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Herbal Drug Discovery Against Inflammation: From Traditional Wisdom to Modern Therapeutics
Published in Amit Baran Sharangi, K. V. Peter, Medicinal Plants, 2023
Shalini Dixit, Karuna Shanker, Madhumita Srivastava, Priyanka Maurya, Nupur Srivastava, Jyotshna, Dnyaneshwar U. Bawankule
A number of triterpenes of oleanane, ursane, and euphane series have been isolated from the gum-resin of Boswellia serrata is used in Ayurveda for the treatment of osteoarthritis, juvenile rheumatoid arthritis. The four major pentacyclic triterpenic acids, i.e., ß-boswellic acid, acetyl-ß-boswellic acid, 11-keto-ß-boswellic acid (most potent) and acetyl-11-keto-ß-boswellic acid are mainly responsible for the inhibition of pro-inflammatory enzymes (Siddiqui, 2011). Andrographolide, and neoandrographolide isolated from the methanolic extract of Andrographis paniculata, inhibit LPS-stimulated NO production in a concentration-dependent manner (Batkhuu et al., 2002). The chloroform extract of the stem has also shown statistically significant anti-inflammatory activity against carrageenan-induced edema (Radhika et al., 2009). The seeds of Aesculus indica possess anti-inflammatory activity due to the presence of aescin, aesculuside A and B (triterpene glycoside) (Singh, Agrawal, and Thakur, 1987). The essential oils (EOs) of many species of the genus Eucalyptus (Myrtaceae), Cordia verbenacea (Boraginaceae), Lippia sidoides leaves (Verbenaceae), Lippia gracilis Schauer leaves (Verbenaceae), and Zizyphus jujube seeds are well established for their analgesic and anti-inflammatory effects. Camphor an active constituent isolated from Matricaria parthenium (Compuestas) has pronounced anti-inflammatory activity in rat paw edema studies (Saxena et al., 1982; Chaturvedi et al., 1974; Pitre and Srivastava, 1987; Rudakov, 1976).
Triterpenoids from Gymnema Sylvestre R.Br. (Periploca of the Woods): Biological Significance in the Treatment of Diabetes
Published in Megh R. Goyal, Preeti Birwal, Santosh K. Mishra, Phytochemicals and Medicinal Plants in Food Design, 2022
The plant family includes 40 species, namely Gymnema yunnanense, Gymnema inodorum, Gymnema montanum, etc., and has demonstrated medicinal properties [41, 50, 74]. Phytochemical studies suggested that the oleanane-type triterpenoids are Gymnemasaponins and Gymnemic acids, while Gymnemasides represents example of dammarane type structure [15, 26]. In addition, some other phytoconstituents (such as flavones, anthraquinones, phytin, resins, β-amyrin glycosides, stigmasterol, etc.) have also been found in the plant. Among the plant parts, shoot tips comprise of highest percentage of Gymnemic acids (54.29 mg g−1 of dry weight) and least percentage is present in seed of the plant (1.31 mg g−1 of dry weight). The triterpenoid structure of Gymnemic acids plays a significant, functional role in its activity showing that ester group in genin portion of the molecule is important for its antisweet activity.
Inhibiting the Absorption of Dietary Carbohydrates and Fats with Natural Products
Published in Christophe Wiart, Medicinal Plants in Asia for Metabolic Syndrome, 2017
Triterpenes have the tendency to inhibit acyl-CoA:cholesterol transferase-2 which regulates cholesterol absorption in enterocytes.87 In fact triterpenes are structurally close to cholesterol. For instance, Ilex cornuta Lindl. & Paxton contains the lupane triterpene lupeol (Figure 1.30), which at a concentration of 100 μM inhibited the enzymatic activity of acyl-CoA:cholesterol transferase-2 (hACAT-2) by 48.2%.129,130 In a subsequent study, Baek et al. (2010) tested lupeol against acyl-CoA:cholesterol transferase-2 and found an IC50 of 13.8 × 10−2 mM, whereas lupan-type triterpene betulinic acid had IC50 of 13.8 × 10−2 mM. In this experiment, the oleanane-type triterpene oleanolic acid was mildly active with 22% inhibition at a concentration of 50 μg/mL compared to untreated group.131 Lupeol inhibited α-glucosidase with an IC50 value equal to 6.2 μg/mL.131
Combinations of Phytochemicals More Efficiently than Single Components Activate Nrf2 and Induce the Expression of Antioxidant Enzymes in Pancreatic Cancer Cells
Published in Nutrition and Cancer, 2022
Marta Cykowiak, Violetta Krajka-Kuźniak, Wanda Baer-Dubowska
A detailed study by Probst et al. (22) on the effect of synthetic oleanane triterpenoid RTA 405 demonstrated that pharmacological inhibition of Keap1 is distinct from that resulting from the loss of functional Keap1 in tumor cells and does not increase cellular proliferation or survival. Thus, the activation of Nrf2 signaling by phytochemicals evaluated in this study should lead to pancreatic cancer cell protection against ROS without increasing cellular proliferation. This suggestion is further supported by the observation that treatment with XAN and PEITC and their combination induced cell cycle arrest in G0/G1. This effect may be at least partly a consequence of reduced cyclin D1 protein level responsible for G1 phase progression (29). Moreover, treatment with these phytochemicals, particularly with their combination increased the level of apoptotic caspase-3 level and to a much less extent L3 protein, a marker of autophagy. The induction of phosphorylating kinases provides additional evidence that they act through a Keap1-independent mechanism (30). Therefore, they do not contribute to the chemoresistance of pancreatic cancer cells.
