, jatrorrhizine, magnoflorine, and epiberberine.*

Antimicrobial*

Increasing research has been devoted to investigating the
anti-pathogenic microorganism effects of Coptis chinensis, and its
antibacterial, antiviral, and antifungal effects have been comprehensively
studied and validated.*

Coptis has a broad spectrum of antibiotic effects against
Bacillus dysenteriae, Mycobacterium tuberculosis, Salmonella typhi, E. coli,
Vibrio cholerae, Bacillus proteus, Pseudomonas aeruginosa, Diplococcus
meningitidis, Staphylococcus aureus, beta-hemolytic streptococcus, Diplococcus
pneumoniae, Corynebacterium diphtheriae, Bordetella pertussis, Bacillus
anthracis, and leptospira. The inhibitory effect is strongest against E. coli,
Mycobacterium tuberculosis, and Staphylococcus aureus. Use of Coptis or its components
individually is commonly associated with resistance. On the other hand, the use
of Coptis within an herbal formula reportedly enhances its antibiotic
effectiveness over tenfold with little incidence of resistance.[19]*

Berberine can inhibit Gram-positive (Gþ) bacteria such as
Streptococcus agalactiae, Staphylococcus aureus, S. mutans, Bacillus anthracis,
S. suis, and Enterococcus faecium[20] [21] [22] [23] and
Gram-negative (G-) bacteria such as Actinobacillus pleuropneumoniae[24],
Shigella dysenteriae[25], and
Escherichia coli.[26] Interestingly,
alkaloids isolated from Coptis, especially epiberberine, can act as urease
inhibitors to treat Helicobacter pylori infection.[27] In
2014, Chang et al. reported that Coptis extracts significantly inhibited
Salmonella typhimurium with a minimum bactericidal concentration (MBC) of 12.5
mg/mL.[28]*

The lyophilized water solubles of Coptis chinensis was
unique in having strong activity against Mycobacterium smegmatis and Candida
albicans. This supports previous reports of aqueous extracts of Coptis being
inhibitory for Mycobacterium auium and for C. albicans and filamentous fungi.[29]*

Aqueous extracts of Coptis chinensis revealed inhibitory
effects for S. aureus, Streptococcus sp., C. diptheriae, Klebsiella pneumoniae,
Vibrio comma (cholerae), and Brucella, less so for Shigella, and non-inhibitory
for Salmonella, E. coli, Proteus 0X-19, Pseudomonas pyocynea and Serratia
marcescens.[30]*

20 kinds of crude extracts of TCM tested against B. hominis,
Coptis chinensis was found to be highly inhibitory. Belamcanda chinensis (Iris
domestica), Scutellaria baicalensis, Pulsatilla chinensis were moderately
inhibitory.[31]*

Giardia. In a placebo-controlled clinical trial, 40 subjects
received either a vitamin B-complex syrup (as a placebo), berberine (5
mg/kg/d), or metronidazole. Berberine administration resulted in a marked
decline in gastrointestinal symptoms (superior to that of metronidazole) and a
68-percent reduction in Giardia-positive stools.[32]*

In another study, 137 children with Giardia were given
berberine, then compared with 242 subjects underwent traditional treatment,
where 88 who given of metronidazole for a period 5-7 days. 90% of those giving
berberine for 10 days observed no Giardia in their stool samples after 10 days
and 83% remained negative after one month, which compared with those treated
with metronidazole 90% and 95%.[33]*

A study compiled a database on Traditional Chinese Medicine
and the Gut Microbiota and found that Coptis chinensis have effects on the
following pathogens: Streptococcus agalactiae, Actinobacillus pleuropneumoniae,
Staphylococcus aureus, Coagulase-negative Staphylococcus, Escherichia coli,
Helicobacter pylori, Salmonella Typhimurium, & Candida albicans.[34]*

Antifungal effect*

This study confirmed the antifungal activity of berberine
against five different standard Candida strains (Candida albicans, Candida
krusei, Candida glabrata, Candida dubliniensis, and six clinical isolates
(CLC1–CLC6). More importantly, the critical role of berberine in inhibiting the
Candida biofilms of the five standard strains, especially for the three
non-albicans Candida strains, was revealed. Furthermore, CLSM was first used to
confirm that berberine could induce high viability inhibition rates for Candida
biofilms, inhibit their formation, and significantly weaken their spatial
structures. Therefore, this research provides a useful reference for multiple
Candida infections and biofilm infections associated with drug resistance.[35]*

Berberine sulphate in concentrations of 25mgm1-1 inhibited
the growth of 11/13fungi, viz. Alternaria, Aspergillus flavus, Asp. fumigatus,
Candida albicans, Curvularia, Drechslera, Fusarium, Mucor, Penicillium,
Rhizopus oryzae and Scopulariopsis. Concentrations of 50mgml could check the
growth of Syncephalastrumas well.[36]*

