A-Type Proanthocyanidins from Lychee Seeds and Their Antioxidant and Antiviral Activities

Abstract

Two new A-type trimeric proanthocyanidins with two doubly bonded interflavanoid linkages, litchitannin A1 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→8)-catechin] (1) and litchitannin A2 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→6)-epicatechin] (2), were isolated from lychee (Litchi chinensis Sonn. cv. Heiye) seeds together with aesculitannin A (3), epicatechin-(2β→O→7,4β→8)-epiafzelechin-(4α→8)-epicatechin (4), proanthocyanidin A1 (5), proanthocyanidin A2 (6), proanthocyanidin A6 (7), epicatechin-(7,8-bc)-4β-(4-hydroxyphenyl)-dihydro-2(3H)-pyranone (8), and epicatechin (9). Their structures were elucidated on the basis of spectroscopic and chemical evidence. It is the first time that compounds 1-4, 7, and 8 have been reported in this species. Compounds 1-9 showed more potent antioxidant activity than L-ascorbic acid with ferric reducing antioxidant power (FRAP) values of 3.71-24.18 mmol/g and IC50 values of 5.25-20.07 μM toward DPPH radicals. Moreover, litchitannin A2 (2) was found to exhibit in vitro antiviral activity against coxsackie virus B3 (CVB3) and compounds 3 and 6 displayed antiherpes simplex virus 1 (HSV-1) activity.

Induction of Apoptosis and Cell Cycle Arrest in Human Colorectal Carcinoma by Litchi Seed Extract

“…To the best of our knowledge, this is the first report to show that LCSP can inhibit proliferation of CRC cells. Previous studies have revealed that Litchi seeds are mainly composed of lichitanin A and proanthocyanidin [13]. The major structure of lichitanin is catechin and epicatechin.…”

“…However, the Litchi pericarp is the edible part of the Litchi fruit, and overdosing may lead to some consumers' uncomfortable “heating” [12]. In recent reports, polyphenol compounds from Litchi seeds were identified and composed of a variety of proanthocyanidins and flavonoid glycoside [13, 14]. Some of these compounds appear to exhibit antineoplasm activities in lung cancer, cervical cancer and hepatocellular carcinoma cells [15].…”

Inhibitory Effect of Lychee Seed Saponins on Apoptosis Induced by Aβ25-35 through Regulation of the Apoptotic and NF-κB Pathways in PC12 Cells

“…As a famous traditional Chinese medicine, lychee seed (Lizhi He in Chinese) has been recorded in the Compendium of Materia Medica ( Bencao Gangmu ) and exhibits many beneficial effects including anti-tumor [15], anti-oxidation [16], anti-virus [17,18], preventing liver injury [19], improving insulin resistance (IR) and sensitivity [20,21], and other pharmacological effects. Previous studies have shown that the chemical constituents of lychee seed are mainly saponins, organic acids, fatty acids, amino acids, sugars, and flavonoids [15].…”

Litchi seed extract inhibits epidermal growth factor receptor signaling and growth of Two Non-small cell lung carcinoma cells

“…The seeds also have the reputation of relieving neuralgic pain in China. In recent studies, a variety of proanthocyanidins, flavonoid glycosides and polysaccharides were identified from litchi seeds [7–9]. Some of these compounds appeared to exhibit anti-neoplastic activities in breast cancer, sarcoma, nasopharynx cancer, lung cancer, cervical cancer and hepatocellular carcinoma cell lines [7, 8, 10, 11].…”