Inhibition of catechol-O-methyltransferase by natural pentacyclic triterpenes: structure–activity relationships and kinetic mechanism
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2021
Fang-Yuan Wang, Gui-Lin Wei, Yu-Fan Fan, Dong-Fang Zhao, Ping Wang, Li-Wei Zou, Ling Yang
Of the oleanane-type triterpenes, oleanolic acid (1) displayed inhibitory potency on COMT activity in a concentration-dependent manner [the blue curve in Figure 2(A)]. However, with the introduction of the hydroxyl group into ring A (seeing Figure 1 for ring labeling), the COMT inhibitory potency decreased such as hederagenin (2) and maslinic acid (3). Polygalacic acid (4) with more hydroxyl groups almost did not inhibit COMT activity and the IC50 value was not calculated due to insufficient concentration-response relationship. Thus, the decrease of lipophilicity of ring A did not enhance COMT inhibition. In spite of minor difference in the ring E substitution position of C-29 and C-30 methyl groups, ursolic acid (7, IC50 = 15.13 ± 1.35 μM) displayed ∼3-fold lower inhibitory potency than oleanolic acid (1). Introducing hydroxyl into ring A of ursolic acid (7) can weaken COMT inhibition, as it did in the case of asiatic acid (8, IC50 = 43.11 ± 5.92 μM). Addition of a carbonyl to the C-11 position, such as 11-keto-β-boswellic acid (10), set up a complete loss of inhibitory potency.
Quorum quenching activity of pentacyclic triterpenoids leads to inhibition of biofilm formation by Acinetobacter baumannii
Published in Biofouling, 2020
Sudipta Paul Bhattacharya, Akash Mitra, Arijit Bhattacharya, Aparna Sen
Pentacyclic triterpenoids have been shown to inhibit QS and biofilm formation in P. aeruginosa (Kannan et al. 2019, Rajkumari et al. 2018). Twenty different compounds with a triterpenoid scaffold have been screened for anti-biofilm activity against Gram-positive pathogens, demonstrating promising activity (Silva et al. 2019). Pentacyclic triterpenoids are classified into three classes, namely oleanane, ursane, and lupane (Jager et al. 2009). Representative molecules from each of the classes, namely GRA, UA, and BA, were tested for their impact on QS. Both qualitative and quantitative analysis revealed that the triterpenoids affected the QS to variable degrees. These triterpenoids demonstrated reduced bactericidal activity with an average MBC > 500 µg ml−1. However, at sub-inhibitory concentrations, each of these compounds affected QS derived pigment formation. Indeed, conserved pockets for interaction with GRA, UA and BA could be detected in LasI and LasR, the AHL synthase and AHL-dependent transcriptional activator in P. aeruginosa. Since triterpenoids can affect the non-AHL mediated QS in Staphylococcus aureus and Streptococcus mutans (Zhou et al. 2013), it is assumed that pentacyclic triterpenoids can serve as a common scaffold to design target specific molecules to quench QS in a wide range of pathogens. For further validation of the QQ potential, knowledge of the impact of triterpenoids on the expression of the genes regulated by LasR or AbaR is warranted. A transcriptomic approach involving QS mutant strains can further corroborate the observation and pinpoint the mechanistic intricacies of QS modulation by triterpenoids.