Phytochemistry

Phytochemistry and pharmacology (Consolidated from Pharmacological Reviews)

Primary Active Constituents:

Terpenoids (entalabdane diterpene lactones) – Andrographolide (primary) is very bitter, colorless and crystalline in appearance. Deoxyandropholide and neoandrographolide are isolated mostly from the aerial parts. May other diterpenes have been isolated as well and can be found listed in this *review*.

Flavonoids – many flavones have been isolated from the aerial parts, roots and whole plant a list of which can be found listed in this *review*.

Miscellaneous compounds – These are mostly isolated from the roots and include four xanthones and five rare noriridoids which can be found listed in this *review*. Arabinogalactan proteins, trace elements, and macro-elements (potassium and calcium). Cinnamic acid, caffeic acid, ferulic acid and chlorogenic acid were also isolated from the whole plant.

 

Pharmacological Research Summaries:

Anti-microbial activity – Aqueous extract, andrographolides and arabinogalactan proteins isolated from the dried herb have antibacterial activity against Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Andrographolide was only active against B. subtilis. All three extracts were found to be anti-fungal against Candida albicans. The five rare noriridoides did not show anti-bacterial activity against any of the above listed bacteria.

Anti-inflammatory/anti-allergic activity – Aqueous extract combined with a methanol extract of the leaves showed significant alleviation of lipopolysaccharide induced release of pro-inflammatory mediators (NO, IL-1b, and IL-6), inflammatory mediators (PGE2 and TXB2), and allergic mediators (LTB4) but no inhibition was observed against histamine release. Andrographolide, isoandrographolide and skullcapflavone-1 significantly suppressed TXB4 released in A23187 activated HL-60 promyelocytic leukemia cells. 7-O-methylwogonin potently inhibited A23187 induced histamine release in RBL-2H3 rat basophil leukemic cells in a dose dependent manner. Andrographolide, dehydroandrographolide and neoandrographolide exhibited anti-inflammatory effects by interfering with COX enzyme activity. The mechanism of dehydroandrographolide may be related to down-expression of genes involved in the inflammatory cascade. Andrograpanin (15-90mmol/L) isolated from the ethanol extract of the leaves inhibited NO and pro-inflammatory cytokines (TNFa, IL-6, IL-12p70) in a dose dependent manner from lipopolysaccharide activated macrophages, with significant inhibition of NO at [30 mmol/L] and almost complete inhibition at [75 mmol/L].  The mechanism of andrograpanin may be down-regulating iNOS and pro-inflammatroy cytokines gene expression levels as well as p38 mitogen activator kinase signaling pathways and the post-translation of IL-12 p35 and p40 proteins.

Anti-oxidant activity – Methanol and aqueous extracts of the leaves, as well as andrographolide and 14-deoxy-11, 12-didehydroandrographolide isolated, exhibited lipid peroxidation inhibition in Srague Dawley rats and free radical scavenging activities against DPPH. The methanol extract activity was significantly higher and different from the aqueous extract. The methanol extract exhibited free radical scavenging activity ranging from 45.67% to 53.82%. The activity of andrographolide was 40.2% and 12-didehydroandrographolide was 46.43%. The water extract exhibited activity ranging from 25.29% to 28.77%. The positive controls showed higher activity than the andrographis derived treatments.

Immunostimulant activity – Ethanol extract of the fresh plant and purified andrographolide and neoandrographolide induced significant (P<0.001) stimulation of anti-body and delayed hypersensitivity response to sheep red blood cells in mice. They also stimulated non-specific immune response of the animals measured in terms of macrophage migration index, phagocytosis of 14C-leucine labeled E. coli and proliferation of splenic lymphocytes. The stimulation of both antigen specific and non-specific immune response was greater with the ethanol extract than either isolated compound.

