Lung-selective enhancers

Sildenafil is a selective inhibitor of cGMP-specific PD-5 and therefore inhibits the degradation of cGMP PD-5, the predominant type in the corpus cavernosum, also is present in other tissues (e.g., lungs, platelets, and eye). TTie selective inhibition of this enzyme facilitates the release of nitric oxide and smooth muscle relaxation of the corpus cavernosa. Sildenafil enhances erection by augmenting nitric oxide-mediated relaxation pathways. It has been suggested that sildenafil s mechanism of action is due to cross-talk between cGMP- and cAMP-dependent transduction pathways within the cavernous muscles. 

Shan Yao is neutral and sweet, and enters the Spleen meridian. It can either tonify the Spleen-Qi or stabilize the Yin. It is especially selected in the formula as deputy to enhance the ability of the chief to tonify the Qi and treat both Qi and Yin deficiency in the Middle-Jiao. Shan Yao also possesses a slightly astringent property, which is helpful in stopping diarrhea. Furthermore, this herb also enters the Lung and Kidney meridians, and is often applied to tonify and stabilize the Qi and Yin of these organs. The common symptoms are lack of appetite, fatigue, loose stool, shortness of breath, thirst and sweating. 

These herbs can regulate the Qi of the Lung, Stomach, Spleen and San Jiao and therefore can be selected in formulas as assistants to enhance the ability of herbs that remove phlegm. 

Hou Po is bitter, pungent and warm, and enters the Spleen, Stomach, Lung and Large Intestine meridians. It can descend the Qi, dissipate the obstruction of phlegm and dry dampness. It can be selected in formulas to remove phlegm as it can effectively reduce the distension in the Upper-, Middle- and Lower-Jiao, and enhance the ability of the chief to remove damp-phlegm. 

Tan Xiang is pungent, aromatic and warm, and enters the Spleen, Stomach and Lung meridians. It has a strong function of scattering cold and opening Qi obstruction, thus relieving pain. It is particularly suitable to be selected for severe pain in the chest and stomach. It is often used with Sha Ren [Amomi xanthioidis fructus) to enhance its function. 

Steric hindrance, that is, the introduction of (5)-Me to C-2, while 2 (/ )-OH is retained, makes a positive contribution to the antimmor activity as well as to the tubulin binding ability. This result may have come from the reduced rotation of the side chain, which thus enhances the ratios of bioactive conformers in all con-formers. The preparation of 2 -Me analog was usually undertaken by (3-lactam approach, in which 3-keto-(3-lactam was attacked by a nucleophile to yield stereo-selectively 3-methyl-3-OH (equivalent to the 2 position in paclitaxel) (3-lactam ready for attachment to baccatin core stmcmres. Battaglia et al. prepared a series of 2 (5)-Me of paclitaxel analogs from 10-DAB and 14(3-OH-10-DAB with different C-3 and 3 -A substitutents, and all compounds 6a-e are comparable with or more active than paclitaxel toward A2780 human lung carcinoma in vitro. °... 

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