@misc{oai:ir.kagoshima-u.ac.jp:00004885,
 author = {Upadhyay, Atul and ウパダヤ, アツール},
 month = {2016-10-28, 2016-10-28},
 note = {博士論文要旨, 博士論文本文, The beneficial effects of bioactive compounds from plants have been investigated in relation to a variety of pathological diseases. Some of these identified compounds have been utilized in the agrochemicals, foods, cosmetics and pharmaceutical industries. This study is composed of investigations, screening as well as isolation and identification of compounds with specific bioactivities. Three indigenous plants from Okinawan islands were chosen for the study. These included Alpinia zerumbet (alpinia), Leucaena luecocephala (leucaena) and Ananus comosus (pineapple). Out of these, the alpinia and leucaena were investigated for a series of bioactivities, while in case of pineapple, the waste obtained from bromelain manufacturing process was studied for possible pharmacological importance.
 The bioactive compounds from alpinia against HIV-1 integrase and neuraminidase enzymes were identified as 5,6-dehydrokawain (DK), dihydro-5,6-dehydrokawain (DDK), and 8(17),12-labdadiene-15,16-dial (labdadiene). DDK strongly inhibited integrase, an enzyme responsible for HIV-1 virus replication, with an IC_{50} of 3.6 μM. Against neuraminidase, a rational target for influenza inhibition, DDK exhibited mixed type of inhibition with IC_{50} of 24.6 μM, and K_i value of 2.8 μM. The mechanism investigative studies showed that, DDK is a slow and time-dependent reversible inhibitor on neuraminidase, probably with a methoxy group as its functionally active site. Furthermore, on analyzing the neuraminidase and formation of atherosclerosis inhibitions by the essential oils of two varieties of alpinia leaf, it was found that the tairin variety, with comparatively larger number of compounds, had better bioactivities than shima variety.
 Mimosine [β-N-(3-hydroxy-4-pyridone)-α-aminopropanoic acid], a non-proteinogenic amino acid, was identified as a potent neuraminidase inhibitor from the leaves of leucaena. The kinetic studies showed the mimosine inhibited neuraminidase competitively with Km and IC_{50} values of 39.1 min^{-1} and 9.8 μM, respectively. Furthermore, a series of mimosine tetrapeptides were synthesized in search for more potent neuraminidase and tyrosinase inhibitor. Mimosine-FFY (Phe-Phe-Tyr) was identified as the best synthesized tetrapeptide, and it exhibited 50% neuraminidase and tyrosinase inhibition at 1.8 and 18.3 μM, respectively.
 The waste obtained during bromelain processing is often discarded and is considered as a burden while disposing them. An attempt was made to study the bioactivities of the pineapple stem waste (PSW) in regards to antimicrobial activity, advanced glycation end products formation, 15-lipoxygenase and neuraminidase inhibitions. Several phenolic acids were identified in PSW with considerable amount of antioxidant activities mainly due to the presence of syringic, ferulic, iso-ferulic acids. A range of pathogenic fungi and bacteria were inhibited by the PSW, with a complete inhibition of Colletotrichum acutatum, a fungus with a very wide host range, but is economically most important on strawberries. The possible reasons for fungal inhibitions may be due to the presence of large amount of benzoic acid in the PSW. The other bioactivities were mainly due to the syringic and hydroxybenzoic acids present.
 Furthermore, Okinawan plants are long-known for the longevity of the islanders. Most of the studies on animal models suggest that phenolic compounds present in fruits and vegetables are responsible for such an effect. In this respect, alpinia leaf, with high phenol content was investigated for longevity assays using Caenorhabditis elegans (C. elegans) as animal model. The results showed that leaves polyphenols could significantly increase the mean lifespan by 22.6%, better than the positive control, resveratrol. Moreover, both under the thermal and oxidative stressed conditions, the leaves polyphenols increase the survival rate significantly better than quercetin. It seems that the up-regulation of HSP-16.2 and SOD-3 reporters attributed to the longevity extension under normal and stressed conditions.
 Our results, therefore, showed that Okinawan plants contain a wide range of phytochemicals that have a broad spectrum of activity. This study certainly aid to the probable utilization of Okinawan plants as preventive or therapeutic agents in diseases and different functional food industries.},
 title = {Biological activities of three Okinawan plants, alpinia, leucaena, and pineapple},
 year = {}
}