Cytotoxicity – Methanol extract, petroleum ether, dichlomethane fraction, and aqueous fraction of the methanol extract were screened for anti-proliferation activity against HT-29 (colon cancer) cells. The methanol extract (50% at [10mg/mL]), petroleum ether (GI50 value of 46 mg/mL), and dichloromethane fraction (GI50 value of 10 mg/mL) inhibited proliferation. The aqueous extract did not inhibit proliferation of HT-29 cells. Andrographolide inhibited all cancer cells screened. Other studies also reported cytotoxic activity of andrographolide against human epidermoid carcinoma and lymphocytic leukaemia cells. In a study at the national cancer institute in the USA, 19-isopropylideneandrographolide and 14-acetylandrographolide were screened and found to be cytotoxic against 60 human cancer cell lines.

Antidiabetic activity – Andrographolide and 14-deoxy-11,12-didehydroandrographolide isolated from alcoholic extract of aerial parts reduced the phenotypes indicating diabetic nephropathy in MES-13 cells. An aqueous extract (50 mg/kg) of raw material produced a significant (P<0.05) reduction (52.9%) in blood glucose level in streptozocin-induced hyperglycemic rats. Freeze dried material (6.25 mg/kg) produced a more significant (P<0.001) reduction (61.81%) in blood glucose level. The aqueous extract did not produce significant reduction in blood glucose level in normoglycemic rats.

Anti-protozoan activity – 1,2,-dihydroxy-6,8-dimethoxy-xantone possessed substantial anti-plasmodial activity against Plasmodium falciparum with an IC50 value of 4 mg/mL. This compound also exhibited in vivo antimalarial activity in mice infected with Plasmodium berghei, where is produced substantial reduction (62%) in parasitemia. This study using root fractions showed more anti-malarial activity compared to a previous study using leaf fractions. Andrographolide, neoandrographolide, deoxyandrographolide, and andrograohoside isolated from the leaves have been shown to have some activity against Plasmodium berghei NK65 in Mastomys natalensis.

Insecticidal activity – Methanol and ethyl acetate leaf extracts were found to be most effective for ovicidal activity against mosquito species Culex quinquefasciatus and Aedes aegypti.

Anti-infective activity – A randomized double-blind placebo controlled clinical evaluation using the visual analogue scale for quantification of symptoms showed that the leaf extract treatment was 52.7% more effective than placebo in reducing symptoms of an uncomplicated upper respiratory tract infection. An extract SHA-10 (1 200mg/day) treatment for a period of five days significantly (P<0.05) reduced the intensity of the symptoms in uncomplicated common cold beginning at Day 2 of treatment over placebo and at Day 4 a significant decrease in the intensity of all the symptoms was observed.

Anti-angiogenic activity – Whole plant ethanol extract and andrographolide significantly (P<0.001) inhibited the B16F-10 melanoma cell line induced capillary formation in C57BL/6 mice by 35.96% and 31.1% respectively and reduced serum levels of pro-inflammatory cytokines and granulocyte-macrophage colony-stimulating factor and the most potent angiogenic factor vascular endothelial growth factor compared with control. Treatment with ethanol extract (10 mg/mL) and andrographolide (0.25 mg/mL) inhibited micro vessel sprouting from rat thoraxic aorta induced by B16F10 melanoma conditioned medium.

Hepato-renal protective activity – Intraperitoneal pretreatment of mic with andrographolides (500 mg/kg) and arabinogalactan (125 mg/kg) for 7 d, before intraperitoneal injection of ethanol (7.5 mg/kg) minimized toxicity in liver and kidney tissues significantly (P<0.001) with reduced levels of glutamic-oxaloacetic transaminase, glutamic pyruvic transaminase, alkaline phosphatase, and LP enzymes in a comparable manner with the reference standard Silymarin.

Sex hormone/function modulation – Oral administration of the leaf extract in doses of 200, 600, and 2,000 mg/kg (30-300 times higher than daily therapeutic doses in humans) were administered to pregnant rats for a period of 11-19 days and did not show any effect on the elevated level of progesterone in the blood plasma of pregnant rats when compared to control groups. This suggests that at therapeutic doses A. paniculata does not induce abortions.