Modulating gut microbiota*

Berberine can lead to an increase in the abundance of
probiotics such as Blautia, Bacteroides, Bifidobacteria and Lactobacillus, and
a decrease in relative abundance of Firmicutes and Bacteroides in the
intestinal tract of animals.[37] [38]*

Another study showed that the berberine selectively enriched
the propionic acid producing bacteria and intestinal barrier repair bacteria
Ackermansia; a Coptis decoction promoted butyric acid producing bacteria, such
as Coprococcus, Faecalibacterium and Oscillospira. Compared with berberine, the
Coptis decoction induced higher flora diversity, and the flora structure was
closer to that of normal animals.[39] The
increase of GLP-1 and short-chain fatty acids in the gut may account for the
structural and diversity changes to the microbiota induced by berberine.[40] [41]*

Antiviral effect*

Previous investigations revealed that Coptis and berberine
have inhibitory effects against respiratory syncytial virus, influenza virus,
enterovirus 71, herpes simplex virus, coronavirus and cytomegalovirus. In
addition, studies showed that the inhibitory effects of berberine were mediated
by downregulating cellular c-Jun N-terminal protein kinase (JNK) and NF-kappa B
activation[42],
suppressing mitogen-activated protein kinase (MAPK) or MAPK/ERK kinase 1
(MEK)/extracellular signal-regulated kinase (ERK) signalling.[43] [44]Furthermore,
berberine could suppress the EV71- induced autophagy by activating the AKT
protein and inhibiting the phosphorylation of JNK and phosphatidylinositol-4,5-
bisphosphate 3-kinase III (PI3KIII).[45] H1N1
infection could be also suppressed by a water extract of Coptis, during which
the main alkaloids served as neuraminidase inhibitors, and among them,
palmatine was the most effective, with an IC50 of 50.5mM.[46] The
specific inhibition of West Nile virus (WNV) NS2B-NS3 protease and viral
propagation by palmatine, with an IC50 of 96mM, was investigated. Palmatine was
also effective against dengue virus and yellow fever virus.[47]*

Scutellaria baicalensis

Scutellaria baicalensis contains a wide variety of
polyphenols, especially flavonoids, which are the main active substances in
Scutellaria baicalensis. More than 40 different polyphenols have been isolated
and identified from Scutellaria baicalensis, including flavonoids and their
flavonols, dihydroflavones and their dihydroflavonols, chalcones and
biflavonoids. Among them, the most representative ingredients are baicalin,
baicalein, wogonoside and wogonin.*

Antimicrobial Activity*

A number of pure compounds from this root have shown
antimicrobial activity including baicalein [48] 2’,5,6’,7-tetrahydroxyflavonone[49]and a
flavonoid, wogonin.[50] The
former has been reported to inhibit Shigella dysenteriae, Corynebacterium
diphtheriae, P. aeruginosa, Mycobacterium tuberculosis and Streptococcus sp.[51]*

Baicalin has a wide-spectrum of inhibitory effect against
Staphylococcus aureus, beta-hemolytic streptococcus, Diplococcus pneumoniae,
Pseudomonas aeruginosa, Bacillus dysenteriae, E. coli, Bordetella pertussis,
Vibrio cholerae, Diplococcus meningitidis, leptospira and various species of
dermatophytes and influenza viruses. Scutellaria baicalensis is most effective
against Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, it was
discovered that the effectiveness of standard antibiotics such as ampicillin,
amoxicillin, methicillin and cefotaxime can be potentiated with addition of
baicalin, a flavone isolated from the herb. With the addition of baicalin, the
effectiveness of these beta-lactam antibiotics was restored against
beta-lactam-resistant Staphylococcus aureus and methicillin-resistant
Staphylococcus aureus (MRSA).[52]*

Bacteriostatic Activity*

Decoction of Scutellaria baicalensis root has been shown
previously to be bacteriostatic for 8 of 11 periodontopathogens including
species of Streptococcus, Bacteroides, Capnocytophaga, Fusobacterium and
Actinomyces.[53] Aqueous
extracts of the root has been shown to be inhibitory to Staphylococcus aureus[54] including
penicillin-resistant strains.[55]*

Antimycotic*

Aqueous extracts of S. baicalensis roots have antimycotic
properties against Aspergillus fumigatus, Candida albicans, Geotrichum candidum
and Rhodotorula rubra.[56]*

Biofilm*

Scutellaria baicalensis could effectively inhibit Klebsiella
pneumoniae biofilm formation with prolonged treatment. Scutellaria baicalensis
might inhibit Klebsiella pneumoniae biofilm formation through down-regulating
integron gene I 1 expression.[57]*

Smilax glabra (contains Naringenin)

More than 200 compounds have been isolated from Smilax
glabra, including flavonoids - Naringenin and flavonoid glycosides, organic
acids and phenolic acids, steroids and steroid glycosides, phenylpropanoids and
phenylpropanoid glycosides, phenolic and phenolic glycosides, other glycosides,
and volatile oil.*

Antimicrobial Activity*

Xu found that the minimal inhibition concentration (MIC)
obtained from the antimicrobial assessment of Smilax glabra extracts
demonstrated considerable activity against Staphylococcus aureus ATCC6538 (50
μg/mL). Ethyl acetate fraction and water fraction showed activity against
Candida albicans SC5314 and S. aureus ATCC6538 with MIC values of 200 μg/mL.
This was the first report on the antifungal properties of Smilax glabra at that
time.[58]*

To further determine the antibacterial potential of this
plant, the two Gram-positive and two Gram-negative bacteria were used to
evaluate the antibacterial activities of methanol, chloroform, n-hexane, and
acetonitrile extracts of the rhizome of Smilax glabra to reveal its inhibition
against the Gram-positive organism, namely, S. aureus and Bacillus subtilis.[59]*

Naringenin is a flavonoid belonging to flavanones subclass.
Several biological activities have been ascribed to this phytochemical, among
them antioxidant, antitumor, antiviral, antibacterial, anti-inflammatory,
antiadipogenic and cardioprotective effects.*

Naringenin possesses antibacterial activity against
Escherichia coli, Staphylococcus aureus, Candida albicans, Alternaria
alternata, Fusarium linii, Aspergillus niger.[60]*

Antiviral*

A study isolated a new mannose-binding lectin named SGM2
from Smilax glabra.[61] SGM2
exhibited antiviral activities against both herpes simplex virus type 1 (HSV-1)
and respiratory syncytial virus (RSV) with the same EC50 of 8.1 μM.*

Two glycoproteins isolated from Smilax glabra also showed
antiviral activity. In the antiviral assay, HSV-1 and RSV were used to
propagate Vero cells and HEp-2 cells, respectively. Antiviral activity was
determined using a cytopathic effect (CPE) reduction assay.*

Another study discovered that the glycoprotein exhibited
antiviral activity against RSV with a median inhibitory concentration (IC50) of
62.5 μg/mL and HSV-1 had an IC50 of 31.3 μg/mL. These results provided
scientific evidence to develop novel drugs for antiviral diseases.[62]*

Naringenin shows a dose-dependent inhibitory effect against
dengue virus, prevents intracellular replication of chikungunya virus, and
inhibits assembly and long-term production of infectious hepatitis C virus
particles in a dose-dependent manner.[63]*

Immune support*

To confirm the immunostimulatory activity of Smilax glabra,
Chu and Ng studied a novel protein named smilaxin purified from fresh Smilax
glabra rhizomes. The results of this study revealed that smilaxin
stimulates the uptake of [methyl-3H] thymidine by both murine peritoneal
macrophages and splenocytes at a potential that is lower than that of the
positive control. It also augmented the NO production by murine peritoneal
macrophages in a dose- dependent manner. Moreover, it inhibited the [methyl-3H]
thymidine uptake in a variety of tumour cells, including MBL2 and PU5. In
addition, smilaxin attenuated the activity of HIV-1-reverse transcriptase with
an IC50 of 5.6 μM and yet lacked lectin and many anti- fungal activities.
Furthermore, it was devoid of translation inhibitory activity in the rabbit
reticulocyte lysate system, indicating that it is a novel protein.[64]*

Further research on Smilax glabra was conducted to study
HIV. Smilax glabra were found to have inhibitory effects against HIV-1 protease
(HIV-PR) and HIV-1 integrase (HIV-1 IN). Results revealed that the ethanolic
extract (2 μL) of Smilax glabra exhibited the anti-HIV-1 IN activity with an
IC50 value of 6.7 μg/mL and the water extract (2 μL) of Smilax glabra with an
IC50 value of 8.5 μg/ml. Comparatively speaking, the ethanolic extract and
water extract of Smilax glabra showed mild activity against HIV.[65]*

Anti-inflammatory

This study focused on the active constituents from the
rhizome of S. glabra, which possess anti-inflammatory activities Results
indicated that syringic acid and trans-resveratrol showed significant
inhibitory effects on NO production. Syringaresinol, 1,4-bis(4-hydroxy-3,5-dimethoxyphenyl)-2,3-bis(hydroxymethyl)-1,4-butanediol
& trans-resveratrol exhibited high inhibitory effects on TNF-α production.[66]*